# Reconditioning Lead Acid Batteries with Epsom salt



## jasonck08

So a few weeks ago I was doing some reading about reconditioning lead acid cells using distilled water and Epsom salt.

I had a couple completely dead (registered 0.5v) 12v SLA's and I thought why not I'll see if I can at least add life to these old dead batteries. They were batteries out of an old electric scooter I got that had been sitting in someones attic for years. I shook them around and didn't hear any water in the cells. They would not take a charge, even from a bench power supply

I opened up the top of them then pulled off the rubber plugs. I added about 1/2 a cup of distilled water then heated it up. Then added about 1.5oz of epsom salts and mixed it up and let it dissolve. Then added some to each cell.

A hobby charger refused to try to charge the battery due to the low voltage. So I put the battery back on the benchpower supply at around 12-13v for an hour or so. I got the battery voltage to increase to around 12v then put it on the hobby charger. The hobby charger would only put a few mA into the battery before terminating at 14.7v. I parlleled it with another healthier SLA and managed to get a for mA more into it, then it terminated again and I repeated the process until I was able to charge the pack several Ah. The 2nd pack was more stubborn and wouldn't charge more than 5mA after this same process. I ended up overcharging the pack for 30 minutes or so using the 7 cell setting on my hobby charger. This allowed the pack to take a bit of a charge, and later on it was content with charging several Ah at the 12v setting.

Now these packs still have quite high resistance but I did manage to get them usable enough for some light usage.

I've heard other stories of people using epsom salts and it really helped their battery out. Their car would hardly start, then after adding it, and cycling a couple times, the cold craking amps doubled.

Pretty interesting stuff. Has anyone here played around with reconditioning Lead acid batteries?


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## SemiMan

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## TinderBox (UK)

Years ago i heard that you put a aspirin tablet in the cells, i don't know if this did anything.

John.


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## SilverFox

Hello Jasonck08,

Years ago when most batteries had filler caps, we "recovered" many dead group 24 batteries by putting 1/4 teaspoon Epsom salt in each cell and slow charging overnight. I am not sure why this works, and it doesn't work on every battery. Going on memory here I seem to recall that we would get some life out of 60 - 70% of the batteries we tried this on.

There are limitations to this. It only works once. If the battery dies again adding more epsom salt will not help. The biggest limitation is that the battery only lasts about 12 months, then it dies again.

We also sized the amount of Epsom salt down and used this for motorcycle batteries. You could recover them at the beginning of summer and they would work fine all summer, but the next year they were very, very, very dead.

I talked with a battery manufacturer about this. He didn't think the Epsom salt would desulfate the plates in the battery, but thought that there may be some reaction with the sediment at the bottom of the stack. He was going to run some tests on this but I never heard back from him.

Tom


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## bshanahan14rulz

You might see if you can find a circuit diagram for a battery desulfator circuit, too. 

cursory search brought up this: http://hackaday.com/2009/02/07/desulfator-in-an-altoids-tin/


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## jasonck08

SilverFox said:


> Hello Jasonck08,
> 
> Years ago when most batteries had filler caps, we "recovered" many dead group 24 batteries by putting 1/4 teaspoon Epsom salt in each cell and slow charging overnight. I am not sure why this works, and it doesn't work on every battery. Going on memory here I seem to recall that we would get some life out of 60 - 70% of the batteries we tried this on.
> 
> There are limitations to this. It only works once. If the battery dies again adding more epsom salt will not help. The biggest limitation is that the battery only lasts about 12 months, then it dies again.
> 
> We also sized the amount of Epsom salt down and used this for motorcycle batteries. You could recover them at the beginning of summer and they would work fine all summer, but the next year they were very, very, very dead.
> 
> I talked with a battery manufacturer about this. He didn't think the Epsom salt would desulfate the plates in the battery, but thought that there may be some reaction with the sediment at the bottom of the stack. He was going to run some tests on this but I never heard back from him.
> 
> Tom



Good to hear someone else that has done this in the past!

All lead acid batteries even SLA's have filler caps. Just many of them are hidden. On the SLA's I worked with I just pryed open the top plastic plate, and it revealed cells with rubber caps on each cell. And yea it won't generally revive batteries that have a dead or really weak cell. I did remember hearing that someone got another 5 years use out of a battery that was very week. So YYMV I guess.




bshanahan14rulz said:


> You might see if you can find a circuit diagram for a battery desulfator circuit, too.
> 
> cursory search brought up this: http://hackaday.com/2009/02/07/desulfator-in-an-altoids-tin/



Yep I've also read about the pulse chargers that you can make that can desulfate batteries. Some people do both -- use epxom salt and use a special charger. 

One video on youtube a guy made his own charger but it was charging a 12v battery to over 18-19v at times for a long period of time. Doesn't exactly seem safe to me... 




SemiMan said:


> Have heard of it as a old wives tale and remember reading someone doing a test and it making little to no difference. From what I understand chemically there is no viable reaction that would cause the removal of sulfation from the plates hence why you still had really high resistance and likely only a small amount of the original capacity.
> 
> I have yet to see a true lab test of a successful desulfation, though lots of adhoc about pulse desulfation.
> 
> Semiman



I'm no chemist and have not done any research as to why this actually causes desulfation, but I will mention that salt when added to water is an electrolyte and it makes the water more electrically conductive. Perhaps that's part of it?

It definitely works... You can see hundreds of youtube videos with people documenting their results and even doing cold cranking amp tests before and after. Do you really need a lab test to be a believer?

I also did this to a motorcycle battery which seems to be working a lot better. Before it would only take about a 1Ah charge, now takes about a 3Ah charge.

Also I was reading about people that converted their lead acid batteries to a lead Alum battery by using Alum powder. Quite interesting.


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## TinderBox (UK)

I have an old optimate III 12v charger i use it to charge sla battery`s it has an automatic de-sulphate mode, it supposedly puts 25v into the battery, though i have never seen the de-sulphate led come on.

John.


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## AnAppleSnail

jasonck08 said:


> It definitely works... You can see hundreds of youtube videos with people documenting their results and even doing cold cranking amp tests before and after. Do you really need a lab test to be a believer?
> 
> I also did this to a motorcycle battery which seems to be working a lot better. Before it would only take about a 1Ah charge, now takes about a 3Ah charge.



A lab test would explore exactly how much capacity is regained, for how long. Another might study the best 'recipe' for recovery. Getting a dead battery to work poorly is worth a little bit, but never knowing when it will die again means I would choose to replace it soon rather than play with acid and open cells.

A battery can take any charge the charger delivers, and that depends on how the charger is built to detect end-of-charge. What is its measured capacity? That will be a damaging test to the cell, but it's for science. Putting 3 amp-hours in a good cell will give you about 2 amp-hours out, depending on what you mean by 'takes a 3 AH charge.'


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## VidPro

*""Before it would only take about a 1Ah charge, now takes about a 3Ah charge.""* there is one clue.

So try this for a Guess.

Because the resistance in the battery changed, so the voltage taper that the normal charger does current would go up, it would heat the battery more, and continue to hit the plates, doing basically the same thing the overcharging, pulse overcharging, or "desulfation" does within the parameters that the usual car charger work under. 

The usual car charger:
Using a ac-dc transformer, and specific peak voltages after bridge rectifying, the usual car charger lightens up on the charge as it reaches the end. The old battery with encrusted plates is high resistance. the addition of epsom salts shorts out the internals of the battery some, and decreases the resistance. the decreased resistance get the usual car charger to continue charging, just like overcharging and "desulphation" algorithms do.
The car alternator also relys on cramming a specific voltage potential in, and the battery voltage increasing, therby slowing down the rate of charge as the battery is more charged. so it acts pretty much the same way. 

IF that was what was occurring, a person risks increased wear and tear on the vehicles electrical system.
I have found more than once, that trying to use a battery that basically sucks (power) because it has bad cell and all, has cause me to have to replace more of the electrical charging system, like alternator, and charge regulator, on the older cars.

epsom salts is magnesium sulfate, basically metals that are water soluable, what is occuring is adding minerals to the electrolyte. generally this is concidered a bad thing like using tap water, instead of distilled. But whatever works, it could allow for overcharging via chargers that do not do that normally.

if a lab did an analisis they would probably discover nothing, because it probably keys on the specific way that a consumer car charger operates, and a lab would use a bench power supply instead, to have "control" of the current going on for testing.
Anyone who attempted to do a "de-sulphation" with high overcharge, or pulse overcharge probably would be doing the same thing, with slightly less damage, and achieve much the same results. 
Also if it was tested in the lab, the self-discharge of the battery might be measured. Depending on a battery that had been through this method, to hold capacity , and capacity over time might show that it can start a car, but not be reliable source of long term energy storage.

At any rate, unless you pull out the lead, melt it back into position there would be nothing long term about any of the methods, they all work for a bit, and the eroded decaying plates still exist, along with the piles of decaying and eroded materials that float down below the plates. Yup, I tried to recover a lot of LA stuff back in time, lots of the stuff that was discarded was usable, and could be coaxed, but never lasted long.

http://batteryuniversity.com/learn/article/additives <mentione there.

one budding chemist says the chemical reaction is magnesium sulfate and the water with an electrical energy produces sulferic acid and magnesium oxide.

more cheap trix PVA:
""The authors claim that (1) the PVA prevents the diffusion of Pb, (lead), ions into the electrolyte. They say this reduces the generation of PbSO4, (lead sulfate), hence (2) helps to reduce sulfation. I have done research in the exact same area. My tests imply that (1) is accurate and (2) is an inaccurate guess.
The 12V batteries were charged to 17 volts, which is way above normal. The authors pointed out that the normal charging voltage is 14V. They said the higher voltage is necessary when additives are put in. Hello! How is a normal automobile electrical system going to cope with this?""

the better question becomes if the battery was charged high "overcharged" then some of that junk on the plates will fall off, or go back to the plates or the solution. it wouldnt mater if you put urine in  its the slamming the power in which reverses the chemical reactions.

http://batteryuniversity.com/learn/article/sulfation_and_how_to_prevent_it/

http://www.fieldlines.com/index.php?topic=143844.0 
discusses that there might be better short term fix chemicals to use. And also discusses cleaning the plates and making alkaline Lead battery.


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## Nubo

jasonck08 said:


> It definitely works... You can see hundreds of youtube videos with people documenting their results and even doing cold cranking amp tests before and after. Do you really need a lab test to be a believer?



Well, there are THOUSANDS of YouTube videos demonstrating perpetual motion, er... "Over Unity" machines. Enjoy!


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## jasonck08

Nubo said:


> Well, there are THOUSANDS of YouTube videos demonstrating perpetual motion, er... "Over Unity" machines. Enjoy!



Your point? Believe nothing you see on the internet? There is plenty of evidence to support that epsom salt does aid to recondition batteries. Just grab a cold cranking amp meter, a worn out battery some distilled water and epsom salt and see the results for yourself.

Why would a company spend money doing a lab test? There is no money in this business... The battery companies WANT you to go trade in your old battery and buy a new one.


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## uk_caver

Am I missing something, or is it possibly the case that the reason adding water and epsom salts might help _some_ geriatric batteries is that _water_ is being added to them?


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## Sylvi

uk_caver said:


> Am I missing something, or is it possibly the case that the reason adding water and epsom salts might help _some_ geriatric batteries is that _water_ is being added to them?



I have tried this works on batteries. But for a short time.

Sylvester.
Sri Lanka.


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## mslisaj

Many many years ago this trick was promoted in a automotive class I was taking. I still have the notes for this fix to this day. It's very interesting to read the comments on it. Now about 10 years ago I had some VX-6 sitting on a shelf that my father had purchased years before. I added this product to a five year old battery that was showing it's age. Now I don't know what was in that additive but that battery worked like new for another FIVE years. The interesting thing about it was that when that battery died it just died. It was good today and gone tomorrow but I would buy that product again if I could find it.

I would like to respond to the folks that say this is snake oil and these things don't work. The other comment that I like is when folks say that if this was that good of a product then the manufactures would use it in new batteries. Well the manufactures are in the business to sell new batteries. We all get this. To double the useful life of a battery is good for us but not the folks that build batteries for a living. Getting more useful life out of a battery today only makes good sense with what a battery NOW costs.


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## uk_caver

I'm interested in what you mean by 'showing its age' and 'like new'.

Does that relate to short-term output current, or capacity/charge retention?

I've certainly had car batteries which could turn the engine over perfectly as long as the car was run regularly, and which supposedly tested as absolutely fine on an appropriate tester, yet which had lost the vast majority of their capacity and either had high self-discharge, or capacity so low that normal low drain currents would flatten them with a few weeks of inactivity.

Something which made a relatively small difference to the performance of an aged battery compared to its original specification could potentially make a rather larger difference to its actual usability as a source of brief bursts of power to start an engine.

Reading around, it would seem that most people who say that Epsom salts work seem to reckon that, for them, it only gave a fairly brief extra bit of life.

As for VX-6, it does seem that supposedly similar things are around under different names.


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## mslisaj

Well to be more specific when I say "showing it's age" I would say getting to be a slow cranker of the engine I am trying to start. I agree that if you have something that is easy to start that it just takes a "kick" to get it running but a start after an overnight sit may take some cranking and it actually holds the load. Now I never ran that battery down just to see how long it would actually crank the engine but it seemed to have a snap about it like a new battery. I have used this in a motorcycle battery too. Where I would only get about three years out of those batteries I now get a good six years before they die. I have never used the Epsom Salt "trick" and I only brought it up in my email to say that I too had even been taught how to use it many years ago. What I treat my batteries with is a product like the VX-6. Again I have no idea what's in it but it works. As I mentioned my motorcycle "uses" batteries because of the amount of time it spends sitting, even with a battery maintainer on it. It was no big deal when the batteries were in the $20 - $30 range but now they are $50 up and if I can stretch the time between replacements for penny's on the dollar I will do that. Now the other battery that I am talking about here I use in an airplane. Again an application where it sits for extended periods. These batteries used to cost in the neighborhood of $90 but now they are over $200. Nothing special about them either except they are certified for an airplane. But again with a good additive I can double the life from four to five years to eight to ten it's worth it to me. 

I wish I could be more scientific for you but from a simple standpoint it works. Now in this forum another gentleman gives a very plausible explanation of the Epsom Salt. It turns the battery solution into a better conductor and allows the energy for charging to travel between the plates better. I had never heard this explanation before but it certainly seems plausible to me. Water is a good insulator and distilled water certainly fills that bill. Also a very deep discharged batter has a low specific gravity which makes it close to water thus the plates are even more insulated. I am no expert and as the old saying goes I know just enough about this to make me dangerous. But with that said I would really like to get my monies worth out of the real investment at todays prices battery.

Hope this help.


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## MethylEthyl

Chemistry explanation:

The type of lead sulfate crystals that form on a neglected battery electrode are very insoluble in water. Magnesium sulfate on the other hand is very soluble in water. From a practical standpoint, all chemical reactions are reversible. If magnesium sulfate and lead sulfate are placed near each other in solution, the magnesium and lead can switch places. Now, part of the big crystal is magnesium sulfate, which is both soluble in water and not too happy in the crystal, and so it detaches and floats around in the battery. Your crystal size has now decreased. Repeat this a few sextillion times, and the lead sulfate that was blocking the electrode is gone (as well as putting the lead sulfate back into solution where it is useful). Note however that the addition of magnesium sulfate will slightly lower the voltage of a battery. 

Since we are waiting on the ions switching places, it helps to stir the solution. You cant stir inside a battery too easily, so simply add some MgSO4 (dissolved in water) and slosh the battery around. Every few minutes slosh the battery around again. For a mid sized car battery, I use about 1 teaspoon MgSO4 for each cell (6), dissolved in water, and then fill the rest of the cell up with water.

As for the aspirin, that's also not a wives tale believe it or not. The aspirin (non buffered) is converted to acetic acid, which both changes the potential of the battery and helps attack the sulfate buildup. This is an emergency last resort though, because your battery will begin to corrode internally when you do this. Magnesium sulfate is much better for a long term solution. Another short term solution that may work is pouring some coca-cola into the cells.


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## mslisaj

Dear Mr. MethylEthyl

I can't thank you enough for this explanation. I have read similar theories on how this worked but it wasn't as clear to me as you made it. Through all the years that I have "kind of" knew this worked I couldn't tell you why it worked. I will be printing off your response and saving it in my educational material. 

As I mentioned in my original post I have purchased "additives" and used them. With my airplane battery these are very old "certified" technologies for aircraft but there is nothing special about them. But the cost, like everything else has gone out of site. I do use additives in that battery to get any real life out of it because it sits a lot of the time. I also use a battery maintainer now too. But in my opinion your explanation of what is actually going on there really works for me and now I know what i'm doing.

Thank you so much.

Lisa


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## PaulRekow

I have some Trojan L16's that were manufactured in June 2005, so a little over 9 years old. I had them hooked up to a 1980 watt solar PV system with an Outback 3648 grid-tied inverter and MX-60 charge controller. I equalized them usually 4 times per year for 2 hours each time until I bought a Sunnyboy direct gridtie inverter because I was having 40% production loss compared to similar sized direct gridtie systems. I did not charge the batteries from Jan. 1, 2014 when I switched from the battery based to direct grid-tie inverter until a couple of weeks ago. When I tried to charge them again a couple of weeks ago, I noticed that one of the batteries had two dead cells and another had one. I have tried equalizing several times to stir up the sulfates, but not luck. I have also tried the Epsom salts with no luck yet. Since these are larger than an average battery how much Epsom salt do you think is needed? Is there anyway to charge or stir up an individual cell?

Thanks, Paul


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## SemiMan

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## Doc Cyrus

Hi Guys, I have read the topic, on some other sites, ratio of Epsom salt was mentioned in equal quantity of ionized water ?in this thread, mentioned ratio of 1/2 cup of water & 1.5 Oz of Epsom salt, what's the ideal ratio ? half teaspoon of Epsom salt for each cell is helpful ?


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## SilverFox

Hello Doc Cyrus,

Welcome to CPF.

With larger batteries we used 1/2 - 1 teaspoon per cell. With normal car batteries we would use 1/4 - 1/2 teaspoon per cell.

Motorcycle batteries were a special case. We would use about 1/8 teaspoon per cell and always marked them with a Drop Dead date. They would work for about 12 months and then just drop dead.

Tom


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## richief

Stumbled on this thread and want to add my experience with epsom salt. Bought an old jd lx176 mower this spring, was sitting outside for yrs and in hindsight needed a ton of work, but is going great now. Well it had no spark, and needed both an ignitor and a coil. While I was waiting on amazon, i decided to try and revive the old battery, heated a half gallon of distilled water in my electric kettle till hot but not boiling, poured water and added epsom salt in an empty gallon jug stirring constantly and adding salt till I noticed granuals not disolving, knowing this is too concentrated added anothe pint of distilled water and called it good. I shook old battery and emptied it completely into a bucket, added water half full shook and emptied again, and thrice. Lots of grey water/mud came out. Added epsom solution to the empty battery and charged at 2 amp for a day. I was quite pleased the battery came back to life. I cut my grass all summer and this battery is still kicking. Cost me about five bucks. I just bought a honda rubicon project and the battery is shallow, still have some solution so this time I am just going to remove some electrolyte from each cell with a turkey baster and add epsom solution and see what happens. Most of the reading I have done on the subject suggest the latter method, but emptying has worked great and I cant tell performance from a new one, and no sign of weakening yet, even after skipping 3 weeks of cutting during dry spell, she still cranked great. If you have the time and vehicle is not depended on as primary it is worth a shot, I still giggle every time i start the mower. Lol


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## IonicBond

Sulfation is only half the story.

When sulfation has been left long enough to harden, it expands.

This bends, warps and can short plates. It also breaks plate grids.

Thus, when these temporary desulfation procedures are attempted, and even if successful, what you are left with is a badly damaged battery that will not support the loads it was designed to do. Revival means temporary or trivial loads.

You now have a battery with high internal resistance / self discharge that needs a lot of charging babysitting, and other nasties like "hot spots" and other things that show up when you try to recharge it like normal.

Your time / money is better spent taking care of the battery in the first place, unless that means nothing to you.


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## IonicBond

Reconditioning as a way to save a battery is an oxymoron. By the time you need it, it is too late, other than for trivial temporary loads.

Unfortunately, in some parts of the world, "reconditioning" kits, pamphlets, and even village recruiters are touted as a way for people to generate revenue from trash. These crap batteries are then resold to the local unknowing community.

The problem is that this trash properly belongs in the already-existing lead-acid recycling plant stream. However, those suckered into trying to make a living from such trash with amateur efforts, actually does *MORE* harm to the environment, by diverting product from those plants that know how to deal with recycling trash, and do so safely and profitably to stay in business at a local level protecting the local villagers from toxic problems.

Caveat emptor indeed.


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## snakebite

that extend battery life site has very bad info.
putting baking soda in a battery is a good way to kill it for good.
looks like some sort of bot generated trash.


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## snakebite

actually it is good to try these techniques to wring a few more years from any item.just have to pick your subject carefully to prevent wasting your time.
it delays manufacturing a new item which is always good for the environment.
and since a scrap battery has a good value for recycling few if any really hit the trash.
the most environmentally friendly use of ANY item is to use it up fully before recycling.
be it a battery or a tv.
the agm battery in my workvan is 15 years old.
i rehydrated it 10 years ago and it still works fine.
even after sitting 2 months without being run it started in 0f temps.
on my wall is a pioneer kuro 60" plasma i got free and repaired.
and 4 free trojan l16 run my lighting and radio stuff from solar.did the edta treatment on those 4 years ago.


IonicBond said:


> Reconditioning as a way to save a battery is an oxymoron. By the time you need it, it is too late, other than for trivial temporary loads.
> 
> Unfortunately, in some parts of the world, "reconditioning" kits, pamphlets, and even village recruiters are touted as a way for people to generate revenue from trash. These crap batteries are then resold to the local unknowing community.
> 
> The problem is that this trash properly belongs in the already-existing lead-acid recycling plant stream. However, those suckered into trying to make a living from such trash with amateur efforts, actually does *MORE* harm to the environment, by diverting product from those plants that know how to deal with recycling trash, and do so safely and profitably to stay in business at a local level protecting the local villagers from toxic problems.
> 
> Caveat emptor indeed.


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## maniac78

Yes. Method with epsom salt really works good for nimh battery. I recondition 3 batteries in this way. Here is instruction how to _*link removed_


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## ChrisGarrett

maniac78 said:


> Yes. Method with epsom salt really works good for *nimh* battery. I recondition 3 batteries in this way. Here is instruction how to _*link removed_



Come again?

Thanks. 

Chris


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