Lead Acid battery reconditioning with Epsom Salt

Discussion in 'The Garage' started by MrPulldown, Jan 18, 2017.

  1. MrPulldown

    MrPulldown Long timer

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    Have any of you heard of this. Not sure how I found it, but I saw a video about reconditioning old car batteries with an epsom salt solution. I have an old car battery that will still show 12 volts, but is too dead to run anything. I did not go and core it, and now have lost the receipt. Figure what the heck. I'll give it a shot. I use to have a pair or deep cycle batteries that I used for welding and general battery backup. I would take one 4 wheelin and such.

    All the text and videos I have read are inconstant with the process. Some simple top off with the epsom salt solution. Some drain the acid and replace with solution. Some rinse the cells with water then fill. And finally one old bat rinsed out the cells with a baking soda solution then filled with the epsom salt solution. Do you have some first hand experience with this. What did you do. What do you recommend.

    I know some of you will say a dead battery is done. Buy a new one. But I already have a new one. I just want another working car battery. Thoughts?
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  2. Strong Bad

    Strong Bad Former World's Foremost Authority Supporter

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    Epsom Salt (Magnesium Sulfate) is an old school trick to bring bad batteries back to life, it doesn't work with all batteries and apparently it never brings them back for very long. Bottom line is what the heck, why not try it?
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  3. MrPulldown

    MrPulldown Long timer

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    Is this your 6666th post. Awesome. 6666.png
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  4. JCool

    JCool Long timer

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    You must have a KLR , don't you. :lol3
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  5. Beezer

    Beezer Long timer

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    baking soda is commonly used to neutralize acid spills... it's a base (so is epsom salt). baking soda would be very bad for the electrolyte, rendering it useless. ya, I've heard of people rinsing out batteries but never done it myself. in the discharge cycle the SO4 combines on the plate & makes a sulfate (giving up electrons)... when you re-charge, the sulfation is driven back into solution (theres more but thats the quick version). when lead/acid batteries get old, the plates get sulfated (didn't all go back in solution).... that is a resistive coating & tends to block current flow. its normal to have some sulfation over the life of the battery & small bits flake off & fall to the bottom. there is space in the case allowed for that. when that space fills up, it shorts the plates. to make a battery act new again you would have to drive the sulfation off the plates and back into the electrolyte

    since epsoms is magnesium sulfate.... dunno.. but I have doubt
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  6. Strong Bad

    Strong Bad Former World's Foremost Authority Supporter

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    Magnesium sulfate is slightly acidic with a pH of between 5.5 & 6.5.
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  7. Disston

    Disston ShadeTreeExpert

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    There used to be a product called VX6 I believe that was used to rejuvenate old batteries. Sold by JC Whitney, maybe others. Used it 35 years ago on a tractor battery I had in my Airhead and got more than another year out of the dead battery.

    I found VX6 by Googling it. It's still around.

    Never heard of the epsom salt trick tho. Let us know how it works.
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  8. Beezer

    Beezer Long timer

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    well dang.... I thought epsom's ph was higher.... guess I should have looked it up
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  9. Strong Bad

    Strong Bad Former World's Foremost Authority Supporter

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    LOL!!! I had to look it up to make sure I was right before posting!
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  10. MrPulldown

    MrPulldown Long timer

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    So I assume that the epsom salt cleans the plates. But what about the acid. If you pour out the original acid and replace with epsom salt solution, does the process of desulfication of the plates by the epsom salt make the epsom salt solution acidic. I also assume that getting rid of some of the flakes/sludge helps this process out. I guess I will pour out all of the acid, in hopes of getting rid of as much sludge as possible. Make a mix of acid and espom salt solution, then fill the cells.

    Again this is more of an experiment than me needing a working battery.

    No I don't own a KLR but I defiantly have a KLR owner mind set. Maybe less "cheap" and more DYI. Maybe that makes me a DR350 owner.
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  11. Switchblade315

    Switchblade315 I make people disappear

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    .
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  12. Sabre

    Sabre PrĂȘt? Allez! Supporter

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    The chemistry geek answer...it's not about pH, it's about the solubility of two different metal sulfate solutions.

    Lead acid batteries are filled with sulfuric acid. In their fully charged state, the negative plates are made of lead, while the positive plates are lead dioxide. During discharge, lead sulfate is created. Some of this coats the plates, some remains in solution; over time, lead sulfate crystals accumulate in the bottom of the battery. As the battery ages, more of the plates are coated with lead sulfate...the plates become "sulfated." Lead sulfate crystals are pretty stable; they are difficult to dissolve in water. Lead sulfate is a poor conductor of electrons, so as the plates become sulfated, they can show full voltage (potential) but won't pass much amperage (current).

    Magnesium sulfate is a metal sulfate and it is readily soluble in water (i.e., easy to dissolve). If you add Epsom salts to a sulfated battery, putting the battery on a charger will then electroplate the electrode surfaces with magnesium. In other words, you're bonding magnesium to the plates which is a far better conductor of electrons than lead sulfate is. This in itself does not "cure" the problem. What it does do is to allow improved current flow so that you can re-dissolve enough lead sulfate to effectively reverse some of the aging that has taken place. With the plates "de-sulfated" to some degree, they will re-acquire some percentage of their lost storage capacity. It's not a total cure-all, but it can indeed give some life extension to old lead acid batteries.

    What you'd do is to dissolve as much Epsom salts as can be dissolved in boiling water, creating a saturated or super-saturated solution. Safely dispose of the old battery acid, then add the mag sulfate solution and put the battery on a charger, preferably a high-current charger (with appropriate ventilation and awareness of the hazard of accumulating hydrogen gas). After a time, the mag sulfate solution should be dumped out and the battery filled with fresh electrolyte.

    The response of the battery to this treatment would be highly dependent on other factors. How much lead has actually ablated off the plates? How warped are the plates? How much buildup of lead sulfate crystals is there in the bottom of the battery, presenting a short circuit path between the cathode and anode plates? How much of this sludge got stuck between the plates as you were dumping out electrolyte?
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  13. Baroquenride

    Baroquenride Everyone dies, but not everyone truly lives.

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    ^ That was awesome dude. I'm always learning new things here. Thanks!
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  14. Beezer

    Beezer Long timer

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    Sabre has the good description. the plates turn into PbSo4 in the discharge state, and when they don't recover 100% in the charge cycle they are "sulfated". over time it gets worse. the idea with the salts is to get rid of the extra sulfur on the plates by driving it into solution (which gets dumped). but ya... you would need new electrolyte after thats done, and I wouldn't expect "like new" performance. I have rescued a few by "putting them on stun" with a charge current overload and some would come back as long as they didn't over heat.

    I can see Epsoms working maybe, but baking soda will neutralize the electrolyte for sure... don't know what it would do to the sulfation
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  15. kantuckid

    kantuckid Long timer

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    Epsom salts goes in the hole when we plant tomatoes! Buy at wally in 1/2 gal cartons-all about the magnesium in the soil and great for soaking tired feet too! Actually was widely used back in my childhood, not so much heard about these days.
    Guy not too far from me had this old motel and a sideline of "refurbished batteries" he got on a deal from a nearby salvage yard. I went there once for another purpose as he had something for sale-looked like he was busy destroying the world with old battery acid to me.
    I'd buy a salvage yard, used battery before I wasted time on a battery re-do. Or if your gonna use it awhile just buy a new one?
    I thought Sabre was a medical guy now we know he's a battery scientist .:lol2
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  16. ttpete

    ttpete Rectum Non Bustibus

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    I no longer have any flooded electrolyte lead-acid batteries. Everything is either AGM or lithium and is far more reliable.
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  17. DonM

    DonM Do-dah Do-dah Supporter

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    Epsom salt is also great to relieve constipation and in a bath relieve muscle soreness! Milk of Magnesia is good ole Epsom salts all dressed up.
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  18. MrPulldown

    MrPulldown Long timer

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    This thread is an example of why this forum is AWESOME!!

    Thanks for the knowledge drop.
    #18