SUA1500 noise while on battery (plug pull)?

[BillP]

I have two SUA1500 running in a room. Both have devices attached to them. I pulled the wall plug for both tonight and they went about doing their business of keeping my devices powered on. However, I noticed that while one is on battery it will make an odd noise that constantly repeats while it's on battery power. The noise will start high and die down, stop and then repeat. It is sort of like when you flick one of those door stop springs. Any idea what the heck this could be? I believe the unit is still under warranty.

This issue is NOT the same noise as posted here: http://forums.apc.com/spaces/5/smart-ups-symmetra-lx-rm/forums/general/2497/gracefull-shutdown-multi...

Thank you.

[BillP · Accepted solution]

I have two SUA1500 running in a room. Both have devices attached to them. I pulled the wall plug for both tonight and they went about doing their business of keeping my devices powered on. However, I noticed that while one is on battery it will make an odd noise that constantly repeats while it's on battery power. The noise will start high and die down, stop and then repeat. It is sort of like when you flick one of those door stop springs. Any idea what the heck this could be? I believe the unit is still under warranty.

This issue is NOT the same noise as posted here: http://forums.apc.com/spaces/5/smart-ups-symmetra-lx-rm/forums/general/2497/gracefull-shutdown-multi...

Thank you.