Does price matter anymore?

[Jeff Liebermann]

Price is price. Batteries go on sale, too, but for whatever reason they
don't seem to be discounted as much as the devices that use them.

Agreed. Most consumers do not buy batteries over the counter. I
would not expect retail stores to even stock replacements.

Gel cells expire in a few years because the electrolyte degrades over
time... charged or not.

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.

Incidentally, I've done moderately well recovering sulfidated gel
cells with a paint shaker. I strap the battery into the shaker and
beat it up for about 5 minutes. I sometimes have to shake it in
different orientations. The idea is to have the vibrations crack the
hard lead sulfate from the surface of the plates and hopefully
eventually fall to the bottom of the cell. The problem is that if the
lump is sufficiently large, it can short the cell if it doesn't
dislodge, sometimes resulting in a meltdown. Also, be sure to inspect
the case carefully for cracks before proceeding as spraying acid
around the shop is not a good idea.

 

[Travis Jordan]

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.

 

[Jeff Liebermann]

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.

 

[Travis Jordan]

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.

 

[Jeff Liebermann]

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.

 

[Travis Jordan]

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.

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.

 

[James Sweet]

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.