Basic Function: If you supply 20 to 65 VDC to the input terminals you always get 13.6 VDC from the output terminals. 13.6 VDC is equivalent to the voltage coming out of the alternator that is charging your car battery. 13.6 VDC is "regulated" meaning stable so it is safe to use it as a 12 volt battery charger if your power source is between 20 volts to 65 volts DC. Condition “NEWMAR 36-12-35ISP DC-DC Converter 20-65V IN 13.6V OUT” Mounting Style Surface Mount Nominal Voltage Rating (DC) Input 20vdc to 65vdc Brand NEWMAR 36-12-35ISP DC Type DC to DC converter Nominal Current Rating 20 Amps Continuous 35Amps Intermittent Current Conversion DC to DC Output Voltage Rating (DC) 13.6 Vdc Measures 17L x 7W x 6Tall in inches.