Renogy Wanderer -- 30A Advanced PWM Negative-Ground Solar Charge Controller The Wanderer is a negative ground controller. This ensure compatibility with any negative ground system, which is the standard and most conventional way of grounding. Any negative connection on the solar module, battery and load can be safely earth grounded as required 4 Stage PWM charging (Bulk, Boost, Float, and Equalization) prevents batteries from over-charging and over-discharging. Protection against: overcharging, overload, short-circuit, and reverse polarity Compensates for temperature, automatically corrects charging and discharging parameters, and improves battery longevity. LED Indicators that inform you about the charge controller's status Compatible with Sealed, Gel, and Flooded batteries