Energy supply device, electric motor and vehicle

The invention relates to a power supply device with a control unit, a first battery and a second battery, wherein the batteries each have at least one galvanic cell, a supply line with an associated diode and a ground, wherein the first and second battery are connected in parallel and each supply line has a current measuring device and each battery has a voltage measuring device between the associated supply line and the ground, wherein the control unit is arranged such that based on respective measured supply current strengths and/or respective measured voltage values and their differences to one another an output power of the power supply device is controlled and/or regulated by the control unit.