Over the past week or so I've had my UPS switch over to battery power briefly when plugging in new devices (possibly limited to just AC -> DC chargers, but haven't tested anything else). I had noticed it originally when plugging in a cell phone charger - even without the phone connected, just plugging the charging cable into an outlet triggered the UPS to switch.
Last night it happened again when plugging in my laptop charger: I plugged in the charger first without it being connected to my laptop, and the UPS switched back and forth for a few seconds between utility and battery before stabilizing. Once it stabilized, I plugged the charger into my laptop and everything was fine.
The UPS is a CyberPower CP1500AVR.
pwrstat on Linux doesn't seem to report any outages, perhaps simply because it's too quick of an occurrence:
$ pwrstat -status
Test Result.................. Passed at 2012/11/09 10:23:02
Last Power Event............. Under Voltage at 2012/10/08 12:20:01 for 3 sec.
pwrstat.log showed an event last night when I plugged my laptop in, but none of the other recent events are there:
2012/09/27 05:09:33 AM Utility failed.
2012/09/27 05:09:35 AM Utility restored.
2012/10/08 12:20:01 PM Utility failed.
2012/10/08 12:20:04 PM Utility restored.
2012/11/09 01:05:11 AM Utility failed.
2012/11/09 01:05:11 AM Utility restored.
To help narrow down causes a little, I believe the first time I noticed this was during/after Hurricane Sandy. During the hurricane I had seen a spark fly off the utility pole. The UPS had briefly switched to battery power then, but nothing else seems to have resulted from the spark (others in the house didn't notice anything at the time)
Is there any other testing I can do, or is it time to call the power company?