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Epsom salt in lead-acid battery
MIS42N:
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.
james_s:
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.
G7PSK:
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.
Rick Law:
--- Quote from: MIS42N on December 24, 2020, 10:22:23 am ---Fascinating video. [... ...]
--- End quote ---
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.
--- Quote from: MIS42N on December 24, 2020, 10:22:23 am ---...
I have tried various rejuvenation methods and sometimes it works and most times it doesn't. Isn't worth the trouble.
...
--- End quote ---
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.
--- Quote from: floobydust 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.
--- Quote from: coppercone2 on December 23, 2020, 06:01:40 pm ---it has low density so its not very destructive compared to outlawed things
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It's the acid spray that makes it extra destructive, to eyes and things.
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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.
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