Autonomous electrical installation, especially for vehicle

A battery (3) is connected in series with the lower voltage system (1) and also in series with a supercapacitor (5) to supply the higher voltage system (2). A DC/DC convertor (4) has higher and lower voltage terminals (4c,4a) connected to the respective systems and a motor alternator (7) is connected to the higher voltage system. An electronic calculator (10) maintains all voltages within required ranges and disconnects the convertor during starting