BU-403: Charging Lead Acid

Learn how to optimize charging conditions to extend service life.

We now study various charging methods and examine why some systems work better than others. We focus on closed-loop techniques that communicate with the battery and terminate charge when certain responses occur.

Lead acid charging uses a voltage-based algorithm that is similar to lithium-ion. The charge time of a sealed lead acid battery is 12–16 hours, up to 36–48 hours for large stationary batteries. With higher charge currents and multi-stage charge methods, the charge time can be reduced to 10 hours or less; however, the topping charge may not be complete. Lead acid is sluggish and cannot be charged as quickly as other battery systems.

Lead acid batteries should be charged in three stages, which are [1] constant-current charge, [2] topping charge and [3] float charge. The constant-current chargeapplies the bulk of the charge and takes up roughly half of the required charge time; the topping charge continues at a lower charge current and provides saturation, and the float charge compensates for the loss caused by self-discharge. Figure 4-4 illustrates these three stages.

Charge stages of a lead acid battery

Figure 4-4: Charge stages of a lead acid battery
The battery is fully charged when the current drops to a pre-determined level or levels out in stage 2. The float voltage must be reduced at full charge.

Courtesy of Cadex

During the constant-current charge, the battery charges to 70 percent in 5–8 hours; the remaining 30 percent is filled with the slower topping charge that lasts another 7–10 hours. The topping charge is essential for the well-being of the battery and can be compared to a little rest after a good meal. If deprived, the battery will eventually lose the ability to accept a full charge and the performance will decrease due to sulfation. The float charge in the third stage maintains the battery at full charge.

The switch from Stage 1 to 2 occurs seamlessly and happens when the battery reaches the set voltage limit. The current begins to drop as the battery starts to saturate, and full charge is reached when the current decreases to the three percent level of the rated current. A battery with high leakage may never attain this low saturation current, and a plateau timer takes over to initialize the charge termination.

The correct setting of the charge voltage is critical and ranges from 2.30 to 2.45V per cell. Setting the voltage threshold is a compromise, and battery experts refer to this as “dancing on the head of a needle.” On one hand, the battery wants to be fully charged to get maximum capacity and avoid sulfation on the negative plate; on the other hand, an over-saturated condition causes grid corrosion on the positive plate and induces gassing.

To make “dancing on the head of a needle” more difficult, the battery voltage shifts with temperature. Warmer surroundings require slightly lower voltage thresholds and a cold ambient prefers a higher level. Chargers exposed to temperature fluctuations should include temperature sensors to adjust the charge voltage for optimum charge efficiency. If this is not possible, it is better to choose a lower voltage for safety reasons. Table 4-5 compares the advantages and limitations of various peak voltage settings.
 



 

2.30V to 2.35V/cell

2.40V to 2.45V/cell

Advantages

Maximum service life; battery stays cool; charge temperature can exceed 30°C (86°F).

Higher and more consistent capacity readings; less sulfation.

Disadvantages

Slow charge time; capacity readings may be inconsistent and declining with each cycle. Sulfation may occur without equalizing charge.

Subject to corrosion and gassing. Needs constant water. Not suitable for charging at high room temperatures, causing severe overcharge.

Table 4-5: Effects of charge voltage on a small lead acid battery
Cylindrical lead acid cells have higher voltage settings than VRLA and starter batteries.

Once fully charged through saturation, the battery should not dwell at the topping voltage for more than 48 hours and must be reduced to the float voltage level. This is especially critical for sealed systems because these systems are less able to tolerate overcharge than the flooded type. Charging beyond what the battery can take turns the redundant energy into heat and the battery begins to gas. The recommended float voltage of most low-pressure lead acid batteries is 2.25 to 2.27V/cell. (Large stationary batteries float at 2.25V at 25°C (77°F.) Manufacturers recommend lowering the float charge at ambient temperatures above 29°C (85°F).

Not all chargers feature float charge. If your charger stays on topping charge and does not drop below 2.30V/cell, remove the charge after 48 hours of charge.

Whereas the voltage settings in Table 4-5 apply to low-pressure lead acid batteries with a pressure relief valve of about 34kPa (5psi), cylindrical sealed lead acid, such as the Hawker Cyclon cell, requires higher voltage settings and the limits should be set according to the manufacturer’s specifications. Failing to apply the recommended voltage will cause a gradual decrease in capacity due to sulfation. The Hawker Cyclon cell has a pressure relief setting of 345kPa (50psi) and this allows some recombination of the gases generated during charge.

Aging batteries pose a challenge when setting the optimal float charge voltage because each cell has its own age-related condition. Weak cells may go into hydrogen evolution as part of overcharge early on, while the stronger ones undergo oxygen recombination in an almost starved state. Connected in a string, all cells receive the same charge current and controlling individual cell voltages is almost impossible. A float current that is too high for the faded cell might starve the strong neighbor and cause sulfation due to undercharge. Companies have developed cell-balancing devices, which are placed on the battery and compensate the differences in cell voltages that occur as a result of cell imbalance.

Ripple voltage imposed on the voltage of large stationary batteries also causes a problem. The voltage peak constitutes an overcharge, causing hydrogen evolution, while the valleys induce a brief discharge that creates a starved state that results in electrolyte depletion. Manufacturers typically limit the ripple to five percent, or 5A for a 100Ah battery.

Much has been said about pulse charging of lead acid batteries. There are apparent advantages in reducing sulfation; however, manufacturers and service technicians are divided on the benefits, and the results are inconclusive. If sulfation could be measured with accuracy and the pulses applied as a corrective service, then the remedy could be beneficial. Assumptions without knowing the underlying results can be harmful.

Most stationary batteries are kept on float charge. To reduce stress, the so-called hysteresis charge disconnects the float current when the battery is full. As the terminal voltage drops due to self-discharge, an occasional topping charge replenishes the lost energy. In essence, the battery is only “borrowed” from time to time for brief moments. This mode works well for installations that do not draw a load when on standby.

Lead acid batteries must always be stored in a charged state. A topping charge should be applied every six months to prevent the voltage from dropping below 2.10V/cell. With AGM, these requirements can be somewhat relaxed.

Measuring the open circuit voltage (OCV) while in storage provides a reliable indication as to the state-of-charge of the battery. A voltage of 2.10V at room temperature reveals a charge of about 90 percent. Such a battery is in good condition and needs only a brief full charge prior to use. If the voltage drops below 2.10V, the battery must be charged to prevent sulfation. Observe the storage temperature when measuring the open circuit voltage. A cool battery lowers the voltage slightly and a warm one increases it. Using OCV to estimate state-of-charge works best when the battery has rested for a few hours, because a charge or discharge agitates the battery and distorts the voltage.

Some buyers do not accept shipments of new batteries if the OCV at incoming inspection is below 2.10V per cell. A low voltage suggests partial charge due to long storage or a high self-discharge induced by a possible micro-short. Battery users have indeed found that a pack arriving at a lower than specified voltage has a higher failure rate than the others. Although in-house service can often bring such batteries to full performance, the time and equipment required adds to operational costs. (Please note that the 2.10V/cell acceptance threshold does not apply to all lead acid types.)

Watering

Watering is the single most important step in maintaining a flooded lead acid battery, a requirement that is all to often neglected. The frequency of watering depends on usage, charge method and operating temperature. A new battery should be checked every few weeks to determine the watering requirement. This prevents the electrolyte from falling below the plates. Avoid exposed plates at all times, as this will sustain damage, leading to reduced capacity and lower performance.

Exposed plates will sustain damage, leading to reduced capacity and lower performance. If the plates are exposed, immediately fill the battery with distilled or de-ionized water to cover the plates, and then apply a charge. Do not fill to the correct level before charging as this could cause an overflow during charging. Always top up to the desired level after charging. Never add electrolyte as this upsets the specific gravity and induces rapid corrosion. Watering systems eliminate low electrolyte levels by automatically adding the right amount of water.

Simple Guidelines for Charging Lead Acid Batteries

Comments

On October 15, 2010 at 3:29am
Ted Exley wrote:

I have a 12 V AGM VRLA Sealed 28Amp Hour Battery, by Power Bat Co Inc. which I use on a golf trolley.  I charge it with a charger which appears to give a charge of 14.6 volts. A couple of hours after charge, the battery gives a voltage reading of 13.5. Charger also has a Float Charge. I usually leave the battrey on Float between rounds of golf ( 2 -3 days)

After using for 9 holes of golf, the power appears to go, yet the battery still shows a charge of 13.1 V across the terminals.  It appears to quickly re-charge again.

Any ideas of what may be wrong

On December 9, 2010 at 8:55am
ayub wrote:

nicely done, very informative.
thanks a lot.

On December 15, 2010 at 7:41am
bernard anderson wrote:

please can someone tell me why my golf battery shows 12-13 v when charged but the AH is showing 5.24 i have two batteries and they are the same readings batteries are one year old.
when i put the batteries on the trolley this drains the battery very fast. cable and motor are ok
also what does the AH stand for.
thanks for your help

On December 20, 2010 at 11:19pm
Dan Davenport wrote:

Bernard. The AH stands for Ampere Hour and is the capacity of the battery. Your batteries can supply 5.24 Amps of current for one hour duration or 1 Amp for 5.24 hours. Voltage and capacity are not the same thing. As stated above, a fully charged 6 cell battery shows about 12.65 Volts when fully charged whether it is a small car battery or a massive forklift truck battery.

If your golf trolley is discharging your batteries when not being used, you must have a short circuit or partial short in the speed controller or wiring. If they discharge too quick during use only, it sounds like they are too small a capacity for the job. 5.24 AH is pretty small to run a trolley motor. Old batteries loose capacity but yours should be in good condition being only one year old. Have you left them discharged for a long period in the garage? Lead acid batteries must always be stored in a fully charged state and be periodically recharged even when not in use. Leaving them discharged is a sure fire way to ruin them.

Hope this helps.
Dan. Laluna Technology.
www.laluna.co.uk

On December 24, 2010 at 2:15pm
Hesham Mohamed Homam Al Hashemy wrote:

Dear Sir,

I would like to ask you two questions regarding the process of charging sealed lead acid batteries, i would be so grateful for you for taking in consideration a simple answer as i am so far from the technology of batteries.
Thanks in advance for your care and co-operation.

1)- I bought 2 new 6v 10Ah sealed lead acid batteries to use instead of the dead ones in my child’s ride-on, i also bought a simple wall charger which states that it charges at 1Ah, does this mean that to charge them for the 1st time i should leave them connected to the mains for 10 hours?
2)- I also have a 12v 1.5Ah charger, can i connect those 2 new 6v 10Ah batteries in series and charge them together and how much time would they take to be fully charged.

Best regards

On December 24, 2010 at 6:23pm
kenet kho tan wrote:

sir, i need to charge 10 6 volts batteries all at a time. what charger will i use and how fast will the batteries gets full, cause i need to use it all day long for my motorized toy car. i have 20 batteries but it drain easily when i charge it with a normal charger. thanks

On December 28, 2010 at 1:05pm
todd anderson wrote:

I have 2 8D batteries in my motorhome. I get about 10 hours use before I need to recharge. It seems to take forever (10 hours) to recharge them with the generator and 6 amp charger. After reading your article, it sounds like I shouldn’t discharge them all the way. Any suggestions for use and charging them faster?

On January 8, 2011 at 12:29pm
Vlad Leho wrote:

A question.  I need to charge three 7.5 AH 12-volt batteries for use in case of extended power failure to my Verizon FIOS phone system, whose battery will only work for 8 hours. Can I use one charger of 1000 mAh output to charge all 3 batteries in parallel and then keep them on a maintenance charge till neded?  Or will I need to charge them one at a time.  Thanks.

On January 12, 2011 at 9:23am
Carl wrote:

In a solar / wind charging system the charging circuit will manage the charging process.

What I need to know is for every 100watts of solar / wind power, how many Amp-hours of battery capacity can I add to the system?

An equaision, rule of thumb, or Max. Min. Optimum values would be most helpful.

On January 12, 2011 at 3:57pm
Carl wrote:

My Solution:

Lead-acid battery charge in 12-16 hours (10 hours with multi-stage methods, 36 hours for larger capacity batteries)

Charging voltage is critical and range from 2.30-2.45 volts per cell

Calculations:
Ah / hours = Amps

To charge a 100Ah battery in 12 hours I need 8.3Amps (recommended)
To charge a 100Ah battery in 16 hours I need 6.25Amps (recommended)

Charging voltage per cell x number of cells = charging voltage

Charging a 6 cell 12V battery at 2.45 volts per cell is 14.7volts max

Watts / charging voltage = Amps

A 400 Watt wind turbine makes 27.2 Amps at 14.7 Volts

Amps x hours = Ah

A 27.7A turbine can charge a 272Ah capacity in 10 hours (multi-stage required)
A 27.7A turbine can charge a 326Ah capacity in 12 hours (recommended)
A 27.7A turbine can charge a 443Ah capacity in 16 hours (recommended)
A 27.7A turbine can charge a 979Ah capacity in 36 hours (large capacity bat.)

For a 24 hour period a capacity ranging between 326Ah and 653Ah is required

A 27.2A wind turbine can charge a 326Ah battery capacity in 12 hours
A 27.2A wind turbine can charge a 653Ah battery capacity in 24 hours

All calculations are theoretical

On January 12, 2011 at 10:57pm
Girish.K wrote:

how to calculate connected load of battery chargers
360V-150A with 80% efficiency

On January 15, 2011 at 8:50am
Gerrion wrote:

Is a very useful page

On January 17, 2011 at 9:22am
Steve wrote:

More of a question:  Is it possible for a 6 volt charger to charge a automobile 12 volt lead acid battery to the point where it will have enough energy to start a car?

On January 20, 2011 at 6:32pm
Steve wrote:

younas - Not sure that I understand your response.

On January 21, 2011 at 5:00pm
catherine wrote:

I have 8 batteries 6v of 415AH. My charge controller goes to 20aac maximum ! Is it safe to charge my batteries at 20 aac up to the absorb point 28.0V

On January 21, 2011 at 6:27pm
Steve wrote:

I don’t think this answers my question.

Is it possible for a 6 volt charger to charge a automobile 12 volt lead acid battery to the point where it will have enough energy to start a car?

On January 22, 2011 at 9:59pm
Vasuki Rao wrote:

Can i use Sealed maintenance free batteries instead of Electrolyte filled ( Distilled water recharge )lead acid batteries.
My Lead acid battery is rated 75Amps, 105 minutes

On January 24, 2011 at 4:05pm
cornflake wrote:

>Is it possible for a 6 volt charger to charge a automobile 12 volt lead acid battery to the >point where it will have enough energy to start a car?

IF your car can turn over with 6V going in, sure…. It probably can’t though.  It’s not good for the battery if that battery is of any use at all.

Let’s just say no….

On January 27, 2011 at 4:24am
Gonzalo P wrote:

Hi!
I have some questions I hope you can help me.

For connecting the battery as a buffer I just nead to conect in parallel the battery with my device and the charger? If the current I am taking is constant is imposible to do this, because my charger will never be able to charge the battery? Is this how the lights with backup work?

In my case my battery is a 12V 7.5A
My device use 12V 0.2A
The charger I was thinking i buying is a 4step of MASCOT - http://www.mascot.no/admin/common/getimg.asp?FileID=1350.
(This because i need that the charger works with 24V as input)

THANKS A LOT!!
Gonzalo

On January 28, 2011 at 9:17am
Juma Ali wrote:

how many 12v 7AH sealed lead acid rechargeable batteries should i use to watch a 62 watts 240V colour TV for 10 hours

On January 29, 2011 at 1:17am
Tajammul wrote:

I have a two year old car battery which gives enough power to start my car when cold , but it refuses to crank the engine after the car runs for more than 10 kms. It immediately jump starts.It will however start again after a rest of about 1 hour without any external help

On January 30, 2011 at 6:14am
alexander wrote:

hello everyone..well i have a banner 12v 55ah battery on my 2001 vw.the battery is 8 months old and i notice that its cant hold the proper voltage.even if i travel for a couple of hours or sort trip the battery after 3 to 4 hours from 12.6v drops to 12v..sometimes 11.8 measured with multimeter.the strange thing is that the car starts ok,litle hard know because of winter with outside temperature 10 deg C.i cant understand so help me out if u can..how can i know if my battery is fully charge or needs a simple charge…or in worse,the battery goes to die and needs replacement?
thanx for your time to read my issue..first time i meet a battery with her own personality.. smile

On January 31, 2011 at 2:22am
Anatoly wrote:

Hello everyone. Be so kind to explain meaning of treatment charge for a battery.

On January 31, 2011 at 4:27am
alexander wrote:

Accept my opologize but i cant understand the meaning of treatment charge..im from greece and my english is at low level..from litle that i can imagine that you meen im charging the battery from the alternator which produse 12v 90A standard bosch car alternator..i have to tell you also that when i start the car running im seen from the multimeter 14.4v a couple of minutes after that at idle the voltage drops at 13.7v stable..all the measuses i taked was with no extra loads..A/C, headlights on, radio etc…. thanx for your time!!
i appreciate

On February 1, 2011 at 9:38pm
Vijay Moongilan wrote:

Please help me about How to calculate AH of 12V, 65AH & 12V, 7AH lead acid batteries are connected in series?

On February 2, 2011 at 11:45am
John Cocula wrote:

I have an 12V, 8AH SLA battery that I want to test.  I have a battery tester from Harbor Freight that has a gauge for reading voltage under load, but the load it provides is definitely too much (100 amps) for my battery.  (I also have a digital multimeter.) What ampere load should I put a fully charged 12V 8AH battery under when reading its voltage, for how long, and what are examples of 12-volt DC devices that could draw that amount of current?  Extremely grateful for experienced feedback!  - John

On February 3, 2011 at 2:16am
Gonzalo P wrote:

Buying the charger is starting to be really hard, because the don’t sell just one. My problem is that for charging the battery of 12V and 7.5Ah i need to use a 24V as supply. I want to know what would happened if I just connect a DC/DC to the battery converting the 24 to 13.9V, Float charge voltage. Is this voltage able to charge the battery? I don’t have problem if charging takes a lot of time?

Thanks again!!

On February 5, 2011 at 9:42pm
abhishek pandey wrote:

    Dear Sir what type of battery charging

On February 13, 2011 at 8:35pm
James Christian wrote:

I’ve been studying this topic quite a bit recently and I would like to take a shot at answering some questions (there are lots of questions here and very few answers):

> How many 12v 7AH sealed lead acid rechargeable batteries should i use to watch a 62 watts 240V colour TV for 10 hours?

ANSWER: I have been interested in these kinds of calculations myself.  Let’s see how I do.  My inverter is rated at about 90% efficiency so I will assume this here.  Also, I will always round up to be more conservative:
A) 62 Watts / 0.90 = 69 Watts DC (amount needed going into the inverter per hour in order to provide 62 Watts AC)
B) 69 Watts x 10 hours = 690 Watts DC
C) 690 / 12 Volts = 58 Amp Hours
D) 58 Ah / 7Ah (per battery) = 9 batteries (at 7 Ah each)


> Please help me about How to calculate AH of 12V, 65AH & 12V, 7AH lead acid batteries are connected in series?

ANSWER: If you connect two twelve volt batteries in series then you will get 24 Volts; however, everything I have read is that you should NEVER connect in parallel or series two batteries of differing capacities.  It could be done once, but I think it would wear out one or both of the batteries quickly over time.

> A question.  I need to charge three 7.5 AH 12-volt batteries for use in case of extended power failure to my Verizon FIOS phone system, whose battery will only work for 8 hours. Can I use one charger of 1000 mAh output to charge all 3 batteries in parallel and then keep them on a maintenance charge till neded?  Or will I need to charge them one at a time.

ANSWER: I would hook them up in parallel and then put my charger on the negative of the battery at one end and the positive of the battery at the other end.  This will distribute the charge evenly.  Also I would recommend the Battery Tender Junior for most sub 100 Ah batteries (and battery banks).

On February 17, 2011 at 3:54am
Ruairi wrote:

I’m Trying to determine the state of a battery.: Is this normal or do I have a fault?
It’s an Elecsol 220 AH battery. This is a sealed flooded cell, using “carbon fibre” technology, and is sold as a “Full Traction design”.

I tested this battery, It initially read 12.76V, and I had applied a top-up charge using a 600ma smart charger intended for smaller batteries.
It’s magic eye was not showing “Green”

I connected a paralell series of 3x 15 ohm,  and 3x 22 Ohm, 10W resistors, with a 1 ohm 10W resister in series with the combination, to use as a current indicator. The whole circuit measured 4.0 ohms, and the 1ohm resistor measured 1.0 ohms using my multimeter.

As expected on connection, the voltage dropped very quickly, and the current was below what would be expected for the voltage. this transient effect took about 30 mins to stabilize, when the current rose suddenly.

I believe this effect was due to thermal changes, and a delay in the chemical reactions in the battery, mentioned elsewhare in article on battery perfomance.

Until 17 hours the voltage and current tapered off very slowly, dropping from 12.29V to 12.07V (in circuit, measured across the battery terminals)
in this time the current dropped from 3.29 to 3.229 amps, ,measured as a voltage across the 1 ohm resistor.

over the following 10 hours to 25 hours the voltage and current fell away very quickly, though as I was not in attendance only 2 data points were obtained. at 18 hours the voltage was 11.59V and current was 3.096. at 25 hours, the Voltage was 11.04, and the current was 2.943
when viewed on a graph, the step chance in rate of fall of voltage and current is very visible, looking like a precipice.

after resting for 15 hours, the open circuit voltage reads 12.26 Volts.

Most guides to rested open circuit voltage suggest that with an open circuit voltage of 12.26V, the battery is about 65% cahrged. My own calculations of drain suggest that I have removed 36% of the stated 220AH capacity.
These statement would indicate that the battery is in good condition, and close to stated capicity.

Is the rapid change in discharge curve normal, or does that indicate there could be a fault?

Thank you in advance for your reply.

On February 17, 2011 at 4:09am
Jin wrote:

For god sake, pls don’t answer any question with misleading answers.

-69 Watts x 10 hours = 690 Watts DC (WTF, power x time= power dc?)

-3x 7.5 ah batteries in parallel = to 1x 22.5 ah battery

On February 17, 2011 at 4:12am
Jin wrote:

to Ruairi
a shorter question?

On February 17, 2011 at 4:20am
Jin wrote:

To Gonzalo P
plz write clearer. I am not sure what is really you question is, but you can’t change a 12v using 24v power supply.

On February 17, 2011 at 4:25am
Jin wrote:

To John Cocula
again, plz clearer question. R u trying to test the current of ur battery? if so, DONT do it. It is unwise, dangerous and no need to test a battery’s current.

On February 17, 2011 at 4:32am
Jin wrote:

To Vijay Moongilan

it is a bad idea. DON’T try it. The 7 ah will used up first, so u won’t have 24 volt. It is like connecting a dead battery and a fresh battery in series. It won’t work.

On February 17, 2011 at 4:42am
Jin wrote:

to alexander
sry, I am unclear about ur problem. U tested the battery when it is cold? N it reads 12.6? Temperature is a big factor to battery performence. A dead battery in cold will work after it warm up, so be sure to know that Voltage reading is not accurate in winter time.

On February 17, 2011 at 4:51am
Jin wrote:

To Tajammul
I am sure your battery is fine. Probabaly want somebody to check your car.

On February 17, 2011 at 4:59am
Jin wrote:

To Gonzalo P
u r right. They should be in parallel. Since ur device uses only 200ma, you only need a charger with 200ma. Think about it. It is simple. No battery: a 200ma power supply will power ur 200ma device constantly. No device:  a 200ma power supply will charge your battery. No power supply: ur battery powers ur device.

On February 17, 2011 at 5:04am
Jin wrote:

to cornflake
it is possible. You need a dc-to-dc converter which is more expensive than replacing your 12 v battery.

On February 17, 2011 at 5:13am
Jin wrote:

To Hesham Mohamed Homam Al Hashemy

1, no, more than 10 hrs
2, yes,
12v x 1 a = 12w
6v x 1 a = 6 w
so a 12v charger is faster.

On February 17, 2011 at 5:22am
Jin wrote:

This page is a good reference about lead acid Battery charging, but few points are incorrect, but not fatal mistake.

Any more question. Email me.  I am not only a total expert in batteries, But in electronics 2.

On February 17, 2011 at 5:53am
Jin wrote:

Ps.

You need to know wt kind of charger you have. A smart charger may need you to choose some options before it works as designed. A simple charger will easily damage your battery if misused. Worst, some cheap charger will damage your battery either way. I use a charger which was designed and built by myself. It is best if u built ur own charger, or you really want to get a more expensive smart charger.

On February 17, 2011 at 11:35pm
George wrote:

Question? I am real stupid with these things. I have it that (re)/charging time is Ah of battery devided by charging amps which means a 100Ah battery recharges with a 7.5A charger in 13 Hours? If I draw 30% from a fully charged battery can I make the assumption that the recharge will take 30/7.5 thus 4 hours?

On February 20, 2011 at 8:10am
Ramya wrote:

Hi,
I am a student from India. I would like to know the lead content of different types of Lead Acid Batteries.

On February 21, 2011 at 8:45am
AnRuaRi wrote:

Summary for Jin of my previous Question:
Background
I bought 2 2nd hand large capacity batteries. I set out to test them to determine if they are working correctly for a 2 year old battery.
I set up a 50W network of resistors to create a loat to discharge them and graphed the in-circuit terminal voltage and current over a period of 25 hours.

The Terminal voltage initially dropped very quickly from it’s resting state, then took about 30 mins to stabilise. It dropped slowly over the next 16 hours (to about 12V, then fell much more quickly over 8 hours to about 11V.
The rested open circuit voltage was then about 12.2V
The calculated AH removed from the battery and the open circuit voltage after the test both indicated about 40% drain re the stated 220AH capacity of the battery.

Question:
is it normal to have this type of shape to the discharge curve:
30 mins. stabilisation time initially.
sudden rapid drop in in-circuit terminal voltage of batter at about 30% discharge (i.e 70% remaining)?

On February 21, 2011 at 8:49am
AnRuaRi wrote:

Follow Up Question: Is this normal?

same set-up as in previous example. 220AH Battery, 4ohm discharge circuit. discharge test over 27 hours.

The second battery presented with significant fluctuations over the first 4 - 6 hours of the test, with in-circuit terminal voltages varying from 12.1V to 12.4V, going up and down over the 4 hour period before stablizing at 12.2V for about 10 - 12 hours.

Is this normal of a symptom of a problem in my battery or circuit?

On February 21, 2011 at 11:24pm
Javed wrote:

Hi,

I want to know if a 12v, 500mA dynamo can be used to recharge a 6V, 4AH lead acid battery with suitable circuitry???

On February 22, 2011 at 12:38am
Sandip wrote:

What is initial current in battery, I want to connect 2no. 12V 42AH batteries in parallel for better capacity.
How much charging current is required for charging above batteries in parallel connection condition. I have a 10A,12V charging machine.
Thanks

On February 22, 2011 at 5:14am
Jin wrote:

To AnRuaRi

so you have discharged your battery using a 50W load with 4 Amps current?  (4 Amps X12.3V=50W) Since 4 amps is your discharge rate, if you have a 220ah battery, then 220/4=55 hours. Have you charged your battery before discharged it? Did you discharge your battery for 55 hours? About your testing circuit, have you used an ampere meter to measure the current? Are your resistors rated at 50W and are not hot to touch?

PS.This kind of discharging test is really not necessary and it is unwise because it will damage your battery.

Answer your question;
Your discharge curve is normal. Terminal Voltage will drop and fluctuate once a load is applied to it. Once you remove the load, the terminal will return to its maximum voltage. In your case, it is 12.2V which is less than 50% capacity; so if you have discharged it for about 55/2=27 hours, then your battery is in a good shape. voltage is not an accurate way for measuring the capacity of a battery when it is either charging or discharging.

You probably need to get me more info about your test.

 

On February 22, 2011 at 5:21am
Jin wrote:

TO Javed

It is easy to charge with a higher voltage to a lower voltage, in your case, a 12V to a 6V. The easiest circuit requires just 1 electronic component which is a 7807 regulator (7 volt regulator). you don’t need any capacitor. It will cost you less than 2 US dollar.

On February 22, 2011 at 5:24am
Jin wrote:

TO Sandip

2X42AH=to a new 84Ah battery. You can basically using any current to charge this battery. The problem is that this is a big battery. Little current will take forever to fully charge it up, so you can safely charge it using 10A.

On February 22, 2011 at 5:27am
Jin wrote:

To George

30% = 0.3

and there is an inefficiency factor you need to consider.

On February 22, 2011 at 10:56pm
javed wrote:

thanx jin,

I have one more question…..

i want to know if i can simultaneously draw power from a 6v 4Ah lead acid battery while   it is charging???

On February 23, 2011 at 5:24am
Jin wrote:

To javed,

It depends. Since you have a 500mA charging current, you can’t continually use more than 500ma for 13 hours. (4 AH/ 0.3A= 13Hr) The battery will be drained, but Yes, you can simultaneously draw power from a 6v 4Ah lead acid battery while it is charging, if your device consumes less than 24wh of power which is the capacity of your battery. (4ah X 6v=24Wh)

So how much is 24wh of energy? if you battery is used to power a high power LED of 3.6V at 700ma (3.6V X 0.7A=2.52W) , 24wh of energy is good for about 9.5 hours of lighting. (24wh /2.52w = 9.5 hr) You will for sure get less than 9 hours because of the inefficiency factor.

On February 23, 2011 at 5:31am
Jin wrote:

I probably make it too hard to understand. To simplify what I have said above, the answer to your question is yes, but if you continually use more power than you have provided from the charger, then the battery will eventually drained.

On February 24, 2011 at 3:34am
Robert wrote:

Please visit our website to learn more about lead acid battery charger. We make 8 steps charging, reconditioning, and testing of battery in one charge cycle. Simple and safe to use.

On February 24, 2011 at 8:37pm
syed hyder wrote:

my question , i have 150AH 12V battery, with an automaticUPS system , it is only 12 months old , but it doesnt seem to give enough power
what to check

On February 25, 2011 at 2:43am
Aamir wrote:

Dear Sir
I have a digital Mulitmeter and want to test 12 volt/ 24 ah batery

Please guide me how i can test a battery through digital multimeter

where should i apply range and what is accuracy of test

On February 25, 2011 at 3:41pm
Cadex Electronics Inc. wrote:

This article has been updated as of February 25, 2011.

On February 25, 2011 at 5:25pm
Jin wrote:

there are still a lot of minor mistakes in this article such as “During the constant-current charge, the battery charges to 70 percent in 5–8 hours”, if you have a 200ah battery, 200ah/8h*0.7= 17.5A, without considering the inefficiency , you have to use at least a 17.5 amps charger, and if you don’t have a 17.5 amps charger, then there is no way the battery can be charged to 70% in 8 hours, so the first graph should be amps against capacity instead of time. and the charging voltage can be used from 2.3-2.5v per cell instead of 2.3-2.45V.

On February 26, 2011 at 11:24pm
Raja wrote:

dear sir,
  Recently i joined in Battery industries. i am interested to know about charging. How there are calculating the Capacity (Ah) in Theoretical Manner and how they are applying the Practical Ah to the battery.
  For Example,
            I am charging 120 AH Battery with 7 A so i should charge up to 17.14 h.
then how much they are applying the excess charge to that battery. Particularly How much they are applying the Excess percentage to the Practical Applications.
            When charging they are maintain the rest to control the temperature of battery while charging. What should be the Max Temperature allowed to the Lead acid Battery.
            Can you give your ideas to me to know about charging. i am waiting for your kind reply from you. i hope you will clear my doubts.

Thanks and Regards
G.Raja

 

On February 26, 2011 at 11:32pm
Raja wrote:

Dear sir,
          when we charge the battery the Specific Gravity of Electrolyte increase. Is it Possible to find out the Value of S.G with Voltage before Charging what will be the Values if them corresponding to our Charging Current with duration.

Can you explain with one example.

Thanks & Regards

  G.Raja

On March 2, 2011 at 9:33am
Cadex Electronics Inc. wrote:

@Jin: The 70% SoC mention does not relate to charge currents and applies to small and large batteries.

On March 4, 2011 at 3:07pm
Cadex Electronics Inc. wrote:

We have updated this article with new information.

On March 4, 2011 at 9:38pm
Noah wrote:

Ya my name is Noah and I took acid from a fourwheeler battery and put it into a smaller motorcycle battery and it bubbles while it is on ten amp what shod I do

On March 7, 2011 at 4:51am
Morteza Nasooti wrote:

please add information about the lead acid batteries’ operating temprature range and what we need to do when the battery room temprature becomes below -20 deg cent. in the winter

On March 12, 2011 at 5:09am
Francesco wrote:

HI, I have a question. I charged a new battery after adding the acid at 12V with 1.5ah. Did I screw the battery or can I recover it with a “smart” charger that follows your above figure?

Regards,
Francesco

On March 16, 2011 at 4:51am
Kannan T wrote:

Dear Sir
            if you have data for SONY US 18650 battery (1.4Ah,4.2V) please send to me that’s very useful to my work

Regards
Kannan T

On March 17, 2011 at 9:24am
Kevin Fletcher wrote:

I have recently received a sample rechargeable battery with the vent cap blown off one of the cells. and the back of the cell swollen.
This is an 18v battery consisting of 15 cells 1.2v 1700ah Ni-Cd.
Is this a weak cell in the chain, having a chemical imbalance during charging / discharge
and why is the vent cap… not venting. ??.
Is it is a sudden build up of reactive gas. ?

On March 18, 2011 at 5:27am
ASIT INGLE wrote:

Dear sir , i am planning to take a Amco battery dealership so my kind request to you that pls provide me the information about how to charge a conventional battery ,mf battery, ups and inverters waiting for your reply
thanking you

On March 18, 2011 at 8:48am
Mike wolf wrote:

I have a new but completely dead Optima battery. My two chargers won’t charge it because they are “smart” [dumb] chargers. To fool the chargers into starting I need to add a second battery. Do I hook the two in series or in parrallel?

On March 22, 2011 at 1:09pm
Bill Yacey wrote:

I have an SCR controlled charger that I built. It has separate controls to set the on threshold and the off threshold. For a wet 12 lead acid cell, should i set the on threshold at around 12.8V, and the off threshold at around 14.5? with the charging window set this small, it tends to pulse a fully charged battery occasionally. Is this an acceptable condition?

On March 23, 2011 at 1:41pm
Blair wrote:

Dear sir, have you ever analyzed the amount of lead contamination in battery acid or are you aware of any data dealing with sampling/characterization of lead contamination in battery acid?

On March 23, 2011 at 1:43pm
blair wrote:

I forgot to add in my previous note “Notify me of follow up comments” dealing with lead contamination in battery acid.

thanks

On March 27, 2011 at 12:23pm
jim hamlett wrote:

why does a 12 volt lead caid battery hold 12 volts and very low on amps?

On April 2, 2011 at 1:44am
Soto Ndiaye wrote:

I need some documentation about Trickle charging Lead-acid batteries algorithms and new Lead-acid Batteries charging algorithms witch can be applied for any type of Lead-Acid Batteries. Any document or information could be helpful for me.
Please could you send me (asap) some documents/information about this subject?

On April 6, 2011 at 6:19pm
max wrote:

Hello

I have a 12v 10ah sla battery. It shows 13v with a multimeter. When a 50w load is applied the voltage drops to 10v. Is this battery dead??

Thanks in advance

max

On April 10, 2011 at 6:43am
John Fetter wrote:

Pulse desulfators came out at the same time battery manufacturers switched from hybrid lead-antimony positive and lead-calcium negative grids to lead-calcium-tin grid alloy. Tin is added to stop surface passivation of the positive grids, which results in batteries going “ooen circuit”. Tin is sensitive to concentration. Below 1.5%, the benefits of tin reverse.
The problem that is being solved by so-called pulse desulfators is not as much sulfation as “open circuit”. The surface passivation consists of an oxide of lead and is very thin. Strong pulsing punches through, restoring battery ampere-hours dramatically. If it was sulfation, the cure would not be as dramatic.

On April 20, 2011 at 4:44am
asef wrote:

please send me charging and decharging curve of seald lead acid 2 V

On April 30, 2011 at 11:49pm
mike wrote:

I have a question…..or two….
If I had a 12V deep cycle battery and i depleted it to 30% or 50%, how long would it take to charge it to 90%-100% power using a typical 13.5v alternator?

On April 30, 2011 at 11:52pm
mike wrote:

and the other question is the same except with a reg, car starting battery.

On May 1, 2011 at 1:58am
asef wrote:

thanx alot…

On May 1, 2011 at 7:44pm
Art Jackson wrote:

I have some old 2vold lead calcium cells that I am trying to maintain/recover. They we used when I obtained them at least 10 years ago!

The cells are C&D Type DCU 13 . lead calcium cells rated at 8HR CAP 150 AH
Date of manufacture was October 1984!

For many years these have been used only occasionally to power my ham radio station and were recharged by “guess and by God” using an older so called “automatic” automotive battery charger then maintained by an unregulated 1Amp solar panel. The charger went on again whenever battery voltage dropped below 12.6V (which was seldom). I later built and connected a variable voltage power supply which will supply 1 amp of pure DC at voltages continuously adjustable from 7.0V to 29.5V

For the last 5 years or so this supply has been connected constantly set at 13.2V except when we leave for the winter and I drop the voltage to 12.8 as I don’t want to risk losing water.

Also during at least the last 5 years the battery charger used to recharge after use has been a three stage “smart charger” which will supply up to 40 amps. I disconnect it after it reaches the float stage, leaving the 1 Amp supply in circuit.

THE PROBLEM:

This year we were away for 10 months and on my return I found that

1)  I had inadvertently readjusted the float voltage to 12.75 volts

2) There had been multiple power failures during the winter and the house sitter may (or may not ) have used a 12V florescent lamp in the kitchen which is connected to this battery.

3) Fluid levels were adequate on my return. Battery charger was attached, limited to 30Amps and ran it’s cycle.

4) After charging SG is as follows:  1.225, 1.225, 1.225, 1.200, 1.225, 1.225

I have run a short (30 minute) pulse desufation   charge ( a function of the automotive charger)

THEN I decided I should look for more information from more informed people and asked Mr Google for help and here I am!

Am I too late? Any thoughts or suggestions?

Thanks

Art

On May 4, 2011 at 11:51am
Darryl wrote:

I have four new 12 volt amg motorhome batteries connected in parallel. what battery tender (charger) spec should I use.

On May 4, 2011 at 11:55am
Darryl wrote:

addition to above message- the motorhome is in storage for 3 months

On May 4, 2011 at 12:10pm
Darryl wrote:

correction to above two postings- the batteries are agm (glass matt)

On May 6, 2011 at 9:19am
Art Jackson wrote:

Darryl:

The battery manufacturer should have recommended charging parameters. AGMs charge differently than flooded cells as you probably know, but each manufacturer seems to have slightly different parameters.

What is the charger in the rig? Converter? Inverter/charger? What make/model.

My Xantrex Prosine 2 inverter/charger has settings for generic AGMs and I can also setup a specific charging algorithm.  Wish I had AGMs!

On May 8, 2011 at 5:42pm
Al wrote:

I am interested in building a 260ah bank using two 6vdc deep cycle batteries in series. My question is after reading several articals suggesting charging rate of 10% AH (so 260AH deep cycle should be charged at 26A) I already own a smart charger with the maximum settiing of 12A. Will this be ok to use? will it damage the batteries? Im thinking it will just take a lot longer to reach full charge. Should I invest in a much more powerful charger or use what I have and just wait for a longer charge cycle to finish?

On May 8, 2011 at 7:53pm
Art Jackson wrote:

Most deep cycle batteries, especially the 6 volt “Golf Cart” batteries can take much higher charging current than than 10% of the AH Capacity. C20 is common as is C30 and even C40 in some instances, though as a rule that’s pretty hard on the batteries.

Charging at a lower rate will not hurt the batteries, it will just take a much longer time to reach full charge.  You have to be aware that charging rate and current is not linear: A “Dead” battery, at 10.5 volts will accept a lot more current than one at 50% State Of Charge (roughly 12.2 volts) and one at 80% at 12.5V. Charging current will taper off as full charge approaches.

If you can afford the time, probably 24 hours or so, then go with what you have.

Remember too that the 260 AH is from fuul to dead. Dead is not good for battery life (that sounds a bit strange doesn’t it?!) Best not to take them below 50%, ie 12.2 volts (no load, resting measurement) then recharge. That really means that a bank of 260AH batteries is in effect a 130AH supply. When I stopped trying to take 320 AH out of my 4 group 24’s they didn’t have to be replaced every 1 o r2 years!

Another good site for battery charging info is www.rv.net. Go to forums, tech issues and be prepared to spend a lot of time reading!

On May 12, 2011 at 6:27pm
al wrote:

I currently own a motomaster eliminator intelligent battery charger to charge 12v lead acid batterys. It charges AGM, DEEP CYCLE or REGULAR batterys at 2/8/12A. If the battery is sulficated it will try and fix it. after the charge cycle compleates it float charges them and monitors them. I am looking to purchace a more powerful charger. Maybe-40 to 60A. I Does anybody know of a decent charger that does all of the above and maybe more!! I would like to reserch products before buying so brand names /manufactures of such device would be very helpful. Thankyou

On May 12, 2011 at 7:27pm
Art Jackson wrote:

I have the motomaster eliminator 40A version and have been fairly happy with it. It did recover 2 group 24 batteries that each had one low cell. If you keep your eyes open Canadian Tire often have them on sale at 99 in stead of 149.

On May 27, 2011 at 10:32am
Smarties wrote:

Is there any implication apart from an extended charge time of charging a 12V lead acid with a charger who’s constant current rate is well below the 10% of AH rating.

Example - 10AH and 300mA charger.

Thanks

On May 27, 2011 at 3:41pm
John Fetter wrote:

Lead-acid responds very well to slow charging. If possible, aim for a 3 to 4 day charge and battery life might well double. The faster L-A is charged, the greater the risk of positive grid corrosion. The only reason batteries are charged in hours rather than days is because most people simply cannot wait.

On May 31, 2011 at 3:41am
dapo wrote:

I have a question: I have a battery bank of 4 pieces of 150AH lead acid batteries used for a 3.5kva inverter system. I am yet to achieve a full charge as I charge for about 5hrs daily at 170vwith 16A charging. What is the max time to get full charging.
Also if I double the battery to 8 batteries, will the charging time double?

On June 6, 2011 at 3:06am
dylan wrote:

I need some help with the estimation of state of charge of a 48V lead acid battery.

I need to measure the state of charge of the battery in a continuous manner like a battery monitor. What method should I employ? I guess the voltage method wouldn’t work, because I need to measure the battery SOC when it is discharging so that I can charge it when it is below a certain SOC and stop charging it when it is above a certain SOC.
Please help me.
Thank you.

On June 6, 2011 at 3:08am
dylan wrote:

I have no other info on the battery. I can measure the battery voltage and also have a current sensor.

On June 6, 2011 at 10:30am
Art Jackson wrote:

DAPO:

A couple of questions: What voltage are your batteries and are they in series, parallel or series/parallel. ie what is the output voltage: 6, 12, 24, 48 etc.

4 150AH batteries in Parallel will have a total capacity of 600AH, at the same voltage.
4 150AH batteries in Parallel will have a total capacity of 150AH but at 4 times the voltage.

It also depends on what type of battery: flooded wet cel;, gel cell, AGM—all charge slightly differently.

I charge at at the 20C rate, that is, 20% of the total AH capacity of the batteries. Some manufacturers say more, some less. It is usually safe to charge at 30C and some AGMs can accept an even higher charge.

SO if you batteries are all in parallel, ie 600AH total, at 20% the initial charge current could be as high as 160 amps.

At 150AH (all batteries in series) 20% is 30 amps.

It would appear that you are charging at somewhere between 2 and 10 percent of Amp/Hour capacity. 5 hours won’t be nearly enough.

To borrow a phrase from a friend, think of charging time as a frog jumping along a long. Each jump takes as much time as the previous but for only half the distance. In theory he will never get to the end.

From 50% charged (12.2V in a 12 volt battery) to 80% (12.4) will go relatively quickly but the last 20% will take much longer as charge current becomes limited buy the batteries.

There is nothing wrong with charging slowly (Unless of course you are in a hurry!)

There is lots to learn about battery charging. Another good source of information can be found at www.rv.net forums in the tech issue forum.

Art

How are you measuring SOC? I am assuming SG.

 

On June 9, 2011 at 8:25am
Ronald Beal wrote:

Thanks sooooooooooooo   much.  Your help is right on time…

On June 25, 2011 at 4:01pm
Anthony Gomez-C wrote:

5 months ago I bought a brand new Lead - Acid Battery, 12v., 73Ah. 1.250g/ cubic cm., 11 Plates (Placas) 20ºC for my Land Rover, which was installed but disconnected.  2 months later I connected the Battery, pressed the starter button and away we went I only used the car twice for two hours at a time, all was fine,
disconnected the Battery and went away for 6 weeks, came back connected the battery and ............. nothing happened, apparently this New Battery is now completely discharged, although the water level is OK. and was left at an average temperature of 12ºC.  I Tried to charge it with my 15 amp. charger, but no luck, the voltage is OK, but the discharge is a mere 5 miliamps which is nothing. Can this battery ever be charged again.  Do I need to empty the liquid (Acid) clean the plates with something liquid then fill the cells up with new Acid, or is there some other method to save this New Battery? Will appreciate any advice. Thank you. Anthony

On June 27, 2011 at 4:57pm
Art Jackson wrote:

You have probably lost the battery due to it being stored in a discharged state.

Do not change the electrolyte. If the specific gravity is low it is because of the sulfate being deposited on the plates instead of being in solution. Changing the electrolyte, or adding more acid won’t help because of the sulfate already built up on the plates.  There is no way to clean the plates except possibly by using a battery desulfater. Some battery chargers have a desulfate mode, sometimes called a reconditioning mode.

There is a very small chance that you can recover the battery but is it unlikely. Sometime a low current charger (just an amp or 2)  left on for days or even weeks can help.

If you didn’t charge the battery before installing it and leaving it disconnected it may well not not been fully charged. Frequently so called charged and ready to go new batteries are not at full charge.  Leaving them for another two months would have allowed them to discharge further and continue to d\sulfate. A couple of hours charging from the vehicle alternator may not have been enough to fully recharge, and then there was another 6 week of sulfating.

A couple of question: What is the battery voltage now? Do you know the specefic gravity? Both these should be checked and recorded.

Check the voltage as it is now, connect your charger and let it run until it shows charged or at least 6 hours which ever comes first.

Next check voltage and specific gravity again. Note that the voltage will be artificially high due to surface charge. Let the battery sit for 24 hours and check the voltage again.

A new fully charged battery should have a SG of 1.265 or better. 1.200 is poor (1.000 is pure water!)

A fully charged “12 volt” battery will be at about 12.6V The charger may well take it up to 14.4 or so while charging.

About 12.2 volts is 50% and 11.8 is approaching dead. (these voltages at no load, the battery at rest)

Anything under 11.0 may indicate a dead cell. This also could be your problem.

One other question, how did you measure the discharge current? Was the starter engaged at the time, lighs on? Please let me know here. I will try to remember to check back here over the next few days for your replies.

One last thought. Did the battery come with a warranty or guarantee? Many companies offer full one year replacement warranty.

Let us know what you find.

On June 28, 2011 at 4:01pm
Anthony Gomez-C wrote:

Hello Art Jackson.

You have been extremely helpful.

This is what I can tell you so far:

All six compartments (Water top-up holes) are still at their correct level.

I have a specific gravity measurer, the one with the 5 colored balls inside a glass tube.
0 balls rising = discharged, 1 ball rising = 25% charged, 2 balls = 50% charged, 3 balls = 75% charged, 4 balls = 100% charged and 5 balls = very charged.
Amazingly all six battery compartments read 75% charged!?

I have a charger on at the moment, at full charge, but it is only charging at 0.75 milliamps.
The voltage from the battery (with charger disconnected) is 11.5 volts, but when connecting a small dash board bulb, it lights up, the bulb being 12v and draws 150 miliamps, any higher rating bulb will not light up.

I measured the discharge currents with the battery completely disconnected as with all my readings, and put my ammeter across the battery terminals.

I think the battery came with a warranty or guarantee, but as I have never come across the existing trouble over a 50 year driving experience, did not keep the Receipt! There is always a first time, even if it took 50 years!

From what I deduct, the battery is 75% charged, but can not discharge large amounts of current?

Cheers,
Anthony.

On July 9, 2011 at 2:34pm
Kenneth Cary wrote:

?? Do I have to disconnect one battery from to other or can I leave them hooked up together to charge. They are 12 volt batterys but I have them hooked 24 volts for my trolling motor

On July 10, 2011 at 4:07pm
Anthony Gomez -C wrote:

Hello Art Jackson.
My case seems to be rather strange!
Before charging the battery the voltage is 11.
After charging the battery the voltage is 12.
The SG before and after charging is still 75% charged? and this is how the battery was found before doing anything to it ?!!
First the starter would not operate, tried the head lights, no go either, all it can light up is a dash board small 12v bulb, bit with an intermittent glow,it glows then goes off, then it glows, then goes off at 2 second intervals!  The discharge between glow and no glow varies between 40 miliamps to 90 miliamps. If I short circuit the battery via my ammeter the discharge is the same.  It seems that the battery can not discharge its 3/4 capacity (SG 75% charged)! Perhaps it needs to be on a continuous discharge, although as mentioned, the discharge would be only between 40 and 90 miliamps.
Not sure whether my battery came with a warranty or guarantee, can not find the receipt.

On July 17, 2011 at 3:15pm
Anthony Gomez_c wrote:

Hello Art Jackson.
My case seems to be rather strange!
Before charging the battery the voltage is 11.
After charging the battery the voltage is 12.
The SG before and after charging is still 75% charged? and this is how the battery was found before doing anything to it ?!!
First the starter would not operate, tried the head lights, no go either, all it can light up is a dash board small 12v bulb, bit with an intermittent glow,it glows then goes off, then it glows, then goes off at 2 second intervals!  The discharge between glow and no glow varies between 40 miliamps to 90 miliamps. If I short circuit the battery via my ammeter the discharge is the same.  It seems that the battery can not discharge its 3/4 capacity (SG 75% charged)! Perhaps it needs to be on a continuous discharge, although as mentioned, the discharge would be only between 40 and 90 miliamps.
Not sure whether my battery came with a warranty or guarantee, can not find the receipt.
Thank you,
Anthony.
P.S. This is my third attempt to publish this information!

On July 24, 2011 at 10:30am
mike wrote:

so lets say i drained my battery supply to 70% and i wanted to recharge it to 90-100%, what would the estimated time be to recharge it?
the battery has 115 amp hours.

On July 29, 2011 at 12:30pm
Daniel T. Le wrote:

I have two 12v 4.5Ah (20hr rate) connected in series for a toy and I also have an addapter with 2 outputs: 32v-375mA or 16v-500mA want to use as charger for the above batteries, can ?? Which voltage should I use and how long should I recharge for or what should I do with what I have for what I need.

On August 11, 2011 at 9:04am
Kanagasabapathy wrote:

Is it possible to recharge a 100 Ah - 12 volt Lead acid battery using a self designed charger with 1A -14 volt? Kindly en light this.

On August 11, 2011 at 7:22pm
M Kanagasabapathy wrote:

Is it possible to recharge a lead acid battery 12V - 80 Ah - C20 by using a charger of specification 14 V -1A. Kindly explain.

On August 11, 2011 at 7:25pm
Kanagasabapathy wrote:

Is it possible to recharge a lead acid battery 12V - 80 Ah - C20 by using a charger of specification 14 V -1A? Kindly explain.

On August 15, 2011 at 3:57am
Jacko wrote:

New question , battery charging with solarpower..
I’ve got 2 Hawker energy SBS60 12 V 50,8Ah batteries.
Float voltage of 2,27v.
So each battery give me 12v x50,8ah x30% = 183Watt x2 = 366w with 2 batteries.
so when i put these in a camper and want to charge them with solarpower…
How do i have to calculate the charge value coming from the solarcells for those 2 batteries ? when in the same time a charge is taken from the batteries by Frigo, laptop,waterpump,led lights etc..about 300watt a day ..

What i want to know = what has to be the value of the solarcells to keep this system good working ...50 watts…70 watts…? or more

Batteries connected parallel i guess or seperated and working with a divider who charge each battery when other is full and then change again ? ..what would be the best solution..

any idee about a good solution is welcome..

greetings jacko (Belgium)

On September 16, 2011 at 9:48pm
jin wrote:

Totally right.

On September 19, 2011 at 10:33pm
yi yew wrote:

Sir,

How to calculate the minimum amp to charge two 6V sealed lead acid battery connected in parallel?

On September 22, 2011 at 8:42pm
Victor Barbarick wrote:

I have 4 Trojan 6 volt T-145 (145 minutes @ 75amps)  golf cart batteries connected in series/parallel in my RV. After storing the RV for several months the batteries hold a charge but drop to about 12vdc.  My question is that when I charge them with the RV inverter/charger they will continue charging in the bulk range up to 14.5 for a period time with the battery temperature at 100 degrees Fahrenheit and the batteries with the batteries gassing to the point that I need to add water to cover the plates.  Is this normal??

On October 3, 2011 at 2:15am
Moti Mazor wrote:

1.  If you connect 2 or 4 lead acid twelve volt batteries in parallel only for charging .
Please let me know if tis is ok and acepted?
2.  Can I charg batery with power supplay ( 14.5 V ) with out any serial resistance for limiting the curent ,  and not with special charger for batterys?

On October 14, 2011 at 5:37am
Tommy lee Singh wrote:

hi, i charge a car battery for a friend every day,(the battery is used for lights and cooking and other daily activities etc), it charges on low. i tried to charge it on high but it begins to bubble. i would like to know how much is this going to cost me per month if a have the prepaid system and charge this battery everyday on low. the charge per a kwh is 65.06c in south africa. will appreciate a response.

On October 14, 2011 at 5:44am
Tommy Lee Singh wrote:

hi i charge a car battery for a friend everyday,(the battery is sed for lights, cooking and other daily activities) i charge ut on low. i tried to charge on high but it begins to bubble. i would likje to know how much it is going to cost me if i charge it everyay on low for a month. the charge per a kwh is 65.05c in south africa, please help.

On October 17, 2011 at 7:00am
mohammed habiibullah wrote:

i have a brand new set of 12volts lead acid battery, i should install the battery and start using it what is the quantity of acid and distilled water in ratio to be added and put for charge , and should i added acid or distalled water , kind of charge low ampere or trikle charge

On October 17, 2011 at 10:15am
Niketan wrote:

How many cells are there in APC RBC 17 battery? It is a 12v, 7AH battery.

On October 21, 2011 at 6:22am
tommy lee wrote:

i asked a question about a week ago and still no reply. disappoionting!

On October 24, 2011 at 12:29am
Marwa wrote:

Hi,
I read many battery charger specs that are used with hybrid wind-solar LED street light systems, some of them mentioned the following:

1-The charger is protected from over voltage when there is no battery or when the voltage at the input exceeds certain limit.

2- When we may need the open circuit protection when there is no battery?

Kindly elaborate on the above two points

Thanks & Regards

On November 7, 2011 at 9:57am
Rajaganesan wrote:

dear sir,
        In Lead acid battery at formation, they are calculating the 3 wt % SO4 from positive and 3.45 wt % from the negative paste, or 72 g. This is equivalent to 73.5 g of H2SO4.

        The concentration of H2SO4 in a 3 wt % solution is 31 g/l. In which PbSO4 = 112.53 kg with the wet paste weight = 1182.8 kg.

          I want to know how they are calculating 72 g and 31 g/l.  I am waiting your favorable reply


Thanks and Regards

  G.Raja

On November 11, 2011 at 10:17pm
Don Rose wrote:

Hi,

Is it true that lead acid batteries should be cycled from time to time by at least a 5% discharge? Or is this an “old wives tale”?

On November 22, 2011 at 9:51pm
pushpa T S wrote:

hi,

i want to measure the battery capacity ??????  i need to charge the battery accordingly by measuring the battery capacity

On December 15, 2011 at 4:16am
eliseo viray wrote:

sir, i need to know what charger will i use to charge 15 to 20 units of 12v 100ah batteries in one charging

On December 18, 2011 at 11:17am
P.K.Jain wrote:

I have discovered that I have 100 Nos 12V-26AH SMF LA UNUSED Batteries lying on shelf unattended for 4 years. The batteries show OCV of 2-3 VDC. How in this world can I revive them. Slow charging or Pulse Charging? Kindly refer resources where I can study the methods of reviving dead batteries.

On December 19, 2011 at 9:57am
Ken wrote:

Sorry I come into this late but I would like some thoughts on some backup system I am setting up.
My Charger is limited to 10Amp
200AH vrla gel 12v batteries
48vdc system with 4 strings (4x4 = 16 batteries )

What is the estimated time my charger will need to bulk charge the batteries ?

On December 21, 2011 at 7:42pm
mattymays wrote:

hi batteryuniversity.com-ers all the best   to every one -  matt

On December 29, 2011 at 9:32pm
Bob K. wrote:

Art,
Did your DCU 13 cells restore or di you happen to open them to see what was inside?

I have started playing with some Rolls S-460 (350AHr) batteries and I need to select a scheme to minimize water loss yet prevent acid separation and sulfate build up.

Any ideas out there?

Bob K.
indexdesigns.com

On December 30, 2011 at 2:40am
John A Bean wrote:

I have 3, 12v 14amp (almost new) AGM deep cycle batteries that were use on a 36v scooter. I plan to add one more for a 48v scooter. When I charged them individually to top them off before I chained them, one battery gets to 13.1 volts but quickly drops to under 12 volts in a day or so when taken off charge. The other two get to 13.2v and stay at about 12.8 volts for several days. My question is; does this drop in the third battery indicate a bad cel and should I replace it before I install four batteries for this 48 volt system? How would it affect the system by using it?

On December 30, 2011 at 3:30pm
Jay Atkinson wrote:

You all are a great resource, thanks in advance for any help you might be able to provide.  We got my 5 year old a little ride on electric car with a weight capacity of 88 lbs this week.  It has a 12V 7ah battery.  The manufacturer recommended a 15 hour initial charge, which we did.  It worked for a couple hours after that charge, which seems about right.
Subsequently, we charged it for 8 hours, also based on recommendations.  After the charge, it sat overnight, and then only ran for about 20 minutes when used the next morning.  I don’t know if the battery isn’t charging, or it isn’t holding a charge.  The charger does not have an indicator light so that’s no help.
Any assistance or advice would be greatly appreciated. Thanks!

On January 4, 2012 at 9:44pm
Anand wrote:

Very useful information for me. I am using a 35Ah flooded lead acid battery(labelled maintainenc3 free) to receive charge from my 100W solar panels, using a charge controller. The battery appears to charge quite quickly using 3-6A for a period of 4 hours. The battery reaches 14V mark, where in the charge controller seems to send reduced pulses of current. I thought the battery was fully charged and the charge controller was wrongly sending current. Needless to say, the battery displayed very less capacity while being used with an inverter. Now I knwo it is due to the absense of the stage 2 of lead acid battery charging this is happening. So, thanks for the info.

On January 5, 2012 at 11:21am
David wrote:

I have an equipment which uses two batteries HITACHI HP38-12 (12V, 38AH) in series. It functions for 3 hours. Can I replace them with two CSB 12V-34AH compromising only the operation time? Can it overheat?

On January 5, 2012 at 7:18pm
Tommy Mak wrote:

If a 12V battery can support 160W for 20 minutes and I connect 2 of these batteries in series, can the assembly support 320W for 20 minutes? If so, is it because the discharge current has been halved?

On January 6, 2012 at 1:54am
Badr wrote:

I have a kende 20A charger and 150ah battery.
The charger is single phase. when I charge the battery the voltage goes up to 19.5v. once I disconnect the charger the voltage drops to somewhere in 13v.
what this high voltage indicates. do I need to replace the charge.
by the way. when the voltage is 19.5 the current charging current is 7amps.

Thanks,
Badr

On January 7, 2012 at 11:35am
Ralph Wanka North Bay ON wrote:

Dear Sir,

My 2004 Cayenne has killed 3 Motormaster MOT-49 batterys.
all with in 20 -30 days.
SUV will not start… remove battery bring to CT ...they put battery on Charger / Tester
Tester Goes thru cycle and TEST come out ” Battery HOT “
? Cell bad or what? 
They give me a NEW BATTERY. .. this is 3rd time !!!
? Can my vehicle cause this malfunction to a battery?

On January 12, 2012 at 10:07pm
Mike wrote:

Hi, great site. I was hoping someone could help answer the following question.

I have a 12v 80amh leisure battery that I will be using on a small boat to power a few small items like a cd player and a small dvd player. The battery will also be used to start an outboard engine.
When running, the outboard will charge the battery, but only when it is running.

I am looking to fit a solar charger to the battery to keep it topped up when the engine is not running

Can I do this? Will the battery be OK when the engine is running as there will be the power from the solar charger and the engine going into the battery?

Any help will be great,

Cheers…...

On January 26, 2012 at 10:30pm
Elango wrote:

    We are planning to install a low voltage (approximately 0 to 5-10v) battery tester/cycler with a minimum of 8 channels to test and determine the charge/discharge characteristics on Li-ion, Li-polymer, Ni-cad, Ni-MH, Lead-acid, and ultra-capacitors. Specifically, we wish to test the maximum safe charge and discharge rates of button cell type samples of the above batteries.
We need to be able to remotely control and receive data from your device through our own proprietary software. The user should be able to program and control each channel independently to determine the charge & discharge curves and other characteristics on the above mentioned batteries. Temperature monitoring on each channel should also be included.

so need to how fast a battery charges & discharges and how to calculate the charging,discharging rates

On January 27, 2012 at 8:03am
Bob Kondner wrote:

Elango,
  I do this for some of my products using a USB based data acqu unit like the LabJack or USB-1208LS units for about $100 to $200. I write coe in Delphi though you can write this code in anything you wish. Add a couple of relays for switching loads and sources and you have a pretty complete system. You want a DC clamp on ammeter that reads down to maybe 10ma (depanding on your battery size). If i can help ia am: bob at kondner dot com sent me an email.

If you really have a VERY GOOD idea of all your test perameters then maybe you can buy something. But a few relays, wires and 500 lines of code is no big deal for me and I end up with a very flexiable tool.

The key is your ability to write code effectivly, you really need to know how to use an existing code tool or you can spend a hunk of time learning.

Bob K.

On January 28, 2012 at 11:56pm
Devaraj wrote:

dear sir,
we r doing project in hybrid bike using RT 12220 12v,22ah battery in that, can we check battery charge level using multimeter…

On January 30, 2012 at 11:34am
miraj wrote:

hi, it’s great and useful information. i was also planning to charge my motorcycle battery but i m confused with this words written on my 12v motorcycle battery ” recharge at 0.3A 5~10 hours” what does it mean and while charging what amount of volt and amp should be given to charge it.

On January 31, 2012 at 10:55am
John E wrote:

Hello,we need some Battery equipment to buy,i will like to know if you can supply us with any of this.example below:


Sealed Lead Acid Battery 12v,80 to 200ah…for solar backup

Sealed lead Batteries 100 to 250Ahms, 12 to 24vots

Please reply back soon,to let us know if you have any of it in stock,if yes,please advise unit cost for each.

And will like to know if you accept credit card payment.

johnmyerick@yahoo.com

Regards

John Erick

On February 6, 2012 at 5:07am
Rajnikant wrote:

Hello,we need some Battery equipment to buy,i will like to know if you can supply us with any of this.example below:


Sealed Lead Acid Battery 2v,1500 to 2000ah…for tetecom backup

Sealed lead Batteries 1000 to 2500Ah, 2 to 12vots

Please reply back soon,to


Regard
Rajnikant Jaipuriya

On February 6, 2012 at 9:35am
Guillaume wrote:

If you are looking to buy batteries, I am pretty sure you are not at the right place.

a) Cadex does not sell batteries, according to their web site.
b) It is not the place to buy any Cadex’s product.

Go on their web site to see what product they offer.
www.cadex.com

On February 18, 2012 at 11:28am
abhi prasad wrote:

can i charge my 12 v(7 amps) rechargeable battery using a battery eliminator (1-2 amps) but kept at a higher voltage???

On February 23, 2012 at 6:53am
Allexsiss wrote:

hey!
i need some help , please!
i have 4 Maintenance-free Lead acid batteries (6 V 4.0 AH/20 HR ) .
each two are connected in series to form a unit that gives an output of 12 volts.
then the 2 units are connected in parallel ...
i’m charging them with a 12-0-12 V / 3 amp inverter ((an AC transformer))
is it ok to use a 16-0-16 V / 5 amp to charge them instead? because the one i’m using is barely charging them and it’s getting very hot after a short time ...
and yes , i’m using them to keep my router running during power failure smile

On February 25, 2012 at 12:00pm
CYRIL wrote:

Sir,
  I have two (100Ah 12V lead acid flooded) batteries which is in 24V connection using for inverter use. Daily power failure is half hour. Daily recharging time is 2 hours. Room tempetatrure 25degreeC. My desired charging time is 16 hours. I have a digital charger which I can set ampere & voltage. Which also enabled by over charge protection. And I wish to get the MAX BATTERY LIFE. So, How much is the CHARGING AMPERE & VOLTAGE ? The charger is a single stage charger.

On March 3, 2012 at 1:54pm
Engr Omawole E.Itshoritshelaju Alexander wrote:

I found this page interesting because i having problems with charging batteries to full capacity.

On March 8, 2012 at 3:38am
Chris Pollard wrote:

Hello.I have a burglar alarm and the control panel has two 6V rechargeable batteries in it that I replaced recently.The original adapter that was supplied with the alarm that plugs in to the 240v wall socket is a 16 VDC 600 Ma but it is is broken.I have replaced it with a 13.5VDC 1000 Ma and I am using it at the moment but I am not sure if it will be safe, now or in the long term…..Could you advise please….....kindest regards…Chris Pollard

On March 11, 2012 at 11:01am
humayun wrote:

dear all…im from a country where electricity is becoming rare day by day…frequent period of power failures of long durations…in such situation can some body guide me how to get my ups charged as quickly as possible…my system specs are as follows:
one 12 volt,  2kva,  pure sinewave generator/charger, 400 ah gel type sealed battery…can use an other charger in parallel with the one i have to increase the charge rate.. while keeping same voltage…????any answer pse….

On March 15, 2012 at 11:31pm
seyi +2348130567222 wrote:

to allexis: the maximum voltage u cud use to charge a 12v lead battery is 14.5 -14.7v,moreover the current passed on the batteries matters a lot.using a 16v charger cud caused the internal resistance of the battery to rise.

On March 18, 2012 at 10:31am
vikram wrote:

Hi,
I am planning to install inverter and battery in my village, Here is my requirement :

- 4 CFL + 2 Fan

In my village electricity is for around 4-8 hours daily. I tried to find most suitable battery and inverter for this, but some how could not find right configuration. It would be really helpful if you guys can give some advice on this.

Thanks a lot for your help.

On March 19, 2012 at 8:56pm
Herbert Norris wrote:

Dear Sir
        Please can you tell me if it is possible to charge my 12v sealed battery up with two 6v chargers -how to wire them up etc .

On March 20, 2012 at 9:02pm
Ankit wrote:

Hi,

What are the effects if i can charge 6v batter with an 5v supply.
As basically my application works on 3V to 5V supply but i also have to give facility to connect 6v battery (Rechargeable). so i converted 6v output to 5V for my application.
but while recharging of 6V battery i gt 5V supply.
So it has any effect on battery Life?
battery is charge till 5 V than also my application is working because my application can work on till 3V so voltage is not an issue.

On March 25, 2012 at 7:17am
Frants wrote:

Hi there.


Very informative. What if the first phase of the charging, the constant current charge, is interrupted before phase two can begin? And then, when charging can continue again (some discharging has now occurred) phase 1 charging resumes?

My understanding is, the state of the battery will determine which state of charge needs to commence. However, since the topping charge, as you say, is sort-off a rest period, what if this rest period cannot be applied, or the constant current charge cannot be completed?

Thank you.

On March 25, 2012 at 2:41pm
Robert Kondner wrote:

Hi,
Good observation. The “Interruption” you describe can fall into two situations.

  1. The battery has been disconnected during the interruption and replacement with a different battery is possible.

  2. The battery has not been interrupted.and the controller is one that monitors battery discharge.

If you have a controller that monitors all charging and discharge currents, and it operates with a VERY low battery drain (10s of ua is reasonable), then as long as the battery has not bee disconnected you retain the battery state. You can pick up a charging profile at a later time.

When battery is disconnected all bets are off. You need to assume a new battery has been connected and you need to charge and/or condition it to a known state.

I believe all battery current should pass through a smart controller. This gives you the chance to prevent over charge or over discharge with a series switch. It is not that expensive with a PIC, some circuits and a couple of FETs.

I have some small chargers at www.indexdesigns.com and I would be happy to describe what I did in the Battery Boss software.  bob at kondner dot com

Bob Kondner


On March 30, 2012 at 4:00pm
ra'ed wrote:

i went to put a specifications to buy a power system for telecommunications stations, the battery will be a 12 v 200ah four battery connected to gather in series to give the -48 vdc and a charger of the same voltage:

Q1: HOW MUCH CURRENT WILL DRAIN FROM THE CHARGER TO CHARGE THE BATTERIES IN THE FIRST BOOT?
Q2:WHAT IS THE SUITABLE CHARGER SIZE? 
PUT IN MIND THAT THE LOAD CURRENT WILL BE 25 A,AND THE SET OF BATTERY WILL CARRY THE LOAD FOR 24 HOUR, THE BATTERIES LIFE TIME NOT LESS THAN 15 YEARS WHAT IS THE SUITABLE KIND OF THIS SITUATION? GEL OR LEAD ACID? VRLA OR OTHER KIND?

On April 4, 2012 at 10:02pm
Bikash kumar sahu wrote:

Plz help me, regarding for charging of a 12V dc battery, i have to design a dc dc voltage converter for 12V to 16V ? but at load condition i am getting only 200-300mA current? I it possible for charging of a battery

On April 9, 2012 at 5:09am
acc wrote:

Hi,
  Can a battery be charged (eg. thru solar panels) and discharged (used for some appliance) at the same time ?

acc

On April 14, 2012 at 12:32pm
Vic Tkachuk wrote:

I have a motorhome set up for 2 regular lead acid 12 volt deep cycle batteries,
I have the chance to buy up to 4 gel cell 12volt deep cycle batteries.  Can I safely
rerig and install 4 using the same charging set up ?  These are batteries which
were used for solar storage (Power PSG-12105)

On April 14, 2012 at 2:16pm
Robert Kondner wrote:

Vic,
You did not say if your existing batteries are flooded plate or what.I assume your existing charge was purchased for whatever type battery you have.

The problem you need to watch out for is a “3 Stage Charger” often looks for the battery voltage to peak when the battery is charged. If you apply such a peak voltage to a sealed lead acid battery, and depending on the charging rate, you might generate more gas than can be internally recombined.

I looked into this PSG-12105 quickly and did not see any charging profiles, the peak voltage mentioned was about 14.1. A Three state might be looking for 14.6 or higher.

Bob K.

On April 17, 2012 at 11:07pm
Gilberto Prida wrote:

I need a replacement (lead acid) battery for a Quipp jump starter which printed information
is the following: Prostar bat.  6PS0070H - 12 V. Cycle use 14.6—15.0 V. Standby use
13.6-13.8 V. Initial current 1.75 Amp. Max. -This bat. has terminals.with holes for bolt
and nut.  I appreciate your answer and the price for this jump startert if is convenient
for this 4 year old apparatus. Thanks in advance….Gilberto

On April 19, 2012 at 11:23am
Phil Murray wrote:

Is it safe to charge a 6v 10aH with a basic 7v 2amp charger?


Thank you


Phil

On April 21, 2012 at 6:31pm
tareti kireua wrote:

Dear Sir/Madam

I use a 100N sealed batterry (12V) in my home powering three light blbs of 7watts each but I only use soler charging only and an electric charger as a backup when sunshine is not surfficient. The charger gives 14.5 max voltage but I just want to know how many hours should I chrge my sealed battery in case solar charging is not availale de to overcast or caherging is really lower than 12V.

Should I use electric charger full day or any advice from you on how to use the electric charger to avoid damage to my sealed batterry.

Hear from you

tareti

On April 23, 2012 at 10:21pm
joe wrote:

Sir,i would like to build a charger for lead acid batterys.  the one i have is a commercial one and inside theres just a transformer a retifier and an ammater.the only protection it has is a thermal switch on the tranformer.Personally i find this a bit dangerous as it does not cut the chaging when the battery emf is reached,(13.8-14.5V).I already ‘ve wired a couple of test circuits one of which used two thyrsistors,one for monitoring the battery votage andthe other is the switch.the problem i’m find with most of the circuits is that as that when i apply the charging, the voltage goes up cos the battery acts like the capacitor and this goes above the sensing voltage set ie 13.8v.would current limit solve this problem?thank you,

On April 24, 2012 at 3:24pm
costas wrote:

Hi,

If you had to charge a 6V 6Ah battery, what maximum current float charger would you recommend?
Would the current output value of the charger be different if I were to use a 4-steo charger?

Thanks!

On April 26, 2012 at 9:50pm
Joe wrote:

Table 4-5 talks about “severe overcharge”, yet maintenance free car batteries are charged by the alternator at around 14.5V in a hot engine bay all the time. Can you explain?

On May 3, 2012 at 8:54pm
Ross Wi wrote:

Can “Negative Pulse and Burp charging” be postpone battery service life and improving battery performance & desulfation?

On May 14, 2012 at 9:40am
Raymond wrote:

I have to make a solar battery charger for a 12v,13AH lead acid battery how do I calculate the charging current required to charger the battery from a flat state in 13hours?

On May 14, 2012 at 10:08pm
HASEEB wrote:

i have two 6v 4.5ah battries. i want to charge them in series. is it ok to charge them with 12v 1250ma adapter. how long it will take to charge them fully

On May 19, 2012 at 9:05am
Tim Hellsten wrote:

Hello.  I have a question.  I have an electric scooter using a 48v 30AH SLVR lead Acid battery.  running a 500watt brushless motor.

I currently charge it with a 48v converter @ 3 A charger plugged into house power over night to charge the scooter.

I want to increase the range so I have had a thought to put a 1000 watt honda generator on my scooter and run the generator while I am driving.


the issue I see right now is that I am probably drawing more power from the battery then my 3A charger is able to put back.  I was contemplating purchasing a 48v 30A charger and charging my batteries as I am driving.

I need some assistance from the folks here. 
can anyone offer some information.  will this work?  will I blow up my batteries?
are there issues charging batteries at the same time you are draining them?

thanks

On May 20, 2012 at 9:45pm
Ian Warner wrote:

I bought a new lead acid batterry for my golf buggy, a Panasonic model LC-XC1228AP after x anount of hours the charger indicates it is fully charged, but I cannot get 18 holes of golf out of it, I contacted the supplier who sent me another one, it is the same. It has been suggested that this type of battery initially needs to be run down completely and then recharged before use.
Can you please advise me.
Regards, Ian Warner.

On May 21, 2012 at 6:13pm
Bob Kondner wrote:

That is only a 28Hr battery. I know nothing about golf cart loads but 28Hr does sound like a lot. What does the golf cart motor require?

I checked, it is an AGM battery. Do you know for how many hours it took how much charge?

No, You do not want to run it down all the way, very bad idea. Just be sure you charge it all the way. To do that you need a volt meter and the specs from the manufacturer.

Bob K.

On May 21, 2012 at 11:53pm
Ian Warner wrote:

Thanks for that info Bob K. It took approximately 3 to 4 hours to show fully charged on the charger. I put a voltmeter across it and it read 13.45volts. The info off the buggy motor is 12 volt 180w. This size battery was supplied with the buggy when bought new. I have used the battry four times now and each time it seems to be getting stronger. I can now get 18 hole out of it, although still quite weak at the end. Once again, thanks for your help.
Ian Warner.

On May 22, 2012 at 12:55pm
Bob Kondner wrote:

Ian,
  If the charger only took the battery to 13.4 V then the battery was not fully charged. I would guess you are using a “Float Charger” which uses a very low vlotage as to not overcharge. You want to see the voltage head closer to 14.4 if the battery is < 70F or to 14.2 if > 70F. At 100F only 14.0V. AGM are not like floated plate, you don’t see the voltage rise up as much at the end of charge. You need a charger with some smarts.
Bob K.

On May 27, 2012 at 7:34am
ryan wrote:

what will happen if electrolite was added to lead acid battery

On May 31, 2012 at 2:56pm
Kiel Durmaj wrote:

@Ryan, All lead acid batteries have electrolyte (hence the term “acid”). You may be referring to AGM batteries which are also referred to as acid starved batteries due to the limited amount of electrolyte.

If this is the case, it is never recommended to add more sulfuric acid to the battery since the concentration/level from the original fill is great enough. Since it would seem have a SEALED lead acid battery and it would only damage that seal to open it enough to add any form of liquid. That being said, don’t open your battery.

Kiel

On June 2, 2012 at 12:11am
mathan wrote:

sir,
flooded battery revival works not suitable why?

On June 8, 2012 at 4:39am
maulana wrote:

how long does a 75 watt solar pannel charge a 120 ah Raylite maintainance free battery, that is 50% full.

On June 21, 2012 at 12:03pm
Sunil wrote:

How to set up a Float voltage on a charger ? Do I need to isolate Battery set or I can set up with Battery set connected ??

On June 23, 2012 at 3:52pm
Clive Pearson wrote:

Hi   I have 3 batteries 12v @ 220Ah wired in Paralell what charger and at what amps would I need to recharge these ,these are for a camper van system

Also a 24v system = 2x12v @220Ah in series same question as above

One other question I know with ohms law if you increase the voltage of a supply you drop the amperage and visa versa if you drop voltage you increase amperage.
What happens in a battery in series as regards the Ah as in for example 2x12v@220Ah in series = 24v as there is a voltage increase does this drop the output amperage regards clive

On July 9, 2012 at 10:38am
Ron Gardner wrote:

I have a vehicle with 225 amp alternator charging a 150 AH battery. When battery level is low (11.8 volts with no load) & I start engine & measure the current from alternator charging battery I get around 45 amps? If I add a 45 amp load the alternator output goes to 90 amps, why does the battery charging by itself only charge at 45 amps? Is there a limit on charge rate that lead acid batteries will charge at?
Any insight would be appreciated.

On July 9, 2012 at 11:13am
Bob Kondner wrote:

Hi,
  There are a LOT of reasons that you don’t get more than 45 amps. The alternator is not a “Zero Ohm Impendence Output”. If you short out the alternator you might get 225 Amps but that must be one heck of an alternator. The alternator output is not like a regulated DC supply.

Plus you have resistance in wires and the battery.  You might want to check voltages at various spots and see where you are dropping any voltage due to wire resistance.

Yes, there are limits to charging rates but that depends on the type of battery. AGM batteries spec very high charging rates but I have never experiments at 100 amps or more. Flooded plate batteries exhibit a sharp increase in voltage as they are charged. The only way to get “100%” capacity, or at least a high level of charge, is to allow the battery to charge up slowly. Getting that last level of charge takes a long time.

Bob K.

On July 20, 2012 at 10:04am
john Bean wrote:

What is the best battery charger to charge a 48v (4-12v 14amp) system? Is a 48v 3.0amp charger sufficient to fully charge them?

On August 5, 2012 at 10:10am
Danilo wrote:

Hello,

i have at home Pb battery 100Ah 12V. Im charging these battery with 5,0 A and i have setup charger with 2,25V/cell. Is these good?
Link for these battery M83CHP12V27

http://www.tpscrail.com/products/gnb/PDF/Element Bloks.pdf

On August 9, 2012 at 12:07am
Kein wrote:

Dear sir,
How do I calculate a battery recharge time so as to ensure it is less or equal to 8 hours for my design below?

I designing a PV system for a 4w transmitter to operate 24 hours per day, 5 days of autonomy, battery losses of 0.85, Depth of Discharge of 75%, nominal battery voltage of 12V DC. I have calculated my battery capacity (Ah) as follows:

(4x 24 x 5)/(0.85 x 0.75 x 12) = 63Ah.

I have also calculated my PV size as below:
Peak power Wp = (1.25 x Transmitter Load x Daily duty cycle)/(Peak Sun Hour)
Wp = (1.25x4x24)/4.2 = 29W ~ will peak 30W 12V mono crystalline panel Isc =18.3A, Voc =20.7V

On August 14, 2012 at 3:38am
Lawrence Coomber wrote:

Can anybody help me with this one.

I have 25 x 12 V 150 Ah Gel Cell Batteries connected in series showing about 320 V output.

I have the series battery bank connected in parallel to a solar array with a constant daily Voltage output of about 330 - 350 V.

The circuit includes a blocking diode between the battery bank and the solar array to prevent reverse current from the battery bank to the solar array.

The circuit is connected to a varying domestic home load. Obviously at night the battery bank is the sole source but in the day the solar supports both the load and also the battery re-charging.

Am I correct in my analysis of this circuit? I have tried to create a simple “balanced” circuit here with minimum of complexity of seperate cahtgers which would not be available because of the series circuit anyway.

Thank you for any commects you can offer.

On August 15, 2012 at 8:04am
sureshkumar wrote:

Iwand install 24 volt ,1kw,dc power in offshore crane72 houre battery back up.crane enginhave 24 volt 30amer battery charging altrenaterr.can you give an idea?

On August 18, 2012 at 11:44am
Baruah wrote:

Is it dangerous to connect a small UPS with a big 150 Ah tubular battery? The ups transformer gets very hot within 15-20 min of charging, but with some improvised cooling aid I keep it going. And how the internal resistance of LA btr changes with charge or discharge?

On August 21, 2012 at 10:40pm
F J Husein wrote:

I was wondering if anyone could help me.  I have 4 12V Lead acid batteries connected in series to my IPS (Instant Power Supply) unit.  The connection between 2 batteries got snapped.  Now I have 2 questions. 
1.  I disconnected the wiring to the positive terminal of the 1st battery so is there any current flowing through the other connections?
2.  How do I rewire the whole system so that it is up and running again?

On August 22, 2012 at 12:32am
venom wrote:

@ F J Husein

so you have a 48V system (12V battery X 4 in series)

1. this is a chain of battery, an open in this chain means no current flows through any of the battery.
2. wiring  
              +      -  c   +      -    c   +      -    c   +    -
            48v                                                 0v
            to IPS positive                                     to IPS negative

+    -  indicates one battery
‘c’ indicates a connection between - and + of adjacent batteries

On August 31, 2012 at 10:31pm
Deepthikumar wrote:

how to calculate the amount of active material for a lead acid battery based on Ah?
how to calculate the SOC using OCV? what is the relation between SOC and specific gravity of acid in lead acid battery?

On September 1, 2012 at 4:44am
Muhammad Farooq wrote:

How much current per hour required for 150 Amp Lead Acid Batteries

On September 16, 2012 at 5:23am
Alex wrote:

Hy, I have a car battery rated 12 V, how do I know the level of how charged is ? From the voltage ?

On September 26, 2012 at 9:10pm
Roy McSheffrey wrote:

Is it possible to have my battery charger running at the same time that I’m running an ac adapter to power my computer,

On September 27, 2012 at 6:22pm
ling michael wrote:

How many % or cc water loss of maintenance free battery during service life, please give me data or water loss curve. thank you.

On October 9, 2012 at 7:00am
Shan Mehmood wrote:

How much charging time can we take a 12 volts, 190 Amp Lead Acid Battery to charge properly using 26 Amp and 12.80 volts charger?
And after charging completion, how much should the battery voltages?

On October 10, 2012 at 12:30am
James Japp wrote:

Some time ago generator died on my old diesel truck, so I have to recharge the two SLI batteries manually (I’ll install an alternator and scrap the stupid generator). The charger that I have is a simple 12V 20A unregulated unit, so I put a digital volt meter across battery terminals and monitor voltage and here I noticed something strange.

After some 30 minutes or an hour voltage reaches certain point between 13.85V and 14.10V and stays there for an hour or longer. Current is also stable at about 5A or more (I got two 66Ah batteries in parallel). Batteries don’t get warm during charging. When I disconnect the charger and continue charging after 10 hours or so it immediately goes over 14.4V or so, no matter whether I left it sit for more than an hour at the same voltage or whether I disconnected it much earlier.

What is going on here? It looks like batteries are just dissipating power somehow, but how’s that possible? How can batteries absorb 2-3A each and keep the same voltage that indicates that they are not yet full and then after some rest period ‘become full’? They are not too close to the engine, so while the truck is running they get to about 25-30°C (77-86F) and overnight they cool to about 15-20C, so I don’t think that the temperature is important factor here.

On October 10, 2012 at 12:47am
James Japp wrote:

@Shan Mehmood

You can’t charge 12V battery with 12.8V charger, that voltage is nowhere near enough to charge a battery.

But I don’t think that you have a 12.8V charger, I’m guessing that you used a digital multimeter and measured voltage across charger terminals when it wasn’t connected to a battery. Digital multimeters (DMM) get confused with pulsed DC and most battery chargers of that size don’t have filtering capacitors (because they don’t need them). DMM tries to read an RMS value of full wave (or half-wave if you charger is very old) and fails. Anyway, RMS voltage is not important value for a battery charger, you wan’t to know it’s peak voltage and to measure that you need an electrolytic capacitor with voltage rating of at least 25V. You need to connect it in parallel with your DMM and charger (don’t mix the polarities) and then read the voltage.
For example, when I measure my charger with DMM it has 12.00-12.20V (it depends on mains voltage which fluctuates in my area), but actual peak voltage is 18.20V.
You don’t actually need to do all this, but you can if you’re interested.

Now to answer you question - no one can tell you how long you need to charge a battery because that depends on many factors - how much have you discharged it, not all batteries charge at the same rate, some take longer and charge current and voltage depend on your mains voltage. So, connect the charger and monitor voltages, for a full charge at room temperature voltage should be 14.2-14.4V, you got more details in this article.

On October 11, 2012 at 1:04am
Wilfred Kube wrote:

I have a Toyota Coaster bus which is fitted out as a motor-home.  The vehicle was manufactured with a 24 volt electrical system, which uses two batteries in series, of 12 volts each.
I have outlined a description of the auxiliary electrical system below, but my basic question is, how can I know how depleted my auxiliary batteries are at the end of a day in which the refrigerator has been working for a long time?
I think the basic rule is that the batteries should not be discharged below 50% of their capacity, but what reliable method can I use to determine when they have reached this point?
There are two auxiliary 12 volt batteries in series, each 120 amp-hour, to provide power for the “house system” – namely refrigerator, lights, water-pump, and various 12 volt power outlets.  The refrigerator is the major user of battery power, because it is a compressor fridge which uses the equivalent of 12 volts 8amps (i.e.96 watts) while it is running, and it runs for approximately 8 to 12 hours in each 24 hour period depending on how hot the weather is.
The auxiliary batteries are charged by two solar panels of 80 watts each, and receive additional charging from the vehicle alternator when the engine is running. There is a battery isolator which automatically disconnects the auxiliary batteries from the vehicle electrical system when the engine is not running.
The voltage regulator for the solar panel charging system provides a constant display for the auxiliary system, including the auxiliary battery voltage.  I have been in the habit of checking the voltage last thing at night, and first thing in the morning, to find how much power the fridge has taken from the batteries.  If the night time voltage is below 24.8volts, then the morning reading is below 24.0 volts.
The problem is that if we have not done much driving on a particular day, and the solar panels have not done much charging because of cloudy weather, the night-time voltage may only be 24.2 volts, and the morning voltage not much above 23 volts.  If the battery is at 24.2 volts when the fridge is not running, then when the fridge starts running the voltage reading drops down to about 23.5 volts.
And so my question remains, what is the lowest acceptable voltage for my auxiliary battery system, so that the batteries are not damaged by being discharged too much.
Thank you for reading through a long and detailed letter, but I wanted to provide sufficient background information.

On October 13, 2012 at 1:54am
Graham Budd wrote:

I have 6x2v full traction batteries linked to give 12v and 860 amps at c20’ my question is how long should I set my charger to run for at bulk, should I set the absorption charge at 14.8. Or leave it at 14.4 volts? My charger is a victron Phoenix multi 2500/12/12v
Thanking you in anticipation

On October 19, 2012 at 1:31am
Kiani wrote:

I have a 12v lead-acid battery that charges to 16.65v when fully charged. why does that happen?

On November 7, 2012 at 1:25am
Patrick wrote:

What do you mean by Cycle use voltage = 14.4-15 Vdc and Stand by use voltage = 13.6-13.8 Vdc located at the battery specification.. When the UPS is running may know what is the standard voltage charge of each batteries.

On November 10, 2012 at 2:24pm
MR TOWNSEND wrote:

I HAVE A MOBILTY SCOOTER WITH LEAD ACID BATTERIES IN I WAS TOLD YOU SHOULD NOT LET THEM FREEZE. THE SCOOTER HAS TO STAY OUTSIDE WHAT CAN I DOO TO STOP THIS FROM HAPPENING?

On November 14, 2012 at 6:17am
David wrote:

I have been using a charger to charge a SLA Battery 12v 21ah,i have put the charger through a charger tester to show the v and ah of the charging cycle,should the voltage have peaks /spikes during charging?

On November 17, 2012 at 10:16am
Lutz wrote:

I have 2x 12v 90Ah gel batteries in series to give me 24V. My load is drawing 0.7A. I am using 2x 130Watt 12V solar panels in series to keep batteries charged. The charge current from the solar panels at midday ojn a full sunshine day is 2.5 A.
It seems my batteries are runnig flat in about 12 days.
I dont seem to find the problem, please help me to solve this problem.

On November 19, 2012 at 4:06pm
Jorge Viana wrote:

Please help me:

We’re building a small solar plant to serve an isolated community within the Amazon jungle. We are using VRLA batteries. How much thermal energy is generated in the charge cycle? Total energy stored 60kW.

Thanks,

On December 1, 2012 at 12:35pm
Merle Frey wrote:

I have a 12 volt Schuyler battery charger if I connect it to a discharged 12 volt battery,  I get on the meter a green light then it goes to 15 amp charge then back and forth from green light to charge. What is causing this to happen These are both marine batteries. but it doesn’t matter if I put the switch on Normal or Marine.  Thanks

On December 2, 2012 at 12:06pm
Ron Kushnier wrote:

I need a Float Charger for my 12 volt car battery.  What I have is a fairly sophisticated Craftsman Ni-Cd battery charger (Mod # 974062-001) for an old electric drill.  The 1 hr charger says it works for 12.0, 13.2, and 14.4 volt batteries.  I measured an open circuit voltage of 30 VDC coming from the charger.  When I attach my car battery to the charger, I see 12 V across the terminals with a constant 60 mA being pumped into battery.  My question is whether 60mA represents enough current for a trickle charge, or am I just powering the clock and other electronics of the car with the car power off.

Thanks in advance.

On December 7, 2012 at 9:03pm
Fred Robson wrote:

deer sir ,

what means it to charge a battery?

On December 14, 2012 at 7:03am
Hugh Leekie wrote:

Some help, please?  I ave a 6V 1.2Ah sealed lead acid battery which is part of our house alarm and which is charged via solar panel. What with the poor summer and now very short light days it is requiring a top up. I have removed the battery from the appliance and am charging it with a charger 6V dc 500mA 3VA.  The battery was showing 4.6V with my digimeter before charging started and now after about 40 hours of charging it is showing 5.75V.  Is this a normal situation—should it take as long as that?  I would welcome some guidance please as the source of the house alarm kit suggests charging at 7.5V 500mA whereas the shop selling me the charger says charge at 6V and that is what the charger is doing (hopefully).  Thank you.

On December 14, 2012 at 7:46am
Ron wrote:

I would check the open circuit voltage of your charger with your meter.  Hopefully, it would be somewhat higher than 6 VDC. Otherwise when it is under load from the battery, it will not be able to pump enough energy into the cells. Also, you may want to change your digimeter to read amps, put it in series with your charger and battery and check the current being drawn during charging.

On December 14, 2012 at 8:56am
James Japp wrote:

@Hugh

Cheaper digital multimeters can’t read the voltage accurately on pulsed DC, which is what most chargers produce. Usually DMM will show lower voltage. It’s best to connect the ammeter in series and to see if the charger is charing the battery. For your application charging current should be at least about 50 mA, ideally around 300 mA, but not higher than 360 mA. OCV of a charged battery should be 6.3V and the voltage on while charging should be 7.2V. 5.75V is a lot lower than it should be. If charging current with that charger of yours is several hundred mA you most likely have dead battery, if charging current is low then your charger is inadequate.

For this kind of battery you could use any cell phone charger, if you could find a way to connect it.

On December 15, 2012 at 6:27am
Hugh Leckie wrote:

Thank you Ron and James for your words of advice. Whilst connected to the charger and charging I put the digimeter terminals across the battery and the reading was 6.5V.  The “bare” battery still only is showing 5.7V so it looks like the battery is on the way out. Time for a replacement. (Incidentally putting the DMM terminals across the charger unconnected leads whilst switched on and set to Dc voltage 20, there is no reading-the red charging light does not illuminate. It does however light when the leads are connected across the battery terminals.

On December 19, 2012 at 8:00am
Denton wrote:

Hi
I have a problem with battery . I use a 6 cell 12 v lead acid battery with an inverter for uninterrupted power supply. I didn’t do any maintainance on the battery for a long time and recently I found that plates in all the six cell were exposed .I have since filled the cells with water .Battery seems to be working but find that its temperature while charging goes beyond 40 degree centigrade.I am wondering if this is normal .I remember reading in the article that normal is around 30 degree .I can say ambient temperature is about 25.

On December 19, 2012 at 9:55am
Bob K. wrote:

Denton,
  First I hope you used distilled water, right? grin

Some info required:
  AHr rating of the battery, obviously a flooded plate
  Nature of charger. Smart? Number and description of charging cycles.

What level of charging current do you see and at what voltage?

If the plates were only slightly exposed I would not expect a lot of damage. If we are tolking 50% of plate exposure well that would be bad.

I worry that if you had a lot of exposed plate perhaps you effective battery capacity has been sriously reduced. So now your charger is effectivly charging a much smaller battery. Once a battery warms up it’s terminal voltages tend to drop. If you charger is in a bulk phase and the battery voltage stays low the charger could stay in bulk mode. If the charging current is high you could end up in a thermal run away situation.

You need to watch the battery termina voltage. If it is not hitting about 14.4V when it should be reacing full charge *23C) then you have a serious battery problems.

Bob K.

On December 24, 2012 at 9:24am
Jerry Marnie wrote:

I have a dozen 6-volt golf car batteries that charge up to about 6 volts each, and drop only about 0.3 volts when tested with a load tester. However they each continue to draw maximum charge current when connected to a variety of chargers, and do NOT charge to at least 6.3 volts, as my other batteries do. Some have normal specific gravity, and some are low.

Is there anything I can do to recondition these batteries??

On January 6, 2013 at 4:17am
abrar wrote:

hello every one i am student of 10th class i have no source to study continue please let me how i made a battery of 4v 0.5Ah thanks in advance.

On January 13, 2013 at 10:54am
Hasnat Jamil wrote:

i have a 12V lead acid battery. It is used for a inverter used for uninterrupted power supply.
-after one year use it is now unused for almost one year(no charging and watering).
-it has voltage 6.28V(measured by DMM) and plates are exposed about one inch.

*what should i do to recover it???

On January 14, 2013 at 2:04am
Hasnat Jamil wrote:

can i put Distilled water in it and charge it with a trickle charger???

......pls anyone grin

On January 15, 2013 at 5:53am
Mithu wrote:

Hello every one
i am charging 12V ,4.5AH   lead acid battery ,and charging up 13.8Volts and recharge the battery if below 12.9Volts , but after fully charged to 13.8v it well recharge again i.e floating charge fully complete charged   and charging

On February 8, 2013 at 3:26am
MANAS KHANDA wrote:

plese send my Email 12 volts dc to 220 AC output, without transformer circuit diagram

On February 16, 2013 at 1:20am
Batte Ryman wrote:

On January 13, 2013 at 10:54am
Hasnat Jamil wrote

I think that battery is sulfatised. So in my opinion you better buy a new one.
Not much choice.

On February 16, 2013 at 8:34am
Batte Ryman wrote:

Hugh Leekie
On December 14, 2012 at 7:03am
On December 15, 2012 at 6:27am

You talk about sealed lead acid, part of house alarm, equipped with solar panel.
House alarm means: there is almost always grid power available and I assume the alarm actually is connected to the gird, with the solar panel purely as backup power source.
My understanding is that this battery will (or at least should) be in float charging modus for almost 100% of the time. And that with proper float charging (at always the correct voltage with respect to its temperature) such a battery could last for 10 years.
If the system is much less than 10 years old, then either the float charger should be inspected and repaired/replaced/improved, or my assumption about the grid connection is false. In either case the battery should be replaced, because as you can read here:
http://www.progressivedyn.com/battery_basics.html the voltage should not have gone below 5.25 V in order to have prevented serious damage.

On February 25, 2013 at 4:42am
aswin kumar wrote:

hi,

we are planning to use 54Ah battery, so i would like to go with constant voltage charging, i have a source of 14V @ 7A but it is the source to all other circuit also. so is it recommended to charge a battery with the same source and more over what will be the intial currnet to charge the battery whether is it calculated by 2C. if it is 2C then main source is loaded and will there be a drop across the volatge.

On March 3, 2013 at 11:28am
Rich wrote:

I am wondering what happens if one accidentally charges an LSI battery with a “deep cycle” charge?


I was using a 10 amp 12v charger on ‘automatic’ setting but set on “deep cycle” instead of LSI. would this ruin my battery or make it otherwise unable to receive a charge?


thanks!

On March 7, 2013 at 6:25am
muhammad arshad wrote:

hi ,,,here is some dangrous with me last few months i bought a new 200 ah battery for my ups ,,,first two month i did not felt the put down water in the battery that was full and cool that i saw my battery started to dry water suddenly and some heating .... i put the water after two weeks i felt the back is just 30 minutes on 100 watts usage .. i checked the battery that was tooooooo hot and there was no water inside ..... i put the water in it…............... and googled   there i found that my battery was sulfated   i desulfated it ,,,first of all i drained all acid inside , and then washed with water   ,,then i put baking soda for many hours in it then drained baking soda water ...then put epsum salt in it   with water and put it at slow charge after 15 hours charging   battery was cool then i put the 50 watts load on it ...back up was just for 20 minutes   .....now i am charging it again at slow current just 10 volts and 7to 8 amp but the backup is till now just 20 minutes ... now i am worry what should i do now can i put sulfuric acid and water mixture in it what should i do pls help me thnx   email is     alpha_19_20@hotmail.com

On March 12, 2013 at 4:44am
sc00by2 wrote:

Very informative page, thank you!

I have a question for you. Using a dc to ac converter connected to a 1700mah lead-acid battery, will I be able to charge a laptop battery that draws 120-watts, and how many of these could I charge?

Thanks!

On March 13, 2013 at 1:41pm
James Japp wrote:

First of all capacity in amp-hours does not give you the total amount of energy stored in that battery, you need to multiply that with (nominal) voltage. For example 12V, 1.7 Ah battery has theoretical capacity of 12*1.7 = 20.4 Wh (Watt-hours).

Label on your laptop charger says 120W which is the maximum power it can draw, it doesn’t draw that much all the time.

Laptop batteries typically have capacities between 40 and 60 Wh, so its two to three times more than 12V 1700 mAh battery, so you probably won’t be able to charge the laptop battery. You could be able to run the laptop (with its battery removed) from your lead acid battery and if your LA battery is 12V one you could use car adapter for your laptop which is probably more efficient than DC-AC inverter. You’ll probably need a lot bigger battery though

On March 22, 2013 at 7:57am
suresh vishwakarma wrote:

a lead acid battery bank having normal voltage of 110 V is to be charge using DC source 160V from initial voltage of 1.8V/cell. Each cell of the battery has internal resistance of .02 ohms battery is being charge up to boost voltage of 2.4V/cell. charging current at a beginning is 5 AMP. What will be current at the end of charging. Draw the circuit diagram of charging circuit showing the value of series resistance used.

On April 12, 2013 at 1:28am
Saurabh wrote:

I have a 12 volt 7.5 Ah battery and i want to charge it with a solar panel of rating 25 watt 21.50 volt and 1.59 ampere….can i connect it directly or do i need any special arrangement?
Thanks in advance

On April 12, 2013 at 8:38am
Bob K. wrote:

Hi,
You definitly need a means to prevent overcharging. You small battery will be highly over driven by your soloar panel. There are a lot lof low cost solar charger modules that will do this for you.  Also, your panel output (1.59 A) is a little high for charging though a charger controller should take care of that. You might get a premature “Full” state during full sun which would leave your battery at less than 100% (80 or 90%).

Bob K.

On April 12, 2013 at 11:15am
Saurabh wrote:

But the max battery charging current is stated as 2.20 amps…is it necessary to have a charge controller or any other things like transistor or opamp can be used…
Thanks for your reply bob
I am a newbie In this field and also dnt hv sufficient funds for charge controller is there any substitute for it

On April 12, 2013 at 11:32am
Bob K. wrote:

Hi,
I assumed, perhaps in error, you had a lead acid of some type. A charging rate of C/20 is nice, C/10 would be ok, but I think you said this is a 7.5AHr batter? 2.2A charging is quite high depending on the battery type. Do that on a sealed gel battery and you will destroy it. Do it on a flooded plate and you will generate a lot of gas and go through water quickly.

You can reach me at “bob at kondner dot com”, let me know what kind of battery you have.

But in general yes, you need some type of charging controller. That will include a voltage reference, op amps, transistors and so on. You can take a look at www.indexdesigns.com for some of my items. These are positioned towards smaller batteries like what you have.

Also, don’t neglect software. These little units I have include maybe 5K line of PIC assembly code. Hand written in assembly, very tight, hard to write. Pull down some data sheets and take a look for some ideas.

Bob K.

On April 13, 2013 at 4:16am
Saurabh wrote:

Sir it is a sealed lead acid battery….with 12 volts 7.5 Ah and 2.2 ampere as max charging current

On April 13, 2013 at 6:29am
matt wrote:

Hello there, I have two 12volt sla batteries one of 12 amp hour and other of 4.5amp hour. i use them for my little audio amp as it is 12v. I Use a solar panel rated as 17,5v at 30w, am i ok charging both batteries at the same time as it is still charging a 12v battery but of the added amps of both batteries at 16,5 amp? all the best matt   uk

On April 19, 2013 at 3:43am
nikhil wrote:

hi,
      i have 12v 600mAH battery. during charging the voltage and current of charger (using lm317) is 14.4 V and 200mA. i used to charge the battery without changing voltage till the current reduces to 18 mA(around 3% of total capacity). the battery shows a max of 14.24v at a particular stage of charging process . i want to know whether my charging method is correct or not. please help me . . .
Thanks

On April 19, 2013 at 3:51am
nikhil wrote:

hi,
      sorry , i forgot to add charging time. my charger took around 6 hrs to charge the battery .the charging rate is c/3, but it doesn’t make any temperature variations ,that’s why i use this charging rate .
thanks

On April 19, 2013 at 4:09am
aswin kumar wrote:

hi nikhil,

you are charging with a constant voltage for 2.40 per cell initially which is ideally charging voltage for fast charging, 14.24v drop from 14.4v is my question why it has dropped more over your charging is in toppping charge which you have to leave it for some time. The best was to find your battery is fully charged or not is connect a load acros the battery and measure the voltage it should be approximately 2.12per cell which is 12.7V approx. And also confirm with the graphs in battery datasheet on constant voltage charging

regards
aswin

On April 22, 2013 at 12:03am
nikhil wrote:

hi aswin,
          first of all thanks for your valuable comment . during charging the battery voltage never exceeds 14.24v. when the battery is allowed to charge for some more time the battery voltage starts reducing .i am using lead acid battery and it is 1 year old. when i connect load(50 mA) after charging , battery voltage will 12.6 or12.7v. since the load is 50mA it should give backup for 12hrs, but the backup is around 5hrs(till 11.9v). that’s my major problem .
thanks & regards
nikhil

On April 22, 2013 at 3:54am
aswin kumar wrote:

Hi Nikhil
if the battery voltage is 12.7V then it means the battery is fully charged, your minimum discharge voltage on light loads can be 1.75V/cell which is 10.5V approx for six cells lead acid battery below which it should not be discharged, we can discharge upto 10.5v only, kindly refer to your battery datasheet for the tabular column of the discharge volatge.

regards
aswin

On April 23, 2013 at 12:09am
nikhil wrote:

hi Aswin,
now i am getting around 8 hrs backup . when i searched about charging in internet , the minimum discharge voltage on most of the sites was 11.9v. that’s why i used that voltage . aging might be the reason for the low backup time .
thanks and regards
Nikhil

On April 23, 2013 at 11:56am
Kelly wrote:

Hi, I have 12 2.2 v batteries in a series as backup for my solar system. I have not once been able to get the batteries up to their specific gravity, once even having to ship them back to the dealer for a full charge. We have increased the charging set points and extended the absorb charge period to no avail.  I am charging them with a generator putting out 120 amps and charging them at 30.0 volts. Do you have any ideas? Thanks so much.

On April 23, 2013 at 2:20pm
Mark wrote:

I have an old acuscope B which has 2 sets 8 batteries wired + to -  .  Cyclon lead acid 2 volt 2.5 Ah batteries. The way they are wired into the box is as 2 separate 16 volts coming together as one at the on off switch. Any idea what volt/ amperage I need. I was told 40 volt, 200 mA, but that doesn’t seem quite right. It has a very old small transformer, but all the writing is gone 30 yrs. ago . Thank you!

On May 21, 2013 at 6:24am
Viktor wrote:

I’m preparing to do the initial charging on a FIAM SDH 17 battery, 640Ah. Manual states that it should be done with 2.7 V per cell, 0.10C10 (64A) ought to be the limitation for charging curent and this should take 15-16 hours, so that, at the and of proces, 1.5-1.6 times capacity of the battery should be delivered. I don’t have axpirience with this kind of work but some of my colegues had problems with high temperatures, gasing… Let me add that I’m in Nigeria so temperatures are higher. Does anybody have some suggestions? Should this charging be done with open cover, because of the presure building up in the cell? Thank you!

On June 2, 2013 at 10:36am
derek wrote:

hi im new to the solar scene i have hooked up 8, 245w 52 voc panels in parlell to a 80v max in mppt charge controller i have 8 6v 220 ah golf cart batteries (it doesnt say at what amp the amp hour drain is at) wired in 24v with one string. this bank i sort of stabbed in the dark with and is way under powered.

Q i was trying to use the bank as a buffer as i have a grease car i was trying to use as a generator to top off with beig a 24v system and a 12 v altenator i was wondering if i could tap into the in on the charge controller side to boost the incoming voltage 52 panels +15 on the car. toget 67 ish as i understand i will still get some high voltage on cloudy days but supplement some amps from the car as the panels will drop off right?

Q can i put a diode in line to protect my car from high voltage when connecting to the panels ,will the cars 60 amp current hurt the panels , will the current leak into the panels as it would be cloudy , will my voltage regulator on the alternator be stressed ?will this scheme not likely work? thanks

On June 13, 2013 at 2:52am
Kosta wrote:

Hi everyone,
I own a velotaxi and use 2 sets of lead acid batteries (not connected). Each set is 4x12V. The “small one” is 12V, 18Ah cheep chinese batts and seems that the cheepest chinese charger works not bad and charge it but “the big set” not really. The big one is 4x12V, 42Ah Varta B35, 2 weeks old (might not be very good choice ). I want to buy a good charger in the low-middle-middle+ price range. Any advice about type, brand, specific model is very welcome and highly appreciated.

Kind regards,
Kosta

On June 13, 2013 at 3:17am
Atu Ben wrote:

(1)Pls i have a brandnew Shoto 12v 100AH VRLA (6-fmx-100A Model) battery i want to use with an inverter for backup during black outs. Battery Terminal Currently reads 12.70v with no load
(2)I also have a transformer type charger rated 6amps 12v DC but reads 19v on the digital meter with no load on the charger terminal.
(3) thirdly i have a BNOS Electronic - Stabilized power supply rated 12Vdc/25Am but reads 13.7V at the terminals with no load

Que: (1) How can i tell with my multimeter if the battery requires charging?
      (2) Can any of the chargers above be used to fully charge this battery when is  
          fully discharged?
      (3) How many hours each would each of the chargers use to fully recharge the
          battery?
      (4) What is your recommended maintenace plan for this battery if not in use for
          about a month?
Thank you very much.

On June 17, 2013 at 12:04am
Quang Dzung wrote:

Hi,
What is different between charging Lead Acid Battery and Lithium Ion Battery?

Can we use the same Charger to charge both batteries if they have the same voltage and ampere rating?

Thanks

On July 6, 2013 at 11:28am
David wrote:

Hy! If you have 30 minits ore one hour pause is it good to charge battery, ore is better to leave battery and continue to work after pause?

On July 11, 2013 at 12:06am
Md. Talat Mahmud wrote:

Hi, I’m an Engineer(Mechanical) working in battery factory as an Executive (Research & Development).

During charging the automotive plate, we found some extra material of white color at surface of the positive plates, i need what is the cause of that happening please suggest me.

is there any prevention or cure??

On August 15, 2013 at 11:50pm
nick rees wrote:

what is the maximum current when charging a lead acid 12v 3.2 aph battery from a 12v power supply secondary output12 v and 240v supply.

On August 28, 2013 at 3:19am
Tony Igbafe wrote:

Can a loosed batery contact cause battery to be bloated? The battery is a VRLB type and is used in a telecom site. Please your swift response will be appreciated. Thank you!

On September 4, 2013 at 4:41am
Andre Van den Wyngaert wrote:

A gel lead battery 12V 6.5Ah takes approx. 2A as max charge current. So a 3Ah cell would take approx 1 amp as max charging current.
The same 12V battery needs 14.8V for a topping charge. So to charge it, you need a 14.8V power supply with a built-in current limiter of max 2A, or lower. Most standard mains adapters don’t have such a built-in current limiter. So even if you were able to find a 14.8V adapter, it will deliver too much current and get damaged.
If you connect a standard 12V DC adapter to a lead battery, it won’t charge. Your need the 14.8V to reach topping charge and keep te battery in good condition. 13.8V will also charge the battery, but will cause degradation (due to sulfatation) after some charge cycles. If you don’t have a real lead battery charger, you can use an inexpensive lab power supply, and set the output voltage to 14.8V (half of it for 6V batteries) and current limit to e.g. 1 amp, or 2 amp if you need quicker charge. You will see that the current will limit, and the voltage will slowly rise during the hours. At 14.8V the voltage stays there, and the current will start decreasing. When it is decreased to approx 50mA (0.05Amp), disconnect the battery; it is full. At that point, you can also set the power supply to 13.8V (6.9V for 6V batteries) and keep it connected to keep the battery full and avoid self-discharging.

On September 4, 2013 at 11:43pm
pavan wrote:

hi,
In my project i am using 6v, 4.5Ah lead acid battery,
i have to stop the charging when my battery charged 100%, how would i know the battery is 100% charged or not.
when full charged condition how much voltage will get at the battery terminals.

On September 5, 2013 at 12:40am
Andre Van den Wyngaert wrote:

Hi Pavan,
If your charger puts the required topping voltage on the battery terminals, and your current has dropped to 100…50mA, I’d say it is full. The topping voltage depends on the battery and the temperature, but for these small Gel cells 7.3V is safe. Don’t apply that voltage forever, but stop charging when the current has dropped to 100…50mA. If you want to keep it connected you have to lower te voltage to 6.9V.
About full charge voltage, that depends on the battery again. Some say 6V is empty and 6.5V is 100% full. But if you test right after charging, the voltage is higher; you need to give it some time to settle.

On September 5, 2013 at 2:42am
pavan wrote:

Hi Andre,

Thanks for your response, i charged the battery upto 7.4v here the current dropped from 100mA to 50mA as you said.
if i dropped the voltage to 6.9v, then how much time it will take to full charge the battery and how much current it will take. i am charging the battery through a solar PV panel and i am using the control circuit program to maintain 6.9v.

On September 5, 2013 at 3:01am
Andre Van den Wyngaert wrote:

Hi Pavan,
6.9V is “float voltage” for maintaining the full charge; you can keep it at 6.9V forever and it will stay full. If your current has dropped to below 100mA at 7.4V the battery is full already.
If I’m right you want to charge it with 6.9V and not 7.4V. That will work, but will take longer time. The current will be lower. If it is empty at the start, the current can be 2 or more amps but will very quickly (within less than a minute) go below 1 amp. This is a “safe charge”, but can slowly degrade the battery over time since internal sulfatation can occur. But I have done this too and it has worked for years… Maybe a topping charge now and then could compensate for the sulfatation; I’m not sure of that.

On September 5, 2013 at 4:33am
Andre Van den Wyngaert wrote:

Hi Pavan,
6.9V is float voltage for maintaining the full charge; you can keep it at 6.9V forever and it will stay full. If your current has dropped to below 100mA at 7.4V the battery is full already.
If I’m right you want to charge it with 6.9V and not 7.4V. That will work, but will take longer time. The current will be lower. If it is empty at the start, the current can be 2 or more amps but will very quickly (within less than a minute) go below 1 amp. This is a safe charge, but can slowly degrade the battery over time since internal sulfatation can occur. But I have done this too and it has worked for years… Maybe a topping charge now and then could compensate for the sulfatation; I’m not sure of that.

On September 5, 2013 at 10:46pm
pavan wrote:

Hi Andre,
Thanks for your superb explanation regarding the battery charging, i had finished my battery charging task in my project but i have to test it.
i am using 6v 4.5Ah lead acid battery Battery, in how many hours it will be discharged when i am using 2watt load for FULL battery.

On September 5, 2013 at 11:08pm
pavan wrote:

Hi Andre,
i have one more doubt,at which voltage i have to turnoff the load from 6v lead acid battery for maintaining the battery efficiency(Mean how many years can i use that battery for the 2watt load).

On September 6, 2013 at 1:20am
Andre Van den Wyngaert wrote:

Hi Pavan,
if you mean: how long can I use the battery when I charge and discharge it regularly: I cannot tell. I use such a 6V battery in a flashlight and it still works for over 4 years now. I use it until the light becomes lower… then charge it again. Load is 750mA.
If you mean: how long can it deliver 2W, well, 2W at 6V is 333mA. You have 4.5Ah so it will last 13.5 hours. But that is theory. It will be a bit less, say 12 hours. I would never discharge below 5.5V; 5V at the very limit. At 5.9V the battery can aleady be called “empty”. Hope this answers your question.

On September 6, 2013 at 10:08pm
pavan wrote:

Hi Andre,
Thank you very much for your explanation, you clarified my doubts.

On September 21, 2013 at 4:35am
nimanabavi321 wrote:

Hello,
excuse me, i have a question.

this is a summer of my state:
i charge my 12 volt car battery at 20 volt and 800 mA for 4 hours and continue with 15.5 volt and 200 mA and continue for 2 day.
after 2( 50 hours)  chargingggg the battery not starting car engine.
at now my battery open circuit voltage is 12.9 voltttttttttt.

NOW, i propose my question:
is my battery Destroy??????????????
Pls answer me.

many Thanksssssssssss.
Best Regards.

On October 8, 2013 at 5:49am
Andre Van den Wyngaert wrote:

Hi,
although you only have put approx 13Ah (amp-hours) in the battery (0.8x4 + 0.2x50), it should be able to start the car, certainly when the open voltage is 12.9V. I guess that while you tried to start, the dashboard lights all went out, and then went on again when you stopped starting. This means the internal impedance of the battery has become too high. Maybe it has been discharged too deep. Or it is simply many years old. But I got the feeling you will indeed need to replace the battery…
Andre

On October 8, 2013 at 6:53am
Abdalla wrote:

Hi
I wanted to buy a rechargeable battery for our 80w solar panel for our holiday house. I have come across few of them but not sure which one is the best. one said 65aH/12v and other 100aH/12. my questions is what does these number stand for.
does it mean they supply 65a/100a per hour
is the 100aH better then 65aH
what does the 12v represent
Thanks

On October 8, 2013 at 7:33am
Andre Van den Wyngaert wrote:

Hi Abdalla,
12V means that 12 volt is the nominal voltage of the battery. You should check if this is the correct value you need, depending on the charger you have.
The Ah value means “ampere-hours” and represents the battery capacity expressed as the product of current (amperes or also called amps) x time (hours). The higher the number, the more capacity. A 65Ah battery can deliver 65 amps during 1 hour; or 1 amp during 65 hours, or 6.5 amps during 10 hours, and so on. The 100Ah has more capacity, so it will take longer to completely charge it, but it will last longer while it delivers power. It is like a gas tank in your car. More litres/gallons take longer to fill but last longer. Disadvantage of 100Ah over 65Ah is price.

On October 8, 2013 at 9:59am
nimanabavi321 wrote:

Hello,
very thankssssss for your Attention Mr Andre Van den Wyngaert dear.
ok.
my battery is good.

pls Mr Andre Van den Wyngaert add me to yahoo id.
my id at this site same yahoo.
i have a problem.
thanksssssss.
best regardssssss.

On November 2, 2013 at 6:53am
T Choudhury wrote:

Can I connect a Solar panel straight to the battery. I did and I am able to get more charging current .
I have 25W panel .
Is this a proper way to charge , if not Why is it so?
Will somebody help me on this

On November 5, 2013 at 4:23am
Pavan wrote:

Hi Mr.Choudhury,

you are not charging the battery in a proper way, why because read the above document carefully.

On November 9, 2013 at 4:06am
Okechukwu Kingsley wrote:

how do i determine the kw rating of a charger which i want to use to charge 12v 45AH battery in order to know the capacity of generator i need to power the charger

On November 14, 2013 at 9:54pm
Edgar wrote:

I bought a Enercell 12 V 5Ah Battery and UPG D1724 Sealed Lead Acid Battery Charger 6V 12V Switchable. I want to get an owner’s directions on how to use charger,how long do I have to keep it on the charger for it to be completely charger. Any response to this matter would be highly appreciated. Thank You

On November 20, 2013 at 6:50am
Gilbert wrote:

Can I use AC-DC regulated power supply to charge my 12V car lead acid battery?
Its voltage output 13.8V, 5amps?

On November 20, 2013 at 7:13am
Andre Van den Wyngaert wrote:

Hi Gilbert,
yes it will be perfect as long as the power supply is current limited. If it isn’t, your initial charge current will too high and damage the power supply. But most variable power supplies have current limiting. If you are not sure, you can connect a current meter (e.g. multimeter set for 10A full scale) in series with the battery and check if the current is not above 5A. If it is, disconnect immediately. Or you can short circuit the power supply with your multimeter (set to 10A full scale again) and check if the short circuit current is not above 5A. If the power supply is not short circuit protected, it can cause damage.
For the car battery, you can charge it at 14.5V as well. But once it is full (current has dropped to below 1Amp) you should lover the voltage to 13.8. You can keep it connected forever at 13.8V. It will stay full and ready for use.

On December 2, 2013 at 2:11am
Viking wrote:

There is a question here. I have connected lead acid battery of 12 V with Sunny Island inverter SI 5048. There is a sudden increase in the voltage per cell from 2.2 V up to 2.6 V when the SOC level is almost 100% ( fully charge). May I know is this good for the batteries? How does this happen ? Hope for your reply soon.

On December 2, 2013 at 3:21am
Andre Van den Wyngaert wrote:

Hi Viking,
http://files.sma.de/dl/5612/SI5048-TB-TEN110340.pdf - This datasheet says the 5048 has a complex charging algorithm (page 99 and up). But imho, 2.6V per cell is quite high. If it is a wet battery (car), it might be OK (car charge often goes up to 2.5V per cell) but for gel cells I’d say it is too high. The 5048 first performs a constant current charge with slowly increasing voltage, and then switches to constant voltage charge AT A LOWER VOLTAGE (according to the manual). If you say it suddenly switches to 2.6V per cell, something might be wrong. But then again, how “complex” is the charging algorithm…. Sorry, I cannot help you further on this.

On December 23, 2013 at 1:48pm
Richard Ferrari wrote:

My almost new 12 volt flooded cell battery was accidently knocked over during winter storage. Almost all of the battery acid has drained out of it. Can I add new battery acid to the battery, put it on my charger and save the battery, or is the battery ruined?

On December 23, 2013 at 3:24pm
Bob Kondner wrote:

If that battery was charge when it went over then acid was removed. You should be able to simply add new battery acid. It should act charged. This is how many batteries are shipped. They are charged, acid removed, shipped dry, and later acid added. You need to monitor the specific gravity of the acid when you do charge. If the battery was partially discharged then you will see the SG go too high. (Use other battery as reference. If So you need to remove some acid from the cells and add distilled water such that the specific gravity reach the correct value when fully charged, about 1.265

Bob K

On December 26, 2013 at 1:02am
George wrote:

How can I use a DC 110 volt motor (old one of a treadmill) to charge a lead acid batter of 200 Ah. The motor when working takes about 2.5 amps. When as a dynamo how much current can be drawn from it to charge the battery. And if the voltage is increased will the current drawing rate for charging come down
George

On December 30, 2013 at 4:11pm
Bruce McGillis wrote:

Drawing from a 120 power utility; how many amperes ( or expressed in watts) is being (used) drawn from the 120 volt power system to charge a battery at 3 ampere rate.
  Note: Assume a 100% charge.
Please reply to     bmcgillis@shaw.ca

On January 6, 2014 at 10:31am
Abhisar prince wrote:

A good site

On January 7, 2014 at 2:20am
mahmood gh wrote:

I use12V/7.2A lead acid battery for internet router . I use battery as secondary power source . The battery is contenusely concet to 13.8 V ( SMPS ) switching power supply . and from battery to router through voltage regular . 
Any problem or incorrect to stay battery contenusely connect to 13.8 volt ? Do i increase or decrease the charging voltage??

On January 7, 2014 at 2:21am
Andre Van den Wyngaert wrote:

Hi Bruce McGillis,
it is almost impossible to answer that question accurately with the numbers you gave. It depends on the battery type and voltage and the charger you use. Assuming it is a 12V car battery, and you have a charger that can deliver 10A secondary, with an overall efficiency of 80%, then the consumed power would be approx. 13.8Vx10A=138W secondary or 138/0.8=172W primary.

On January 7, 2014 at 2:37am
Andre Van den Wyngaert wrote:

Hi Mahmood gh,
I’d say you can keep a 12V lead acid battery (probably a gel cell if it is a 7.2Ah cell like you said) at 13.6…13.8V for its entire life. The cells I use have this value written on the body and they call it “standby use”.
Andre

On January 7, 2014 at 3:12am
Andre Van den Wyngaert wrote:

Hi George,
interesting question! If the motor draws 2.5A at normal load, I’d say it should not deliver more when used as generator. The copper wire and collector (I assume it has a collector since it is a DC motor) are designed for this current. So it can deliver 275W approx. (110Vx2.5A)
Now about voltage. I don’t know how your generator behaves when the load current is decreased below 2.5 amps. If the voltage raises above 160VDC, you cannot use the below solution.
But I think that you can use e.g. a Tracopower TEP 160WIR DC/DC converter: http://www.tracopower.com/fileadmin/medien/dokumente/pdf/datasheets/tep160wir.pdf or comparable. This one has an input voltage range of 43…160VDC, which should be good. The secondary DC voltage of this one is 15V, but you can adjust it down to -20%; so 13.8V is certainly possible, if you want to keep the battery connected all the time.  The power supply is 182W with heat sink mounted, so it will take care that he generator is never overloaded, since it will current limit the secondary. But you will have to take care that the DC/DC converter is good enough cooled, because it will have to work in ‘limiting’ condition almost all the time until your battery is full.
Like I already said, the only risk here could be that when the battery is full, the charge current drops to such a low value that the generator outputs a higher voltage than 160V which could damage the DC/DC converter. You should test that before connecting anything. A possible solution could be that you permanently connect a small light bulb to the generator, so you always keep the secondary voltage below 160V.
I hope this helped a little bit…
Andre

On January 10, 2014 at 12:23pm
FIYAZ wrote:

hi… I want to charge Sealed lead acid battery of 12V 7 AH with an adopter of 15V 1.2 Amp is my charger correct.? how long will it take to charge the battery fully. is there some indication that shows the battery is flly charged now. being sealed battery i can’t check specific gravity, i can only check voltage at 2 hour time strecthes and when it shows 13.2 volts. assuming each cell of 6 cell battery is 2.10 volts.
Weighting eagerly for your reply
best Regards
fiyaz abbas

On January 13, 2014 at 2:05am
Andre Van den Wyngaert wrote:

Hi Fiyaz,
you cannot connect the adapter directly to the battery, because you can damage the adapter. When the battery is empty, it will draw more than 1.2 amp, and the final charging voltage is too high as well. So you should reduce the voltage and the charge current a bit. It depends on the type of adapter how to do that. Is it a voltage regulated adapter or not? If it isn’t, you have more than 15V when there is no load (like 18V or more). If it is always 15V, it is regulated. In that case, you can reduce the voltage to 14.3V by adding a standard 3amp diode like 1N5401, and reduce the current by adding a 2.2ohm 5W resistor. Total cost 1 euro. So you connect the negative of the adapter to the negative of the battery directly, and the positive of the adapter through the diode and then through the resistor to the battery. So the resistor and the diode are in series. If you have no charge current, the diode is in the wrong direction and should be reversed.  Actually, the line on the diode should point to the battery. That’s all; it should work. Final voltage on a full battery will be 14.3V, so you should disconnect the battery then at the latest. But when the voltage is 13.8V, the current has already dropped to 200mA and not much charge is added anymore; the battery is then almost full. Since the charge current is decreasing while you charge, it is hard to tell how long it will take for a full charge. But I think 10 hours won’t be far wrong.
Best regards,
Andre

On January 16, 2014 at 11:25pm
schnitzelboy wrote:

Hi, I’m just a little confused about minimum temperature for charging a Lead Acid battery.  It says to never charge a frozen one, but what happens if you start charging warm and later it gets below freezing?  I believe it said it doesn’t freeze until -15 Celsius or because of the acid. 
I live in Calgary, Alberta and I am parking my car for the winter, and it is outside.  I have a 2A trickle charger connected to the battery inside my car.  It is smart enough to tell when it is full and switch to a charge maintenance mode.  Can I leave this thing on the battery all winter to keep it charged?  Keep in mind, it can get up to -40 Celsius with windchill, every once in a while.

On January 19, 2014 at 7:12am
George wrote:

I want to buy a deep cycle traction battery of 600 Ah 12 volts.

I like to make a solar panel for charging these batteries. What should be the capacity of
the solar panel in watts and the voltage out put and the current to charge these battery.

Alternatively if I use a wind mill what should be these numbers ( voltage out put, current capacity of the wind mill dynamo. )

appreciate your response. Kindly give any precautions I should take to have a better system that lasts long enough.

On January 22, 2014 at 7:06pm
Tom Calamaco wrote:

I bought a new 12V 7AH Sealed Lead Acid battery. Do i have to charge it when new before using it?

On January 22, 2014 at 9:12pm
George Mathew wrote:

Dear Andre Van den Wyngaert, Thank you very much for your reply about the DC motor dynamo. It was very informative for me Thanks again.
George

On January 23, 2014 at 1:52am
Andre Van den Wyngaert wrote:

Hi Tom Calamaco,
Lead batteries are never empty when sold. But it won’t be completely full either; it will be somewhere in between. I would charge it first to be sure you don’t discharge it to much.
Andre

On January 23, 2014 at 5:32pm
David wrote:

Dear Andre Van den Wyngaert, I’m designing a charger / psu for my boat. The batterybank is about 400Ah. As is the charger / psu can give about 4A @ 14,7V and about 26A @ 12V ( 16V @ 0A). It’ll not be a constant current charger but I can change how the power curve will be, but I’m not sure of how it should be.. I’m not sure how much power I’ll use when I’m in port. What voltage should I have on the charger / psu when I’m using power in port without making H2 gass when the battery is fully charged? I can make it up to 800W regardless of voltage, but I dont want to make it too complex, so I’m not making it with any PWM. I might make a cutoff @ 14,7V or a bitt less, but I hav not figured out how to make that work yet.

Should I lift the power curve a bit? (then i have to lift the no load voltage allso..) What should I do?

On January 24, 2014 at 6:50am
Andre Van den Wyngaert wrote:

Hi David,
like the explanation on top of this page says, you will need a topping charge voltage of approx 14.4V (or slightly higher if you wish). The current limiting of you supply will limit the current during the first stage of the charge (constant current) while the voltage raises slowly to 14.4V. The voltage then stays 14.4 (that’s the voltage setting of you charger) while the current will start decreasing. BUT you cannot leave the voltage at that level. Once you reach the 14.4V you can leave it there for max 48 hours, but then you must terminate the charge manually, or the charger must drop its output voltage to 13.8V. I have built such a circuit myself (for 5 parallelled 7Ah cells). Once the current drops below a certain limit (200mA in my case), the voltage goes down to 13.8V and stays there, so you can keep it connected forever.
Best regards,
Andre

On January 29, 2014 at 3:19am
KATY wrote:

can you please tell me, what is the maximum level of discharging the Battery in stand by mode

On January 29, 2014 at 5:11am
Andre Van den Wyngaert wrote:

Hi Katy,
that depends on some factors, but I’d say that it’s best to never discharge below 12V (if it’s a 12V battery). When you discharge further, you will see that the voltage decreases quite fast. Some say at 11.9V you can call it “empty”. You can go lower, but since the voltage drops so fast the delivered energy is negligible, and you will damage the battery.
If you stop discharging at 12V, I think it’s always safe.
Best regards, Andre

On January 30, 2014 at 12:40am
KATY wrote:

Thank u Andre and I am in need of one more information about temperature compensation. I got an information that there is a -0.05 V compensation in float voltage. is there any compensation in CC and CV too?. Can you please help me.

On January 30, 2014 at 2:10am
Andre Van den Wyngaert wrote:

Hello Katy,
I think the compensation in float voltage (CV in standby use) is -0.02V per cell for each 10°C the temperature raises.  So for a 12V battery it is -0.12V per 10°C. At 0°C it is 13.8V. At 10°C it is 13.68. And so on. Negative too: at -10°C it is 13.92V. 
I am not aware of any restriction of the CC charge current as function of the temperature. But that does not mean there isn’t any, of course… But when you are not really “on the edge” of allowable charge current for your battery, it won’t matter.
Best regards,
Andre

On January 31, 2014 at 1:55am
KATY wrote:

THank you andre. Sorry andre I have missed a term above. I am also in need to know the temperature compensation for the Gassing voltage. Can you please help me.

On January 31, 2014 at 2:43am
Andre Van den Wyngaert wrote:

Hi Katy,
I’m afraid I can’t help you on this one. On the internet, I found this table for lead acid 12V batteries::
-20°C: 17.82V gassing voltage
-10°C: 15.9V
0°C: 15.24V
10°C: 14.82V
20°C: 14.49V
30°C: 14.19V
40°C: 13.98V
50°C: 13.8V
Hope this helps you out…
Best regards,
Andre

On March 18, 2014 at 8:22am
T. Collins wrote:

Schnitzelboy -  About your cold weather concerns.  Keep the battery fully charged and you will have no issues with the battery freezing.  The Specific Gravity of the electrolyte of a fully charged battery will vary from battery manufacturer to manufacturer but should be somewhere around 1.3 kg / cubic dl. 

At this specific gravity the electrolyte will remain liquid at -60 degrees Celcius.  You can search the web for phase diagrams is you would like to double check my assertion.

Your trickle charger will offset the effect of self-discharge of the battery and the charging process adds energy (and heat) into the battery.

Bottom line:  No worries.

On March 19, 2014 at 5:50pm
binu a v wrote:

sir, i am an engineering student. i want to charge 12V 1.2Ah lead acid battery using a source which produce an output of 20V, and current in the range of 10mA, so can i charge the battery? if i can then provide me with required cicuitary please

On March 20, 2014 at 2:09am
Andre Van den Wyngaert wrote:

Hi binu a v:
charging with 20V 10mA is possible, but it will be slow. There are several ways to do it, and it will actually depend on some parameters you did not give. For example: should the current be limited, or can your source deliver “as much as possible” like a solar cell.
The below solution 1 has limiting. The others don’t.
1: use a simple series resistor. chances are small you will ever overcharge the battery with this small current. Value (20-13.8)/10mA = approx 560ohm 1/4 watt grin.  But just in case, you can put a zener diode over the battery to limit the voltage to 13.8V. A 14V zener will do, 0.5W, 10 cents. If you use a solar cell and there could be some discharging of the battery into the solar cell at night, you can add a small series diode 1N4148 betwen source and battery.
2: use a linear regulator to lower the voltage to 13.8V. You can find circuits on the internet with e.g. the LM317. It has an adjustable output, so you can set it to 13.8V (check datasheet, need 2 resistors: www.farnell.com/datasheets/1674527.pdf)
3: use a small 1W or so DC/DC converter like www.ti.com/product/lp2951. Is actually overkill, but in fact you could get some more charging current out of it. Input power is 20V 10mA = 0.2W. So you can get 0.2 / 13.8 = 14ma charging current out of it, if it had 100% efficiency. But it never has, so you probably won’t win a thing. It is a different situation if you sometimes have more power available and you want the most out of it (referring to the solar panel again). Then you could consider a DC/DC. They even exist in special versions for solar panels, where they search the most optimal working point to get the most power out of it. But probably not for low power like yours, so they would have higher cost and maybe more losses than benefits in your case.
If you need more information just ask, but please provide more details then.

On March 25, 2014 at 11:10pm
Jeff Bailey wrote:

What is the issue of using a 13.8V float voltage to charge 12V batteries?

I am needing to charge multiple independent batteries from a single power source (Solar panel). Using a 14.5V regulator and a 3A diode I can provide a maximum of 13.8 volts to each battery. Each battery is used for different loads - hence the multiple independent batteries. The batteries only get used on the occasional weekend so have a week or 3 to recharge.

I am sure this is better for the batteries than having them connected in parallel across a standard multi-stage solar regulator? Especially given that the batteries are different chemistries (mix of old and new SLA, an old car battery and an old truck battery)

On April 1, 2014 at 12:52pm
John wrote:

My automatic charger charges initially at 16V and I am concerned that this is too high.  I called the tech and he said that this is the design optimum. It has an AGM setting with initial charge at 12.5V which he said would not fully charge a conventional lead acid battery.

Please evaluate these comments. Thank you.

On April 1, 2014 at 1:03pm
John wrote:

Sorry: AGM voltage corrected.

My automatic charger charges initially at 16V and I am concerned that this is too high.  I called the tech and he said that this is the design optimum. It has an AGM setting with initial charge at 15.5V which he said would not fully charge a conventional lead acid battery.

Please evaluate these comments. Thank you.

On April 8, 2014 at 9:48am
wynn wrote:

Hello writer, you have a great and helpful article. I am hoping that you could help me with my problem.
I am working in a plant. Our system requires 24VDC Back-up Supply. In the battery room, the setup is like this: 4 12VDC batteries are there. They are divided in two groups. Each group is composed of batteries connected in series to form a 24VDC Supply. The two groups are connected in parallel to the charger. The Charger Voltage is 29.4VDC and Charger Current is 40.1A. The charger is set to float charging. These are the problem: 1. Group no. 2 is overheating. 2. Group no. 2 has seen gassing in the cell cap. Is my system still normal? If not, can i ask you some recommendations on what to do?

On April 15, 2014 at 8:08pm
Jagat Modi wrote:

Can any body share the probability of lead acid automotive battery being exploded durting cracking of an engine ? And also the same battery being used for DG starting with permanent float cum boost charger connected ?
And what are the SOP for lead acid batteries used for such applications ?

On April 16, 2014 at 7:15am
Azerty wrote:

My 12V 18 Ah lead acid battery is fine after charging, there is no trapped gas. But if I let the battery sit for 24 hours (nothing connected to the terminals) and I tilt the battery slightly, pea sized gas bubbles appear from between the plates and bubble to the top in more than one cell. As if gas develops over time which is trapped between the plates and can not escape to the top apart from at the sides (by tilting 10-20 degrees).
New gas appears every day.
Is this normal, what does this say about the battery, is it ok (to use) ?

On April 19, 2014 at 3:05pm
Kawika wrote:

Is there a formula of the amount of amps for proper charging of AGM batteries? I am taking a 600 AH string off line and putting a 150 AH string in place for a temp string but I don’t want the rectifiers to cook the batteries. I can adjust voltage if need be but want to understand if I need to adjust the amps. thanks

On April 25, 2014 at 3:48am
karthik wrote:

Dear sir,
    I have 12v,7.5amps Lead acid battery.so i need to charge this battery by 12v dc,3.5amps SMPS.If it is possible or not

On April 28, 2014 at 1:02am
Andre Van den Wyngaert wrote:

Hi Karthik,
you need 13.8V float voltage and preferrably 14.5V topping charge voltage to charge a 12V cell. You cannot do it with a 12V SMPS. Maybe there is a possibility to tune the SMPS to 13.8V?

On April 28, 2014 at 1:07am
Andre Van den Wyngaert wrote:

Hi Wynn,
you say the charger is set to float charging. Yet the voltage is 29.4V DC which is way too high for float charging lead acid batteries, in my opinion. You need approx 27.6V for float charging. If your voltage stays 29.4V all the time, you stay in topping charge as described on page 1 of this article.

On May 13, 2014 at 8:05pm
Jasmine Martinson wrote:

Hello, I have an inverter and 12 x 6volts batteries along with a generator for changing purposes. Just bought 12 new batteries I am in a 3rd world country and they fill the acid in the batteries when they get here. Wondering if these batteries should be floated before used. Also how long should they be charged and on what level of charge I am in Haiti and it’s above 90 F almost all the time. Thank you for your kind reply.

On May 14, 2014 at 6:16am
Bob Kondner wrote:

Hi,
  It is normal to ship the batteries dry and fill them with acid as they are sold.

When manufactured the plates are build using PbO2 which is the charged condition. When the acid is added they act as fully charged..

It will take a few cycles to reach full capacity and the pressing of PbO2 into the plates does not seem (my limited observation) to form the best contact. After 2 or 3 cycles you should see full capacity or better.

Bob K.

On May 20, 2014 at 8:16am
David Franer wrote:

How can I read the anxwers to the questions posed on the page?

On May 21, 2014 at 1:21am
Andre Van den Wyngaert wrote:

Hi David,
this is actually a “comments” page. But since some people started to ask questions and some people started answering them, you will find answers to some questions between the comments. At least, they are in chronological order, so if someone gave an answer you will find it somewhere below the question…
Good luck!
Andre

On May 22, 2014 at 4:29pm
George wrote:

I have an unusual application where I need short bursts of high power but much much lower average power.  The idea is to use a battery bank to provide the peak power with a much lower power charger and prime power source (ac mains or motor-generator) to supply the average power, i.e., using the batteries as a buffer. 

Here is a nominal scenario employing 50 88 Ah 12V automotive starter batteries.  The worst case (<5% of cycles) the power rapidly ramps over a few seconds peaking at 200 kW and then slowly tapering down to near zero over the next 45 seconds or so.  The peak current required is thus around 350A and the total energy required for a cycle is less than 1.75 kWh. Then the system has at least 10 minutes to rest/recharge.  More nominal cycles are at 2/3 these levels and commonly less.  (Operation is over the daytime only and there will be extended periods (days) where saturation charging can be applied using best practices.  Operating temperatures will rarely exceed 35 C and storage will typically be at 20 C or less.)  The charger power is under 15 kW so the charging rate is C/3 or less.  A key requirement is durability – on the order of 10,000 cycles – which further drives using a large number of batteries to reduce the stress (DOD and peak current). 

An 88 Ah 12V battery holds about 1 kWh so 50 hold nearly 50 kWh.  So the worst case depth of discharge from one cycle is about 1.75/50 or only about 3.5% and more typically under 2.5%, i.e., essentially micro-cycling.  So many batteries are employed to provide the peak power and for durability, not for the energy capacity. Calendar lifetime is also a strong consideration and leads me to my real question.  In Batteries for a Portable World, Revision 3, page 217, there is mention that stationary batteries employ a lower acid concentration (SG ~1.225) to reduce corrosion and prolong calendar life.  Would it make sense to dilute the electrolyte in the automotive starter batteries to around this level to improve calendar life?  I understand this would reduce the open cell voltage a bit requiring somewhat more current (or adding a couple more batteries) but could this move the calendar life out well beyond 5 years?  I see references for up to 10 year service life for stationary batteries and I assume operating with lower SG to reduce corrosion is a big driver.

Ideally I would like to be using lithium-phosphate to provide the power/durability at much lower weights but capital costs and BMS complexity are important considerations for a prototype demonstration system.  [An even better solution is using ultracapacitors but I will not go into that.]  Hopefully when these initial batteries become marginal in 5 – 10 years the lithium (or ultracapacitor) option will be more palatable but this is a potential bridging strategy until that time.

On May 22, 2014 at 5:45pm
Bob Kondner wrote:

George,
  I have been looking at something similar here but at 2KW. I would worry that 200KW from 50 pieces of 88AHr 12V batteries is probably not going to work. t 350A load is going to drop your battery voltage terribly. And dropping the voltage probably means you will need MORE current.

I have a 12V 350AHr battery (2 pieces of Rolls 460) and getting 200A at 10V delivered to my load terminals is difficult. Batteries, wires safety devices, the drops all add up.

I would be very curious what you get for battery voltage during a 45 second test at 350A.

Bob K.

On May 23, 2014 at 8:21am
George M wrote:

Bob,

I have not constructed the system yet so all I can do is an analysis.  These would be starter batteries with CCA values >900 A.  That says they can produce 900 A (new) for 30 seconds at 0 F without falling below 7.2 V (1.2 V per cell).  The operating temperature in this application is rarely under 50 F and more typically 70 F or higher.  This is more in the Hot Cranking Amperage temperature range which yields considerably higher current ratings, let’s assume 1400 A HCA.  If the open cell voltage is >2.2 V the string voltage is > (50*6*2.2) = 660 V.  1400 A HCA should guarantee that the voltage drop is less than 350/1400 * (2.2 - 1.2)  = 0.25 V/cell.  This would drop the string voltage to no less than 50*6*1.95 = 585 V.  350 A at this voltage would be 205 kW.  (This does ignore cabling drops so maybe a little higher current.)  Note that the peak power only lasts a few seconds and then tapers off to near zero by the end of 45 seconds.  This means the battery current will also be dropping to near zero (and the loaded string voltage rising) over a cycle.  So 350 A is the peak current, not a constant current over the cycle.  And again I need to reiterate this is the worst case condition that applies to less than 5% of cycles.  More typically the power levels are 2/3rd this level or below.  Automotive starter batteries are employed for their power density.  Deep cycle batteries would not be appropriate for this application. 

There is an existence proof for batteries used in a similar application that are currently achieving 5+ years of service life.  This means the lifetime issues are getting into the calendar life limits of the batteries.  My question is, can I increase the calendar lifetime of batteries in the application by intentionally diluting the electrolyte towards the value used in stationary batteries?

On May 23, 2014 at 9:37am
Bob Kondner wrote:

George,

Yes, a starting battery would be more appropriate than my deep cycle.

Can you test a single 12V battery and see what it does? I would be very curious as to the voltage drop.

I just ordered a small quantity of LiFePO4 cells (18650 sized, about 1AHr) with 35A continuous rating. (About $3 a cell) I want to measure the pulse characteristics. I do wonder if nanoparticle Li (like what A123 was producing) would be the cheaper route. You could get 120A for 10 sec out of those. For 200KW you are talking about 550 cells.

Bob K.

On May 23, 2014 at 12:31pm
George M wrote:

Bob,

I am still about a 9 months from starting prototype construction and purchasing the batteries will be one of the last component sets acquired for just this calendar lifetime issue.  The CCA test is very definitive and my analysis above should be conservative.

What I use for the power buffer is not fundamental to what I am trying to demonstrate in this prototype.  I would like to use LiPo similar to those produced by A123 but the cost and BMS complexity are unacceptable at this time.  Your cost is better than I have heard for such high-C rate cells.  Can you share your vendor information.

-George

On May 23, 2014 at 1:30pm
Bob Kondner wrote:

George,

hugebattery.com They quotes a IFR18650 at $3 for quantity 20. I still have to receive a datasheet so I am still totally in the dark on these. For me I just need 2KW for short (IE Motor starting periods) bursts. Deep cycle batteries after that.

I am bob at kondner dot com and Skype: rkondner

Give me a shout and we can take it off line.

Bob

On June 2, 2014 at 4:56am
George Moore wrote:

I posed a question in my post of 6/22 above that has not yet been addressed by anyone.  I got into a side discussion with Bob Kondner but the fundamental question was never addressed. “Would it make sense to dilute the electrolyte in the automotive starter batteries to around this level [that of stationary batteries] to improve calendar life?  I understand this would reduce the open cell voltage a bit requiring somewhat more current (or adding a couple more batteries) but could this move the calendar life out well beyond 5 years?”  Further details of the application can be seen in the referenced post.

Any comments to these questions would be much appreciated.

George M

On June 21, 2014 at 3:35am
Hari Narayan wrote:

This site also gives good info on charging lead acid batteries:
http://electronicspani.com/battery-charging-of-lead-acid-batteries/

On June 21, 2014 at 3:36am
Hari Narayan wrote:

This site also gives good info on charging lead acid batteries:
http://electronicspani.com/battery-charging-of-lead-acid-batteries/

On June 24, 2014 at 6:52pm
George M wrote:

One Last Time:

I posed a question in a post of 6/22 above that has not yet been addressed by anyone,  “Would it make sense to dilute the electrolyte in the automotive starter batteries to around this level [that of stationary batteries] to improve calendar life?  There is reference to some stationary batteries having up to 20 year lifetime attributed to reducing the specific gravity (acidity) to reduce corrosion.  I understand this would reduce the open cell voltage a bit requiring somewhat more current (or adding a couple more batteries) but could this move the calendar life out well beyond 5 years?”  Further details of the application can be seen in the referenced post.

Any comments to these questions would be much appreciated.

George M

On July 9, 2014 at 1:16am
Mark Hull wrote:

To George M:

I don’t track BU posts much, but yours caught my eye. I hope this doesn’t come too late.

I am/was an aerospace electrician for over 30 years. I am not an engineer, but having worked in the battery shop for several years I beleive I can give you some usefull information.

Reducing the S.G. of the electrolyte would theoretically increase calender life. However you would also be decreasing capacity. When manufacturers of starter batteries started offering 3 year no pro-rated replacement, reducing the S.G. of their batteries to reduce grid corrosion was one of the things they did in order to offer that warranty..

The 20 year batteries you’re referring to are generally constructed with solid lead plates aka Plante type cells. Depending on who the manufacturer is sometimes it’s only the positive plate. That said, and after reviewing your original post, IMHO using flooded batteries is not your best option. AGM batteries are. This is due to their very low internal resistance. They are able to supply very high rates of current while generating very little heat. You didn’t specify if all your batteries are in parallel connection, but I am assuming from your original post that they are. Also what you described in your original post sounds very much like the requirements needed by those who build those mega watt audio competition cars and vans. Originally, they used very large capacitors to augment the quick response required by their MOSFET amplifers driving large subwoofers. For the most part they are all now using AGM batteries simply because AGM can supply the extremely quick reaction time needed by the amps and are able to supply it for much longer times than what the capacitors are capable of. AGM also offers very quick recharge times of C/5 or greater. You also stated that you were looking for a 10,000 cycle lifetime. I don’t know of any manufacturer that has tested their batteries under the conditions you’re wanting including the LiFePO4 ones. That said, I still beleive that AGM offers the best option concerning lead-acid. Heat is the enemy. Whether from external ambient or from charge/discharge cycles. Since your external conditions seem well controlled, your left with the latter. Again, due to the ultra low resistance AGM is the only way to go. Odyssey battery and Concorde/Lifeline are the 2 manufacturers that come to mind. I also wouldn’t count out Fullriver Battery either. They are Chinese in orgin, but they’ve had overall good reviews.

I also don’t beleive you need anywhere near 50 batteries for a max discharge of 350 amps over 45 seconds. I think you could get by with 10 or less group 31 size batteries.

The other extremely important consideration in longevity is charging. Since no 2 batteries charge at identical levels, they should all be charged individually. This is borne out in the golf cart world where 6 to 8 batteries are connected in series and charged by either a 36 or 48 volt charger. This set-up always leads to premature failure since some of the batteries in the string charge before the others do leading to an overcharge in some and under in others. In a parallel string you still have the same problem. Individual charging is the only solution for maximum lifespan.

So what would I do in your situation in light of no hard data to draw from. I would start with 8 Group 31 AGM batteries and 2 each four bank marine chargers. Procharge or NOCO are the two best multibank chargers out there for the money. Charles Industries chargers also offer a much more sophisticated charger that allows you to program the charge parameters yourself (but at a premium price too). Then I would start tracking the performance data and add banks on an “as required” basis. I think you’re going to be surprised at how well the smaller group will perform. I’m going to check the “notify me” on this. I would be interested on how your project goes….

Regards,
Mark

On July 9, 2014 at 10:05pm
Mark Hull wrote:

To George M,

I had some more time to reflrct on this. Fullriver makes a Deep cycle AGM battery in the BCI standard 8D. These 175 Lb behemoth’s are rated at 1830 cranking amps ar 32 degrees F. This is a standard 30 second test before it drops below 7.2 volts. I would think that 1 or 2 of these at the most should siffice your requirements. This would dramatically reduce the number of connection points improving overall efficiency. Just my 2c.

On July 10, 2014 at 5:55am
Bob Kondner wrote:

Hi,
If you look at George’s requirements you see a short period (10s of seconds or so) at 200KW.

To 1830 Amp at 7.2V is only 13KW. he would need about 13 of these “Behemoth Batteries”.
Bob K.

On July 10, 2014 at 6:23pm
Mark Hull wrote:

Hi Bob,

Point taken. Probably shouldn’t be posting at 1:20 AM. I was zeroing in on the 350 peak amp. But something still doesn’t add up. How can he have a 200,000 watt peak and a 350 Amp peak in the same cycle? If I still remember Ohm’s law correctly;

350A x 12.6V = 4,410 watts (ignoring voltage drop for the moment)
200,000 ÷ 12.6 = 15,873A (not the 350 as stated).

So how can he have a 200kW (200,000 watts) and a 350 A peak in the same 45 second cycle?

Also, he states that an 88 AH battery has about 1kW. It would appear that he’s just multiplying 12V x 88A = 1,056. He’s not taking Peukert’s law into account. Starter batteries are all rated at a 20 hour rate, not a 1 hour rate.

Like I said, I’m not an engineer, nor do I profess to be an expert by any means. I reviewed his post several times and the math is still not adding up to me. Am I wrong? It’s got me wondering now. (Almost wish I hadn’t jumped in now. It always gets me in trouble).

Kindest Regards,
Mark

On July 10, 2014 at 7:04pm
Mark Hull wrote:

Hey Bob,

I just went over his May 23rd post reply to you. In his original post I can’t determine if he’s designing his battery bank in series or parallel. On his May 23rd post it would appear it’s series??? Is he needing high voltage 585? 660? at 350A. Or is he needing 350A at 12.6V?  350A for 45 seconds at 12.6V isn’t much of a problem. If he really is needing the 200kW, WOW! I don’t think the Tesla needs that!!!

AGM’s are still the only way to go though IMHO.

Mark

 

On July 11, 2014 at 6:35am
Bob Kondner wrote:

Hi,

At 200KW you want to work with as high a voltage as is reasonable, and the and the load is very importance naturally.

600V is probably an upper limit, that is 330 Amps for 200KW. That would be 50 pieces of 12V batteries in series.

Their is a problem drawing high currents from a 12V battery such that the voltages drops below 8V, the problem is about 50% of the power is being dumped into the battery as heat. Draw 1000A from a starting battery and see how long before it starts to generate steam!

On July 11, 2014 at 12:09pm
Mark Hull wrote:

Hi Bob,

Agreed. Ohm’s law. Increase voltage, decrease amps. But you still don’t want to use flooded batteries in this application for the very reasons you state. I wish the OP would clearly state what their actual voltage and amp draw requirements are. Because 200 kW does not equal 350 amps at 12.6 volts. That violates Ohm’s law. I looked up the Tesla battery back. Taken from Wikipedia. The referances used are sound:

“Tesla Motors refers to the Roadster’s battery pack as the Energy Storage System or ESS. The ESS contains 6,831 lithium ion cells arranged into 11 “sheets” connected in series; each sheet contains 9 “bricks” connected in series; each “brick” contains 69 cells connected in parallel (11S 9S 69P). The cells are of the 18650 form-factor commonly found in laptop batteries. Sources disagree on the exact type of Li-Ion cells—GreenCar says lithium cobalt oxide (LiCo),[112] while researchers at DTU/INESC Porto state lithium manganese oxide (LMO).[113] LiCo has higher reaction energy during thermal runaway than LMO.[114]

The pack is designed to prevent catastrophic cell failures from propagating to adjacent cells (thermal runaway), even when the cooling system is off.[115] Coolant is pumped continuously through the ESS both when the car is running and when the car is turned off if the pack retains more than a 90% charge. The coolant pump draws 146 watts.[45][116][117][118]

A full recharge of the battery system requires 3½ hours using the High Power Connector which supplies 70 amp, 240 volt electricity; in practice, recharge cycles usually start from a partially charged state and require less time. A fully charged ESS stores approximately 53 kWh of electrical energy at a nominal 375 volts and weighs 992 lb (450 kg).[119][120]”

I have much personal experience starting stationary diesel engines in the cold. Most were using 24 volt ststems and 4 8D batteries in series/parallel configuration. Their starters pull well over 800 amps. I’ve had to crank these over 30 seconds and I had a digital volt meter to monitor the batteries. Voltage never dropped below 20 to 21 volts until after about 45 seconds. Oh well, seems he’s not monitoring the discussion board anyway. Have a great weekend! I’m outta here….......

Cheer’s
Mark

On July 27, 2014 at 11:36am
tonykid wrote:

Question. MY solar battery can’t reach even 12.8V in what ever charger I charge. pls what should I do

On July 27, 2014 at 5:26pm
Bob Kondner wrote:

Well, you have a problem. Hookup a cheap automotive charger but not for long. You should see that bring up the battery voltage. Do not leave such a cheap charger on your battery for long, cheap auto chargers will damage batteries if left connect for a long time.  You did not give a lot of info about your system but 12.8 is pretty low for a peak charging voltage.

Bob

On July 28, 2014 at 2:07am
tonykid wrote:

Sir is the battery ok,because I used many different type of charges

On July 28, 2014 at 9:24am
Bob wrote:

You have not given me enough information to confirm that you battery is good or bad. You did not state the capacity and type of batter nor did you supply information about charging time and current. Gather that information and ask again.

Bob

On July 29, 2014 at 1:26am
Mark Hull wrote:

+1 Bob.

Tony,
Need the following:

1. Brand of battery (preferrable to look up specs
2. AH rating (20 Hr rate)
3. Age of battery in service (very important)
4.Type of battery (flooded, AGM, or Gel) (also very important)
5. If flooded, what is specific gravity of electrolyte each cell?
6. List chargers used and what settings you used.

 

On August 4, 2014 at 11:53pm
ashwanth wrote:

List chargers used and what settings you used

On August 16, 2014 at 12:22am
ASLAMAZADLITON wrote:

In a LEAD-ANTIMONY Battery Factory ,
1) where plates are charged in SERIES CONNECTED VATS at FORMATION SECTION through a CONSTANT Voltage RECTIFIER , what is the detail formula for determining the optimum Current and Optimum charging time ?
2) What are parameters ( CCA , OCV , SG of H2SO4 , etc. ) and what range of value are confirmatory to a low knowledge Battery workers that each of the BATTERY , he is sending to Customer are well PASSED ?
3) Which of the following option is better in terms of quality and why—
a) Battery produced from Charged plate ( as stated above ) followed by H2S04 Acid filling followed by Bo0st Charge with Battery Charger .
b) Battery produced from NO Charge plates followed by H2SO4 filling followed by Charge by Battery Charger .
4) What type of Charger will be most appropriate to CHARGE our battery mentioned at 3( a) or 3( b) ? Is it a constant voltage Charger ?
5)What is the formula for determining the specification ( VOLTAGE & AMPS ) of a above noted ( point-4 )charger with Number of Battery are in series connection ?
6) If we made a graph with the voltage and amp. shown at the meter connected with the above mentioned constant voltage charger with time of charging ( MINUTES ) , what will be the shape of this graph ? At what point of the graph , operator will understand all the series connected Batteries are optimum charged .

On August 16, 2014 at 12:26am
ASLAMAZADLITON wrote:

In a LEAD-ANTIMONY Battery manufacturing Factory ,
1) where plates are charged in SERIES CONNECTED VATS at FORMATION SECTION through a CONSTANT Voltage RECTIFIER , what is the detail formula for determining the optimum Current and Optimum charging time ?
2) What are parameters ( CCA , OCV , SG of H2SO4 , etc. ) and what range of value are confirmatory to a low knowledge Battery workers that each of the BATTERY , he is sending to Customer are well PASSED ?
3) Which of the following option is better in terms of quality and why—
a) Battery produced from Charged plate ( as stated above ) followed by H2S04 Acid filling followed by Bo0st Charge with Battery Charger .
b) Battery produced from NO Charge plates followed by H2SO4 filling followed by Charge by Battery Charger .
4) What type of Charger will be most appropriate to CHARGE our battery mentioned at 3( a) or 3( b) ? Is it a constant voltage Charger ?
5)What is the formula for determining the specification ( VOLTAGE & AMPS ) of a above noted ( point-4 )charger with Number of Battery are in series connection ?
6) If we made a graph with the voltage and amp. shown at the meter connected with the above mentioned constant voltage charger with time of charging ( MINUTES ) , what will be the shape of this graph ? At what point of the graph , operator will understand all the series connected Batteries are optimum charged .

On August 16, 2014 at 8:27am
Bob Kondner wrote:

Hi,
You asked so many complex questions it is difficult to help but let me try.
1. If you have pre-charged plates then the concentration of H2SO4 will be fairly high. I suggest you find a manufacturer of a similar battery type and read their application notes.

2. A NO CHARGED plate will require a lower level of H2SO4 as acid will be formed as PbSO4 converts to H2SO4 during charging. Ensuring a quality battery is being shipped is difficult. My suggestion is find a discharge profile for a “Good” battery and verify each production battery matches that profile. But it takes time to construct and verify a profile. The time and equipment required to verify each battery might be too costly. Sample the batteries coming out of production if required be you can count on some percentage of bad batteriests being shipped to the customers.

3 I think construction from charged plates I I understand PbO2 is pressed into plates, I never heard of PbSO4 being used in plate construction.

4. Asking what is the “Best Charger” is a little silly, there are many different aspects to charging a battery, the best depends on the application. In General you want a multi staged current limited constant voltage where the applied voltage varies with the various charging phases.

5. There is no fixed formula. The literature from books and manufacturers is filled with all types graphs and charts.

6. Look at the top of this web page! Look at the literature. Make your graph and make certain it matches!

Bob K.

On August 30, 2014 at 4:39am
Jeff Deutsch wrote:

I have an old Sears 10A.unregulated, manual or auto shutoff battery charger. The auto shutoff circuit is three transistors with an adjustment pot, driving an SCR. Because of the voltage drop in the SCR it always charged at a couple of amps higher in manual mode, with the SCR bypassed. It was not working in auto or manual and I checked transistors and SCR and when all checked out I put it all back together and it worked but not quite right in auto. I’ll probably never know what was wrong. In auto mode it used to shut off cleanly but now it will drop to a couple of amps and not shut off but if I switch to manual for a minute and back auto it shuts off but then comes back on after a minute. . I’m pretty sure I am putting a higher top charge in manual that quickly bleeds off. The fact that it can shut off tells me the SCR is OK but the shut off pot probably needs to be readjusted. For a maintenance free car battery, do I set cut off while connected until charger shuts off? Is 13.5V correct or another voltage?  Can it even be set while connected or do I have to tweak the pot until I get 12.6V. while disconnected after top charge has bled off? Thanks.

On September 6, 2014 at 1:58am
kapil G. wrote:

I am using 2 sealed lead acid batteries of 12V, 3.6 Amp Hr. in series to get 24 V , I want to use two stage charging algorithm CC-CV, I want to know what should be ideal current for cc modeand ideal voltage range in CC mode and when to shift from CC mode to CV mode in terms of state of charge or in terms of battery charging voltage.

On September 23, 2014 at 3:10am
Andre Van den Wyngaert wrote:

Hi kapil G. ,
It depends on the manufacturer of the cells - maybe you can check the website. But 3.6Ahr you can typically charge with 800…1000mA maximum; I would take 500mA as a max to be on the safe side.
So for 2 cells in series, current is still 500mA. Max voltage is approx 29.5V. So you keep CC 500mA until the voltage reaches 29.5V. Then you keep the voltage constant at 29.5V until the current drops to approx 100mA. Battery is full at that point. Then you lower the voltage to 27.6V and keep it there forever if you want.

On September 23, 2014 at 7:27am
kapil G. wrote:

Thank you ’ Andre Van den Wyngaert ’  , your suggestion will help me. I will work over it . If any problem persist i will post here.

also, Thanks for Battery University!

On October 18, 2014 at 10:29am
alan daykin wrote:

Some time ago I read an article on rejuvenating deep discharge battery’s by over voltage charging for a short spell .can anyone help as it was on my old pc.

On November 1, 2014 at 2:09am
OH wrote:

Hello!
I’m new here.
I wish we could share knowledge in this amazing batteries website!
Thank you all!

On November 4, 2014 at 4:06am
S T wrote:

nicely done, very informative.
thanks a lot.
www.eletorial.com

On November 20, 2014 at 3:08pm
JR wrote:

I have an off- grid cabin with the following electrical setup:  Two “banks” of batteries connected with a 1-2-ALL-OFF marine type manual switch, a 45A Progressive Dynamics RV battery charger/power supply, and a 1500W inverter.  The charge comes from a gas powered generator.  The primary battery is a pair of 6V golf cart GC2’s in series and the secondary is a 12V deep cycle marine.  When set to “ALL” both banks are connected to each other. When the generator is running, whichever bank is selected on the switch is connected to the charger, and also the house load.

My question is,  What is the best method of charging “bang for buck” wise as far as time running the generator?  My tendency has been to use each bank separately until both reach discharge (warning sounds on inverter) then set the switch to “ALL” and charge both banks in parallel for the bulk charging portion.  Then after the total voltage comes up (all batteries in parallel) after a few hours of running the generator, charge each individually (set to 1 or 2, not ALL) for the remainder of the charge, alternating between each so they can rest.  Is this correct, or should I be bringing them both to full float charge completely separately?  The only reason I don’t is it’s a lot of generator run time at a very low load.  With both banks in parallel do the pair of 6Vs and the 12V balance out to the reading I see on the inverter’s display, or am I really overcharging the smaller capacity battery?  I would appreciate suggestions - OR is this a case for a battery isolator?  If so I’m not sure how that wiring diagram would look.

thanks

JR