At 03:54 AM 05/04/2002 -0500, Tim Hughes wrote:
Joe wrote about silver oxide batteries:
>>
Section 12.4.3 (on the shelf life of silver oxide batteries) plots
shelf lifetimes at various temperatures, the lowest being 21 degrees
centigrade, but one can extrapolate. The low-rate cells used in watches can
easily last 10 years at 21 degrees centigrade (room temperature). Our beloved
357 battery is considered ultra high-rate (it's a matter of battery cell
construction). High-rate cells will lose 30f capacity every three months at 21
degrees centigrade. In three years, the total loss will be 10%. I guess that
ultra high rate may lose more. At 4.6 degrees centigrade, the loss rate is
0.65 0.000000e+00very three months. Anyway, the max shelf life they talk of is
ten years for low-drain, and three years for high drain cell constructions.
As with mercury batteries, the ultimate limit is that the barrier film between
anode and cathode eventually dissolve, and also the silver migrates.
...
[snip] [Tim responds]
Certainly reducing temperature will help in the normal way as with most
batteries but the seals are damaged by stiffness/contraction at very low
temperatures (particularly if the temperature cycles when you open the freezer
door!), and condensation+salts cause surface leakage. So don't push your luck.
Remember dropping the temperature only 15C (refrigerator compartment ) will
more than double shelf life.
[end quotes]
Thanks, Tim. I was wondering when someone else was going to step up to the
plate on this one. When I contacted Varta way back in '99 about future
availability of their V625PX cells, I got one of their engineers to give me
some info, and he finished up by offering me the advice (unbidden by me)
*NEVER* to freeze a V625PX, or any other cell, for that matter. Couldn't
guarantee the integrity of the cell's casing if I was to do that. Since having
the casing fail would seriously compromise the cell's life, I assumed freezing
was just bad, bad, bad. And of course, who wants mercury in amongst the frozen
cheese-stuffed jalapeños?
Damn. Now I'm gettin' a might peckish. ;-)
Garth
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