Anyone have ideas on how I can take advantage of a panel thats on my camper through the winter months? Its about A 24 X 42" panel. Not sure the watt. Turing camping season, It charges 2 batteries, and I have a 3000 watt power inverter. The batteries are Unhooked for the winter, and I think they need replaced, because when charged up fully, I could only run light powered stuff only for 20 min or do. Sound like bad batteries?