I use one of these plugged in to my car's always-on cigarette lighter. It works. My battery is never flat, even if I don't drive for a month or two. http://w

I use one of these plugged in to my car's always-on cigarette lighter. It works. My battery is never flat, even if I don't drive for a month or two. http://www.harborfreight.com/15-watt-solar-battery-charger-68692.html http://www.harborfreight.com/15-watt-solar-battery-charger-6...