Squeeks, although I do recommend a 110Ah, an 85Ah will do fine (should give 2 full days work before needing a charge). I would definitely recommend buying a good brand battery though. Our batteries are: 110Ah Varta, 130Ah US Battery (shown on the battery megastore site) and a 110Ah Voyager. All 3 are good batteries, they're all 2.5yrs old and the voyager is now dying, the varta is still good but the US Battery (130Ah) is an absolute workhorse - will easily run 2 pumps all day for 2 days and has only lost about 5% efficiency since new. Well worth the money and will most likely get another couple of years of hassle free service.