Back UPS BR800 switching to battery a mystery

[Anonymous user]

Hi;

I have a BR800, purchased in 2009 for my personal PC.It works normally most of the time, but fairly often late at night (early in the AM) the unit will switch to battery and remain that way for several minutes. I had to disable the audible alert so it would not awaken me.

The sensitivity setting was at medium.

Since there was no power interruption when the switch to battery occurred, I checked the line and found it to be well within spec, at 125V, 59.94Hz (using a Klein Tools multimeter).

I changed the sensitivity setting to low last night and will see what happens over the next few weeks, but I am perplexed.

Why is my BR800 switching to battery power?

Could there be noise on the AC line? This is a commercial power line,

This event occurs mainly during the wee hours of the morning, but occasionally at other times.

The unit passes the test program.

The Power Chute software does not indicate a power failure after this event, but note that the BR800 is not normally connected to the computer, and the computer is not usually running when the event occurs.I do not know for sure whether it is the BR800 or the Power Chute software which is responsible for keeping the log for this type of event, but I have always thought the log is kept within the BR800 and downloaded when the Power Chute software is run.

I would appreciate some info on this, as I am concerned that my BR800 will fail completely.

Thanks

FW

[BillP · Accepted solution]

Keep in mind, a UPS can go to battery power for more than a typical "blackout" or power outage that you're probably expecting. Electrical noise, change in voltage over time, and sags or brown-outs can also force the UPS to battery. Plus, measuring the voltage/frequency while the UPS is not rejecting the input power probably isn't too helpful unfortunately since it is running online when you're doing that (based on what you've mentioned so far). My only concern is that voltage in the US is nominal (expected) 120V. 125V is a tad high and I mentioned that because the tightest voltage transfer ranges (tied to sensitivity setting) you may see on your UPS are at 127V - so, overnight, if it jumps to 127V, it could go to battery.

Lowering the sensitivity is a good start but I would not be too worried if it does this happen periodically overnight because it could be another type of power event and the UPS is just doing its job protecting your equipment.