I have 2 of these on my van and i love them because you just leave them connected to you batters at all times and there mounted next to my batteries and i just plug them in at night and there charged in the morning. yeah and only charge like 2 times a month also.
http://www.amazon.com/Dual-Pro-Charger-Three-Bank/dp/B0000XQ76S/ref=sr_1_15?ie=UTF8&qid=1297053716&sr=8-15