"Travis Jordan" hath wroth:

Jeff Liebermann wrote:
I've never seen an expiration date or "use before xx/2007" on any gel
cells. I couldn't find any references to electrolyte degradation with
age using Google. I did find the usual references to sulfidation in
lead-acid cells caused by the crystallization of hard lead sulfate on
the electrode surfaces when left discharged for long periods. This
causes a general reduction in cell capacity followed by a possible
shorted cell if allowed to persist. Is this what you're talking
about? If so, pulse charging does a fairly decent job of preventing
sulfidation. I could not find any claims that it's a problem with a
charged battery, as I would expect to find in an operational UPS. Got
any references? This is interesting.

http://www.mpoweruk.com/leadacid.htm

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.

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
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Jeff Liebermann wrote:
I'll see if I can find some details on the chemistry of such
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:

Jeff Liebermann wrote:
I'll see if I can find some details on the chemistry of such
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.

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.

Let us know what you find out.

Of course. Bug me if I forget.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

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.



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.