"philo " wrote in message
...
On 7/15/2013 8:12 PM, garyr wrote:
"Allodoxaphobia" wrote in message
et...
On Mon, 15 Jul 2013 07:21:25 -0700, garyr wrote:
The 18 volt battery for my hedge trimmer has died. I took the pack
apart
to
check on the size of the batteries and found something strange.
Cemented
to
the top and bottom of the batteries is a layer about one-half
millimeter
thick of what appears to be layers of thin films. The films are flakey,
somewhat like mica, and have a metallic appearance.

Any idea what that might be?

Photo?

I don't think a photo would tell you very much. From a short distance it
resembles slightly crumpled aluminum foil. At first I thought they were
layers of metalized plastic film, but closer inspection ruled that out.
Could it be some sort of thermal conductor which would attempt to even
out
the temperature of the cells?





Very possibly a thermal fuse that opened due to battery over temperature.
If that's the case, very likely there has been a cell failure so if it is
a fuse I would not advise bypassing it.


A photo would probably help though.

Perhaps I didn't give a full enough description. The battery pack contains
15 Sub-C cells. The area of the top and bottom of the pack is about 12
square inches (~3" x 4"). The 0.5 mm thick layer covers the entire area of
the top and bottom of the pack.