SU2200RM3U - Proper output voltage while on batteries

[MarkGinger_apc]

What is the tolerable output voltage on a SU2200RM3U? On one of my units I am getting 72V output when the unit operates on batteries. Can someone please share the range?

[MarkGinger_apc]

Hi Rob,

Measuring on positive/negative on the 15A outlet.

[Anonymous user]

Sounds suspiciosuly like an inverter failure ? ... are there any abnormal whine/vibration sounds when its operating on battery  ? what is the DC voltage at the battery pack terminals ? (on an SU2200 it should be around 48 volts DC on battery,  54 volts DC online)
Dave

[Anonymous user]

Note that inexpensive AC voltmeters measure Peak voltage and then calculate the equivilent RMS voltage. This means they only read correctly on relativly clean sign waves. Most UPS units do not produce a perfect sign wave, so your meter might not be reading correctly, on that waveform. UPS units that make good sign waves are very expensive.

So the UPS might be working correctly. Can you try it on a "known good" UPS? Or borrow a better voltmeter?

HTH

[MarkGinger_apc]

I am going to set it up today again and measure the voltage during online operation and on battery operation. Will report back.

[MarkGinger_apc]

I thought the RMS voltage problem only applied to non sinewave UPSs, as in the Back-UPSs. The smart ups should show actual voltage on a voltmeter at output.

[BillP]

Yes, you're correct. Non-True RMS meters only display a problem when using a step approximated sinewave. I don't think this issue occurs on devices like yours with a Pure Sinewave.

[Anonymous user · Accepted solution]

I didn't know the SmartUPS output a sinewave. But maybe the output is not as good a sinewave as it is supposed to be??