UPS works when unplugged but not during a real power outage

[Anonymous user]

I have had a XS800 for quite some time but was finally was able to see it in action (or lack there of) with some recent storms we've had. I've tested this unit every so often by unplugging it from the wall and letting the computer run on the battery for a short while and then plugging everything back in. For some reason when there is a real power outage, the computer and my external HD's all die and I get the overload warning on the UPS (red overload light and constant tone). When power is restored, I can turn the UPS back on and boot the computer and then yank the UPS' power cord and it works as expected. Any idea what in the world might be going on here?

[BillP]

does the overload LED come on flashing or solid? also, is that the only LED that comes on?

[Anonymous user]

This morning, just for the fun of it, I decided to throw the breaker in the panel for the area where the UPS is located. I wasn't sure if or how this would make a difference, but I thought it could be worth a try. The UPS worked as I would expect, providing power for the system. Still unable to recreate the overload condition.

I also forgot to mention that when the computer is running on battery power, there's a noticeable hum coming from the UPS and a slight hum coming from the computer. I'm not sure if this is normal, but worth mentioning.

[Anonymous user]

The overload light is the only light on at the time and is on steady.

[BillP]

ok can you give a little bit more of a break down as far as the equipment plugged in?

what are the specs on the computer? is it a power factor corrected power supply? any other details will be helpful

thanks!

by the way, a steady overload LED indicates an actual overload (rather than a fault) so we want to see if we can figure out why its doing that sometimes.

[Anonymous user]

Now that's a handy little piece of information. The booklet for the meter says it's average responding, which explains the reading I got and similar readings from a small, low wattage DC to AC inverter I sometimes use in the car. Thank you for that one.

[Anonymous user]

Currently I have a newer 20" iMac with a 2.4 GHz Core 2 Duo. There's also a WD MyBook external drive and a Drobo with four drives in it that are also plugged into the UPS. I do have to admit that when this UPS went into service, there was a smaller, older computer with none of the externals. I also realize that this power supply might be running near max. capacity when on the battery. I know that one time the UPS didn't perform, the computer was asleep and when I do the unplug test, it's normally running. I thought that perhaps the computer tries to wake up during an outage and the combination of the computer waking, plus all of the external drives spinning up might have caused a spike and caused the overload. I tried that scenario and the computer remained asleep and even waking the computer while on battery power did not cause the overload warning. So far I have been unable to manually recreate the overload condition. As a side note, when everything was running on battery power, I hit the UPS with a meter and there's 98 volts at the outlets.

[BillP]

you might see 80-100 volts when measuring a Back UPS' output voltage with a non-true RMS voltmeter because of the fact it outputs a step approximated sinewave.

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now if your voltmeter IS a true RMS meter, then thats a different story. it usually says it right on it.

[Anonymous user]

I received a phone call last night from home, seems there was another power outage and the UPS acted up again. I wasn't there, but I got as many details as I could over the phone. I was told that red overload LED was on, but this time was blinking. Blinked twice, then off, blinked twice more and off, cycling like that over about 20 to 30 seconds. The warning tone was on steady the whole time. Also, the UPS did not return to normal operation when the power came back on. I told the person who was home to shut the UPS off with the button on the front of the unit and then turn it back on. I was told that the green and yellow lights were blinking for a bit (sounds like the self test) and went back to green steady. The computer also turned back on (it's set to restart after a power failure). What does this new blinking pattern represent?

[BillP · Accepted solution]

flashing overload with a constant tones indicate a fault. if it is still under warranty, i recommend contacting support for a replacement.

[Anonymous user]

I guess I'm just going to chalk this one up to an internal fault then. Perhaps it was the fault of the fault (ha ha) that I was having the problem and now it's finally done for good. I've been thinking about upgrading to something larger anyway and perhaps this is my excuse. Now I just need to decide if I'm going to splurge for a unit that has a real sine wave output.

Anyway, thanks for your help.

[Anonymous user]

Hello there,
I have a similar problem, and have just registered because of it.

I got ES 350 a few days ago and according to the chart on the package, it was supposed to provide backup for at least few minutes for my tiny minitower and 19" LCD monitor.
I tested it manually several times, and computer stayed on. There was no sign of overload. Then, last night, we had a storm, and there was a tiny electricity glitch. Computer did not even get a chance to stay on, and now it seems the battery does not back up anything anymore. I left the UPS plugged in all night thinking that maybe battery was not charged enough or something. The same thing happens this morning. I used to have UPCs before both by APC at work and other manufacturer at home, and this never happened.

Then I saw your thread, and the whole thing really makes me wonder.

[BillP]

a 350VA UPS provides about 180-200 watts depending on the exact model and rating of it.

a 19" monitor could be 60-75 watts and a computer could be the same or maybe around 100 watts.

when this happened, did the UPS turn off after a while? how long did it take you to notice the computer was off? is it possible it could have ran for 2-3 minutes and by the time you got to it, it was at a low battery?

[Anonymous user]

Thank you for a fast reply.
It was a power glitch that lasted for a second or two. I noticed immediately, although I do suspect the battery was low before it happened. What confuses me most is that there was no low battery warning or overload warning.

[BillP]

so it did turn the UPS entirely off immediately?

[Anonymous user]

No, UPS stayed on. It just seems that battery backup outlets do not provide power at all when there is no electricity.

[BillP]

hmm ok. another thing you could check if it happens again is getting a voltmeter to see if any voltage is coming out of those outlets.

[BillP]

hmm yes the UPS should hum a little bit when operating on battery. i have heard of Mac power supplies humming while running off of a step approximated sinewave before so this doesnt shock me 😕