I have an APC SU2200 (SmartUPS, 2200VA) 3U tall, that I put new batteries in a
few months ago. So far it's just sitting, plugged in, turned off, with no load.
I got curious as to how much power it was sucking out of the wall outlet, so I
plugged the UPS into my Kill-A-Watt device and plugged that into the wall. Here
are the numbers I observed:
122.2 Volts
1.48 Amps
31 Watts
181 Volt-Amps
0.17 Power Factor
The values were identical with the unit turned on, also with no load. The only
thing running inside the UPS is the battery charger; the inverter is completely
bypassed and is not running.
I then ran the UPS into a test cycle, again with no load, but this time the
inverter turned on and powered the load, thus disconnecting itself from the
commercial AC power. Surprisingly, there was still a little bit of power being
used, probably by the transformer and line sampling circuit. Here are the
readings I got during the self-test:
122.4 Volts
0.09 Amps
0 Watts
11 Volt-Amps
0.06 Power Factor
As far as I know, the utility's kilowatt-hour meter on the side of my house,
which is a rotating aluminum-disc style, measures WATTS, not Volt-Amps. Somehow
APC has managed to get their charging circuit to draw a lot of current while
keeping the power factor and Wattage power extremely low. I suspect it's highly
capacitive.
So here's where you all get to jump in. Is this UPS costing me a lot just to
keep the batteries charged (180 VA) or am I only being charged for the wattage
it draws?
Bob M.
