Abstract: An automatic ignition controlled battery charge and discharge system for vehicles such as RV's boats and the like, that have an engine with a charging system connected to a main battery, an ignition switch controlling the engine, and a plurality of auxiliary batteries. When the engine ignition is turned on, the main battery connected to a generator or alternator of the engine is placed in parallel with a plurality of auxiliary batteries for charging, and when the engine ignition is turned off, the main battery is isolated from the plurality of auxiliary batteries, to allow the auxiliary batteries to discharge without affecting the voltage potential of the main battery.