BX1500 won't return to AC after power outage

[Anonymous user]

The unit has been fine for years. In the last two outages, it won't return to AC operation after an outage. Even with everything turned off, it goes to battery. Looking for answers here, I downloaded Powerchute to see what happens. I pulled the plug for 60 seconds and replugged. The battery had dropped to 75% charge and the input voltage dropped to 100 volts. The charge continued to wilt and the input voltage dropped to 97 volts. I shut everything down and waited an hour. Now the battery is at 54% but is charging, the UPS is running on AC, and the input voltage is back up to 120. I'm certain the line voltage in the house was not actually low.

What's preventing my unit from recovering after an outage? Are the batteries too old? No indication from the battery light.

[Anonymous user]

Since I got no replies to this question, I bought new batteries. The unit behaves the same way. So, maybe I need to buy a new unit. But I'm certainly not eager to buy an APC since there seems to be no technical support.

The common thread seems to be that the unit thinks the input voltage is less than 115 when it's not. And as long as it thinks this, it won't switch back to AC. Last night the unit went on battery for unknown reasons. The new batteries died, and then it shut down. This morning it would not go back to AC. I turned it off and waited an hour, then tried again. Still it would not go back on AC. The input voltage claimed it was 93 volts when it was not. Seven hours later I tried again and it came up.

Having it is worse than having nothing. It shuts down with no power outage, and then won't start up again.

[Anonymous user]

I'm just another end user chiming in here. (Mostly -- I have no affiliation with APC or Schneider Electric, but I have done component level repairs on many of their UPS products and maintain a lot of them for clients.)

If you have a decent quality AC voltmeter, you might check to see if the voltage is really sagging at the outlet where the UPS is connected.

I don't think you'll find that it is. If this is the UPS model that I'm thinking of (white tower, sometimes with a grey plastic foot), I have found them to be particularly unreliable (in stark contrast to other APC products). I've got several of these here with different faults, mostly failure to return to an "on line" state of operation after performing a self test or after a power failure. APC's other models (including current production) are much better.

Someone elsewhere on this forum did manage to pinpoint a possible cause of this failure. There's a transformer that's used for voltage and current sensing purposes by the UPS's microcontroller and seemingly it fails. I think they actually went to the trouble of sourcing a suitable replacement. (If I could find the post, I'd gladly link to it.) I've got enough other units that I haven't even bothered to look at my own pile of failed BX series units. They're likely heading for the e-waste bin after I've picked whatever parts out of them that I want.)

APC's stance is that these units are not repairable, and it certainly can be dangerous to repair these things for a variety of reasons. The results/risks of attempting any repair are strictly your responsibility.

Though there are APC employees moderating here, and occasionally participating, I think this forum is primarily user-to-user. You'd be better served by calling APC's telephone technical support using whatever number is appropriate for your country of residence.

[Anonymous user · Accepted solution]

William .... thanks for the information. I guess it's time to move on.