Balancing circuit for series connected electric energy storage elements

A balancing circuit for series-connected electrical energy storage elements, in particular capacitors (C1, C2), is proposed. Each energy storage element is provided with a bypass circuit (3 or 4) for limiting the charging voltage, which contains a voltage-controlled current source (1 or 2) fed by the energy storage element for generating a bypass current. The bypass circuit thus absorbs an increasing portion of the charging current starting from a preset value for the rated voltage and thereby protects the respective energy storage element from overload. The voltage-controlled current source is preferably realized by a power transistor, which can be a MOSFET or a bipolar transistor. This balancing circuit is used with particular advantage in energy storage devices that contain a number of capacitors, in particular double-layer capacitors, connected in series.