In one embodiment, a system for monitoring and indicating remote battery charging comprises a sensor unit, a power source, at least one remote battery, and a wiring harness; wherein the sensor unit comprises an analog to digital converter (an “A/D Converter”) and a display means such as lights (e.g., LEDs) and/or a screen (e.g., LCD). In one method of use, the system for monitoring then monitors the power supply (the source) as well as the auxiliary charging system (e.g., the liftgate electrical system) and provides advanced warnings or signals when the system is not receiving sufficient power or is otherwise not functioning properly.