BU-803: Can Batteries be Restored?

Battery users and entrepreneurs often ask, “Can batteries be restored?” The answer is, “It depends.” Most battery failures are permanent and cannot be repaired, but there are exceptions. Sulfation on lead acid batteries can be removed if caught in time; crystalline formation, also known as “memory,” on nickel-cadmium can be dissolved through deep-cycling. Read more about Memory: Myth or Fact?, and “sleeping” lithium-ion packs can be boosted if they have been over-discharged. Read more about Safety circuits for modern batteries.

Permanent battery defects include high internal resistance, elevated self-discharge, electrical short and capacity fade. Poorly designed chargers, exposure to excess heat, harsh charge and discharge cycles, and inappropriate storage contribute to early aging. Let’s examine the cause of these non-correctable battery problems and explore what we can do to minimize them.

Low-capacity Cells

A manufacturer cannot predict the exact capacity when a battery comes off the production line, and this is especially true with lead acid batteries that involve manual assembly. Fully automated cell production in “clean rooms” also causes performance differences, and as part of quality control, each cell is measured and segregated into categories according to their inherent capacity levels. The high-capacity A-cells are reserved for special applications and sold at premium prices; the large mid-range B-group goes to commercial and industrial markets; and the low-grade C-cells may end up as consumer products in department stores. Cycling will not significantly improve the capacity of the low-end cell, and even though the cell may look good, the buyer must be aware of differences in capacity and quality, which often translate into life expectancy.

Cell Mismatch, Balancing

Matching of cells according to capacity is important, especially for industrial batteries. No perfect match is possible, and if slightly off, nickel-based cells adapt to each other after a few charge/discharge cycles similar to the players on a winning sports team. High-quality cells continue to perform longer than the lower-quality counterpart, and the cells degrade at a more even and controlled rate. Lower-grade cells, on the other hand, diverge more quickly with use and time, and failures due to cell mismatch are more widespread. Cell mismatch is a common cause of failure in industrial batteries. Manufacturers of professional power tools and medical equipment are careful in the choice of cells to attain good battery reliability and long life.

Let’s look at what a weak cell does in a pack that is strung together with strong ones. The weak cell holds less capacity and is discharged more quickly than the strong brothers. Going empty first, the strong brothers overrun this feeble sibling and the resulting current on a continued discharge pushes the weak cell into reverse polarity. Nickel-cadmium can tolerate a reverse voltage of minus 0.2V and a reverse current of a few milliamps, but exceeding this level will cause a permanent electrical short. On charge, the weak cell reaches full charge first and it goes into heat-generating over-charge while the strong brothers still accept charge and stay cool. The low cell experiences a disadvantage on both charge and discharge. It continues to weaken until finally giving up the struggle.

The capacity tolerance between cells in an industrial battery should be +/– 2.5 percent. High-voltage packs designed for heavy loads and wide adverse temperature ranges should have lower tolerances. There is a strong correlation between cell balance and longevity.

Li-ion cells share similar deficiencies with nickel-based systems and need management. The mandatory protection circuit supervises the serially connected cells by clamping the voltage when exceeding 4.25 and 4.35V on charge, and disconnecting the pack from discharge when the weakest cell drops to between 2.50 and 2.80V/cell. This prevents the stronger cells from pushing the depleted cell into reverse polarization. The protection circuit acts like a guardian angel that shields the weaker siblings from being bullied by the stronger brothers. This may be help to explain why Li-ion packs for power tools last longer than nickel-based batteries, which normally do not have a protection circuit.

The capacity of quality Li-ion cells is consistent and the self-discharge is low. A problem arises when the cells exhibit a discrepancy in self-discharge. This can be attributed to lower-quality cells or high-temperature spots in a large automotive battery, which hastens aging. Balancing is required and there are two methods: Passive balancing bleeds the high-voltage cells; active balancing shuttles the extra charge from higher-voltage cells to the lower-voltage cells without burning the energy. Active balancing is the preferred method on EVs.

With use and time all batteries become mismatched, and this also applies to lead acid. Shorted cells and those having high self-discharge are a common cause of cell imbalance and lead to subsequent failure. Manufacturers of golf cars, aerial work platforms, floor scrubbers and other battery-powered vehicles recommend an equalizing charge of 3–4 hours if the voltage difference between the cells is greater than +/– 0.10V, or if the specific gravity varies more than 10 points (0.010 on the SG scale). An equalizing charge is a charge on top of a charge that brings all cells to full-charge saturation. This service must be administered with care because excessive charging can harm the battery. A difference in specific gravity of 40 points poses a performance problem and the cell is considered defective. A 40-point difference is one cell having an SG of 1.200 and another 1.240. A charge may temporarily cover the deficiency, but the flaw will resurface after a few hours of rest due to high self-discharge.

Shorted Cells

Manufacturers are at a loss to explain why some cells develop high electrical leakage or a short while still new. The culprit might be foreign particles that contaminate the cells during manufacture, or rough spots on the plates that damage the delicate separator. Clean rooms, improved quality control at the raw material level, and minimal human handling during the manufacturing process have reduced the “infant mortality rate.”

Applying momentary high-current bursts to repair a shorted NiCd or NiMH cell has been tried but offers limited success. The short may temporarily evaporate but the damage in the separator remains. After service, the repaired cell may charge normally and reach correct voltages; however, high self-discharge will likely drain the battery and the short will return.

It is not advised to replace a shorted cell in an aging pack because of cell matching. The new cell will always be stronger than the others. Consider the biblical verses: “No one sews a patch of unshrunk cloth on an old garment. If he does, the new piece will pull away from the old, making the tear worse. And no one pours new wine into old wineskins. If he does, the wine will burst the skins, and both the wine and the wineskins will be ruined” (Mark 2:21, 22 NIV). Replacing faulty cells often leads to battery failures within six months. It’s best not to disturb the cells. Instead, allow them to age naturally as an intact family.

Shorts or high leakage in a Li-ion cell are uncommon. If this occurs, the cell becomes unstable and a massive amount of power can dissipate, leading to a possible venting thermal breakdown. Such a leak can be compared to drilling a small pinhole into a high-pressure gas pipeline and holding a match to it. The resulting explosion could rupture the pipe. Similarly, the rushing current in the cell heats up the tiny malfunction, causes a major leak and releases all energy within seconds. (Read more about Safety circuits for modern batteries)

Cell disintegration caused by internal disturbances lies outside the safeguarding ability of the protection circuit. Most cell failures occur when the battery has been damaged by shock and vibration, has been overcharged or has been overheated. Li-ion cells for electric powertrains and demanding industrial applications use a heavy-duty separator to reduce the risk of an electrical short. These batteries are larger than consumer-type packs. Saying that Li-ion has twice the energy density of NiCd can be a misnomer; some long-lasting Li-ion cells have a specific energy as low as 60Wh/kg, the same as NiCd.

Caution: Applying a high current burst works best with nickel-based batteries. Do not use this method for lithium-ion cells.

Loss of Electrolyte

The loss of electrolyte in a flooded lead acid battery occurs through gassing, as hydrogen escapes during charging and discharging. Venting causes the electrolyte to become more concentrated and the balance must be restored by adding clean water. Do not add electrolyte, as this would upset the specific gravity and shorten battery life through excessive corrosion.

Permeation, or loss of electrolyte in sealed lead acid batteries, is a recurring problem that is often caused by overcharging. Careful adjustment of charging and float voltages, as well as operating at moderate temperatures, reduces this failure. Replenishing lost liquid in VRLA batteries by adding water has limited success. Although the lost capacity can often be regained with a catalyst, tampering with the cells turns the stack into a high-maintenance project that needs constant supervision.

Nickel-based batteries can lose electrolyte through venting due to excessive pressure during extreme charge or discharge. After repeated venting, the spring-loaded seal of the cells may not seal properly again, and the deposit of white powder around the seal opening is evidence of this. Losses of electrolyte may also occur as part of faulty manufacturing. Dry-up conditions result in a “soft” cell, a defect that cannot be corrected. On charge, the voltage of a “dry” cell goes high because the battery has no clamping action and does not draw current.

A properly designed and correctly charged lithium-ion cell should not generate gases, nor should it lose electrolyte through venting. In spite of what advocates have said, lithium-based cells can build up an internal pressure under certain conditions, and a bloated pouch cell is proof of this. Read more about The Pouch Cell. Some cells include an electrical switch that opens if the cell pressure reaches a critical level. Others feature a membrane that releases gases. Many of these safety features are one-way only, meaning that once activated, the cell becomes inoperable. This is done for safety reasons.

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On April 17, 2011 at 12:09am
Joe Doherty wrote:

How does this article stand with todays improved “Smart Chargers” are there any significant changes now, in 2011??

On July 28, 2011 at 3:07am
Bryan Stensaas wrote:

Dear Sir,
I am a missionary in Uganda E. Africa.  As we have daily power outages here I have developed a battery backup system using a triplite 2400w 24v inverter and 16 200a sealed lead acid batteries wired in series and in parallel to make the 24v.  I use the system powering a radio station and it would keep it going about 24 hr.  The batteries have lasted about 1 1/2 yrs but I am getting only 4 hrs from the system.  Batteries here are extremely expensive (around $300 each).  I took one of the old ones I had replaced and popped off the flat cover and found 6 small holes for the cells.  Is there a way that I can recharge these batteries?  On regular car batteries here they drain the battery and refill them with a new mixture of acid and water and they seem to work for some time.  If I could renew these batteries and even get another 6 months out of them it would be a very big savings. 

Because of Christ,
Bryan & Cheri Stensaas
Missionaries in Uganda

On November 18, 2011 at 11:20am
matej wrote:

Bryan, you do not state whether the batteries were new, or used. If they are only 1 1/2 years old and if there were times when your batteries were discharged for longer than few hours, sulphation is most likely the problem. In that case I would recommend you to try electrical desulphation. But maybe your charge/discharge currents were too high, or wrong charge voltages. Is there still enough water in the cells you popped cover from?

On December 3, 2011 at 7:08am
John Fetter wrote:


You need to stop using garbage for batteries. Sealed lead-acid is useless for cycling - no matter what the “experts” say. The ONLY type of battery suitable for the kind of duty you describe are good, old fashioned, flooded lead-acid motive power (traction) types. They will last ten years. No other battery will last even half as long.

On January 26, 2012 at 2:05pm
John Fetter wrote:

What is interesting about pulse technology is that there is evidence it does not actually reduce sulfation at all but gets rid of a totally different problem known in the trade as “open circuit” Symptom: The battery fails suddenly, with little or no warning..

It appears an ultra thin oxide layer or a sulfate layer can develop over the surfaces of calcium-lead alloy positive grids over time, (few years). The pulsing breaks down this layer.

All very low or ultra low maintenance and no-maintenance and all sealed lead-acid batteries have calcium-lead alloy positive grids. Pulsing works on these types of batteries. It does not appear to work on the “old fashioned” flooded antimony-lead alloy types, (nor on calcium hybrid types which actually have antimony-lead alloy positive and calcium negative grids).

Simply pulse for several hours and the “dead battery” problem seems to disappear.

On January 27, 2012 at 12:07am
Bevan Paynter wrote:

John- would you agree that a wla batt that has been left alone for say 6 months & will not take a charge & measures say 11v is effectively dead? Yes- then my pulser or if you like batt zapper is connected- the pulses measure at 1st 350v- then over period of several hrs drop to say 15v- then bat is put on constant volt charge of 14v- when the amps have dropped to say 50mA that batt is fully charged- confirmed by a high rate (200A) discharge test- so I have saved that batt! And it was the zapper that did it! And NO- the zapper does not charge the batt- it can’t- that would be energy from nothing!- I feel we are getting somewhere here- educating us & others. On a slightly diff sub- do you agree that a batt in a vehicle with a gen lasts twice as long as a batt in a vehicle with alt- seems to be gen has 150 magnetic moments/sec & alt has 350 mms- lower figure leads to deeper charge of plates whereas alt leads to surface charge- so by that reckoning a home batt charger from mains, thru a regulator filter setup, should be as good for extend batt life as a gen- if bat periodically charged using previous setup. One thing I know for sure- the worst thing for a wla batt is sitting on a floor(even though kept fully charged- & periodically shook or put on vibration machine to alleviate stratification)- so- just use batt in vehicle- say weekly- long runs. I have had batts from tips last 5 years! Cheers- Bevan.

On January 27, 2012 at 1:02am
John Fetter wrote:


I am not criticizing pulsing but I am very skeptical about the effect it has on sulfation. And what you are describing supports, rather than contradicts my contention.

Lead-calcium alloy positive grids are garbage. I have hand-built hundreds of lead-acid battery cells in my experiments. I have obtained automotive battery plates in an unformed condition from battery manufacturers in the US, Brazil, South Africa, Ukraine, etc., etc.

I have built identical rated cells from sets of positive plates made with antimony alloy and calcium alloy grids, negative plates all made with identical calcium alloy grids. (The antimony positives, calcium negatives are called hybrids.)

Simply connected all the cells in series and cycled them from 100% down to 20% and back up, etc., etc.. After 10 cycles the antimony grid cells had gained 10% in A-hs and the calcium grid cells had lost 80% in A-hs. This told me there is something weird going on with calcium. All the positive plates looked exactly the same but the calciums were not working any more.

Yes, the cells can be restored by pulsing. No, it is not sulfation.

Lead-sulfate requires at least the energy of a full charge to eliminate. An oxide layer requires only that the film be pierced to a sufficient extent. Then, once pierced, the battery can be charged in the ordinary way.

The problem can be treated chemically as well. Not by sulfation potions but by a material that attacks the thin oxide film. I have restored batteries that way.

To paraphrase Galileo Galilei, “In questions of science the opinions of thousands are not worth the humble reasoning of a single individual”.

On January 27, 2012 at 2:08am
John Fetter wrote:


An old fashioned generator is controlled by a voltage sensitive relay. The generator “pushes up” the battery voltage, hence creates a charging current. When the voltage is high enough, the voltage relay opens the circuit to the field, and the field slowly collapses, thereby reducing the battery voltage. As soon as the voltage has fallen sufficiently, the voltage relay closes, the field builds up and the cycle is repeated.

An alternator produces three phase, which is rectified and fed to the battery. There is a solid state voltage controller that operates the field in exactly the same way. Alternators are inherently more robust than generators in that they can be rotated much faster. This allows the alternators to begin charging at lower engine RPM.

The only factors I can see that might affect battery life are a generator’s inability to keep a battery charged in stop-start driving, leading to sulfation, (!) and an incorrectly calibrated voltage regulator that can either undercharge or overcharge the battery.

Alternators are several orders of magnitude more reliable than generators.

Automobile manufacturers often put batteries near exhaust manifolds. That is just plain dumb. The regulator does not “know this”, so the battery ends up being severely battered.,

Modern cars are festooned with current gulping gadgets that stay on 24/7. So the batteries end up being discharged, often at more than 50 mA continuously. The self discharge of a modern battery is overwhelmed by this drain and the battery ends up permanently undercharged. This can reduce battery life to under 2 years. The battery manufacturers love it. The automobile manufacturers could not care less. This is bad engineering and the consumer is therefore being deliberately ripped off.

On January 27, 2012 at 3:28am
Andersen Chong wrote:

Good day, very interesting topic, Hi John, i am setup a hybird 1kw solar and 1kw wind system in my house running with 24 system, day time are running with direct grid tie inverter to reduce the amp from the fit, and once the battery fully charges sunlight down then will change to pure.true sine inverter to supply all lights and elctronic system, this process is running every day and times,  John, please kindly consult me, if the system like above, what type of the batteries is suitable for me? Battery cost are really killing me if i choose the wrong type for my need. Thank you so much in advance. Cheers to going green.

On January 27, 2012 at 4:41am
John Fetter wrote:


There is only one type of battery that is (a) economical enough and (b) technically suited, both at the same time, to daily deep cycling. Old fashioned, flooded lead-acid motive power.

There are three varieties. (1) The old fashioned golf-cart type; (2) the American flat-plate-positive type; (3) the European tubular-positive-plate type. They get more expensive from (1) to (2) to (3). The first will last two+ years, the second six+ years and the third type will last 10 years.

Lead-acid motive power does not mind being partially or totally discharged. By totally I mean down to 1.75V/cell or 20% state-of-charge. You absolutely MUST ensure the batteries reach 100% gassing charge, (2.55V/cell), at least once every two to three weeks. You will need to water the batteries from time to time. Amazingly, most, (not all), users in the USA, South Africa, Australia use tap water! I recommend inexpensive deionized or reverse osmosis.

Do not, I repeat, do not believe the people that tell you that VRLA, sealed, maintenance-free batteries are suitable.

On January 27, 2012 at 12:24pm
matej wrote:

Bevan. And what is your peak current at those 880kHz? At least roughly..?

I have tested circuits at hundreds of kilohertz as well, even at several MHz but they did not produce better results than the unit I currently use.
Are you measuring the specific gravity of the batteries you rejuvenate? Is it rising as you pulse? Your results are really lightning-fast,

Are you using inductive or capacitive pulses, and positive or negative (into or out of the battery)? With sharp <100ns or soft edges? Could you maybe share the schematic?
Mine (the one I talked about) is just an ordinary boost converter powered by a LC low pass filter from the battery being desulfated .. Just like the old Alastair Couper design, but more powerful. And the electrical efficiency is about 90%.
I have tested circuits at hundreds of kilohertz as well, even at several MHz but they did not produce better results than the unit I currently use. In one experiment, pulsing the battery at 16kHz has brought SG from 1,18 to 1,22 in three days but then suddenly stopped rising, after few days of no progress I tried to retune the pulser to 12kHz and the SG started to rise again and needed about 5 days to stop at 1,25 - 1,26. So now I am using frequencies from 1kHz to 12kHz with good results.
Are you measuring the specific gravity of the batteries you rejuvenate? Is it rising as you pulse? Your results are really lightning-fast .. maybe it is really the calcium insulating layer you are treating .. but if you measure SG and it rises as you pulse, it is sulfation, i think John would agree ..??

On January 27, 2012 at 4:00pm
John Fetter wrote:

Battery plates in sulfuric battery acid have a nanoscopically thin surface or boundary layer that presents capacitively. (This can be exploited by introducing activated carbon into the negative plates, turning the lead-acid battery into an ultra- or super-capacitor.)

I am guessing. I suspect that high frequency pulsing simply charges and discharges this “capacitor” in ordinary lead-acid batteries, sapping energy from the pulses. So reducing the pulse rate probably makes more energy available to do the job at hand.

The battery Matej describes was obviously in a discharged state and the pulsing caused it to become charged. However, I think the battery had both an oxide layer problem and was in a reversible sulfation condition at the same time. I suspect a couple of hours of pulsing, followed by straight charging would have sorted it out.

On January 28, 2012 at 12:25am
Bevan Paynter wrote:

John & Matej- all I know is how to get more life out of batts- I do not know if calcium or other material is being used in plates- the manu does not say usually! As to sg- this is a oxymoron!- & completely irrelevant to wla batt life! As is o/c term voltage! I have had a car batt that started my car for 5 years once a week- long runs- the o/c v were 12’2v- yet that batt started that car reliably time & again! It failed with an o/c cell eventually. I have a batt from the tip that the sg says is dead flat!-yet that batt puts out 200 amps with very little volt drop! Ocv is 12v5(fully charged). So my friends- what the books say & what is real are different things!. Matej- the circuit I used to build my zapper came from Silicon Chip magazine- but I used my own up rated parts wired direct- eg- they had 100v mos-n-fet I used 500v- etc-etc-etc- the circuit is inductively coupled using my own wound air inductor of about 100uH. Download circuit from SC website. Another question for the expert John- there used to be batt recond places that would sell one a recond batt for say $20 at time when new was say $120- WITH 3 MONTH WARRANTY. I saw what they did- got lots of batts- put em on high charge rate- those that charged up- they tipped old electrolyte out- refilled with new electrolyte- seemed to work for while!. Any scientific validity to what they did? Cheers- Bevan.

On January 28, 2012 at 1:50am
matej wrote:

Hi Bryan.So you pulse mainly car batteries? I mostly do the deep cycle batts from PV , UPS systems etc. Yes I can agree that o.c. voltage is not very relevant, as it is also temperature dependant etc. But I really have experience that SG is very relevant in terms of battery Ah capacity - this is not only theory from a book, but mainly my own experience with many, mostly deep cycle batts: Battery that has low SG when fully charged, does have low Ah capacity. I have never had a battery that has low SG and has good Ah capacity. It seems that the capacity is roughly proportional to SG of the weakest cell: 1,15 -little or no Ah capacity to 1,28 -full Ah capacity .
When SG is low, the CCA (cold cranking amperage, that’s what starts the car) is also lowered but even this lowered rate might be enough to start a car fine: Actually right now I am pulsing a 60Ah car battery, that has 5 cells at 1,24 and one at 1,20 and still started the engine normally with no problems. But there were some problems with the engine recently - it won’t start and that is where they found the battery has low capacity - it will crank only for few seconds. They had to keep it on a charger constantly when they serviced the engine.
So I really believe that SG is very relevant to battery Ah capacity - I believe if you would do the Ah tests in deep cycle batteries, you will find the same.

On January 28, 2012 at 1:59am
matej wrote:

John - the battery I described was definitely NOT in a discharged state - it had OC of 12,8V right before pulsing started and this did not change after pulsing, yet the SG and Ah capacity changed dramatically. But yes there might be the oxide layer problem too, who knows, but SG measurements before and after pulsing clearly say it was mainly sulphation.
Prior to pulsing I always put the batteries on 13,7V for at least 24hrs, but mostly two-three days at room temperature, before doing any measurements and pulsing.

On January 28, 2012 at 4:58am
Andersen wrote:

- John,

Thanks for fast respone, so you means even AGM & gel series battery is not good as the batt you had mention?

The 1st you mention for the life time are too short.. 2 years average, overall, i did not saves, the 2nd, will not save as much.. 3rd is too expensive…

Especially all batteries are imported, our government tax is blood sucker, all oversea imported batteries price so high price here… So upsad.

On January 28, 2012 at 5:14am
John Fetter wrote:


I believe 13.7V is no more than a high float voltage. It does not charge a battery in the accepted sense. A battery that reads 12.8V could be at full state-of-charge or at full state-of-discharge, depending on a number of factors. Battery voltage is meaningless when measured or expressed arbitrarily. (This is more fully described on evbatterymonitoring.com - a website run by a well known state-of-charge instrument manufacturer.)

Did you treat your battery to 13.7V prior to measuring 12.8V? That would definitely give you a false indication of the condition of the battery.

Sulfation defines the battery plates as functionally inoperative. This must be reflected by a much lower than normal battery voltage.

Logically, if you apply 13.7V to a sulfated battery, then disconnect and the voltage stays at 12.8V, the battery either was not sulfated or became desulfated in the process. The voltage of a sulfated would collapse on disconnection.

The information you present regarding SG fits a situation involving (a) a battery that is simply discharged or (b) a battery with an oxide layer problem.

On January 28, 2012 at 5:43am
John Fetter wrote:

Andersen - the AGM and gel are twice as expensive and quarter to an eighth as good as flooded lead-acid. I personally would definitely use Trojan golf-cart batteries or any other brand that uses rubber based separators. I would not touch batteries with polyethylene separators. If you are terribly worried about cost, give plenty of extra TLC to the batteries you use. You might then get 6 years out of your golf-cart batteries, or even much more.

On January 28, 2012 at 7:15am
matej wrote:

John:  Yes I did charge the battery at 13,7V for 3 days at room temperature, which according to vast majority of commercial lead-acid battery datasheets leads to full charge. Actually they mostly specify 100% charge in 20hrs. Most UPS systems use only float voltage charging at 13,5 to 13,6V (room temp). Then, I completely disconnect the battery and leave it like that at room temperature for several hours to stabilize. Then and only then I measure SG, voltage, capacity test etc.
In the early stages of my experiments I also tried to charge with higher than float voltage, 14,4V and more .. but this did not lead to any significant improvement in capacity or specific gravity. Many times it only colored the acid to dark red or brown, and caused the acid to smell bad.
Where did you get the information that “Sulfation defines the battery plates as functionally inoperative. This must be reflected by a much lower than normal battery voltage.” ??
That is completely false in terms of o.c. voltage. It only applies if the voltage is tested under load, which is not what I’ve been talking about. Sulfation - partial coverage of plates by crystallized lead sulfate -  reflects to increased battery resistance and lower capacity. That may reflect to lower voltage of battery UNDER LOAD. But it has nothing to do with open-circuit voltage. I thought you know this, you really surprise me now.

I already wrote that stabilized o/c voltage of sulfated (small Ah capacity) and desulfated (good Ah capacity) is virtually the same. I have had several 100Ah batteries that had only 2-3 Ah EACH as per C/20 load test. They have been left totally discharged for more than 2 weeks. They were measuring stabilized 13,0 - 13,1V OPEN CIRCUIT, just as almost any fully charged 12V battery i have had. None of many charging attempts of mine or their former owner were successful. After I popped the covers, SG was 1,18 in the weakest cells. After pulsing for 2 weeks the SG of weakest cells rose to 1,24 and the C/20 capacity of one battery was 38Ah, the other 48Ah. The stabilized voltage was still in the range 13,0 - 13,1V !!
They were already returned to the PV system they came from, as the renewed capacity is satisfactory for their owner.

You obviously try, for some reason, to undermine the concept of pulse desulfation while continually ignoring the main proof of this concept that I have mentioned several times: Specific Gravity of sulfated battery being charged with DC voltage for days, does not increase or only little, but with pulsing it increases much more, many times to 1,28 or close to that.

You never tried to explain this, so please do before commenting on pulsing as ineffective in sulfation removal.

On January 28, 2012 at 7:55am
Andersen wrote:

- John,
May i know what is TLC? Just add it in for every cell? Thanks

On January 28, 2012 at 9:08am
John Fetter wrote:

Anderson - absolutely yes. TLC stands for Tender Love and Care.

On January 28, 2012 at 9:10am
John Fetter wrote:

Sorry, I meant Andersen.

On January 28, 2012 at 9:21am
John Fetter wrote:


On application of 13.7V, if a battery is NOT sulfated it CAN accept a charge. If a battery IS sulfated it CANNOT accept a charge. By definition. Electrochemistry 101.

On January 29, 2012 at 9:16pm
Andersen wrote:

Good day, John,

Finally i found the Trojan batteries distributor in my country, may i get your consult again? Which modal of Trojan flooded battery to suit for my 24v system and plan like last times i said. And i am also worry, i keep my batteries at indoor inside my storeroom, i am afraigh the gas will BOOM my store.. \_/

On January 30, 2012 at 2:03am
John Fetter wrote:


I keep batteries indoors, on charge, in a store. So what. You can ask for flame arrestors as well as auto filling if you are that way inclined. I personally would not bother. I cannot advise you on battery rating. Trojan have a solar, wind advisory department. Search trojan batteries flame barrier, etc., etc. I would use T105 or similar. They will try to sell sealed types. Refuse. Do not allow yourself to be their AGM/gel guinea pig.

On January 30, 2012 at 10:33am
Andersen wrote:

Good day, John,

Thanks for so many prompt reply, today i look at my store, i have many SLA battery, i am wonder if i can open the top cap, and fill in distill water or table salt, do you think will be work better?

On January 30, 2012 at 2:37pm
John Fetter wrote:

Andersen, I would use only distilled water.

On January 31, 2012 at 1:48am
matej wrote:

Andersen, as John says. I would also not use anything but distilled (or osmotic) water. Yes you can open the top cap on SLA (VRLA), that is what I do often. However with new battery, which you do not charge with higher current than C/10 and do not let it stand discharged and thus sulfate, you have one or two years minimum before water needs to be added. Just do a capacity test every few months, if capacity is >80% I would not open the caps. Maybe just few days of electrical pulsing will recondition it close to 100% again.

On January 31, 2012 at 5:39am
John Fetter wrote:

Once upon a time the battery industry actually made good batteries. Their ONLY disadvantage was that they needed watering. Then the industry came up with a maintenance-free concept - saying the automobile manufacturers were demanding maintenance-free. Yet cars still needed water for the radiator, oil for the engine and air for the tires.

The electrochemistry in maintenance-free sealed lead-acid must be run in a very peculiar way in order to stop the batteries drying out. Gassing can be reduced, never eliminated. So what they do is they hold the electrolyte in glass fiber matting or gel that has minute cracks all over. The oxygen that is given off by the positives travels via the matting or the cracks in the gel to the negatives, where it combines with the hydrogen that is given off, to form water. Sounds like a brilliant idea until it becomes apparent this recombination activity discharges the negative plates! You can charge and charge and charge. The negatives will always be partially discharged. Guess what! The negatives sulfate up!

The positives of batteries made long ago were made of lead-antimony alloy - the new ones are made with lead-calcium alloy. This helps to reduce gassing but introduces all kinds of extra problems. These grids cannot tolerate overcharging. They cannot tolerate overdischarging. The grids either fall apart or they develop “open circuit”, an oxide layer that leaves the active material isolated.

I was involved in a project to build the biggest battery in the world. When people have to spend tens of millions of dollars on a battery installation, they generally try to do their best. The battery was run from the local 220KV grid, via transformers and inverters. It had a capacity of 40MW-h. Used for load-leveling in California. It was charged during the night, discharged during the day. The battery absolutely had to be designed for maximum life. The design life was 4000 deep cycles. The cells were the same size as submarine battery cells. The positives were American flat-plate with grids made of lead-antimony-arsenic. The negatives had lead-calcium alloy. The separators were made of porous rubber/ glass fiber. The electrolyte was liquid and the battery was filled with watering caps. It got me interested in finding commercially viable ways of making batteries last longer, (without the use of arsenic and with only the lowest percentage antimony)

I am not expressing metely an opinion when I recommend flooded motive power batteries for cycling in wind and solar.

On February 16, 2012 at 1:01am
N.senthil wrote:

Dear sir
          I am using 54v 300ah vrla battery bank out door. I don’t have backup I found that some cells are faulty it discharging soon for that cells can I add distilled water and charge

On February 17, 2012 at 11:16pm
Bevan Paynter wrote:

If your cells have removable tops-check electrolyte level (if your cells are flooded) if not flooded- nothing you can do- except find reason for failure- remove each cell to check- if o/c failure- zapper can work- also sulphation failure- as has been said many times- SLA incl VRLA have limited life- esp if deep cycled! ( though label may state differently!). If electrolyte level is below plates, only add enough low ppm water to cover just - charge- when fully chgd- top up( electrolyte level rises with charge). General advice without seeing your batt/s- setup.

On February 18, 2012 at 1:59am
John Fetter wrote:

N.senthil: I agree with Bevan Paynter. I should point out that without knowing the age of your batteries, others are unable to work out the cause of the problem. Batteries age, like people. Have accidents or pass away, like people.

On July 6, 2012 at 5:40am
Oscar Ormond wrote:

Just spent a few hrs looking at websites run by battery rejuvinating franchise operators. If their desulfaters are really as good as they claim, why are they so desparate for total strangers from other cities and other countries to sign up to promote it?

They say people who want to set up with their spesial units must first be trained, have spesial quality control, keep records, receive a certifecate. Hey, to charge any battery plug in, switch on. big deal

If their stuff really works, why are they not running big service centers in their home towns. ANSWER. Their stuff does not work!!!!  They want the people that get mad with them to be far away, that’s why.

On July 7, 2012 at 12:47am
Bevan Paynter wrote:

Oscar, my own experiments have told me that desulfators or pulsers are usually a waste of time on sulfated batts- but may work on oxide filmed batts. Really, the only life extension of any batt is to never over discharge,overcharge, or let terminal voltage drop to where sulfation or other growth on plates occurs. That said, batts have a certain life- it can be as short as 3 months or as long as 10 years depending on above care regimes. Yes, batt desulfator sellers have an agenda to sell their product(for profit!- not to help you!- same as batt additive sellers!) I just ran an experiment on a car batt 4 year old, used only once a month to start a car & then a long run- should have been as new(no discharges-older car)- on start @ month was getting more sluggish- then ok. Removed- octv (OPEN CIRCUIT TERM VOLTAGE) was 12,38v- put on charge to equalize-destratify- octv still low - added 1 level teaspoon of magnesium sulphate to 2 cells- 1 level teaspoon of dcbla to 2 cells(dicarboxylic acid)- 2 cells untreated- charged- no change in octv or sg(specific gravity)- added 15ml of INOX batt conditioner to 2 untreated cells- charged- next day the 2 Inox cells had sg of 1.273!(AS new!)- added Inox to last 4 cells- charged - next day ALL had sg 1.273!- & octv 12.8v! Now- how did this as new sg & octv relate to starting performance?- not very much at all! Which means a waste of time trying to get as new performance out of an old batt! Previous to this, I emptied electrolyte out of 3 diff car batts (@ charging) added 1 lev teaspoon dcbla to each cell & filled with rain water-after foaming stopped, tipped out mixture & added new electrolyte- charged- a great improvement(octv rose from 12.2v to 12.5v- hltv(high load term voltage) rose from 10v to 11v(under 200 amp load). Will next try adding Inox to these 3 car batts to see if improves or worsens! With car starter batts it is important to get data of what batt is like before doing anything- use a dmm(digital volt meter) connected to car batt(cig lighter socket) to see exactly what batt volts drop to under starter load- lower the drop worse off batt is- then try what ever & recheck!

On July 7, 2012 at 2:57am
John Fetter wrote:

Beval - Inox mx2 is made by Candan Industries Pty Ltd., a specialist lubricant manufacturer located in Loganholme, Brisbane, Australia. It consists of 5 percent cadmium sulfate, the rest mainly water. The cadmium electroplates out onto the sulfated non-functioning negative plates, covering specific areas of the plates with a thin film of cadmium metal, thus giving the battery cells temporary-working cadmium negative plates. After that the battery can be charged. But it will be capable of delivering very little long-term ampere-hours.

Cadmium was tried by the very early battery manufacturers. It achieved nothing of practical benefit so they gave it up. After that, the bring-back-to-life merchants began using it. They claim it cures sulfation. That is a fantasy. All it does is give a battery a few temporary ampere-hours. Cadmium cures have been around for over 100 years.

On July 7, 2012 at 3:01am
John Fetter wrote:

Bevan - I apologize - I wrote Beval instead of Bevan. Better buy some reading glasses!.

On July 7, 2012 at 1:58pm
Oscar Ormond wrote:

Thanx Bevan. Hey John, i looked up cadmium sulfate. this stuff is realy dangerous. Its poisonous and causes cancer. Battery Equaliser and Candan Enterprizes both sells this stuff to ordnary people who don’t know how dangerous it is. It sofens your bones man and they just break when you try stand up.

On July 8, 2012 at 1:18pm
John Fetter wrote:

Oscar - One of the most dangerous things any one can undertake is to be be born. That has a greater than 99% risk of dying over the next 100 year period. Flying has never been shown to be even remotely dangerous - it becomes dangerous only when the plane does not land properly. The lead in lead-acid batteries becomes very dangerous when eaten, the acid becomes very dangerous when drunk. There are one billion of these things being driven around the face of this planet, no one seems adversely affected. Try not to drink the cadmium sulfate. It is surprisingly easy not to.

On July 8, 2012 at 11:36pm
Bevan Paynter wrote:

John- one would think that the suppliers of cadmium sulphate should have a poison label attached, & that the 95% of water should not be coloured a pretty blue/green! Now- suppliers say reverses sulphation- my sg readings agree- or is that mixture a sg improver?ie, if an amount added to water-sg 1.00- raises sg thus? Guess only trying this out will settle the question! Otherwise, John, I would have to think that this stuff really dissolves sulphation! I will carry out further experiments when i get some more mx2. What I do know for sure is that carboxylic acid(EDTA is a form) lowers sg by chelating the sulphation present in plates- so one has to refill with new electrolyte. ( to get   octv & sg as original). IF mx2 works!-would save a bit of mucking around to get otherwise lost batt useful life!. Bevel.

On July 9, 2012 at 1:53am
John Fetter wrote:

Bevan - I did the experiment. Tried cadmium sulfate. I built a battery cell in a glass jar so that I could see what was going on, rather than wearing a blindfold working on a conventional opaque case battery.
The negative plate changed, from the bottom up, gradually into a more metallic looking plate. The on-charge cell voltage did not seem to change but when I stopped charging, the cell voltage stayed above 2.35V for many hours.
After charging a little more, the bottom of the negative plate began to develop mossing, also called dendrites, that spread out.
So I tried discharging the cell. Most of the moss seemed to disappear but some had broken off and was left behind.
What I saw suggests that the cadmium provides a substitute for the lead/ lead sulfate that is in the negative plates, helping to charge the positives. That would certainly help to raise the electrolyte SG and should be good enough to crank an engine.
I have been unable to ascertain, thus far, whether cadmium sulfate gets rid of sulfation but I am working on it.
My results seem to indicate that brand new lead-acid batteries treated with cadmium sulfate will deliver more amps for cranking engines.

On July 9, 2012 at 11:36pm
Bevan Paynter wrote:

John- dendrites were a problem with NiCd batts/cells- shorting em out- I used to blast s/c cell with 330v from flash cap- worked! It is interesting that cathode & anode of normal cells is opposite with lead acid batts! Incidentally, mx2 container DOES have poison label & advice for treatment if “accidently swallowed!”!  A source of cadmium would seem to be old NiCd cells/batts! Cut em open very carefully- avoid breathing any vapour or skin contact!

On July 13, 2012 at 1:20am
John Fetter wrote:

Bevan - A few days ago I was cleaning out my accumulated battery junk and came across some leftovers from experiments I had conducted towards the end of 2007. A plastic bucket filled with discarded battery acid and discarded battery plates.
I had received some individual battery plates from four different manufacturers on which to conduct some experiments. When I was finished with them I put them all into the bucket - and forgot about them.
After finding the bucket it began to dawn on me that there was a possibility the plates it contained might actually have become valuable due to the time they had been sitting in the acid. The first thing I did was to measure the acid SG. It was 1.285. After more than four years - obviously become totally sulfated.
I carefully took out the plates and lay them down in a row on some newspaper.
Some were flat, some slightly buckled, some severely buckled. Positives and negatives alike.
On careful inspection I discovered all the buckled plates had buckled in the same direction. Away from the side from which they had been pasted. Some plates had extra active material on the pasting side. The thicker this extra layer, the more buckled the plates. The plates that appeared to have been pasted to equal thicknesses on both sides were flat.
Lead sulfate takes up more space than healthy active material, causing the plates to expand - and some to buckle. Expansion through a chemical reaction can develop gigantic pressures that easily punch through separators, cause battery terminals to lift and battery cases to balloon.
Simple experiment, profound implications. Surely if manufacturers pasted the plates to an even thickness on both sides, designed connectors to cope with expansion, battery failures would come right down?
Now that I have sulfated plates with a known history, I can test all the popular desulfation cures with 100% confidence.

On July 14, 2012 at 12:12am
Bevan Paynter wrote:

John- batt electrolyte is 1.285 in bucket then plates are not sulphated- all else being equal! In a batt electrolyte is 1.26-1.27 if batt is fully charged- ie all acid is in water- if batt fully discharged electrolyte sg is 1.00- ie all acid is in plates(0v octv). So are you saying plates were all flat 4 years ago? & it is the fact that they have been sitting doing nothing that has warped them? Yes- sulphation warps plates- usually positive- crystals build up, warping, puncturing seperators, shorting out, bulging case ends, disintegrating pos grid connections. If more material has been plated on one side than the other, then it is obvious that MORE crystals will build up there! So because of neighbouring neg plate, the warp force will take the easiest way out! If you want to demonstrate the efficacy of desulphation methods, then you need what the average owner has- ie a sulphated batt that will not deliver previous starting amps!- though said owner/s have done nothing wrong according to batt manufacturers! The crime is the batt is more than 2 years old! From the birth of lead acid batts, there have been ads to buy this/that to rejuvenate your batt!- much the same chemicals used as now! I can state that there ARE NO magic formulas to fix your batt- the batt manu,s have tried em all in interest of market share! gUESS there are those among us who wish for a miracle- remember when I thought that electrolysis of water to produce on demand hydrogen to run ICE worked! It,s ALL been tried before folks! IF these fads worked- they would ALL be standard- folks!.

On July 14, 2012 at 1:42am
John Fetter wrote:

Bevan - The plates were sitting at the bottom of a plastic bucket filled with battery acid. The water in the acid evaporated over time, raising the SG, until evaporation ceased. This is a well documented characteristic of battery acid. The high SG promotes sulfation. The plates remained totally submerged and are therefore guaranteed 100% sulfated. And their history is known to me with 100% certainty.
The plates were free to move as they buckled. Therefore I was able to make an important observation about the exact way they buckle that would have been impossible had the plates been located inside a battery.
I assembled one of the sulfated negatives and a proven healthy positive into a battery
cell, in a glass jar and connected to a power source. The voltage rose to the limit I had preset = 2.6V and the current sat at just a few milliamps. (I use an electronic regulated power supply.) Twenty-four hours later a few more milliamps but otherwise no joy. It would not charge. The negative grid was gassing and that was the only area causing the few milliamps to flow. The active material simply sat there. This example negative plate was very definitely sulfated.
The reason why I did not test a positive plate from the bucket, together with the negative is because positive plate sulfation is easily reversible.
Next, I tested the effect of cadmuim sulfate. Very interesting result. Cadmium metal electroplated onto the negative grid, grew dendrites. The cell began to draw some current. After a few hours the cell stabilized. So I gave it a discharge test. I got 10% of the factory rated ampere-hours. Did it again. Still got 10%. I did notice the open circuit voltage of the cell was HIGHER than normal, likely because of the on-plated cadmium. (The electrochemical potential for lead is -0.1262, cadmium is -0.4030.) The sulfated active material just sat there doing nothing. If this had been a fully assembled car battery, it would DEFINITELY have cranked the engine and started it. But it would have been incapable of doing anything beyond that.
I intend to run many more experiments until I have gone through all the plates I salvaged from the bucket.

On July 16, 2012 at 12:07am
Bevan Paynter wrote:

Thanks John- very interesting.  I am still playing around with std car batts that have elevated self discharge due to sulphation- you know- charges up ok, then a few days later octv of say 12.4v instead of std 12.6v- ends of case slightly bulgy. I put em on 16v charge for while, check sg, then tip out old electrolyte. flush out batt with rain water twice, refill, add 1 level teaspoon carboxylic acid per cell- put on 16v charge. Foams up- after couple hours of alternating charge & sitting there, bubbling slows down, 16v charge draws less amps, charge volts drop, pressing in on case ends sends bubbles up, ends are now level. can now tip out mixture, flush out twice with rain water, then add new std electrolyte 34% sulphuric acid, put batt on charge std 14.4v- when amps have dropped to minimum- batt is as fully charged as it’s design intends(these starter batts are lossy from new!). Several days later if octv are 12.6>, batt puts out say 11v at 200 amps, batt has been rescued! I have found that the latest fad so-called desulphators(pulsers) are a gimmick where real sulphation is involved- takes weeks!- where they do work is where the fault is an insulating layer of oxide After all , a battery can be looked on as a giant capacitor- how can a layer of pulses penetrate deeply enough to do anything- especially as powered from batt itself! The apparent reason why generator charge systems allowed car batts to last twice as long is I believe that the gen charge was a square wave with hash, due to sparking etc at brushes. This allowed batts to charge better, & also tended to disperse sulphation on plates..

On July 16, 2012 at 1:28am
John Fetter wrote:

Bevan - I have continued charging and discharging the same sulfated, cadmium-sulfate-treated plate six times. A new plate of this kind has a capacity of 9 ampere-hours. I finally managed to reach 3 ampere-hours. I could see the improvements began to level out during the fifth and sixth cycle. If this happened to a car battery, I can see that this would be enough to make the average, unsuspecting car owner happy. I have no doubt this battery would deliver ample starting current. However, the battery would still be two-thirds sulfated and would definitely not last more than a few months after treatment.
I am curious to know which carboxylic acid you use. Vinegar or acetic acid, is a carboxylic acid. Soap, which is predominantly palmitic and stearic acid, is a carboxylic acid. The carboxylic acids that are solid are surfactants.
There appears to be a tremendous amount of physical activity involved in making these batteries work again -  if you take actual labor cost into account, it makes very little sense.

On July 16, 2012 at 11:50pm
John Fetter wrote:

Bevan - I have removed the negative plate I “revived” with cadmium sulfate from the cell. Carefully examined it in very bright light to see which areas of the plate were charged. This can actually be seen with the naked eye by the appearance of lead, which has a different color to lead sulfate.
To my surprise the lead formed alternating bands of equal width with the lead sulfate. The bands are about 50% wider than the grid spacing and run in the same direction as the pasting. This suggests the manufacturer of the battery did not mix the paste thoroughly.
I suspect the areas that were successfully charged contain the most carbon black.

On July 17, 2012 at 12:04am
Bevan Paynter wrote:

John- the name of the product is LO-Chlor multi-stain remover- a powder- cost me $28 for a kg at a swimming pool chemical supplier-98%dicarboxylic acid complex- it definitely removes sulphation from batt internals- after treatment as I said, can see pos plates- brown- neg plates-grey. Not much labor involved- just tip out contents a few times- refill- charge.As to longevity- that is to be still ascertained- I have only been using this procedure for about a month- the batts I have treated & are using in my cars are excellent now(2 of)- octv rose from 12.28 & 12.3v to 12.7v. The batt I treated using mx2 cadmium sulphate I don’t know(another car)- octv rose- ultv seemed to slightly fall- time will tell in all cases!. Yes batts are so cheap these days- hardly worth playing around with them- but guess I have that type of personality- an enquiring mind. And if my type of treatment works, & if others apply- can only be beneficial to environement.

On July 17, 2012 at 2:07am
John Fetter wrote:

Bevan - Here is something that defies established understanding about sulfation. The color of the active material in sulfated negative plates is CHARCOAL, not white!!!
A white lead sulfate precipitate definitely covers just about everything inside the cells, but that seems merely incidental.
I have seen it stated many times that this coating is responsible for all the problems. I decided to find out if this white stuff is as impermeable as people claim it is. I opened a badly sulfated battery, let it dry and using an eye dropper put drops of water onto the worst of the dried white affected areas. The water was absorbed faster than as if I had I dropped it on newspaper. This would seem to indicate the white sulfate is HIGHLY PERMEABLE.
Lead sulfate precipitate is white - its surface reflects light. Lead sulfate in the form of ordered crystals are charcoal - their surfaces to not reflect light.
Washing out that white stuff makes the battery look better. I am not sure whether it helps to make it work better.

In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. (Galileo Galilei)
If you can’t explain it to a six-year-old you don’t understand it yourself. (Albert Einstein)

On July 17, 2012 at 11:45pm
Bevan Paynter wrote:

Yes John- but the white stuff that washes off is not the stuff that causes hard, insoluble crystals- mainly on pos plates, that causes s/c & case swelling- or is it more correct to say that the white stuff is an early form of the hard stuff. Well this stuff I used restored the swollen case at both ends to a flat surface- so I would have to say that it definitely gets rid of hard lead sulphate crystals- in about 2 hours.It’s a pity that Einstein couldn’t work out a theory of everything- but then neither can anyone else!

On July 18, 2012 at 12:43am
John Fetter wrote:

Bevan - Seasoned battery experts all agree that sulfation in the positive plates is fully reversible. Sulfation in the negatives can be difficult to impossible to reverse. Sufate crystals are bulky, the pasting usually asymmetric, hence the plates warp.
If you dissolve the lead sulfate and wash out the battery, you end up with a battery with little or no active material in the plates. The battery will have been desulfated. It will also have been “debatteried”.

On July 21, 2012 at 2:40pm
John Fetter wrote:

I have just finished testing a popular make of industrial lead-acid battery pulse desulfator. Two 15 A-h cells that had been stored unused for three years, refused to take charge when hooked to a conventional charger. Applied 2.6V per cell, current refused to build up, showing the cells were deeply sulfated.
This particular pulse charger was designed to work with a wide variety of batteries, voltages, currents. Connected the pulse charger and immediately the batteries began to accept charging current. Average voltage 2.7V, peak pulse voltage 3.15V, average current 2.7A. The batteries gassed furiously.
On discharge test, cell 1 gave 1 ampere-hour, cell 2 gave slightly less than 3 ampere-hours. My sulfated test cells had not recovered.
I am not claiming pulsing does not work. I am, however, saying pulsing is unlikely to desulfate a battery. Pulsing most likely does something else inside a battery.

On August 26, 2012 at 1:09am
John Fetter wrote:

I am an electronics nerd. I just happen to enjoy experimenting and lead-acid batteries provide an ideal subject for research with a focus on physics rather than on chemistry.
The owner of the industrial lead-acid battery pulse desulfator wanted his machine back promptly after I had done my testing, probably because I had found it wanting.
So I went ahead and designed and built my own pulser. I had been working on small, 1.5 Ah single cells, so I purpose designed the pulser for these cells. The pulser produces 10 volt, 10 microsecond pulses at somewhere in the region of 10 amps and at a 2 kilohertz rate.
It charges my 1.5 Ah cells beautifully. But most of the pulsing energy is getting lost in the wiring. I put my oscilloscope probe across the output of the pulser, saw 10V. Put it directly across the cell and there was only 3.5V. Then I made a special acid-proof extension to the oscilloscope probe, put it into the electrolyte of the cell and measured what was going on between the plates, near the plates and on the plates, etc. from the inside.
I saw nothing out of the ordinary. The pulsing produced above average voltages that were all in correct proportion.
I ran one cell with a sulfated negative plate on pulsing, another with a sulfated plate on pure direct current charging. After one week, cannot see any special advantage in pulsing. All of that can still change. I am patient.

On August 27, 2012 at 11:54pm
Bevan Paynter wrote:

John- what horsepital are you a patient in?(only yolking!) The benefit of a desulfator is that it can “persuade” recalcitrant batts to accept a charge or else!! Talking bout genuwine sulphated batts here folks! Measure maybe 0.5 volt open circuit!!! AND not your so-called electronic pulsed desulphators!!- they have VERY little use!!! But 240v dc works wonders!!!! Just today had 6v sla vrla measuring 0.2v- put electric d/s on- volts rose to 112v-@ 5min came back to 73v- then smoke came from neg post- terminated attempt. Cut open- completely sulphated up & pos plate disintegration- put into tip bag. Other batts have been rejuvenated, but depends on degree of sulphation(only!)

On August 28, 2012 at 4:14am
John Fetter wrote:

Bevan - What can I say? My suggestion to readers: Whatever you do - don’t try Bevan’s recommendation at home. Six volt batteries usually explode when connected directly to 240 volts dc.

On August 28, 2012 at 11:12pm
Bevan Paynter wrote:

John- you are jumping to conclusions without knowing all the facts- YES- unlimited 240vdc WOULD blow the !@#$$%%% outof 6-12v batts etc-BUT!- current is limited by inline resistor- chosen to give a selection of currents-eg 300mA,600mA, 1A,3A,6A, 8A. With a non- or lightly sulfated batt, volts at posts are much same as batt nom volts- batts are a giant capacitor! BUT! don’t touch posts!!- 240v dc is even more LETHAL than ac! Anyway, works really great to rescue otherwise doomed batts- the volts when 1st connected tells if batt can be rescued, or(as in case of 6v batt mentioned, is finished- if volts were say 66v & came down to 6-7v, batt is ok- 1st few minutes tells story.)

On August 29, 2012 at 12:20am
John Fetter wrote:

Bevan - This is an interesting subject. I responded to the information in the form you had presented it. Had you included the information about the resistors, I would have pointed out that it takes a spark created by a potential greater than 24V to ignite hydrogen, when it is present at an optimum concentration together with oxygen. The
current can be miniscule.
Batteries develop internal open circuits just often enough to cause explosions. At 12 volts, an open circuit is simply a nuisance. At 240 volts, regardless of your resistor, you run a high risk of finding out what it is like to be at the receiving end of a battery explosion.
Battery explosions are not uncommon. Submariners and miners will readily agree to that. Their batteries are high voltage. I have seen the consequences of some spectacular battery explosions. Every year automobile battery manufacturers have to deal with a surprisingly large number of claims from irate people who did something silly with their car batteries. They appear to be able to connect jumper leads in the strangest of ways, put their metal watch straps and items of jewelery, tools, etc. directly across a battery output, causing sparks, red-hot metal to cling to them, often leading to explosions and personal injury - in some cases the need of a new face. Hence the warning labels.

On August 29, 2012 at 11:16pm
Bevan Paynter wrote:

John- thank you for info-so electronic pulsers-which use pulses at up to 1300v,repeated at say 1-2-more - Hz- are safe?!!!! Or are you saying that because pulsers are NOT dc but pulsed dc-are safe!? Now what makes you think that what I posted is not a pulsed dc device? You are guilty of jumping to conclusions without knowing all facts! Something which a tv/electronics technician with 50 years experience learned long,long ago!.

On August 30, 2012 at 12:11am
John Fetter wrote:

Bevan - Thank you for your interesting comments. Am I jumping to conclusions?
If you paint a picture in which you are applying 240V dc to a six volt battery, that is your picture, not my interpretation.
If you then paint an entirely new picture in which you are applying 240V dc via resistors, that is your picture, not my interpretation.
If you change your mind again, paint a picture in which pulses up to 1300V are applied, you are the one who (a) is painting the pictures, (b) keeps painting different pictures.
There are pulsing devices that discharge the energy stored in inductors into the batteries and pulsers that discharge the energy stored in capacitors into the batteries, repeatedly, in common use. The former capable of producing excess voltage across small gaps and capable of igniting hydrogen. The latter I witnessed in use.
One person’s 50 year experience does not equate to possession of universal wisdom.
I have spoken to a person who acquired holes in the face by an exploding battery, that had to be repaired by plastic surgeons.

On September 1, 2012 at 12:43am
John Fetter wrote:

In July, after I finished testing an industrial battery pulser, it occurred to me that perhaps simply switching a battery charger on and off might be worth investigating. I reasoned that the charger had to deliver at least 2.6V per cell. I built the cells with new positives and 100% sulfated negatives. The cells received a few hundred milligrams of cadmium each plus an electroplating additive compatible with lead-acid battery functioning, cadmium and sulfuric acid.
The per-cell voltage rose almost immediately to 2.6V, with very little current flowing. The charger was switched on for one hour, off for half an hour, repeatedly. After a few hours cadmium could be seen electroplating onto the negative grids. It took several days before the electroplating could be seen beginning to migrate into the sulfated active material. At the end of one week I was ready to give up. It looked as if nothing was happening anymore. I decided to carry on.
During the second week, there was a change. The electroplating began to grow in patches all over the negative plates. So I ran a discharge test. I measured nearly 50% of the original ampere-hours.
At the end of the third week virtually the entire negative surface was covered with cadmium. It looked untidy. Very fluffy. So I ran another discharge test and measured 100%.
Why did I switch the charger on and off? To encourage the cadmium that had been electroplated on last to redissolve in the acid, leaving behind an area of desulfated active material that would spread progressively farther into the deeply sulfated bulk when the charging recommenced.
Why did I use the electroplating additive? To prevent the cadmium electroplating predominantly onto the grids and to encourage it to spread into the sulfated bulk.
My previous attempts had been based on conventional methods. None of them had worked on 100 PERCENT SULFATED plates. This one had worked although it seems hardly worth all the effort.

On September 1, 2012 at 1:26am
Bevan Paynter wrote:

John-you did WHAT!!!? Are you a brainiac or WHAT!!———————-what?  Folks, I have found that to make a car starter batt last for many,many years- it is necessary to remove it from vehicle after each run( I made quick detach system) & put on 14 v constant voltage charge- you will be astounded at amount of charge needed after LONG run in correctly functioning auto charge system- this is why batts sulfate up- & thus only have a short life. Big Jon, I have found that any additive is useless- but saw on CR4 today(Iam a long term member) that some poster said use baking powder(NOT baking soda)- said it works!- must try!!

On September 1, 2012 at 2:06am
John Fetter wrote:

Bevan - Again, what can I say. What I did was no more than to run an experiment to find out how far I could go with “desulfation”. That’s all there is to it.
I began using a permanent charger for my car many years ago. Simple. No need to disconnect the battery from the car. On connection, the charger measures the battery volts, decides if it must charge or float. It always ends up on float, at 13.5V. That voltage counteracts aux. equipment and keeps the battery in superb condition. Telephone exchange batteries are usually run at the exact equivalent 24 cell voltage. They can last 30 years. 14V makes the battery gas and is inclined over time to corrode the positives.
I prefer to work on big batteries.

On September 8, 2012 at 3:17am
John Fetter wrote:

RE: Aug 26 posting - Desulfation, pulsing vs direct current. High frequency pulsing 20% recovery, switching direct current on and off once per hour 30%. The cell receiving direct current is winning. I know pulsing can bring “tired” batteries back but what I have been seeing suggests the popular explanations need to be revised. .

On October 25, 2012 at 6:00am
Guina wrote:

Hello.. I have a simple question for a simple digital camera battery which I left charging at my office. My problem is I can only check it after 3 days long weekend. Is there any consequences in electricity when it is over charge? i’m worried that it will cause of fire. I would highly appreciate anyone’s advise. Thank you.

On October 26, 2012 at 5:31pm
RAMM wrote:

Even in the most sophisticated cells, efficiencies are never 100%. Explain why.

Many Thanks in advance

On October 27, 2012 at 1:49am
John Fetter wrote:

Henry Cavendish discovered that electrical current is proportional to potential difference. He forgot to publish his finding. Georg Ohm, 1789-1854, published his book entitled Die galvanische Kette mathematisch bearbeited, (The galvanic Circuit investigated mathematically), in 1827. Ohm was credited and the law was named after Ohm.

Directly and indirectly, circuit resistance causes batteries to be less than 100% efficient.

On November 20, 2012 at 7:40pm
Stuart wrote:

John/Bevan - thanks for all the great insight!  We’re setting up an experiment to test 3 desulfators using 6V 100AH [3DCU-9] clear case batteries.  We have 4 new and 15 used [partially sulfated?] for the test.  One question - can you suggest the best way to determine the capacity of the batteries so we can test capacity of the used batteries before and after processing with the desulfators?

On November 20, 2012 at 11:33pm
John Fetter wrote:

Stuart - Step 1. Charge the batteries. Then give them a slow 30% A-h overcharge to make absolutely certain they are 100% fully charged. Discharge one battery at a time with 0.2 ohm load. Should take about 2.5 hours down to 1.75V/cell. Measure actual time. The actual time taken for each battery can then be compared. That is all there is to it. Make sure the temperature is roughly the same for all the batteries.
I have become amazed by the tens of thousands of people all over the world, all looking for same desulfation pot of gold at the end of the rainbow. All looking around to see what other people are doing and then going ahead and doing exactly the same. The competition is horrendous.
It is not sulfation that ultimately determines lead-acid battery life but corrosion of the positive grids and subsequent shedding of the positive active material.
We are emotional creatures. The human mind readily accepts anecdotal information but resists factual information. Only a couple of hundreds of years ago sewerage flowed down the streets of Europe, into the rivers. People drank from these rivers. They refused to believe there could be dangerous substances in their drinking water. The stench became so bad, the building of sewerage systems was suggested to get rid of the smell, not to overcome the health problem. They were amazed to discover their health problems disappeared. I mention this not as a criticism but simply to explain the human mindset.

On November 21, 2012 at 7:03am
Stuart wrote:

Thanks John!  I’ll report back on our findings.  We have over 700 batteries in our Data Center UPS’s, CAT generators, etc. and some local guys have built a machine we’re testing alongside 2 “commercial” desulfator/rejuvenators.  For the record, I don’t expect them to work but seems like a fun experiment.
Do you have any confidence in any of the commercial load testers such as soctester.com?  I’m not an electrical expert - just very curious and willing to spend the time to run a proper test.

On November 21, 2012 at 11:50am
John Fetter wrote:

Stuart - If your objective is to make these batteries last longer, i would suggest you search on line for information on lead-acid battery corrosion control. I looked at the soctester.com website. It bombarded me with flashing images and I gave up.

On December 9, 2012 at 5:49am
Mike Mullins wrote:

A question ,  just curios I have some acid for a small aircraft battery and it is a different sg than for auto batteries. I am not going use it in auto but it brought a question to mind of the difference of the batteries. I am a a&p have not practice lately,  I think I use to know but now I ??? (Shows my age) sorry. Are old school batteries with Lead antimony available some where?

On December 11, 2012 at 12:56am
John Fetter wrote:

Mike Mullins - Different SG, same acid. Aircraft batteries are fundamentally the same as automobile batteries, just a lot more old fashioned due to all the regulations. Lead antimony that is still in volume production is mostly industrial.

On December 11, 2012 at 5:10pm
Mike Mullins wrote:

Thanks John, I guess I should have asked what is it in the batteries which specifically requires different sg acid not an important need just curious.
And went on the web site that sells charger-mantainer- desulfation. They are all over the fact that their unit desulfats and it is the largest reason for battery failure.  I know where you stand on the issue,  the hole subject is very interesting to me. Thanks for your response and insight.

On December 12, 2012 at 1:15am
John Fetter wrote:

Mike Mullins - You can expect batteries that are required to deliver very high currents for brief periods to have higher SGs - up to 1.320. The penalty is shorter life expectancy. Batteries intended for more leisurely applications have lower SGs. Car batteries between 1.260 and 1.280. Standby batteries 1.240. Lower SGs are sometimes used to help maximize battery life, especially in hot conditions.
Battery plates are made with materials that are batch produced. As expected, there are Monday morning batches and so on. (One example: All batteries include a small amount of a very important substance called lignosulfonate. It is made from trees. When different trees are used, battery quality changes. There are numerous other factors.) The variations result in plates that are not the same. Batteries made with these plates can include cells that are not matched. These cells end up with different SGs. Modern batteries are made to a price, not to an exact standard. Manufacturers will deny this, of course.
The vast majority of people who need a replacement battery for their car will buy the cheapest, (sorry, least expensive). They control the quality of batteries. Bargain hunters ensure that the quality sits on a threshold as close as possible before becoming garbage.

On December 12, 2012 at 4:17pm
Mike Mullins wrote:

Thanks John, very informative. I wish I were smart enough and young enough to be a good Chemist.

On December 12, 2012 at 5:14pm
John Fetter wrote:

Mike Mullins - I am definitely not a chemist. Power electronics is my game. Controlling 40 megawatts with the turn of a tiny potentiometer or a digital command. I found out by accident that I seemed to be able to understand the underlying principles of batteries and could make a living out of that knowledge.

On June 30, 2013 at 11:29pm
shahrukh wrote:

Pls do reply…ok my battery (mobile, li-ion) was in water for 5 days how can it recover & if not why????

On August 13, 2013 at 10:07am
Mike Steeves wrote:

Hello John, I have a 30 foot canoe on which I use a B&G 3 h.p.  electric motor powered by 4   batteries.When not in use, the batteries are charged with a 48 volt battery charger. I have had to replace several batteries over the years.  I continued to use my 48volt battery charger over the winter. One spring I ended up having to replace it ($600). This past winter, I did not charge the batteries and now they will not recharge.

On August 19, 2013 at 7:52am
Dandy wrote:

Can i restore my swollen blackberry battery ? if Yes how ??

On August 30, 2013 at 9:03pm
Mohsin qazi wrote:

Anybody can you tell me how to completely empty ups battery and wash it (by which liquid acid or water any other thing) and how to refill it by using 66% distilled water and 34% sulphuric acid by volume (i mean how to mix them) please help me what to do .Thanks.

On October 2, 2013 at 2:29am
Nollie wrote:

Can anybody tel me what is the formula of the EDTA

On October 2, 2013 at 11:29pm
Bevan Paynter wrote:

Ethylene Diamine Tetra-acetic acid or acetate- synthetic invented in Germany in 1930,s to replace citric acid which they had to import. All needed is chelator(which both are) which means clawing agent to dissolve sulphation- can use anything which promises to remove stains from pools etc- but only in moderation- 1 teaspoon per cell. Important to realise that the “clawing/ stripping action” actually removes the sulphated lead from plates! Which drop to bottom of case.

On October 10, 2013 at 11:18pm
Larry Jarrett wrote:

IF you want to make an old battery work better ,you can dump all the acid out mix 8 oz. of baking soda in 1 gal. of water. fill each cell with the baking soda mix and leave in until it quits bubbling.. now flush out the the battery at least 3 times but rock it back and fourth real good before dumping it each time. now mix 8 oz. of Alum ( the Pickling spice ) in 1 gal. of water and fill the cells. now put on charge. the battery will get stronger each time it is charged for a while. then level off. you can not check an alum charged batter with a ball float device as it will not have the same specific gravity as an acid filed battery. if you want to know more please contact me. this works very good as you can discharge the battery more the a lead acid battery and not hurt it.

On October 11, 2013 at 2:58am
John Fetter wrote:

Larry - Please would you like to explain for the benefit of the readers how this idea works in the battery and where you picked up this information.

On October 21, 2013 at 3:08am
shafiq wrote:

Please give me the formula to calculate the amperes of negative snd positive plate of tubular
Battery for inverter .depending upon the size of plate.

On October 21, 2013 at 6:33am
John Fetter wrote:

shafiq - It is interesting that you can see a connection between tubular plates and an inverter. Please explain.

On October 22, 2013 at 8:59am
gul murad musofer wrote:

here i need a help from you all. i have been given a task to check the the agm deep cycle battety that which battery is usable or which battery is dead in a big store . as that batteries are used . so how i check them ? through vmeter or hydomeyer?  or battey analizer? details of the battety are agm 70 ah 12v maintance freee. i need help from you all how to check all the battries?


On October 22, 2013 at 11:06pm
Bevan Paynter wrote:

Use dmm on dc volts- good batt is 12v8- lower is either not charged or is u/s thru sulphation or s/c or o/c cell/s. Can try charging each batt with 14v constant volt charger to see if improves. If you had impedance tester it would simplify task- simply put, a new/good batt would measure 4-6 milli Ohms- a bad batt would be say 9-+ milli Ohms.

On October 29, 2013 at 3:02pm
Sylvester Wijesinghe wrote:

I have been for last 50 years in Electrical Automotive and heavy Industry machinery field. Daily come across Battery problems. I find that lead acid batteries can be regenerated with Epsom Salt to last about 6 months or more. When battery fails to start engines.
Any one had tried this.

On October 29, 2013 at 4:04pm
Oscar Ormond wrote:

Dear Mr Sylvester Wijesinghe, Been there tried that found it didn’t work because it is an old wife’s tale. You must be another one of these magic potion experts trying to sell to unsuspecting customers.

On October 30, 2013 at 3:32pm
Sylvester Wijesinghe wrote:

Dear Mr Oscar Ormond, Yes you may be correct. I have tried this it worked to me for few used Batteries. Not for all what i tried. If newly removed from a vehicle it will work.After about 30 days or later they will not recover.
At the moment I use one battery which is regenerated after removing, in 14 days in my vehicle works very well. I only shared my experience, not to make money.
Living in a developing country in Metropolitan area having few commercial buildings.
In Sri lanka

On November 21, 2013 at 4:13am
manoj wrote:

I have emptied my battery to carry it to one place to another. Will my battery work if i put acid and water mixture again.

On December 28, 2013 at 3:41am
Andrew wrote:

In a “perfect” lead-acid battery, assuming no losses, upon discharge, 1 gram of lead active material turns into 1.46 grams of lead sulfate, delivers 0.26 ampere-hours.

Recharging this battery, assuming no losses, requires application of 0.26 ampere-hours, to turn the 1.46 grams of lead sulfate back into 1 gram of lead.

The same battery affected by sulfation, assuming no losses, must receive recharging ampere-hours in proportion to the percentage of lead sulfate, in order to restore the 1 gram of lead.

I have two questions:
1. How do sulfation products, that do not attempt to put a proper charge into batteries, restore batteries?
2. How do sulfation products, claimed to be able to dissolve hard sulfate, recover battery ampere-hours?

On January 11, 2014 at 11:53pm
John Fetter wrote:

I have a question as well. A battery that is sulfated, does not deliver output. If lead sulfate covers the plates, choking the battery and if lead sulfate is white, why do the plates not look predominantly white?

On February 9, 2014 at 1:26pm
Matt wrote:

Can’t help but wonder what the relationship between Cadex and batteryvitamin.net is? It seems the information presented here and information found at batteryvitamin.net is very similar.

On February 9, 2014 at 11:06pm
John Fetter wrote:

Matt - This website presents information and invites comments relating to batteries, the other website relates to a product.
There is no connection.
I have been submitting comments on this website and I have written an article that is on the other website.
Perhaps you have a conspiracy theory you might like to share.

On February 9, 2014 at 11:14pm
Bevan Paynter wrote:

To my knowledge- batt vitamin was invented by John Fetter- who posts here as do I- I don’t know of any tie up with Cadex- John is just a bloke who has his own opinion on matters batteries!  If seems similiar- it could be that it is right!

On May 4, 2014 at 6:03am
Danko wrote:

John Fetter wrote:

“I began using a permanent charger for my car many years ago. Simple. No need to disconnect the battery from the car. On connection, the charger measures the battery volts, decides if it must charge or float. It always ends up on float, at 13.5V.”

If I understand you correctly, you have a charger in your car that is somehow connected to the battery. Is that correct?

On May 4, 2014 at 5:20pm
John Fetter wrote:

Danko - No. I park the car in a garage. There is a power outlet. The charger is located next to the power outlet. I connect when the car is parked. Not every time but at least every couple of weeks. I leave it connected until I use the car again. Sometimes the charger remains connected for days, weeks.

On May 7, 2014 at 3:03am
Danko wrote:

And you don’t remove battery from car? I heard that it’s not a good solution. It can mess your electronics in car.

On May 7, 2014 at 3:46am
John Fetter wrote:

Danko - I have done this for decades, many cars, no problems. Connect clamps, then switch on. Afterwards, switch off, then disconnect clamps. No sparks. No surges. No problems.

On October 21, 2014 at 11:48am
Joe Carter wrote:

Won’t to know if you can rebuild gel battery for a auto scrubber the battery is a ev185a let me know you can email me back at jcarter@mfisd. Txed.net or joe.carter44@yahoo.com thank you very much sir

On March 7, 2015 at 6:31am
Bill wrote:

I’m bring back to life a new car battery that sat idle in a car for 14 years. When I pulled it out, the cover caps were loose and just resting atop the holes. Cells 1 - 3 were dried out with about 2 tablespoons of white powder above the #1 cell. Cells 4 - 6 were full of rain water to the top of the holes. Poured that out then dropped some soda in it and saw no reaction.
I heated up 40 oz. of distilled water then mixed in 9 teaspoons of Epsom salts. Distributed that between the cells then topped them off with more distilled water. Placed it on a 5 amp charge and checked out a few days later with my load tester. It showed 12v with BAD cca’s. Left it on the 5 amp charge for the next 10 days and now shows 13v w/520 cca’s when tested after being off the charger for a hour. After a few days the charge drops to 12.5v w/400cca. Cells 2 - 6 show 1275 - 1300 yet cell 1 took forever to reach 1200 and several more days to reach 1225. When using my hydrometer that cell shows zip for a surface charge but when I fill & discharge the hydrometer a few times to mix the electrolyte it finally registers a low charge. I’m thinking that the white powder found above the #1 cell was sulfuric acid crystals so that cell has a lowered acid content. I do have 2 - 3 oz. of fresh battery acid left over from my new m/c battery so was considering to remove 2 - 3 oz. of the low gravity electrolyte on top then add 2 - 3 oz. of the fresh acid to replace what evaporated out of the cell. Would this bring that cell on par with the rest or should I keep it on the 5 amp charge longer?