Abstract: The increasing number of mobile battery-powered small appliances with different feed voltages and connecting devices is calling for a universal and compact energy supply apparatus which provides for an uncomplicated and at the same time cost-efficient adjustability to as many small appliances as possible. To this end, the present application proposes a universal power supply unit consisting of an energy station with an integrated voltage converter in combination with various appliance-specific adapter cables with a group of electronic components. This generates an individual programming signal in the adapter cable which when coupling the adapter cable to the energy station causes a corresponding setting of the required output values. This leads to a simple matching of the unit with various small appliances and provides for a large field of applications. In particular, by feeding solar energy the power supply unit may be rendered autarchic in terms of energy.