Trickle charger for car battery, motorcycle, boat, etc. - Automatically switches from full charge to maintenance mode to maintain batteries during prolonged periods of storage without overcharging or damaging the battery - Multi-stage charging provides a more thorough battery charge - Suitable for all types of 12V lead-acid batteries, including gel cell and AGM A new one costs about $47. This one has been used very little and costs $30. Thanks for looking.