Are you talking about an uninterrruptable Power supply ? Like for a computer?
There are a bunch of threads about it on here, many i have replied to. The just dont have the capacity to run your equipment for any significant length of time. Here is the link to one of the threads. https://www.saltwaterfish.com/vb/show...t=power+outage
good luck...
I use a computer UPS as a voltage regulator, evening out spikes and drops in the current. Later on it will also act as a simple supply to run while the generator kicks in. Plus, generators give out very Very dirty current, so it will smooth that out and keep my equipment life higher than it might otherwise be.
I was just surfing the magical interweb... ***)
I got an idea for a UPS type backup system a-la DIY.... I'm not sure if this is what you were talking about dieselndix but.... Theres a company called tripp-lite that makes power inverters/charge controllers and other power equipment. ebizzle has some of their equipment for decent prices. They make a 24 volt system that can handle up to 2400 watts continuous... With the 24 volt setup you could do 4 batteries, 2 pairs in series and then in parallel to the charger (i think that should work) that way you could have 4 large capacity deep cycle batteries for backup. You could run most anything you needed on your tanks for a 2-4 days without much trouble. Just a thought...