Author Topic: Epsom salt in lead-acid battery  (Read 9045 times)

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Offline Red Squirrel

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Re: Epsom salt in lead-acid battery
« Reply #25 on: December 23, 2020, 02:52:37 am »
A few days ago I tried one of those pulse battery chargers on a deep cycle battery that had never been used but had sulphated trough age. There was a very loud noise from the garage late at night and the alarm went off.
When i went to investigate the garage reeked of sulphuric acid with everything covered in the acid and the battery was completely demolished.
I have never seen a battery blow up so completely and I have seen a few over the years.
The charger had also been thrown across the garage with the plug being ripped out of the wall and the casing Brocken. I have tried other remedies for sulphated batteries in the past without much success and this pulse charger is the worst one I have ever tried.
In future I will just recycle the batteries it is cheaper in the long rub.


Woah that's pretty crazy.   I do wonder as well if this was a hydrogen explosion, though I would not have thought a single battery would produce enough at a fast enough rate to get that catastrophic.     But yeah if the charger failed in some way where it was delivering line voltage to the battery or something, I could see it.  The hydrogen would build up inside the cells and escape out slowly, then some source of spark ignited it.
 

Offline floobydust

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Re: Epsom salt in lead-acid battery
« Reply #26 on: December 23, 2020, 04:40:46 am »
A common lead-acid battery charging tragedy is a shorted cell. If you originally read open-circuit voltage under 10V, you have to be careful.
Chargers will act as if the battery is dead and pile on the current, bulk-charging. Then after a while, the remaining cells get overcharged and gas, end-of-charge is never reached.
It also frequently happens in UPS as the gel-cells age and a cell shorts and then the remaining cells are overcharged and roast, the case bloats out, until cells dry out and the battery goes open-circuit to protect the server room from blowing up lol.

A smart charger will start off applying low charging current until the battery voltage comes up to nominal 1.94Vpc (11.6V) before going into high current bulk-charging. Even DIN 41773-6 etc. miss this important test. A battery with a shorted cell rarely will make it to that high a voltage. A good charger also keeps track of coulombs because putting in say double the Ah rating into a battery indicates trouble, more-so after the battery was already charged up like in a UPS.

Hydrogen requires the smallest ignition energy,  pretty much the easiest gas to light up as well as acetylene. At 12VDC it's about 3A. But at 24V only 0.15A, and 50V 60mA so a pulse-charger might be a dangerous idea with a really old battery.
I would say the battery may have originally had a shorted cell or badly sulphated, so it's just a hydrogen generator. Some pulse chargers dump as a boost-converter into the battery and high ESR would let high voltage spikes into the battery, then any spark will ignite inside. Or later it must have developed a new short and a lead flake made a hot spot to light up the gas.
Anyhow, really bad to have the battery ignite, super dangerous :scared:
 

Offline james_s

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Re: Epsom salt in lead-acid battery
« Reply #27 on: December 23, 2020, 04:43:00 am »
It has to be hydrogen, there's nothing else flammable in a battery. I'm actually not all that surprised, I've put electrodes in soapy water and held a flame to the little bubbles of hydrogen and oxygen that form and a bubble about the size of a pea makes a bang that will spray water in your face if you're not careful. It's not just hydrogen you get when you put electricity through water, it's hydrogen and oxygen in a perfect stoichiometric mix. I doubt the charger was malfunctioning, it just gradually created hydrogen and over the course of a few hours it was enough to fill the space. What set it off I don't know, but the result is not surprising.
 

Offline Red Squirrel

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Re: Epsom salt in lead-acid battery
« Reply #28 on: December 23, 2020, 04:52:23 am »
I've had several of my Crappy Tire batteries die to a shorted cell.  Normally what happens is I start getting hydrogen alarms (still at a safe threshold at that point) so I go investigate by touching all the battery cells and will find one that is warm.  That is usually the culprit. 

I'm down to 3 batteries now as I stopped replacing them, when I'm down to just 2 or even 1 I will probably look at replacing with Surette golf cart batteries instead of marine, hopefully those will be better.

Basically when a cell is shorted, it's like if the battery is now a 10v battery instead of a 12v as it will have 5 working cells instead of 6.  You could in theory use it normally if you had equipment that is 10v such as a 10v charger and other things that can run on 10v.  Not that you can really buy stuff like that off the shelf.   The shorted cell itself will be a write off and you'd probably want to find a way to jumper it to create a higher amp rated path but if you caught it fast enough the other cells should be ok.  If you did not catch it fast enough then the other cells will have been overcharged and probably be dead too.   The overcharging part is what will be generating so much hydrogen.  Though the shorted cell will probably generate a ton too until it goes flat.
 

Offline james_s

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Re: Epsom salt in lead-acid battery
« Reply #29 on: December 23, 2020, 05:04:57 am »
Years ago I drove my car with a shorted cell in the battery for about 3 months before I got around to replacing it, never occurred to me at the time that it would be dangerous, glad nothing happened.
 

Offline Red Squirrel

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Re: Epsom salt in lead-acid battery
« Reply #30 on: December 23, 2020, 05:05:21 am »
Also just remembered I need to test my hydrogen sensor as it's been a while.  The way I do this is a little sketchy, I place a cup of salt water on top of the server rack and put two electrodes in it, plug it into a GFCI outlet.  The alert will show up on my alarm screen within a minute and come on my phone within the next polling interval.   

There is probably a better way of doing that, but good enough for Canada, and leaves enough time to go out for a rip eh.
 

Offline Rick LawTopic starter

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Re: Epsom salt in lead-acid battery
« Reply #31 on: December 23, 2020, 05:52:03 am »
That was a hydrogen explosion for sure. I don't know what set it off, maybe a broken connection sparked? I'm sure what happened though is electrolysis released a mix of hydrogen and oxygen which would be in perfect proportions and something ignited it causing an explosion.

A few days ago I tried one of those pulse battery chargers on a deep cycle battery that had never been used but had sulphated trough age. There was a very loud noise from the garage late at night and the alarm went off.
When i went to investigate the garage reeked of sulphuric acid with everything covered in the acid and the battery was completely demolished.
I have never seen a battery blow up so completely and I have seen a few over the years.
The charger had also been thrown across the garage with the plug being ripped out of the wall and the casing Brocken. I have tried other remedies for sulphated batteries in the past without much success and this pulse charger is the worst one I have ever tried.
In future I will just recycle the batteries it is cheaper in the long rub.


Woah that's pretty crazy.   I do wonder as well if this was a hydrogen explosion, though I would not have thought a single battery would produce enough at a fast enough rate to get that catastrophic.     But yeah if the charger failed in some way where it was delivering line voltage to the battery or something, I could see it.  The hydrogen would build up inside the cells and escape out slowly, then some source of spark ignited it.

You need a lot of energy to do this damage, so I wanted to understand it.  I've been chewing on it since I saw that photo...

I think two events are at work.  Hydrogen and Oxygen mix is ignited causing a rapid energy release (explosion part), followed by an implosion since water takes far less volume than its composition hydrogen and oxygen when separated.  It would be bending the casing outward, then as rapidly bending (sucking) the casing inward.  What the explosion weakens or broke, the implosion would finish the job and tear it apart and blow it away.

That's what I can think of, but I am no expert.   Hope there is one with a more accurate/better explanation.

Learning from this:  Venting...  It is far more importing than I originally considered.
 

Offline G7PSK

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Re: Epsom salt in lead-acid battery
« Reply #32 on: December 23, 2020, 08:40:19 am »
I dont think there was a shorted cell as the battery had a high resistance from sulphating it had never had any load as it was an unused one and there is no sign of sludge at the bottom of the cells, not that I could have seen any before the battery blew up but there was no indication of sludge from the explosion and no sludge in any cell afterwards. Whenever I have had batteries blow up in the past it has always just been an end cell nothing like this one.
As some has said it could be that the switching charger went short and put the full 240 volts through the battery, I will have to get the charger out of the scrap and try testing it.
 

Offline james_s

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Re: Epsom salt in lead-acid battery
« Reply #33 on: December 23, 2020, 05:59:34 pm »
I would bet that what happened is an open circuit developed somewhere and the current from the charger created a spark when the circuit opened or perhaps multiple sparks from an intermittent connection. I had a car battery go open circuit just a few years ago, it was fine when I parked the car one day then I got in to go to work the next morning, turned the key and nothing, later testing showed it was completely open somewhere internally.

A mix of hydrogen and oxygen is extremely explosive, try it with the soapy water like I did and see for yourself, the tiniest bubbles will make a snap similar to those "pop its" things you throw on the ground and they go bang. Larger bubbles will make quite a bang, and the volume inside a battery like that is orders of magnitude larger. A party balloon filled with hydrogen/oxygen mixture might blow out the windows if it ignited inside a closed room. It's really powerful stuff. If it wasn't so trivial to make you can bet it would be outlawed.
 

Offline coppercone2

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Re: Epsom salt in lead-acid battery
« Reply #34 on: December 23, 2020, 06:01:40 pm »
it has low density so its not very destructive compared to outlawed things
 

Offline floobydust

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Re: Epsom salt in lead-acid battery
« Reply #35 on: December 23, 2020, 09:57:59 pm »
What's interesting is the source of ignition. You can't ignite much of anything with only a 2V spark. That leaves heat, hydrogen needs 500°C (932°F) so I am thinking a short happened in a cell, from a glowing lead flake? The battery doesn't look that bad though.

I see badly sulphated batteries just boil away, they don't do much else. This agitates all the corroded pieces. Within a cell, large gas bubbles form under the plates and then come up. I have a habit of tilting a battery to burp all that. But ignition at the bottom you'd think would blow out the bottom. Hmmm the second cell from the left has a bent up interconnect, all others are fine.

It would be good to know the charger model to avoid the whole idea.
I think pulse-charging is pseudo-science, lead sulphate crystals are stubbornly bonded to the plate's pores and after 100 years nothing has really cured it.

it has low density so its not very destructive compared to outlawed things
It's the acid spray that makes it extra destructive, to eyes and things.
 

Offline Rick LawTopic starter

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Re: Epsom salt in lead-acid battery
« Reply #36 on: December 24, 2020, 02:01:55 am »
...
It would be good to know the charger model to avoid the whole idea.
...

If it isn't too much trouble, I like to know what charger too.

I was in the market for a charger, I went to my local auto-parts store only to see they are selling the same stuff I could get from Amazon or eBay/AliExpress.

Trouble with cheap stuff proliferating.  Paying a higher price means just paying a higher price but not necessarily better quality.
 

Offline james_s

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Re: Epsom salt in lead-acid battery
« Reply #37 on: December 24, 2020, 04:49:24 am »
What's interesting is the source of ignition. You can't ignite much of anything with only a 2V spark. That leaves heat, hydrogen needs 500°C (932°F) so I am thinking a short happened in a cell, from a glowing lead flake? The battery doesn't look that bad though.

2V? If a cell goes open circuit you have the entire open circuit voltage of the charger, which in the case of one designed for de-sulfating could be pulses of 100V or more. If you have current flowing through a circuit and you open the circuit it doesn't take much voltage to make a spark, shorting the output of a 1.2V NiCd cell will make sparks.
 

Offline floobydust

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Re: Epsom salt in lead-acid battery
« Reply #38 on: December 24, 2020, 05:48:20 am »


2V? If a cell goes open circuit you have the entire open circuit voltage of the charger, which in the case of one designed for de-sulfating could be pulses of 100V or more. If you have current flowing through a circuit and you open the circuit it doesn't take much voltage to make a spark, shorting the output of a 1.2V NiCd cell will make sparks.
I'm using the IEC 60079-11 spark tables for hydrogen ignition energy values. I assumed it was a short within a cell that lit up the gas, not an open circuit. I don't see enough corrosion to cause an open circuit in the interconnects. They're built for 100's of amps for cranking.
Maybe at some time in storage it had frozen? That breaks everything up.

Nobody uses epsom salts or pulse chargers in the third world.
 

Offline G7PSK

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Re: Epsom salt in lead-acid battery
« Reply #39 on: December 24, 2020, 08:29:14 am »
Up until the late 1970's there was a company in Cambridge (Cambridge battery services) that repaired lead acid batteries as long as they were the rubber cased variety with the top sealed in with bitumen,they would not repair the plastic cased ones that were coming in at the the time as they could not open or re seal them, from that bit of film it would seem you can, but the old elf n safety would have a fit if they saw that.
 

Offline MIS42N

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Re: Epsom salt in lead-acid battery
« Reply #40 on: December 24, 2020, 10:22:23 am »
Fascinating video. When you think about it, a lead acid battery should be fully recyclable. When it is dead, all the acid and lead are still there as lead sulphate. The case is reusable. With a little bit of ingenuity I think someone could design a battery and a recycling machine so dead batteries go in one end and rebuilt batteries come out the other end. It annoys me that a dead battery may fetch a few dollars at a recycle yard and you then buy back all the same ingredients for hundreds.

I have tried various rejuvenation methods and sometimes it works and most times it doesn't. Isn't worth the trouble. Lithium batteries are OK if you are looking for size and weight savings but for deep cycle stationary use lead carbon is good. Not much more expensive than AGM but 4000 deep cycles  - that's over 10 years in an off grid system. Even better are liquid NiCd batteries, almost indestructible. I have some that are 25 years old and still good (2.4V @ 415Ah, weigh 50kg). I'd like to see the adoption of liquid metal batteries for grid storage - very long lifetime (nobody knows how long). Only problem they have to be hot to work - probably no good for domestic use.
 

Offline james_s

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Re: Epsom salt in lead-acid battery
« Reply #41 on: December 24, 2020, 07:03:18 pm »
The batteries are fully recycled, I don't remember where but I saw pictures of a recycling plant where they had a huge machine that the batteries were dumped into which would grind them up and separate them into the raw materials. It probably makes more sense to do it that way and ship the raw materials to a plant that makes batteries than to try to tie it all into one operation but I don't really know.

Either way it takes a lot of effort to break them down into raw materials and purify those, then turn those back into battery parts and then you have to ship the completed batteries around which being so heavy probably accounts for a substantial portion of what you pay for a new battery. Imagine how much a truckload of car batteries weighs and how much fuel it takes to carry those around to retailers.
 

Offline G7PSK

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Re: Epsom salt in lead-acid battery
« Reply #42 on: December 24, 2020, 07:29:28 pm »
No idea how good the recycled batteries in that video are but the one that Cambridge battery services turned out were not as good as brand new ones, the plates they made were packed by hand and were just not as hard or robust as the one coming out of factories such as Exide or Oldham etc at the time.
 

Offline Rick LawTopic starter

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Re: Epsom salt in lead-acid battery
« Reply #43 on: December 24, 2020, 08:05:57 pm »
Fascinating video. [... ...]

Indeed interesting!  A lot of work.  In the USA parlance, it would be beyond even a re-built.  It would be a re-manufactured battery since every part was attended to.  It was so much work done there that if done in the USA, the cost of labor and parts/material would far exceed the price of a new battery.

...
I have tried various rejuvenation methods and sometimes it works and most times it doesn't. Isn't worth the trouble.
...

I am nearing that conclusion as well.  Seeing some of the "so very simple to do" videos on youtube, I just want to see what can really be done.

I am arriving at: if trickle charge doesn't do it, that's it... almost

In my web-search based research, I found two articles research papers showing pulse-charging works.  Pulse-charging is beyond what I can do, but I found some "self-powered" pulser.  Just clip it on the battery and powered by the battery, it send pulses back to the battery.

Per my research, these self-powered pulser pulses too slow and with too little power to do much.  Since I do have 4 UPS/BoosterPac SLA's at hand, I'm going to try that and see if it does anything meaningful at all.  Once I get it, I will start with my tiny 7AH battery.  Right now, it self-discharges to 4V-5V quickly.


What's interesting is the source of ignition. You can't ignite much of anything with only a 2V spark. That leaves heat, hydrogen needs 500°C (932°F) so I am thinking a short happened in a cell, from a glowing lead flake? The battery doesn't look that bad though.

I see badly sulphated batteries just boil away, they don't do much else. This agitates all the corroded pieces. Within a cell, large gas bubbles form under the plates and then come up. I have a habit of tilting a battery to burp all that. But ignition at the bottom you'd think would blow out the bottom. Hmmm the second cell from the left has a bent up interconnect, all others are fine.

It would be good to know the charger model to avoid the whole idea.
I think pulse-charging is pseudo-science, lead sulphate crystals are stubbornly bonded to the plate's pores and after 100 years nothing has really cured it.


it has low density so its not very destructive compared to outlawed things
It's the acid spray that makes it extra destructive, to eyes and things.

The exploded battery G7PSK's posted has damage way beyond my expectation.  I have been chewing on that.  I want to understand it.

I am arriving at this theory:

Hydrogen may be a contributing factor, it may even be the trigger, but hydrogen (ignition or not) is merely a contributor but not the main source of energy of the explosion.  It is the steam pressure.

Pure sulfuric acid has a boiling point below 150 C.  Battery acid is diluted so the boiling point is lower.  Even 150 C is not hard to reach.  Once it reach boiling point, boiling will turn all the liquid into gas rather quickly.  True that as pressure increases, boiling point increases.  But the energy injected into the system by the "charge" current can likely continue to push the temperature up enough to continue the boiling for some time.  Plastic separator between cells is not good a thermo insulator.  Neighboring cells would likely heat up and join the party.  Between boiling and electrolysis, the pressure can build up rather high if there is no vent to release the pressure.

Steam has the ability to blow up steel-boilers in a steam engine, it sure has no difficulty creating damage commensurate with what is shown in G7PSK's posted picture.

This is my theory and of course I don't know if I am right...  My gut feel is hydrogen ignition is not enough.  The scale of energy of steam matches my gut feel a little better.

EDIT:
1. Corrected the wrong quote.  I inserted the wrong quote in the reply when I first saved.
2. Changed the wording "articles" to research papers.  They were not merely someone writing an article for a magazine but serious research paper.  One from IEEE, and another from 2017 IOE Graduate Conference.
« Last Edit: December 24, 2020, 08:19:10 pm by Rick Law »
 


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