Decomposition of the Electrolyte
Cells with gelled electrolyte are prone to deterioration of the electrolyte and unexpected failure. Such cells are commonly used for emergency applications such as UPS back up in case of loss of mains power. So as not to be caught unawares by an unreliable battery in an emergency situation, it is advisable to incorporate some form of regular self test into the battery.
"Travis Jordan" hath wroth:
Thanks. Very strange. This is the first I've heard of this problem. The plates deteriorate with repeated charge/discharge cycles, but not the electrolyte. The above URL is the only one I've seen that mentions any form of electrolyte deterioration in lead acid batteries. If it's really a problem, I would have expected to see warnings, lab analysis, and storage life expiration times. I can see sulfidation in the discharged condition causeing something that resembles premature failure, but not in a fully charged battery as found in a UPS. Pardon my cynicism, but I don't believe it's for real. I'll see if I can find some details on the chemistry of such electrolyte deterioration.
-- Jeff Liebermann jeffl@comix.santa-cruz.ca.us 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
electrolyte deterioration.
I first heard about this from an engineer friend who worked in the (automotive and marine) lead acid battery industry. I was grumping about the failure of my alarm panel's gel cel after only four years - with perhaps only one discharge / charge cycle during that time, and he told me that it was because the electrolyte that "became neutralized" (his words). I didn't think to challenge him at the time.
Let us know what you find out.
"Travis Jordan" hath wroth:
Sounds fishy. The electrolyte is just sulfuric acid with some type of gelling agent. I'm not sure what he meant by "neutralized" but it kinda sounds like dilluted. Methinks that can't be right. There's nothing H2SO4 can break down into that isn't a gas. There's no H2S smell, so that's not it. Disolving lead into solution is the same as discharge. I'm mystified.
My guess(tm) is that most premature stationary battery failures are from overcharging. That's overcharging the battery, not the customer.
Of course. Bug me if I forget.
-- Jeff Liebermann jeffl@comix.santa-cruz.ca.us 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
I wonder if it has something to do with the slow but regular decline in recombination rate (where the H2 and O recombine to form water)? I thought that was only supposed to happen as the result of charge and discharge cycles, but maybe there is more to the chemistry than I know.
I hadn't heard of that either, not that it couldn't happen, but the most common cause of lead acid battery failure is sulfation of the plates.
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