Russell said:
I have a APC Smart UPS 1500va backup power supply about 3 years old.
It is giving a failed battery error. In fact the battery is ok.
Assumption, the mother of all screwups. I've been fooled by what
looks like a good battery, but turns out to be defective. Just
measuring the terminal voltage is not a sufficient test. If I'm not
sure, I use an automobile headlamp across the battery and see how long
it will run. The runtime varies with the battery size and type, but a
dead or dying battery will be very obvious as the bulb will not last
very long (usually a few seconds).
Other sloppy ways to test a battery is to just substitute a known good
battery (or batteries). If that works, it's a good assumption that
the previous set are bad. This is my favorite "test" method.
Also, a physical inspection of the battery is handy. A bluging gel
cell battery is almost certainly a dead or dying battery. It will
eventually burst and leak caustic goo all over the UPS.
I have removed the cover and inspected the pcb etc and no burnt or damaged
components found.
It's easier to just smell the board to look for dead parts. UPS's
have difficult to access PCB's. If there is a fried component, you'll
smell it before you'll see it.
Has anybody seen or know a reason that can cause this problem.
I've repaired a substantial number of APC UPS's. In the overwhelming
majority of cases, it's a dead or dying battery. The dying variety
are difficult to detect. They look good, "test" good, but don't last
very long on backup. I have some known good battery packs on the
shelf which I substitute. (It's also a good idea to keep gel cells
charged when in storage, so this test is a good way to recharge my
inventory). Same as before. If the new batteries work, by
implication, the old batteries are bad.