Votronic MPPT Solar Charging Controller MPP 430 Duo Digital Increased MPPT charging current by 10% to 30%; Automatic charging programs adjustable for gel, acid/lead-acid and AGM/fleece batteries for optimum charging results; All solar charging controllers are also available with humidity-proof electronic system for boats. Main Charging Port I: Automatic charging and conservation of charge of the (main) board supply battery; Auxiliary Charging Port II: Current and voltage reduced for recharging as well as trickle charge of the vehicles starter battery, thus ensuring continuous starting capacity. Overcharge protection: Reduction of the charging current of the battery in case of excessive solar power and full battery. Immediate recharging in case of power consumption to always ensure the best possible charging state of the battery. The charging voltage being free from peaks is controlled in such a way that any overcharging of the batteries is excluded. Unattended Charging: Standard protection against overload, overheating, reverse battery and back discharge of the battery; Charging Cable Compensation: Automatic compensation of voltage losses on the charging cables. On-board Mains Suppression Filter: Unproblematic parallel operation with wind-driven generators, petrol-driven generators, mains supply chargers, dynamos etc. Connection for External Battery Temperature Sensor. Ready for connection of the VOTRONIC Solar Computer for optimum control of the system. Displayed Values: Battery voltage, charging current, charging capacity, stored capacity and energy (V, A, W, Ah, Wh). Votronic Solar Computer is a large display with time-controlled adjustable illumination which ensures excellent legibility.