UPS Diagnosis - is it dead Jim?
I have two BackUPS CS500 that decided to go Friday evening.
After extracting them from the cabinets and resetting them they'd power on but not take any power from the wall (known good lead and socket). I bypassed them and left them on the bench until Monday.
Monday, we test the batteries with a multimeter and they appear healthy. There's no bulging or other deformation. I put the batteries back in the UPS and they take power from the wall and it self-tests fine and powers on. If I add load (desktop pc) they're happy.
If I start them up with load (desktop pc powered on as soon as UPS is powered on) they display "replace battery" warnings and beep. However, there's enough juice to run the desktop PC for about 10 mins (stopped testing then).
They (and their batteries) are ~3yrs old. Usual load on them is a 48-port rackmount and a couple of POE injectors. They're used to smooth out our rubbish power supply in smaller network cabs.
Do I replace the UPS or the batteries?