said by birdfeedr:Running the UPS is minimal cost in the real world. I get 16 to 18 hours of runtime before my ONT has to use it's own BBU. I use a dozen of the APC 1500XS/Back UPs Pro 1500 models with extended runtime batteries for my electronic devices. The extra power use of the UPSs is extremely minimal.
Easy, yes. Efficient, no.
When on battery, my ONT draws 10 watts. When the battery is charged, the BBU PS uses 20 watts just to maintain. That's the FiOS equipment. Now add the losses to run and maintain the second UPS.
I'm not disagreeing with your solution, but there's another one (or two or three).
*My* real solution is to use a backup generator to run lots of stuff in my house in the event of a power outage. The experiment with the battery is mostly to expand the list of options.
If I knew a particular battery solution would give me 36 hours of runtime, I can compare it to other solutions that would provide the same. How do I specify a UPS that would give me 30 hours of runtime with a 20W AC load?