I’m a complete electrical idiot. I’m looking to run some gear with the above specs 600W max draw, average 250W. Looking to run for 4 hours, maybe 8? I assume I’d need to run the engine, at least intermittently, or are there batteries that would be able to do this? It’s for a computer type application with a PC PSU if that matters. Want to put it in the back, plugged into a US household plug outlet.