William R. Walsh wrote:
Don't expect that it will work. If any of my APC UPS units (about 12)
are anything to by, the only way you'll know the battery is dead is
when it fails to support the load. Most of these are not cheap units,
either--they are SmartUPS units that have a true sinewave inverter. So
far, only one has ever illuminated the "battery fault" indicator as a
result of a self test.

I've had mixed luck with that, too. What I do now is log the battery
voltage and percent charge, and judge by how far they drop during the
self-tests whether the pack is on its way out.