"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