battery tender 5 amp/2.5 amp, 12v battery charger and maintainer: 12v/24v onboard marine battery charger for boat engine - mountable, heavy duty, weather resistant boat charger - 022-0258-dl-wh battery tender the battery tender selectable 2.5 amp/5 amp microprocessor-controlled charger will charge both flooded and sealed lead acid batteries. with reverse polarity protection and a complete 4 step charging program, the heavy duty selectable battery charger has a 2-year warranty and is packed with features, lightweight and vibration resistant.