Alternative battery backup for 120V desktop computer

[mcrn22]

If anyone else comes down this road, I ended up finding an affordable solution that works for my use-case.

I observe ~30 minutes of battery backup at ~200 watts and cost ~$80 in the LiFePO4 batteries for each APC unit.
(1) APC Back-UPS Pro BR1500MS2 with two new 12V 7Ah LiFePO4 batteries
(2) APC Back-UPS Pro BR1500MS with two new 12V 7Ah LiFePO4 batteries
(3) APC Back-UPS Pro BR1500MS with two new 12V 7Ah LiFePO4 batteries

 

[krby]

I'm coming into this discussion really late, apologies for not reading the whole thread. Regarding just the USB communication portion of the original post, I just went through this exact problem and solved it for myself.

What you likely want is an MCU like an Arduino or Teensy, and to use the HID UPS Arduino library along with the sample sketch it has. Using that and an AC Detector module I now have a thing that is recognized as UPS over USB to Windows and MacOS. If you want it to work plugged into a Linux box you'll need to do a bit more work, the v2.8.1 and earlier releases of NUT don't correctly parse the AC Present / not present values yet.