Epsom salt in lead-acid batteries?

[bluegoatwoods]

A guy at work was telling me that he keeps his trolling motor batteries alive for years using a mixture of epsom salt and distilled water. The mix he uses is ten heaping tablespoons to one quart of water.

I was thinking, 'well...maybe' until he mentioned that he drains the liquid out of the battery to start with. I asked him if he meant that he uses this stuff as the electrolyte. (Am I using the right term there?) He didn't seem to know what the word meant. Anyway, though, it's clear to me that he's using this stuff as the liquid between the plates of a battery.

He tells me that he doesn't know how long it'll last since he just changes it yearly. And he said that he's brought batteries back from the dead with this stuff.

I don't know just what epsom salt really is. Maybe a solution in water makes a reasonably strong acid. But this sounds a bit too good to be true.

Anyone got any notion on whether this can possibly be a good idea?

 

[jonescg]

Epsom salt is magnesium sulphate - MgSO4. Its no different electrolytically than sulphuric acid - H2SO4. There is a possibility that there will be some MgO salts being deposited on the plates, but essentially instead of H+ ions moving around, you have Mg2+ ions moving.

 

[bluegoatwoods]

So, though the chemistry might not be perfect the electrical properties should be workable? That's interesting.


Just for fun; would a magnesium sulfate molecule be one atom of magnesium plus one atom of sulfur plus 4 atoms of oxygen? I'm no chemist. But my, very modest, understanding of the nomenclature would seem to point in that direction.

And would an MgO salt be composed of one magnesium atom plus one oxygen atom?

 

[emiyata]

So, though the chemistry might not be perfect the electrical properties should be workable? That's interesting.


Just for fun; would a magnesium sulfate molecule be one atom of magnesium plus one atom of sulfur plus 4 atoms of oxygen? I'm no chemist. But my, very modest, understanding of the nomenclature would seem to point in that direction.

And would an MgO salt be composed of one magnesium atom plus one oxygen atom?

The stuff works great. They say it cleans the plates. I have used it for years. Last battery 7 years on a car Walmart battery and the battery post on the outside went bad.
Kmart sold this bottle to made batteries regain capacity. It had cadmium in it. Worked great and I think EPA banned it.

 

[bluegoatwoods]

That's cool. Thanks.

When you say that the stuff works great, you are talking about an epsom salt/water mix, right?

I have a couple of old batteries with nearly zero life left in them. I might as well give it a try. Certainly have nothing to lose.

 

[999zip999]

Where are you going to put the acid ? Becareful have some black long sleve rubber gloves and googles. Don't rub your eyes.

 

[Lessss]

As long as the lead plates are still intact it will work.

 

[emiyata]

That's cool. Thanks.

When you say that the stuff works great, you are talking about an epsom salt/water mix, right?

I have a couple of old batteries with nearly zero life left in them. I might as well give it a try. Certainly have nothing to lose.

Yes epsom salt/water mix . Tilt it back and forth with mix added. Do a full charge then full discharge and charge again. Don't be worry if you see stuff in the battery acid water epsom mix. That stuff will go to the bottom in time.
Now how to pick a good flooded cell. first pick one with plenty of space from the bottom of the battery to the plates. The less distance you have the bigger the chance over time you will fill that area with lead coming off the plates and it then causes a shorted cell . You want lots of lead in the plates so pick the heavy battery.

 

[Sunder]

Interesting. I've heard of using Epsom salts to boost the life of a sagging battery for another year or two, but never heard of it being used as a complete replacement for sulphuric acid.

One would assume if it was anywhere near as effective as sulphuric acid, it would be replaced, as there are less hazards. (I'm about to take an Epsom salt bath, to relieve muscle aches after a long ride, if that gives you an idea how safe it is...)

 

[spinningmagnets]

There are several reasons a lead acid battery would go bad. Every time you fully discharge a battery and then fully charge it, some of the lead plate melts away. Once the plates start to develop holes in them, then there is less plate surface area with which to react with the sulfuric acid/water. This is why deep-cycle batteries have thick plates. Car starter batteries have many thin plates because they are used to provide a lot of amps for a only couple seconds to start the engine, and then they are immediately recharged to full.

When discharging, the H2SO4 is split into the H2, and the SO4 (sulfates), and then recombined when charging. When discharging the sulfates begin coating the plates (lead oxide and lead di-oxide). As more plate surface area becomes coated, there is less surface area to provide the reaction, so the voltage goes down.

If we are talking about Flooded-Lead-Acid (FLA) instead of gel-electrolyte, topping off with water and performing an extra-long charge will electrolyze the extra water, and any weakness of O2 or H2 in the electrolyte will absorb the loose O2/H2 thats floating around during the extra charging (I forgot the proper name for it). whenever charging/discharging FLA, there will be H2 in the air, do not smoke...

If there is a weakness of sulfate in the electrolyte, the epsom salts will re-invigorate the "S04" portion of the electrolytes.

If a SLA/FLA is left completely discharged for an extra long period of time, the sulfates on the lead-oxide/lead-dioxide plates will have crystallized, and the longer they are in that state, the harder it will be to get them to go back into solution.

It would be interesting to see if there is a chemical that can dissolve the sulfates while leaving the plates unharmed. Then you could drain and rinse the battery, then re-fill with new sulfuric-acid/water. It sounds like it would work for a fairly new FLA, but with the gel-electrolyte in SLA it might be a hassle to open up the case, perform re-invigorationm, and then re-fill with new gel-electrolyte (they are designed for this). Often old SLA's are toast simply because someone let them drain down over winter, and the crystallized sufates refuse to dissolve. In that type of situation, the lead plates should be like new.

For long tern storage of any lead chemistry battery, disconnect both posts completely and clean the top, since dust and humidity can perform a slow short.

 

[emiyata]

Junk yard batteries when epson salt mix is used and then new acid charge would normally give 70% capacity. Then I would add this cadmium battery liquid and that would take you to 90% capacity. No longer sold.
It's a lot of messing around to save 20 to 50 bucks.

Steve

 

[999zip999]

The battery light on the car came on and two cells are low on water. I would like to give this a try. Any advise Please. Thanks

 

[999zip999]

Since nobody chime in I had the battery checked at the the local auto store he gave me a print out on the health of my battery. It seemed o.k for a 3yr. old duralast. I couldn't find epson salt at the 99 store without spearmint and menthol scent. Plus the 3yr. old battery I felt is just low because of the use of my battery operated bike. A downside of a e-bike is your car can be dead if not care for. I think I need a small float charger for good car battery health. After a full charge the car just fires up and the misfire at idle has gone away. Low battery voltage for the computer ?
I did charge with with my hyperion 1420 with two HP 600 @ 24v. 1000watt. ( is this over kill ) with the pb setting at 7amp. it only put out 3amp. and then ramp down to .49a for 10hr. on the charger. Couldn't hurt a good long slow charge.
Just didn't have the balls to put epson salt in a 3yr. old battery now a 6yr. old battery different story. I will go find one and get back to you.

 

[smpt2]

I had a seven year old very dead battery, I tried Epsom salt with a three day trickle charge it came up to 7 volts. then i put one t spoon full of sulfur in each cell in less than a hour i had a full charge it has held the charge for over a week today , more than 12.4 volts what is going on ?? what is the answer?? Edward