Back-UPS RS1500 switches to Batery even with AC connected and detected.

[Anonymous user]

Hello, I have an issue with my BackUps 1500. 

When I power it on, it switches to Battery. No matters if it is connected to AC or not. I also notice an electric hi-frequency buzz (not from buzzer but from circuit itself). PowerChute reports a variable AC input between 184 and 207 Volts but using calibrated instrumental i measure stable 225 Volts.

Since I am an electronic technician, I replaced capacitors and checked welds with no results.

I tried powering the UPS on and removing batteries during autocheck. It lights the replacement led. Then I plugged batteries in again. It turns led off and stays online. Then if I remove AC cord, it switches to battery again and wont go back online while AC power is restored.

As an additional information: While Online, powerchute shows AC power accurately. It changes to variable as it told above when it is on battery mode.

I appreciate any idea or info about this issue.

Tnx

[Anonymous user · Accepted solution]

Which exact Back-UPS model do you have? From the description and capacity, I'm guessing it's the white plastic tower model.

If so, all I can tell you is that these things seem to be very failure prone. Every one of these that I've had has failed, and most of them failed in this exact manner. (One suffered a failure of a surface mounted 7812 voltage regulator, which rendered it completely dead.) Setting the sensitivity to "low" will buy you some time, but affords moderately less protection for attached loads and ultimately, even this is not enough.

I feel pretty confident that something is drifting out of tolerance, though what it is I'm not sure. I would have guessed capacitors, but you've mentioned replacing them. All of mine are 120 volt models (since I'm in the US). I never did think to check what, if any, incoming voltage value was reported by the UPS. As best I remember, I've since scrapped the afflicted units.

I really wish that APC and Schneider Electric would provide schematics and service literature, even if only for older and retired models, to those of us who know what we're doing.

[lmstearn_apc]

Better software and logging as well. Good idea to have a lifetime history- if nothing more than dates and warnings and error codes. If the UPS has ever been hit by a surge, there's nothing to say (at least on mine, 700G) it ever was, and to the extent of the impact.

[Anonymous user · Accepted solution]

I have no history of this equipment but it was working properly until it needed battery replacement. When this was done, it started having this issue.

Is there a way to get a Log from the UPS itself? Sadly, user had no powerchute or similar installed.

tnx in advance.

[Anonymous user]

Hi! tnx for your answer.

Indeed, it is the white plastic tower mode. The only model reference i see is "Back-UPS RS 1500" there is no other mention on any other place. it is 120/220V dual input.

Sensitivity is set to LOW but nothing changes.