Charging Lead Acid
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.
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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.
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2.30V to 2.35V/cell |
2.40V to 2.45V/cell |
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Advantages |
Maximum service life; battery stays cool; charge temperature can exceed 30°C (86°F). |
Faster charge times; higher and more consistent capacity readings; less sulfation. |
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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 (SLA)
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 increases the voltage slightly and a warm one lowers 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
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Charge in a well-ventilated area. Hydrogen gas generated during charging is explosive.
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Choose the appropriate charge program for flooded, gel and AGM batteries. Check manufacturer’s specifications on recommended voltage thresholds.
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Charge lead acid batteries after each use to prevent sulfation. Do not store on low charge.
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The plates of flooded batteries must always be fully submerged in electrolyte. Fill battery with distilled or de-ionized water to cover the plates if low. Tap water may be acceptable in some regions. Never add electrolyte.
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Fill water level to designated level after charging. Overfilling when the battery is empty can cause acid spillage.
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Formation of gas bubbles in a flooded lead acid indicates that the battery is reaching full state-of-charge (hydrogen on negative plate and oxygen on positive plate).
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Reduce float charge if the ambient temperature is higher than 29°C (85°F).
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Do not allow a lead acid to freeze. An empty battery freezes sooner than one that is fully charged. Never charge a frozen battery.
- Do not charge at temperatures above 49°C (120°F).
Comments
nicely done, very informative.
thanks a lot.
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
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
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
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
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?
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.
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.
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
how to calculate connected load of battery chargers
360V-150A with 80% efficiency
Is a very useful page
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?
younas - Not sure that I understand your response.
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
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?
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
>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….
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
how many 12v 7AH sealed lead acid rechargeable batteries should i use to watch a 62 watts 240V colour TV for 10 hours
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
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.. 
Hello everyone. Be so kind to explain meaning of treatment charge for a battery.
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
Please help me about How to calculate AH of 12V, 65AH & 12V, 7AH lead acid batteries are connected in series?
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
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!!
Dear Sir what type of battery charging
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).
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.
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
to Ruairi
a shorter question?
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.
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.
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.
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.
To Tajammul
I am sure your battery is fine. Probabaly want somebody to check your car.
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.
to cornflake
it is possible. You need a dc-to-dc converter which is more expensive than replacing your 12 v battery.
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.
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.
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.
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?
Hi,
I am a student from India. I would like to know the lead content of different types of Lead Acid Batteries.
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)?
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?
Hi,
I want to know if a 12v, 500mA dynamo can be used to recharge a 6V, 4AH lead acid battery with suitable circuitry???
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
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.
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.
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.
To George
30% = 0.3
and there is an inefficiency factor you need to consider.
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???
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.
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.
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.
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
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
This article has been updated as of February 25, 2011.
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.
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
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
@Jin: The 70% SoC mention does not relate to charge currents and applies to small and large batteries.
We have updated this article with new information.
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
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
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
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
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. ?
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
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?
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?
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?
I forgot to add in my previous note “Notify me of follow up comments” dealing with lead contamination in battery acid.
thanks
why does a 12 volt lead caid battery hold 12 volts and very low on amps?
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?
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
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.
please send me charging and decharging curve of seald lead acid 2 V
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?
and the other question is the same except with a reg, car starting battery.
thanx alot…
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
I have four new 12 volt amg motorhome batteries connected in parallel. what battery tender (charger) spec should I use.
addition to above message- the motorhome is in storage for 3 months
correction to above two postings- the batteries are agm (glass matt)
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!
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?
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!
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
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.
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
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.
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?
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.
I have no other info on the battery. I can measure the battery voltage and also have a current sensor.
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.
Thanks sooooooooooooo much. Your help is right on time…
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
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.
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.
?? 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
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.
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!
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.
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.
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.
Is it possible to recharge a lead acid battery 12V - 80 Ah - C20 by using a charger of specification 14 V -1A. Kindly explain.
Is it possible to recharge a lead acid battery 12V - 80 Ah - C20 by using a charger of specification 14 V -1A? Kindly explain.
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)
Totally right.
Sir,
How to calculate the minimum amp to charge two 6V sealed lead acid battery connected in parallel?
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??
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?
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.
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.
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
How many cells are there in APC RBC 17 battery? It is a 12v, 7AH battery.
i asked a question about a week ago and still no reply. disappoionting!
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
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
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”?
hi,
i want to measure the battery capacity ?????? i need to charge the battery accordingly by measuring the battery capacity
sir, i need to know what charger will i use to charge 15 to 20 units of 12v 100ah batteries in one charging
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.
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 ?
hi batteryuniversity.com-ers all the best to every one - matt
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
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?
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!
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.
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?
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?
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
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?
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…...
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
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.
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…
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.
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
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