BU-201: How does the Lead Acid Battery Work?

Learn about the differences within the lead acid family and find out what the cons and pros are.

Invented by the French physician Gaston Planté in 1859, lead acid was the first rechargeable battery for commercial use. Despite its advanced age, the lead chemistry continues to be in wide use today. There are good reasons for its popularity; lead acid is dependable and inexpensive on a cost-per-watt base. There are few other batteries that deliver bulk power as cheaply as lead acid, and this makes the battery cost-effective for automobiles, golf cars, forklifts, marine and uninterruptible power supplies (UPS).

The grid structure of the lead acid battery is made from a lead alloy. Pure lead is too soft and would not support itself, so small quantities of other metals are added to get the mechanical strength and improve electrical properties. The most common additives are antimony, calcium, tin and selenium. These batteries are often known as “lead-antimony” and “lead­calcium.”

Adding antimony and tin improves deep cycling but this increases water consumption and escalates the need to equalize. Calcium reduces self-discharge, but the positive lead-calcium plate has the side effect of growing due to grid oxidation when being over-charged. Modern lead acid batteries also make use of doping agents such as selenium, cadmium, tin and arsenic to lower the antimony and calcium content.

Lead acid is heavy and is less durable than nickel- and lithium-based systems when deep cycled. A full discharge causes strain and each discharge/charge cycle permanently robs the battery of a small amount of capacity. This loss is small while the battery is in good operating condition, but the fading increases once the performance drops to half the nominal capacity. This wear-down characteristic applies to all batteries in various degrees.

Depending on the depth of discharge, lead acid for deep-cycle applications provides 200 to 300 discharge/charge cycles. The primary reasons for its relatively short cycle life are grid corrosion on the positive electrode, depletion of the active material and expansion of the positive plates. This aging phenomenon is accelerated at elevated operating temperatures and when drawing high discharge currents. (See BU-804:How to Prolong Lead Acid Batteries)

Charging a lead acid battery is simple, but the correct voltage limits must be observed. Choosing a low voltage limit shelters the battery, but this produces poor performance and causes a buildup of sulfation on the negative plate. A high voltage limit improves performance but forms grid corrosion on the positive plate. While sulfation can be reversed if serviced in time, corrosion is permanent. (See BU-403: Charging Lead Acid.)

Lead acid does not lend itself to fast charging and with most types, a full charge takes 14–16 hours. The battery must always be stored at full state-of-charge. Low charge causes sulfation, a condition that robs the battery of performance. Adding carbon on the negative electrode reduces this problem but this lowers the specific energy. ( See BU-202: New Lead Acid Systems. )

Lead acid has a moderate life span, but it is not subject to memory as nickel-based systems are, and the charge retention is best among rechargeable batteries. While NiCd loses approximately 40 percent of their stored energy in three months, lead acid self-discharges the same amount in one year. The lead acid battery works well at cold temperatures and is superior to lithium-ion when operating in subzero conditions. According to RWTH, Aachen, Germany (2018), the cost of the flooded lead acid is about $150 per kWh, one of the lowest in batteries.

Sealed Lead Acid

The first sealed, or maintenance-free, lead acid emerged in the mid-1970s. Engineers argued that the term “sealed lead acid” was a misnomer because no lead acid battery can be totally sealed. To control venting during stressful charge and rapid discharge, valves have been added that release gases if pressure builds up. Rather than submerging the plates in a liquid, the electrolyte is impregnated into a moistened separator, a design that resembles nickel- and lithium-based systems. This enables operating the battery in any physical orientation without leakage.

The sealed battery contains less electrolyte than the flooded type, hence the term “acid-starved.” Perhaps the most significant advantage of sealed lead acid is the ability to combine oxygen and hydrogen to create water and prevent dry out during cycling. The recombination occurs at a moderate pressure of 0.14 bar (2psi). The valve serves as a safety vent if the gas buildup rises. Repeated venting should be avoided as this will lead to an eventual dry-out. According to RWTH, Aachen, Germany (2018), the cost of VRLA is about $260 per kWh.

Several types of sealed lead acid have emerged and the most common are gel, also known as valve-regulated lead acid (VRLA), and absorbent glass mat (AGM). The gel cell contains a silica type gel that suspends the electrolyte in a paste. Smaller packs with capacities of up to 30Ah are often called SLA (sealed lead acid). Packaged in a plastic container, these batteries are used for small UPS, emergency lighting and wheelchairs. Because of low price, dependable service and low maintenance, the SLA remains the preferred choice for healthcare in hospitals and retirement homes. The larger VRLA is used as power backup for cellular repeater towers, Internet hubs, banks, hospitals, airports and more.

The AGM suspends the electrolyte in a specially designed glass mat. This offers several advantages to lead acid systems, including faster charging and instant high load currents on demand. AGM works best as a mid-range battery with capacities of 30 to 100Ah and is less suited for large systems, such as UPS. Typical uses are starter batteries for motorcycles, start-stop function for micro-hybrid cars, as well as marine and RV that need some cycling.

With cycling and age, the capacity of AGM fades gradually; gel, on the other hand, has a dome shaped performance curve and stays in the high performance range longer but then drops suddenly towards the end of life. AGM is more expensive than flooded, but is cheaper than gel. (Gel would be too expensive for start/stop use in cars.)

Unlike the flooded, the sealed lead acid battery is designed with a low over-voltage potential to prohibit the battery from reaching its gas-generating potential during charge. Excess charging causes gassing, venting and subsequent water depletion and dry-out. Consequently, gel, and in part also AGM, cannot be charged to their full potential and the charge voltage limit must be set lower than that of a flooded. This also applies to the float charge on full charge. In respect to charging, the gel and AGM are no direct replacements for the flooded type. If no designated charger is available for AGM with lower voltage settings, disconnect the charger after 24 hours of charge. This prevents gassing due to a float voltage that is set too high. ( See BU-403: Charging Lead Acid )

The optimum operating temperature for a VRLA battery is 25°C (77°F); every 8°C (15°F) rise above this temperature threshold cuts battery life in half. ( See BU-806a: How Heat and Loading affect Battery Life ) Lead acid batteries are rated at a 5-hour (0.2C) and 20-hour (0.05C) discharge rate. The battery performs best when discharged slowly; the capacity readings are substantially higher at a slower discharge than at the 1C-rate. Lead acid can, however, deliver high pulse currents of several C if done for only a few seconds. This makes the lead acid well suited as a starter battery, also known as starter-light-ignition (SLI). The high lead content and the sulfuric acid make lead acid environmentally unfriendly.

Lead acid batteries are commonly classified into three usages: Automotive (starter or SLI), motive power (traction or deep cycle) and stationary (UPS).

Starter and Deep-cycle Batteries

The starter battery is designed to crank an engine with a momentary high-power load lasting a second or so. For its size, the battery is able to deliver high current but it cannot be deep-cycled. Starter batteries are rated with Ah or RS (reserve capacity) to indicate energy storage capability, as well as CCA (cold cranking amps) to signify the current a battery can deliver at cold temperature. SAE J537 specifies 30 seconds of discharge at –18°C (0°F) at the rated CCA ampere without the battery voltage dropping below 7.2 volts. RC reflects the runtime in minutes at a steady discharge of 25. (SAE stands for Society of Automotive Engineers.) See also BU-902a: How to Measure CCA.

Starter batteries have a very low internal resistance that is achieved by adding extra plates for maximum surface area (Figure 1). The plates are thin and the lead is applied in a sponge-like form that has the appearance of fine foam, expanding the surface area further. Plate thickness, which is important for a deep-cycle battery is less important because the discharge is short and the battery is recharged while driving; the emphasis is on power rather than capacity.

Figure 1: Starter battery
The starter battery has many thin plates in parallel to achieve low resistance with high surface area. The starter battery does not allow deep cycling.
Courtesy of Cadex


Deep-cycle Battery

The deep-cycle battery is built to provide continuous power for wheelchairs, golf cars, forklifts and more. This battery is built for maximum capacity and a reasonably high cycle count. This is achieved by making the lead plates thick (Figure 2). Although the battery is designed for cycling, full discharges still induce stress and the cycle count relates to the depth-of-discharge (DoD). Deep-cycle batteries are marked in Ah or minutes of runtime. The capacity is typically rated as a 5-hour and 20-hour discharge.

Figure 2: Deep-cycle battery
The deep-cycle battery has thick plates for improved cycling abilities. The deep-cycle battery generally allows about 300 cycles.
Courtesy of Cadex

A starter battery cannot be swapped with a deep-cycle battery or vice versa. While an inventive senior may be tempted to install a starter battery instead of the more expensive deep-cycle on his wheelchair to save money, the starter battery would not last because the thin sponge-like plates would quickly dissolve with repeated deep cycling.

There are combination starter/deep-cycle batteries available for trucks, buses, public safety and military vehicles, but these units are big and heavy. As a simple guideline, the heavier the battery is, the more lead it contains, and the longer it will last. Table 3 compares the typical life of starter and deep-cycle batteries when deep cycled.

Depth of discharge

Starter battery

Deep-cycle battery




12–15 cycles

100–120 cycles

130–150 cycles

150–200 cycles

400–500 cycles

1,000 and more cycles

Table 3: Cycle performance of starter and deep-cycle batteries. A discharge of 100% refers to a full discharge; 50% is half and 30% is a moderate discharge with 70% remaining.

Lead is toxic and environmentalists would like to replace the lead acid battery with an alternative chemistry. Europe succeeded in keeping NiCd out of consumer products, and similar efforts are being made with the starter battery. The choices are NiMH and Li-ion, but the price is too high and low temperature performance is poor. With a 99 percent recycling rate, the lead acid battery poses little environmental hazard and will likely continue to be the battery of choice.

Table 4 lists advantages and limitations of common lead acid batteries in use today. The table does not include the new lead acid chemistries. (See also BU-202: New Lead Acid Systems.)


Inexpensive and simple to manufacture; low cost per watt-hour

Low self-discharge; lowest among rechargeable batteries

High specific power, capable of high discharge currents

Good low and high temperature performance


Low specific energy; poor weight-to-energy ratio

Slow charge; fully saturated charge takes 14-16 hours

Must be stored in charged condition to prevent sulfation

Limited cycle life; repeated deep-cycling reduces battery life

Flooded version requires watering

Transportation restrictions on the flooded type

Not environmentally friendly

Table 4: Advantages and limitations of lead acid batteries. Dry systems have advantages over flooded but are less rugged.

Last updated 2018-08-29

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Comments (115)

On March 22, 2011 at 4:56am
Taimur wrote:

how much current and voltage are requird for a 9v , 1a bettery.

On May 6, 2011 at 11:25pm
Bob wrote:

Article particularly table comparing deep cycle and starter batteries most helpful.

On May 10, 2011 at 4:24am
inbasekaran wrote:

Please add topics on FUEL CELLS the latest emerging technology

On September 20, 2011 at 10:13am
Ed Anderson wrote:

Question - Charge rate - is there a minimum charge rate to recharge a flooded LA battery?  I will be using a 100 AH deep cycle battery to back-up a water pump.  The inverter has a transfer switch and a 2.5 amp charger bulit in.  I know the charger can maintain the battery but can it recharge it after use?  If I use 50% of the capacity, and then the power comes on, can that 2.5 amp charger recharge the battery or do I need to use another charger to bring it back up to full charge?


On December 13, 2011 at 4:13am
NOOR E ALAM wrote:

Technical sub matter written in a very easy laguage, thanks to the writer

On May 11, 2012 at 9:18pm
Monikanta Bera wrote:

have a battery bike with led acide battery 7 anpair 12volt 4 battery with series link continew charg and discharge but noe it can not properly get backup so what can I do

On August 29, 2012 at 9:19am
Andy Amason wrote:

Question: I have a sailboat that is equipped with a switch for dual batteries. Battery # 1 is used for start up while Battery # 2 is used for lights, fans, radios etc.. while anchored. The engine is a small outboard (mariner 10 hp) The battery switch allows me to turn to Battery 1, Battery 2, or both. I like to start on # 1, have the switch in the both position while running, then switch to # 2 while anchored overnight. Battery # 1 is a starter battery while battery # 2 is deep cycle.
The question is will i damaged either Battery 1 or Battery 2 by having the switch in the “Both” position while running. I like having the switch because it allows me to isolate the start up battery from drainage while anchored overnight, and it allows me to use the engine to recharge battery # 2 while running, and I can isolate it from start-up drainage. I may not even need a cranking battery on such a small engine but I already have one, so it has been what I’ve used.
(Battery 1 is 800 CCA while battery 2 is 600 CCA)
Thanks for your advise.

On September 23, 2012 at 11:09pm
sreeraj wrote:

Please do let me know the following details for Liion battery
1.the safe charging (80%) volt 2.safe discharge with 80%DOD 3. charging current rate (ranges if any) 4. discharging current rate (ranges if any)
If i do select 80%chargin n discahrging what could be the life time of the battery.

On September 25, 2012 at 8:24pm
Justin wrote:

You are doing it right. The only problem you might have is after you start your outboard in the morning and switch to both.
When you switch to both, the deep cycle or “overnight” battery will be at a lower state of charge. Soon as you throw the switch to both, the start battery will quickly dump some of it’s charge into the overnight battery, trying to balance out. As long as you run the outboard long enough to fully charge both batteries, you will have done no harm at all.
Hope this helps.

On November 3, 2012 at 11:31pm
Jeffrey Lim wrote:

I use 2 -12v 10Ah SLA batteries for my electric bicycle motor 24v 10Ah. Is there a way to increase performance to the motor with a different type of battery.? Is there a high performance battery that would work better and give me more power .?

On November 10, 2012 at 9:26am
HEETEL64 wrote:

I am about to reverse engineer the car battery so that it can be used alternatively to fulfill it’s true potential. Think people, don’t be SHEEPLE.

On November 10, 2012 at 9:32am
HEETEL64 wrote:

The posts are following a trend. How are you going to truly change the corporations that are feeding the less enlightened areas of the planet. Do not, just introduce a different way of using what they already have so that they can fit into the bigger picture that is important to us but not to them.

On December 1, 2012 at 11:28pm
John Fetter wrote:

HEETEL64 - It might be useful to the rest of us if you explain what you are aiming to achieve.

On December 2, 2012 at 3:13am
Heetel64 wrote:

Sorry John Fetter, I was thinking along the lines of bleeding the gas from the battery if it could somehow be given a constant charge from the alternator and using the gas as an additive during the combustion process of the engine itself. I believe this could only be done if a separate sort of battery were connected to the alternator that was specifically designed not for charging or starting but just for the production of the gas. I have recently been looking at the benefits of using some sort of water splitter to do the same thing but ther just might be a possibility of using existing battery technology instead of going down the water route. Just a thought.

On December 2, 2012 at 9:17am
John Fetter wrote:

Heetel64 - Intriguing idea. Surely you must be thinking of using the gas as a combustion improver and not as a fuel source. I suspect the hydrogen might have some positive effect. The oxygen merely combines with the oxygen of the air.
The efficiency of the best industrial scale electrolysis hydrogen generators is less than 50%. It makes me smile when I read about hydrogen fulled cars.
Simple idea to verify. Get hold of a bottle of hydrogen gas, regulator and put it into a car engine. Put the car on a dyno. Measure fuel in, power out. Alternatively, use one of those small generator sets. Easy to load up accurately and relatively easy to measure the fuel consumption. I tried some methanol mixed with gasoline on mine once. It did make it run more evenly.

On December 2, 2012 at 8:38pm
HEETEL64 wrote:

Firstly my invention is to be used as a combustion aid or additive.it must be accessible to all without fear of cost. It is not a replacement for existing technology or fuels. I would not want to go up against the BIG BOYS OF INDUSTRY.

On December 2, 2012 at 11:16pm
John Fetter wrote:

HEETEL64 - An individual does not stand a chance against the large corporations, no matter how well patented the invention. Even a couple of million dollars is not enough to fight an effective patent infringement case nowadays. They simply counter-claim the patent is invalid, dish up thousands of other additive patents, and slowly work through them, until the inventor’s money is gone. Also bear in mind courts are strongly biased against inventors from other countries. In other words, large corporations simply take what they want to take. Tyranny of numbers. The intermittent windscreen wiper case is a famous example. I hold more than a dozen patents. I deliberately stick to the smaller technologies. One did hit the jackpot, did what it was supposed to do, right up to expiry.

On December 3, 2012 at 12:21am
HEETEL64 wrote:

You are right, try not to seems to be the Dameclean Sword waiting for those brave or foolhardy enough.
On a tangent, I had a thought that quite possibly the 2 battery system might actually be the solution for the sulfation problem. Consider one being the master as it were for daily requirements and the other a slave used to dump a top up load once the master is no longer receiving the charge required. Consider what I said in an earlier post about one battery receiving a constant charge with a view to making gas and marry it to the concept of dumping it’s load ( sorry about that one ) into the depleted main battery.

On December 3, 2012 at 12:52am
HEETEL64 wrote:

How is it that the car battery has not been replaced by a modern take on the capacitor ?

On December 3, 2012 at 12:59am
John Fetter wrote:

HEETEL64 - Both batteries will most likely end up sulfated. The solution is simple. Apply a gentle overcharge to a lead-acid battery from time to time. People who claim batteries wear out through sulfation are barefaced liars. Lead-acid is naturally inclined to discharge slowly. Sulfation is a consequence of allowing this to happen. Neglect. When lead-acid is gently overcharged regularly, it lasts for decades. Some battery manufacturers are happy to suggest their batteries be slightly overcharged. Others say nothing, hoping to sell more batteries that way. The process that causes the best maintained batteries to wear out eventually is positive grid corrosion, followed by positive active material shedding.

On December 3, 2012 at 1:13am
John Fetter wrote:

HEETEL64 - A capacitor costs more than a battery. The consumer will only buy the cheapest piece of technology on offer. As long as it cranks the engine to the end of the warranty period. The lead-acid car battery has become a mere commodity. It has become a grudge buy. The days of people wanting to buy good stuff are long gone. The consumer is in charge. The consumer decides. No manufacturer dares to make a battery that lasts.

On December 3, 2012 at 1:27am
HEETEL64 wrote:

Point taken about capacitor.
As for regular overcharging to prolong battery life, I guess making this knowledge universally available could increase sales in rechargeable overcharges for the masses who are not scared of the battery manufacturers warning that any interference will cancel the battery warranty. If not given a regular boost, the thing has a limited lifespan anyway. I find it a pleasure learning from you. It never occurred to me that there was a relation between the pre existing battery boosters and sulfation. The secondary battery option would of course not be a lead based unit so some sort of competitively priced hybrid would have to be used. The market for a rebranded hand held overcharging unit could have potential.

On December 3, 2012 at 2:05am
John Fetter wrote:

HEETEL64 - Selling an ordinary charger is not a very marketing oriented thing to do. Pulse chargers can be regarded as ordinary chargers with extra sizzle. A product plus a pseudo-technical explanation. Hence they sell quite well to the “enthusiast” market segment. Pulse chargers deliver energy pulses, meaning their output volts and amps adjust automatically to suit the load. The simple fact is they can keep batteries in quite good condition. I tried to desulfate with several types of pulse chargers, per sales blurb. The results were not impressive. In the end I came to the conclusion it is an over-traded gadget market.
I looked at the industrial battery market for opportunity. Found a way to reduce water consumption, reduce self discharge and improve industrial motive power battery life, all based on one simple automatic service routine. After they used it for a couple of years, they love it, but getting past the front door the first time is excruciatingly difficult. Too many people in the professional segment have heard too many battery remedy hoax stories.

On December 29, 2012 at 8:18pm
raga wrote:

during charging batteries of inverters (150amp) will it affects human life

On December 29, 2012 at 8:30pm
DR .S.JOHN wrote:


On December 29, 2012 at 8:31pm

no its not harmful

On February 6, 2013 at 4:11am
Muhammad Sarwar wrote:

I have a 24V 320Ah Battery.I was purchasse before 1 yar . we facing problem his one cell is battery dead.TOC for Dead Cell after charging finish is 1.4 V. After 45 minutes, it downed to 0.7V..(charging voltage of bank is 29.7v and volts /cell is 2.3 to 2.5volts and of defective volts 2.0 and when unplug charger, then volts of good cells are 2.4 to 2.6 /cell and defective cell volts are 1.8 and slightly decreased without load.)?(after charging, specific gravity of good cells is 1.275 whereas of defective
cell is 1.100. Same as without charging)
Please sen me his bettre solution.

On February 14, 2013 at 11:18am
Steve Bradish wrote:

I have 12 new Hoppecke 2volt (1415ah c-20) OPzS lead acid batteries(24v system) with an Outback Mx60 solar controller.  The Outback has a problem where I can’t change the settings which are absorb 29.5v, float 28.2.v.  The new batteries call for the charge be 26.8 to max of 28.8 and float up to 27.6.  My question is whether these higher settings on the Outback will be a problem for my new batteries?

On February 14, 2013 at 3:29pm
John Fetter wrote:

Steve - Your batteries will be fine. Battery manufacturers like to quote figures that are usually too conservative in the real world.

On February 15, 2013 at 5:20am
Heetel64 wrote:

Mr John Fetter I hope you can help me with this one please.
I intend to draw a maximum of 12v DC via two bicycle dynamos that are daisy chained with a view to charging up to six marine batteries. My source will be a stream that runs 24hrs so I understand that some sort of shunt charge controller would be required. I know that once the batteries are fully charged that the not controller will dump the excess to ground or back into the grid or else I will just let it heat the water in the well or maybe I will concoct an additional add on to split H2O BUT what I don’t know is how many controllers I will need. Two batteries will feed internal and external lighting and the other four will be used to power fridge, entertainment system as well as other units that are around the house. How many controllers would you think I will need and how do I daisy chain the batteries to feed the inverter that leads to the circuit breaker box? Hope you can help.
Did you get to try my other idea regarding how much gas could be drawn from the car battery to aid engine combustion ?

On February 15, 2013 at 4:59pm
John Fetter wrote:

Heetel64 - It is my understanding that bicycle dynamos have permanent magnet fields. This means that the output voltage is proportional to the speed of rotation. If you are feeding water from a constant head, then with a light electrical load such as your fully charged batteries, plus a small dummy load on the upstream side of an isolation diode, the dynamo speed will be constant, the voltage will be constant.  The flow of water will have some kind of restriction. This will tend to limit the output current of the dynamos. You can get all the control you need with a valve to control the rate of flow of water.
With reference to your gas question, I suspect the amount of gas is too small by several orders of magnitude. Looks futile.

On March 4, 2013 at 11:42am
Randy wrote:

I understand what happens to a cranking battery used for deep cycle. I don’t see it explained WHY/HOW a deep cycle battery is harmed when used to crank an engine. I have a two battery system same as Andy Amason except the engine is a large V8. These applications are never below 40* F and it seems to me that deep cycle would crank fine. What am I missing?

On March 4, 2013 at 12:22pm
John Fetter wrote:

Randy - A deep cycle battery will crank an engine. However, deep cycle is optimized for long life, has thicker plates, is not designed for very high discharge current. You might find the cranking volts down a bit if you are using the same ampere-hour rating. If your deep cycle battery ampere-hours are way above normal, then the cranking volts will probably be fine. Deep cycle will probably outlast cranking battery by a factor of three PROVIDED you give it a bit of an overcharge every few months. Over 15.3 volts. The regular 14.2 volts is not enough.
Bear in mind that every time it cranks an engine, a battery has a small piece of its life taken out of it.

On May 20, 2013 at 11:23am
Hamza wrote:

if a lead acid battery stored for 26 months. what is the probability to be dead??

On May 21, 2013 at 5:33am
John Fetter wrote:

Hamza - Try charging it. It might or might not recover. Then you will have your answer.

On June 16, 2013 at 8:07pm
Daniel wrote:

I am a bit confused about this articles use of gel, SLA, VRLA, and AGM.
Correct me if I am wrong, but;
1) SLA and VRLA do not specify if electrolyte is a gel or liquid absorbed in to a membrane.
2) VRLA allows enough pressure for recombining gas/oxygen to make water. SLA not necessarily so, but might be the case.
3) VRLA could have gel or AGM (absorbed glass matt) as the electrolyte.

Lastly a question, what are typical charge acceptance rates for each ‘technology’?

On July 9, 2013 at 3:47pm
hind wrote:

what is the name of the manufacturing process of making the p.v.c insulators in flooded lead acid battery ??? is it thermoforming ? or what ?

On July 9, 2013 at 3:56pm
John Fetter wrote:

hind - There are two methods used to make PVC separators.
1. Sintering. Thin layer of PVC/ silica powder is subjected to enough heat to bind but not to melt particles.
2. Solvent. PVC/ silica powder mixed with enough solvent to wet but not to dissolve particles.

On August 6, 2013 at 11:03am
Bob wrote:

I’m a researcher presently working on an invention that would require a higher capacity customized battery directly from the manufacturer, pls I want to find out if manufacturers would be able to produce a deep cycle battery of 12V 7500 Ah, 24V 6500 Ah and 48V 5000 Ah no matter the size and weight. I saw 2V 3200 Ah on net but, I need any of these 3 for my project instead of connecting 2V 3200 Ah batteries in series and parallel to achieve the result.

On August 6, 2013 at 2:21pm
John Fetter wrote:

Bob - How deep are your pockets? You have not indicated whether you need deep cycle or float -type batteries. The cells will be individual cells at this size.

On September 20, 2013 at 11:02pm
Shahid Ahmed wrote:

I am using sealed AGM deep cycle batteries for solar streetlight system. I noted that some battery terminals had a white powdery deposit on them. I was told that one do not require to coat them with white petroleum jelly as we do for flooded types. Can someone explain.

On September 21, 2013 at 7:30am
Heetel64 wrote:

Bob, the manufacturer that you refer to has his priorities in place already. To achieve the customised aspect of your research, try yo look at older versions of current technology. Remember that the old stuff was not so much restricted or constricted by modern day technological advances or fancy patents. Also older stuff was much bigger as the following links in the chain were not so refined, hence demanded greater input.

On October 27, 2013 at 1:10am
Shahid Ahmed wrote:

No answer to my comment dated 20 sept13. Can someone educate me on this?

On October 27, 2013 at 4:22am
Heetel64 wrote:

Shahid, the answer to your question should be sought via self education. No disrespect intended. Teach yourself the results of various reactions in relation to exposure to exernal additives. Don’t get me wrong if I say to you that many people on this site will not answer such a basic query. I started in the same way and was made to understand that this is not a place to seek answers, rather a place to share ideas. Type in to your search engine something like ’ the corrosive effects of exposure ’ or even ’ how elements in the periodic table conflict ‘. The answer you’re looking for is within the what is the effect on metals within an open or confined environment.

On October 27, 2013 at 4:28am
Heetel64 wrote:

Sorry shahid, forgot to point out that quite simply an external ’ something ’ is being attracted to the terminal. LOOK FOR THE SOURCE.

On November 20, 2013 at 6:48am
Al wrote:

Two part question: Why does corrosion (sulfation) occur on the positive battery post (external) in most cases and why does it form on the negative post in an increasing number of cases

On February 4, 2014 at 11:50pm
m salman wrote:

what will be the phenomena of a llead acid battery that has been damaged due to overcharging and are the damages reversable? How do you recognize a battery that has been damaged by overcharging vs a battery that is sulfated?

On February 5, 2014 at 3:04am
John Fetter wrote:

m salman - Overcharging to excess causes the positives to disintegrate, mud to form, dendrites to form and causes flecks of separator material to become suspended in the electrolyte. The damage is likely to be permanent.
Sulfation is a term that goes back to the early days of the lead-acid battery. It represents an assertion of authority by desulfation proponents to explain and justify the eventual performance deterioration and failure of lead-acid batteries, regardless of the actual cause of failure.

On March 19, 2014 at 10:35pm
vaishnav wrote:

i am using a piezoelectric material.amp rate is very low.can you suggest me a charging circuit and battery?

On April 6, 2014 at 7:12am
ikdhar wrote:


On April 6, 2014 at 7:28am
Oscar Ormond wrote:

ikdhar - As often as you would want to empty you wallet. If you can avoid it, avoid it.

On May 2, 2014 at 11:33am
Udit wrote:

Hello i want know about Tubular Bags ie; Gauntlets i mean what are the tests which tells us about the tubular bag we usie is Perfect for the battery, its bursting strength, electrical resistence etc.
please specify the name of test for laboratory

On May 2, 2014 at 11:34am
Udit wrote:

Hello i want to know about Tubular Bags ie; Gauntlets i mean what are the tests which tells us about the tubular bag we use is Perfect for the battery, its bursting strength, electrical resistence etc.
please specify the name of test for laboratory

On May 21, 2014 at 6:56am
r simmonds wrote:

A good artical but for one one.,he refers to “power in a battery”.power is the rate of doing work,you cant store power, so I assume he means energy.
People who write these should ensure the facts are correct,especially true when it is for teaching purposes

On May 21, 2014 at 7:27am
Oscar Ormond wrote:

Mr simmonds

Minor detail, not unlike your numerous typos…......

On May 21, 2014 at 7:37am
r simmonds wrote:

It may be a minor detail,but this is important for students learning about physics. I worked in lab with a well known accumulator manufacturer for many years after gaining a degree, I still work with these

On July 20, 2014 at 3:07pm
John McNeely wrote:

I need to run a 12-volt, 30-lbs. of thrust Minnkota trolling motor. The users guide suggests a Deep-Cycle, 12 volt Marine battery of 105 ampere hour. But I’m using this on an inflatable boat. So weight is key. What would be the least expensive option and battery type (AGM?) that would give me as close as possible to the 105 ah and be light weight and easy on the pocket book.



On July 20, 2014 at 8:29pm
r simmonds wrote:

“30lbs thrust trolling motor”
I dont know what this refers to,but you need to know the power consumption,or current and time its in use to calculate A/Hr of the battery.
You have to put up with the weight of LA technology,if you must have the benefits of Lead Acid,or you could use lithium-ion.

On July 25, 2014 at 4:27am
Diego wrote:

Hi, need help from an expert.
I´ve read a lot about motorcycle batteries since I´m a seller in Spain and I like to know as much as I can of the product I sell.
My doubt is: What type of battery are those that have a separated acid container to fill the battery and seal them permanently?
What kind of sealed battery it converts in? I read that VRLA sealed batteries are Gel Or AGM, I understand that this type of battery are VRLA too…bat not gel or agm I suppose. 
I am confused


On January 30, 2015 at 11:53pm
Sharad Patankar wrote:

what is the difference between round, square, and elliptical tubular bags? is there any change in performance of battery?

On May 19, 2015 at 5:54am
Johnnie Wong wrote:

Please to read

On August 8, 2015 at 3:57am
Kosta wrote:

Are lead acid batteries considered to be “dry” or “liquid” type ones?
It’s important to know for airplane safety regulations…
Many thanks

On August 8, 2015 at 5:13am
John Fetter wrote:

Kosta - There are manufacturers who make lead-acid batteries especially for aircraft. You cannot use batteries in aircraft that are not certified. Both “dry” and “wet” types have been used. The “wet” types are especially designed not to spill.

On August 8, 2015 at 5:52am
Irish Rama wrote:

Kosta, hybrid lithium ion batteries are used in aircraft. As Mr Fetter pointed out, both types are in use. Dry, wet and even gel. The Boing website has some interesting information.
‘Fit for purpose’ in aviation requires certification from the relevant authorities.
Nowadays, large planes use a variety of batteries in a plane. One for startup,another for critical electrical systems and so on. Also there are backup components in case of failure. Having said that, modern planes are designed to keep on functioning even in the event of certain systems failing. That includes batteries. Interestingly, if you see a plane battery, you would probably be looking at something the size of a car battery albeit with a protective box around it.

On August 19, 2015 at 8:51am
Carlos wrote:

Does anybody know where to find a detailed design criteria for pasted plates in terms of its AH output?  I´ve been looking for this, and found it for solid Pb plates, but for pasted PbO2 plates information is not that available, pieces here and there without a complete picture…  any help deeply appreciated.

On August 19, 2015 at 9:22am
John Fetter wrote:

Carlos - Try obtaining a copy of a book by German design engineer Hans Bode entitled LEAD-ACID BATTERIES, translated into English by R J Brodd and Karl V Kordesch, ISBN 0-471-08455-7, published by John Wiley & Sons, New York, 1977.

On August 19, 2015 at 9:41am
Carlos wrote:

Thanks John…  Looks like a great book…  Forgot to mention in my question that it´d be nice if not too expensive… hehehe.  It costs US$ 245.  I´ll try to find it in a local library.  Appreciating your help.  Regards.

On August 25, 2015 at 12:03am
Bevan Paynter wrote:

Very disillusioned with lead acid batts, had ideas to recycle em, reduce internal resistance, restore cca etc. Nothing I tried worked beyond 2 years extra. One fools oneself without a comprehensive tester. Just bought abatt analyzer from Jaycar $79- marvellous! So in summary lead acid batts have a very limited life (by design I would say!) Guess the market worldwide is billions!

On August 26, 2015 at 11:53pm
Bevan Paynter wrote:

With jaycar batt analyser, I can see what actions are helpful and what are harmful. For instance, overcharging or equalisingis said to be helpful. I put 2 batts on 16v for an hour. In both cases cca was reduced and internal resistance increased by large amounts. This is permanent. So I say DO NOT CHARGE LEAD ACIDBATTS ABOVE 14.2volts!

On August 27, 2015 at 1:26am
bertie wrote:

Bevan Paynter

The batt analyser you mention is the Jaycar QP 2261 so-called cranking amps tester. It is incapable of measuring amps. It has two flimsy leads with clamps that are attached to the battery terminals to measure volts. It is well known that the battery voltage drops when the engine is cranked - but there are many factors that affect the amount the voltage drops, therefore the instrument can only make a wild guess about the condition of the battery. You made a wild guess based on an instrument that also made a wild guess.

On August 28, 2015 at 11:43pm
Bevan Paynter wrote:

Bertie I have extensive experience in electronics and just about everything else. I have made my own testers. So I know when something works. The batt analyser does give a representative quick analysis of a 12v sli batt. I have checked with my own testers(resistive) & results are similar. This analyser uses conductance testing. I have no alliance with jcar, I just wanted to tell others about this device. Yes the traditional tester (resistive) used thick cables to carry the current (mine uses 200 amps). My interest is in understanding batts. And I have thru experiment done that. My understanding says that lead acid batts are made to fail. John Fetter no doubt would agree! Cheers!

On August 29, 2015 at 3:07am
bertie wrote:

Bevan Paynter

It is impossible to obtain a reliable measurement of battery output current by measuring its voltage with a voltmeter. V=IR. Two out of the three must be known accurately in order to work out the value of the third. A big battery, a small battery, a big engine, a small engine, a stalled engine, a cranking engine that is cold, a cranking engine that is hot, provide dramatically different currents. If the voltage is known but the other two are not,  sorry, you’re guessing.

On August 30, 2015 at 11:15pm
Bevan Paynter wrote:

So what are you saying , this device is a fraud? If so address your comments to consumer affairs. I am happy with device and couldn,t care less about your biased opinion.

On August 31, 2015 at 12:03am
bertie wrote:

Bevan Paynter

This is supposed to be a technical discussion. This is not about a product but about a statement you made, regarding maximum charging voltage, which you are apparently unable to substantiate. Tell us how you worked this out.

On August 31, 2015 at 12:21am
Bevan Paynter wrote:

I said that I put 2 batts on 16v for an hour each and that cca was reduced after and Internal resistance was increased, this was measured by q2261 & by my own testers. This is not a fantasy it happened. So I can say that 16v charging is harmful to sli batts!

On August 31, 2015 at 1:48am
bertie wrote:

Bevan Paynter

The QP 2261 measures voltage - not current. It assumes that for a given voltage drop of a battery during cranking, the battery must have delivered a corresponding current. It assumes that for a larger voltage drop, there must be a larger battery internal resistance. Batteries that are given a gassing charge are at a higher open circuit voltage than batteries that have been standing for quite a while. This top of gassing charge voltage is a battery electrode surface effect. The extra voltage fades quickly when the engine is cranked. The way the QP 2261 instrument works means that you were given a phantom reading. It assumed that the larger voltage drop meant a lower cold cranking amperage. Next time use a proper current transducer.

On August 31, 2015 at 11:26pm
Bevan Paynter wrote:

Got info from web re conductance testing. Appears test parameters are critical eg temp clamp location etc. Conducted test on batt at room temp 10’c then put batt in warm spot home brew cabinet 25’c for 2hrs & retested. Cca fell by 40, intenal res rose by 7milliohms .So it appears this device is just barely useful. It tells you what you already know from car starter behaviour. It appears it might be useful for testing individual batts in a bank providing parameters are same. So when overcharging at 16v for hour,int temp would have risen changing test results! Wonder how many more this toy will trap?

On September 6, 2015 at 11:50pm
John Fetter wrote:

Bevan - Recent work done by researchers at the University of Twente in the Netherlands has shown that metal-liquid interfaces are inhabited by nanobubbles. Atomic force microscopy revealed that these bubbles consist of roughly 20-100 nanometers diameter gas bubbles as well as gas micropancakes consisting of roughly 2 nanometers thick by several thousands of nanometers diameter flat gas objects. The bubbles adhere to the metal surface and can persist for hours, sometimes days. Nanobubbles can only exist in liquids that are predominantly water. This persistence has surprised scientists because according to their theoretical models, such bubbles should last only microseconds before dissolving in the liquid.
Researchers found that nanobubbles are easily formed on the surfaces of electrodes of electrochemical cells. Simply pass an electric current through the cell to cause the electrodes to give off gas. Some of the nanobubbles that are formed grow to full size and can be seen bubbling, but most remain.
A lead-acid battery will have such nanobubbles adhering to the surfaces of their plates for quite some time after having been charged to gassing. They would have the effect of significantly increasing the apparent internal resistance of the battery. It would seem that desulfation enthusiasts might be chasing after a fair number of mirages - believing that the test results obtained from batteries that have just been charged are indicating sulfation. They run their reconditioning routines and presto - the batteries work.

On September 7, 2015 at 3:45am
John Fetter wrote:

Bevan - You can find an easy to read explanation of nanobubbles using this link to an article written by Australian scientist Dr Phil Attard: http://personal.chem.usyd.edu.au/Phil.Attard/nanobubble/nanob.htm


On September 8, 2015 at 11:47pm
Bevan Paynter wrote:

Hmmm, nano bubbles, could have some effect maybe. As to pulse desulfation I have found it works best on vrla agm batts, after injecting H2O say 10ml into ea cell. Batt has further useful life eg pre 5v @ 6+v. Also 12v versions. I should mention this is a self made direct drive desulfator which uses 200amp pulses. A volt meter shows batt volts falling , when low put batt on normal reg chgr. Works for me! Of course best remedy is prevention by keeping batt chrgd.

On September 9, 2015 at 12:59am
John Fetter wrote:

Bevan - How do you determine that a battery that you have before you is sulfated?
It seems to me that there can be quite a few conditions that would give rise to the same kinds of symptoms.
Has the term sulfation perhaps not become a convenient popular expression used to describe any battery with an ailment?

On October 15, 2015 at 8:24am
Francesco wrote:

“The primary reasons for its relatively short cycle life are grid corrosion on the positive electrode, depletion of the active material and expansion of the positive plates”

expansion of positive plate: is this right? As far as I understand is the negative one which increase, no?

On December 28, 2015 at 7:39pm
Norman Nipnoile wrote:

Can anybody tell me?..How many farad expanders are needed for a sub set of Li-Po diode deducers when all I really need is 5000 MF battery output cycles when running a cold and frozen trimetric equalizer?..Its really stressing me out and any input would be much appreciated!

On December 28, 2015 at 11:15pm
bertie wrote:


On February 22, 2016 at 11:13pm
Daniel wrote:

Please do you have an idea about the voltage of a 2V battery cell when discharged to 70%?

On February 22, 2016 at 11:48pm
John Fetter wrote:

Daniel - Cell voltage on its own is not a reliable indicator of state of charge. It varies with temperature. It varies with electrolyte specific gravity. That’s not all. It depends on whether a cell is disconnected and also on how long it has been disconnected (a) from a load or (b) from a charger. If a cell is in the process of being discharged, the higher the rate of discharge, the lower the voltage. If a cell is being charged, the higher the rate of charge, the higher the voltage. A cell that is at 30% state-of-charge connected to a big charger can be at 2.4 volts and in the process if being heavily discharged can be at 1.8 volts.

On June 27, 2016 at 3:45pm
Andrew C wrote:

Hi. Thanks for the informative site.. couple of questions if I may?

Have a number of old (between 3-6 years old) SLA batteries (12v 7ah) new in box for children’s battery powered ride-ons ... I put the multi-meter on them and was surprised that the worst only showing 5.73v best just over 6v—Working on a max possible charge of 6.35v i calculate the worst of these batteries at 90% charge - far higher than I expected? I would have guessed the batteries charge would have been substantially lower and ready for the recyclers… but are these batteries OK and will they have a reasonably life expectancy if we use them?

Additionally there is a label on the battery “Charge battery before using to initiate them” —- Have they discharged less than I expected because they have not had this “initiating” charge? Is this “first” charge significant?

Many thanks in advance! 

On July 5, 2016 at 3:47am
Sohail Suri wrote:

Question: How does a leadCrystal battery manufactures. Is it same as Deep cycled batter as mentioned above with thick lead plates.

On July 26, 2016 at 5:27am
azhar 07 wrote:

can any one answer my question

How to decide battery plate ah with its wight

On August 1, 2016 at 12:51am
Qashem wrote:

i feel problem in lead acid battery grow load volt after filling H2SO4 ,how can i solve this plz advice me.

On September 8, 2016 at 7:12pm
Jim Waters wrote:

I have 5 Trax30 MMPT controllers on a bank of 10)ea 200ah batteries.  The problem I’m having is during the day (running 2 small 460 watt 5000 BTU air conditioners - from the 5 arrays - 2 of the MMPT controllers seem to take the bulk of the charge or demand.  If I disconnect either or, another will pick up charge.  Otherwise, (such as cloud conditions) the other 3 range from 1 to 8 or 10 amps from the panel until the voltage drops to about 13.1,  Then the other 3 will kick up and slowly regain charge on all after the cloud passes. In pure sun days, the two taking the brunt of the work never change.  The battery system is all parallel, panel VOC is max 73, charge up to 30 amp per controller (but again, 2 of them seem to take the bulk of the charge/load). 

I’ve been reading that if left in this SOC condition, the two hardest worked will eventually die/fail.  I’ve wired the 5 on every other battery and the inventor at the end of the chain of the bank.  Neither of the two hardest worked are wired to the same battery as the investor.  I do have a 300amp breaker between 2 bank of 5, as a just in case measure, though it’s never tripped.

Anyone have any ideas on how I can get the other 3 to charge from the PV’s more evenly.  I’ve had them all during a sunny day producing 25-29 amps in , but only if disconnecting one of the 2 that carry the bulk.  So I can only figure It’s capable of alot more.  - twitterpaded… LOL

V/R - Jim

On September 8, 2016 at 7:17pm
Bob wrote:

I have a jumper box which has inside a “sealed acid-lead battery” that I use to start up cars with a dead battery. I looked everywhere and for hrs to find out what is the “Cranking Amperes” and the “Cold Cracking Amperes” on a “sealed acid-lead battery”. They only tell you the “Amperes Hour” but no luck with the Cranking Amperes .. does any one know? thx

On September 10, 2016 at 7:20am
John Fetter wrote:

Jim - It stands to reason that all MMPP controllers cannot be identical. One will initially push more current into the battery, raising its voltage, after that the rest will “see” a battery that is more charged than it really is and will reduce their outputs. You say you have five MMPP controllers on one battery. It is inevitable they will fight each other. One or two will carry all the current. Impossible to sort out. You must have ONE MMPP controller per battery.

On September 12, 2016 at 9:58am
Jim Waters wrote:

For clarification (to my previous message)  there’s 10 Batteries, with 1 MMPT controller (basically every other battery) for a combined 150 Amps of charge) so there are 5 Trax 30 total….. Though the 2 still seem to do the bulk of the work to charge.

On September 15, 2016 at 1:52pm
Chuck Herold wrote:

How does the process of recharging Lead Acid batteries. Is there a reverse flow, from Pos to Neg? Or what

On September 25, 2016 at 2:30am
parsuram wrote:

what is gel battery and how does it work . con your explain to me

On November 15, 2016 at 4:54pm
Anita wrote:

to Parsuram
A modern gel battery (also known as a “gel cell”) is a VRLA battery with a gelified electrolyte; the sulfuric acid is mixed with fumed silica, which makes the resulting mass gel-like and immobile. Unlike a flooded wet-cell lead-acid battery, these batteries do not need to be kept upright.

I suggest you Google your question, there you will find lots of explanation

On November 15, 2016 at 5:02pm
Anita wrote:

To Chuck Herold
yes of course the current flow reverses, (not the voltage)
the process is a chemical reaction of electro-plating

the battery stores a chemical reaction, not electricity
that reaction can be in either direction, which consumes or produces electricity
the electricity you take from a battery is not the same electricity that was put-in
in a capacitor, it is the same electricity (the same electrons)

On November 26, 2016 at 12:23pm
Osama Badran wrote:

i want to ask about
availability of finding VRLA(GEL/AGM) batteries for SLI application to be installed instead of wet lead acid.
i thought that the AGM is only used for deep cycle application

On November 28, 2016 at 10:58am
Mark Phipps wrote:

I have been dealing with wheelchairs(primarily SLA batteries and occasionally AGM) for over 20 years and greatly appreciate your website. It has helped me quite a bit to iron out some of the various “methods” of battery use.
I have a couple questions about charging:
How long can the batteries be left on the charger, and does it vary depending on the charger?

This is what I have always told customers:Every day that you use the chair, plug it in overnight and unplug it in the morning. If your wheelchair sits for more than 3-4 weeks, plug it in over night and unplug it the next morning.
Is this correct?

Thank you very much!

On December 29, 2016 at 10:21am
Ajay Jain wrote:

sir can we use positive plate lead sellanium and negative lead callcium .
kindly give answer with explanation.

On January 7, 2017 at 4:48pm
Boris wrote:

Tell about “Optima” battery. High purity lead-tin alloy. Wound cell configuration utilizing proprietary SPIRALCELL TECHNOLOGY®

after 3 years it stop working. voltage was 11.9. i charged many times now voltage normal but power is droped. i have a optima yellow 55A. I think it need desulfate. i have a turnigy smart 6 charger with 25Amps power. I charged 14.4 volts with automated amperage control. it start charging 5.5 Amps and stuck 2 Amps. Charging Factory limit 13.8 to 15.0 volts; 10 amps maximum; 6-12 hours approximate.

How i can desulfate it?

On April 29, 2017 at 2:35pm
Bill wrote:

How much should a 12v lead acid battery discharge before recharging?

On June 17, 2017 at 3:23am
Raghunathan.K wrote:

I have a Reva D.C. drive indian make electric car,which uses"Exide” make 6V,225AH Lead-Acid batteries-8 Nos,controlled by 48 V, 400 Amps controller and a charger suitable for 230V, 50C/S A.C.power (single phase).The present condition of the battery is totally drained and needs replacement. The battery cost if it is done through Reva’s authourised service Agency it will very expensive.If I buy chinease make Gel batteries of same rating will it work.(shipping Lead-Acid batteries are not advisable)Is China make batteries are reliable and their performance is dependable.Please advise me if there is any alternate way of getting battery from some other country.      Raghunathan.

On June 21, 2017 at 12:21am
dennis wrote:

While under a failed load test, a cell boils and hisses. What is wrong with cell?

On September 11, 2017 at 12:51pm
Phil wrote:

I have 4 sealed lead acid calcium batteries on a narrowboat wired in 24v config. 2 sit lengthwise across the boat on one side; 2 sit lengthwise running down the boat on one side. The boat tends to lean side to side slightly with changes in weight placement. Does the orientation matter and will it affect the life of the batteries.
Regards Phil

On December 16, 2017 at 11:17am
Abdulsemed wrote:

keep up on good work i Really satisfyed on your Golden job

On January 1, 2018 at 6:40am
Sherry wrote:

Can somebody explain me that which material is using for making the plates of acid battery….waiting for the answers

On February 12, 2018 at 3:20am
Omprakash G wrote:

I have a questions…. plz any one can help me..

How to calculate, how quantity is required to produce per Ah in lead acid battery…?

On March 5, 2018 at 10:02am
Santiago wrote:

I can’t find good info about connecting lead acid batteries of diferent sizes in parallel.
I ussually find it is not recomended, but not why.
Manufacturers ussually recomend once you setup a system never add batteries in parallel.
What are the real problems of doing so?

On May 8, 2018 at 1:30pm
James Jones wrote:

I recently had a bad battery replaced in a 2015 Chevy Colorado truck.  It was replaced by the dealer under warranty.  The new battery will start the truck but the voltage checks 11.65 volts after the truck has not run for a few hours.  In m experience a lead acid battery that check less than 12.5 volts when fully charged is bad.  Should I return to the dealer or is there something about today’s batteries that this normal.

On June 27, 2018 at 3:24pm
Jon Seavers wrote:

I have a couple of deep cycle lead acid 12V batteries (Kirkland Brand), 125 amp-hours each.
I want to run a 120 volt dryer-blower off a 2000 watt inverter for 20 minutes.
I calculate… 2000 watts/120 volts = 16.6 amps on AC side, 16.6 amps X 120/12 volts = 166 amps on the DC side. 166 amps X 20 minutes = 55 amp-hours. Add efficiency losses and we are still under 75 amp-hours. So, the capacity is there, even with just one battery (and I have 2).
Question: If I am drawing that much power from the battery, are there any problems or concerns? Overheating? Safety? I realize that this will shorten the battery life somewhat, but I only expect to do this a few times each year.

On October 7, 2018 at 3:35pm
David McNiven wrote:

Hi, I’m trying to think of ways of making FLA batteries more tolerant of heeling on my sailing boat by keeping the plates covered while discharging or charging.
Would adding dilute acid to raise the level be a problem if I maintain the original concentration? Thinking of modifying the filler caps with normally-empty (possibly spherical) reservoirs to catch spills and still allow venting while heeled up to 20 degrees from vertical. Would it fail by altering circulation, causing a gradient in concentration or something else with dire consequences that I’m ignorant of?
Thanks - and thanks for everything I’ve learned here so far!

On October 29, 2018 at 9:21am
Wayne Crowson wrote:

I have 4 Crown 6V batteries connected series/parallel @ 440Ah/12V (nominal). These are on an RV with 400W solar panels and Morningstar TS-45 PWM charge control. The batteries are 5 years old. They are all doing well and recently I performed an equalize charge. Before equalizing all 4 batteries SG reading on all cells was 1300+! The voltage at 100% SOC was 12.80V. I discharged the bank to 50% resting/pausing at 90%, 80,70, etc. and testing SG.
At 90%SOC the voltage was still 12.8V with SG of 1.285 (averaged). At 80% - 12.7V/1.260SG (avg). 70% - 12.6V. However, now 3 batteries were now reading 1.260SG and 1 batt. reading 1.270. @60% the readings were: 12.4V and the 3 batts. were showing between 1.210-1.250 SG. The 1 odd battery was reading 1.275 SG. Finally @ 50% SOC voltage was 12.4V and SG was 1.190-1.210 for 3 batteries and the odd one was 1.270.
Sorry for the info overload but, the question is why would the one oddball battery consistantly show higher SG readings than its siblings of the same age and conditions? I don’t know if it’s relevent, but the oddball is the one with the positive cable to the rest of the system. Would changing battery positions in the bank change anything? The bank is still performing very well. I’m just curious about the 1 battery and if I should be concerned.

On November 5, 2018 at 9:24pm
saquib wrote:

Dear sir
  i am saquib here i want the grid paste how is made and its formulation for the 50 kg paste for the lead acid battery