BEST SELLER!! For vehicles that arent driven every day, or for storage during the winter, we use this compact, 1.5 amp 12 volt automatic battery charger. Just install in the vehicle and leave it in place then just plug it into any extension cord. It charges the battery whenever voltage drops by one volt. When the battery reaches full charge, it shuts itself off automatically to prevent overcharging. Charger includes on-off charging indicator. Two-year manufacturer warranty.