15 amp bench battery charger maintains and charges any AGM, GEL, or WET automotive or marine 12V battery Fully automatic high frequency charging delivers 3 stage charging, automatically switching from fast charge, to top-off, to trickle charge Battery reconditioning feature helps extend battery life; 40 amp engine start helps start your vehicle in about 90 seconds Equipped with reverse polarity protection; LCD screen displays charging status and battery status with easy to understand icons Features a patented alternator check which indicates if the alternator is maintaining battery level; ETL Certified for performance and safety Automatically compensates for lower voltage caused by extension cords