I ran across an interesting failure on an Optima "yellow top" battery.
The battery is about a year old, and failed with only about 6v on it.
Charging immediately brought the voltage up over 12v at low current, but
when charging stopped, voltage quickly fell back to 6v.

When we lifted the battery out, we noticed that both ends of the yellow
cover had detached from the base; they flexed upward a little bit. The
case was no longer sealed.

For fun, I sawed off the posts, and plied off the cover. Inside, there
was no apparent damage, but the cells were almost totally dry. I added
about 8 oz of water to the 6 cells, which was completely absorbed.

The battery then became partially functional. It will accept a charge
and hold its voltage short-term, but has very low amphour capacity and a
high self-discharge rate.

It appears that the battery was damaged during installation by
"dropping" it into place, such that the edges of the yellow cover caught
on the adjacent batteries, and broke the seal. It then dried out over
time, and failed.

Just a word to those using Yellow Tops. Don't carry them around by their
yellow tops, and be especially careful not to drop them next to other
Yellow Tops such that the edge sits on top of an adjacent battery. It is
apparently easy to break the seal!
-- 
Lee A. Hart                Ring the bells that still can ring
814 8th Ave. N.            Forget your perfect offering
Sartell, MN 56377 USA      There is a crack in everything
leeahart_at_earthlink.net  That's how the light gets in - Leonard Cohen

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