I run a 6v 12ah battery on my rule 360. Plenty of circulating water inside my 6 gal tank lasts over 8 hours on a single charge. Got the battery from kayakfishinggear.com back when I was always kayak fishing.
To stop your liveys going belly up, have the inlet in the bottom so the oxygenated water is through the whole tank. Also if the water is moving in a circular motion all the better as well