I have a APC Smart-USP 1500 (rack mount, 6 years old model) which behaves very oddly - once a day (exactly at 8:06) it "clicks" and I get a power failure->power restore event logged. It happens regularly, not every day, but always at 8:06. Obviously there is no scheduler. UPS self-test is set up to fire once in two weeks so it's not it. I have it batteries replaced quite recently, but it did not help. Perhaps controller fails, but if so, why it happens so regularly?
Perhaps I wouldn't care, but today, instead of traditional power fail->power restore event, it started shutdown procedure that shut down 3 of my servers. It indicated batteries ran out, while they were fully charged - after I started it up everything went back to "normal".
Any suggestions before I trash it?