Question UPS didn't last through 2-minute power outage

GeorgiaOverdrive

Distinguished
May 30, 2014
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I have computers on six UPSs. Today we had a 2 minute and 5 second power failure. One UPS didn't hold the computer up for that time period. It is a 1000VA unit, so somewhere around 700 watts. The load on it is 375 watts. When power came back on, it was showing 41% of capacity, whereas the others were showing 70-90%. It passes its self-test. Now it is recharging, and showing 81% of capacity.

Why did it drop within 2 minutes, when it showed 41% capacity left? Is the battery too old?

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And a followup: is there a way to tell if the UPS will stay up, other than pulling the plug out of the wall when it has a load on it?
 
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Ralston18

Titan
Moderator
Remember that most UPS performance claims are established under ideal laboratory circumstances. As is the case for many, many products...

Does not surprise me that actual performance was less than advertised/marketed.

And if the UPSs' and/or batteries are old then the end performance may be further degraded.

From my viewpoint, the only way to know for sure is to do as much as possible a "real world" test. Pull the plug...

But do use a test computer that is identical to your computers as closely as possible.

And be sure that the computer users understand that the UPS is intended to provide enough operational time for a graceful shutdown. Not to keep working until it all dies....