UPS failure modes (was: fire at NAC)

David Raistrick drais at
Thu May 29 18:37:03 UTC 2003

> I've seen two previous APCs (both Matrixes) fry batteries...  The
> batteries balloon up, and get really hot, and are too big to extract from
> the chassis.  APC's solution to this is to have us take the entire UPS
> offline for several days to completely dissipate the heat, and then try to

I've got a few APC SmartUPS's in the shop at home that I disassembled last
week.  Two SU1400's and one much older SU 2000.  All of them had
overheated and exploded cells.  The 1400's all leaked and were /very/
wedged in.  I ended up removing the outer shell, then the circuit board.
Once these were out of the way they frame spread enough to allow the
swollen casings to slide out.  Both of these had acid all over the

One of these had been leaking so long that it ate a ~1/4 inch hole through
the bottom.

The 2000 had the worst batteries, but once I got the plastic battery
casing opened (I CAN see why they stopped using this design...) and got
all of the connections apart, the cells just dumped right out.

Maybe I'll take some pictures of the was sort of fun to see
how they had expanded and wrapped around each other. :)

I've only heard one report of APC's that caught fire...and even then it
was just the carpet below that caught fire.


david raistrick
drais at

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