APC Back UPS XS 1500

Anonymous user · ‎2021-06-29

Hi everyone. Please direct me to the proper area if this is not it. I have an APC Back UPS XS 1500. The sockets in the back read 115 volts when plugged in to AC but only read 88 VAC when on battery. The batteries are charged. Am I looking at a new transformer? I am new to the UPS field so be easy on me. Thanks.

Anonymous user · ‎2021-06-29

Thanks for the reply. Is that the reason when I plug my box fan in to check it the fan runs slower than when on line voltage? I was given this UPS and I am trying to figure it out. I don't have an extensive electrical background.

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BillP · ‎2021-06-29

Good day Neal,

It has something to do with the voltmeter that you are using. Our BackUPS provides a step approximated sine wave when it runs on battery. Non TRUE RMS voltmeters won't be able to read the exact voltage it provides but a True RMS voltmeter will. Below are some APC knowledgebase articles that would help you out.

[True RMS Voltmeter Required to Read Stepped Approximated Sine Wave|http://nam-en.apc.com/app/answers/detail/a_id/1493/kw/true%20RMS%20voltmeter]
[Different Types of Voltmeters|http://nam-en.apc.com/app/answers/detail/a_id/4119/kw/true%20RMS%20voltmeter]

Anonymous user · ‎2021-06-29

Thanks for the reply. Is that the reason when I plug my box fan in to check it the fan runs slower than when on line voltage? I was given this UPS and I am trying to figure it out. I don't have an extensive electrical background.