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