STANLEY BC15BS Fully Automatic 15 Amp 12V Bench Battery Charger/Maintainer with 40A Engine Start, Alternator Check, Cable Clamps 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