My Back-UPS shuts off with constant tone about once a month for no reason..

[Anonymous user]

It's happened about 3 or 4 times since I bought it a few months ago. It's connected to an outlet that has power but for whatever reason the APC will shut down and make that terrifying constant beep and I have to get up to reset it. I have my PC, TVs and gaming consoles connected to it along with some other small devices but I never have too many things turned on at once. Most of the time they're only in standby and thus not drawing much power. So about once a month whenever I'm doing something on my PC everything just shuts off and I hear that terrifying beep. I've tried disconnecting a few things from it to lessen the load but it still shuts off. Now I'm going to try only using two of the battery backup outlets and two of the surge protector outlets. I guess it's worth mentioning that my house is old and has faulty wiring. The APC is connected to a two-prong outlet via an three-prong adapter... It's my only option since the landlord won't pay for an electrician to upgrade it. That said, why would my APC randomly shut off once a month if there's still power coming from the outlet?

[Anonymous user]

I could only suggest that the UPS believes it is being overloaded. I don't know which model you have, but having a computer, several TVs and gaming consoles connected to it really could be causing a momentary overload.

When it switches to battery, your UPS outputs an AC waveform that is very different from the smooth sinewave your utility power provides -- or should provide. Some computer and electronic power supplies behave poorly when this takes place and will overload the UPS or cause the controller to "think" that an overload has taken place.

Any number of things can make the UPS switch to battery. Some of these are so brief that you'd never notice them.

By having your UPS plugged in to a two pin electrical outlet with no ground connection, its surge suppression capability is greatly reduced. It should otherwise operate normally. Old wiring and electrical service equipment are generally safe IF they're in good condition and not overloaded or otherwise abused. If you have any reason to believe that the electrical equipment is not safe, either demand that it be fixed or hire an electrician yourself.

This behavior may also be the sign of weak batteries, although I'd not expect that to be a problem if the UPS was new when you bought it. You can determine when it was made using the serial number: after the first two letters of the serial number, the next four numbers indicate when the UPS was made, in year/week format.

[Anonymous user · Accepted solution]

Thanks for the reply. I have the BN450M mode and the serial starts with 9B1726, so I'm guessing it was made in week 26 of 2017? That would be late June to early July. Well, one of the things I did was plug my heavy duty equipment like the PC and TVs to the surge protector outlets and use the battery outlets for light weight equipment. Modem, router, phone, PS4, PSTV and a few other things. I got the idea of doing that from a comment I read by somebody else with a similar problem. They said their APC would go on battery and shut off randomly but the things connected to the surge outlets still drew power from the wall. So I'm going to see if that happens should it randomly go battery mode again, which I hope it won't.