Need a fuel gauge for your battery's
and have $200 dollars burning hole in your pocket, then this is what ya need.
http://www.energyoutfitters.com/default.htm?http://www.energyoutfitters.com/products/p_m_electronics/xantrex_link10.shtm It shows you current bat volts and amp's It even tells you at the current amp draw via a timer how long you have till your empty.