Why does my UPS switch off without warning?

[perrorist_apc]

I have a 9-year old SUA 1500I UPS that reports no problems. However, without warning, it emits a blip sound and then switches off. I can switch it back on but I've no idea why it turned off. I now feel like my UPS needs its own UPS.

[BillP]

My first thought is maybe the battery is faulty and when the UPS wants to go to battery for a particular reason very quickly, it is turning off. (FYI: Reasons a Smart-UPS Will Transfer to Battery | FAQs | Schneider Electric US)

How old is the battery? Also, when you go to turn it back on, are there any LEDs on the front panel? And when you turn it on, does the UPS run through its short on battery self test?

If it were me, I'd do a pull plug test and start with seeing how it behaves. Plug a non critical load into the UPS and make sure to remove any USB/serial cables that can interfere in the UPS shutdown behavior. Then, pull the UPS plug from the wall to simulate a power event and see what it does. If it turns off, I tend to blame the battery assuming it is not brand new, but if the UPS is passing the self test when you power it on, that may not be the case.

[perrorist_apc]

The battery was installed in January 2012, so it's probably not far off needing replacement. I suspect you're right about the self-test, as it occurred around the time the self-test usually kicks off.

When I switched the power back on, all five charge lights came on (96%) and the self-test completed without complaint. No other lights are showing.

In the past, when the battery has begun to lose capacity, it's been reflected in shorter backup times rather than turning itself off.

[BillP]

Hmm, it still could be a UPS issue of some type, especially since it passes the self test. Did you try the pull plug test?

Also, it could be something like a relay weld but this usually displays some type of solid/flashing LED combination to indicate a failure mode when the UPS would turn off.

[perrorist_apc]

Yes, I pulled the plug out and it switched immediately to backup. After a minute I plugged it back in. Charge was four lights out of five for a few minutes, before returning to fully charged.

Is it possible that a malfunctioning attached device could cause the problem?

[BillP]

It could I suppose, but I don't think it is likely. Have you ever seen your UPS using Automatic Voltage Regulation (boost or trim)? There are lights above and below the "online" LED that indicate this. I was wondering if it could be an issue with that relay when the UPS tries to go use AVR and fails.

[perrorist_apc]

No lights. It's performed very well so far.

How long would you expect the battery to last? It's 2 years 8 months old and hasn't seen much use. It was exhausted once only.

[BillP]

A battery can last anywhere from 2-5 years on average, some people get 10! It really depends on several factors - environment, build quality, use, amount of discharges/usage, etc.

[perrorist_apc]

Thanks. Since that failure, the UPS has performed without any issues. I'll treat it as a one-off and hope for the best.

[BillP]

Do you have a USB or serial cable attached to this UPS? I'd be interested to see if the UPS recorded a self test or if it was just an on battery event in quick succession due to electrical noise, etc. Sometimes a faulty serial cable connected can cause this too is why I ask.

How much load is on the UPS? (Left bar graph)

[perrorist_apc]

I think this must be related to my original post:

This morning I heard the UPS switch self-test three or four times in quick succession. I looked at the panel and saw that the charge lights were set at the lowest (one light, which flashed briefly). No other lights were displayed. Gradually, the battery increased its charged state to 100%.

Is it possible for the unit to flash discharge the battery? Is this indicative of an electrical short? The unit is running normally again, but I can't help wondering when the next event will occur.

[perrorist_apc]

No connection, but perhaps I should. I'll get back to you on the load.

[perrorist_apc]

Powerchute Business Edition, latest version, running under Windows 8.1 Pro x64.

[BillP]

Hi,

PowerChute should not be using 25% of the CPU. Is the UPS connected via USB or Serial? Would you share the log file(s) all files under Program Files\APC\PowerChute Business Edition\agent\log and Program Files\APC\PowerChute Business Edition\agent\proclog.txt.

I have added you as a friend so you can send the logs to me directly instead of posting them.

Thanks,

[perrorist_apc]

As mentioned in my email to you, the process is running now using negligible resources following a system reboot.

[perrorist_apc]

It's reporting 9.7% UPS Load.

[perrorist_apc]

It's now risen to 15.6% and stayed there.

BTW, why does the monitor take up so much CPU. It's showing 25% all the time.

[BillP · Accepted solution]

What "monitor" specifically are you talking about? PowerChute or something else?