021-0134 - Safe, No Spark Charging! Deltran's advanced SuperSmart Battery Tender Battery Management System is light years ahead of any standard battery charger. It's the first fully automatic, constant-current battery charger designed to charge and/ or maintain up to ten 12 volt batteries simultaneously at 2 amps. (Note: Please allow 1-2 weeks for shipment of this unit). To avoid dangerous dead-short sparking, microchip circuitry will not activate output voltage until clips are correctly connected to battery. Simultaneously charges and/ or maintains up to 10 batteries.