Trickle charge your vehicle's 12V battery with the Coleman 6W Solar Trickle Charger. Can be connected to all rechargeable 12V batteries.
I use this with a $50 garden tractor battery and power an entire set of shortwave radios and mobile weather station. I've had a similar panel for years and was thrilled to find this one. It will definitely keep a battery topped off. As with any battery charging operation, never leave unattended and use volt meter to monitor voltage.