BatteryMINDer 12 Volt OnBoard Battery Restorer/Conditioner - Model# OBD-12 Conditions and desulphates batteries therefore guarantees significant increase in both your battery's life and performance can be used only for 12-V battery systems. Installation is a simple two wire hook-up. Auxiliary charger connector allows easy connection to installed batteries when connecting a stand-by or maintenance type charger, if needed. A single unit can serve up to a six battery system. No external power source is needed. This item does not charge the battery. A separate charger is required to maintain or charge your battery