NAN DAO&reg; Solar 30A Waterproof Charge Power Controller / Regulator 12V / 24V 30 Amp for Boat RV Marine Work voltage: 12v / 24v auto; rate charge current: 30A rated load current: 30A Protects battery from overcharge and discharge Double digital LED display; full automatic operation. Detects day and night using the PV array. Intelligent control is realized by using microprocessor and dedicated control calculation.