Path: utzoo!utgpu!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!ames!amdahl!greg
From: greg@amdahl.uts.amdahl.com (Greg Bullough)
Newsgroups: comp.sys.ibm.pc
Subject: Exploding clock cards
Keywords: meltdown lithium batteries
Message-ID: 
Date: 1 Dec 88 16:09:33 GMT
Organization: Amdahl Corporation, Sunnyvale CA
Lines: 19

The other night, as I was walking by the room where my XT sat running,
I heard a bang, like the sound a TV makes when its high voltage arcs.
In fact I assumed the monitor had arced, due to dust or whatever.

Next time I brought the system up, I noticed that the SEFCO clock wasn't
working. I bought a new battery, and when I went to install it, found that
the old battery had exploded and burned, with enough force to bend the
battery clip back to a 45-degree angle. There were chunck of battery
innards all over the inside of the inside of the PC. This was no quiet
self-destruction.

Investigation showed that the SEFCO clock card had +5 volts across the
lithium battery terminals! Now it's hard to determine the circuit from
the PC board, but there doesn't seem to be much that protects the
battery from the supply voltage...

Interesting, indeed.

Greg