The Battery Extender 2 Amp battery charger maintainer is fully automatic. It is ideal for charging small batteries and keeps stores lead-acid batteries charged. Energy efficient, meets the highest industry standards. Auto-voltage detection automatically detects 6-Volt or 12-Volt batteries Non-conductive rust-proof case designed for added safety and durability Microprocessor controlled multi-stage charging for added precision, safety and battery life Float-mode monitoring automatically maintains optimum battery charge Reverse hook-up protection helps protect battery and charger from damage