Academic battery question.

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jonjo

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If a fully charged wet acid 140ah battery had its acid contents poured into a container where would the stored energy end up? Would there be an almighty spark as the last drop of acid was drained away?

Actually this question is not completely academic. I am considering the practicalities of buying and using a second domestic boat battery for 3 months and then mothballing it for a few years.
 
There will be no spark. /forums/images/graemlins/grin.gif
You are merely pouring slightly stronger acid than from a flat battery into an acid proof container for storage (?). /forums/images/graemlins/wink.gif

This is how shops that sell batteries keep their stock. When you buy one they fill the fully charged battery with acid and there you have it.
 
When the battery is charged, material on the positive plates is converted to Lead Oxide and on the the negative plates to Lead, whilst the concentration of the Sulphuric acid increases.

Electrical energy is stored as chemical energy in these conversions. On discharge, electrical energy is recovered as material on both plates is converted to spongy Lead Sulphate and the concentration of the acid is reduced.

If the acid is removed after charging, the chemical composition of the plates would be preserved and replacing the more concentrated acid later would allow the battery to continue to provide the stored energy.

There is one proviso. The material on the plates has to be in a "spongy" form to present a large surface area to the acid. I am not sure, but any residual acid, trapped in the material on the plates when the acid is tipped out might continue to react with the plates to seal off some of the internal surfaces with a layer of lead sulphate.

Ultimately, a battery fails when the surface of the plates (both internally and externally) gets progressively converted to an inactive form of lead sulphate which can not be restored to lead and lead oxide by recharging.

The formation of this inactive form of lead sulphate is encouraged by leaving a battery in a discharged state and/or by discharging it to too low a voltage.
 
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If a fully charged wet acid 140ah battery had its acid contents poured into a container where would the stored energy end up?

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That would give you a dry charged battery.

In the old days this was the standard way of shipping new batteries. The factory supplied them charged, but no acid, the dealer filled the new battery with acid / distilled water mixture ready for you to use. Safer and lighter way to ship the new batteries.

Brian
 
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That would give you a dry charged battery.
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I'm not sure that it would. Many years ago, I worked briefly in the Lucas battery factory which supplied motor manufactures and retail. I may be wrong, but I seem to remember that the plates were loaded with the correct lead compound and were then passed through a mild heating process before assembly into the case, to make a dry charged battery. As said, the acid was introduced at the point of use, but that was for the first time. I suspect that a drained, mothballed, battery would deteriorate.
 
The question was quite clear - if a fully charged battery is emptied of electolyte where does the eneregy end up? It must be either in the drained electrolyte or in the dry battery. I assume the erudite answers above mean it stays in the battery.
 
[ QUOTE ]
The question was quite clear - if a fully charged battery is emptied of electolyte where does the eneregy end up? It must be either in the drained electrolyte or in the dry battery. I assume the erudite answers above mean it stays in the battery.

[/ QUOTE ] No, no, the energy is not 'in the plates' or 'in the electrolyte' but in the battery, which requires both. If you pour the electrolyte out it's no longer a functioning battery.....

A little thought experiment: If you pour out the electrolyte, then immediately refil the battery with new electrolyte of the same SG is the battery charged? I should think so but is it charged with the same energy?
 
Thanks all, so far I have decided that decanting a battery of electrolyte for long term (nearly dry) storage looks problematic.

I am still not clear on the raw science and conservation of energy. I was vaguely aware that metals like to react with other elements because the resulting compound has a lower energy state.

Someone else said charged battery electrolyte is more acidic, so is there stored chemical energy in the battery acid? We are talking about enough energy to power a 1 kw bar fire for 40 minutes.
 
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T
Someone else said charged battery electrolyte is more acidic, so is there stored chemical energy in the battery acid? We are talking about enough energy to power a 1 kw bar fire for 40 minutes.

[/ QUOTE ]There's stored chemical energy in just about any compound, just so long as you create the right conditions to release it.
 
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