I have the heater, fog/flood lights, and all the excess whatnots hooked to that little ranger battery, a good cold day makes that battery pretty week. I would guess if I could fit a regular car sized battery under that little hood I would be golden. I have always wanted one of them jumpers, but years back had one(as big as an air compressor), and when I needed it it was dead. Of course it isn't the fancy ones of todayMaybe you had it with for another reason but those little lithium jump packs are pretty slick. Mine stays in my boat and then gets transferred to the ranger for the winter.