Not cheap but very good. A friend sells the line. A two pound battery is running the 110 ac lights and 12 volt ac through a inverter all nite, solar panels on top of trailer recharge them in 2-3 hours. Doesn't use his generator. This thing is the size of a riding lawn mower- motorcycle battery. Can be mounted anywhere it's so small. He's getting 300 bucks and his has 1200 ccamps and spins his 632 BBC with no effort, 3 year warranty too. Save 50-75 lbs on regular bat.