Abstract: The present invention relates to a system for charge balancing over a plurality of rechargeable energy storage devices coupled in series, said system comprising a plurality of balancing units each assigned to one of the rechargeable energy storage devices, an AC signal generator for providing an AC signal to the plurality of balancing units, and a capacitive coupling between the AC signal generator and each of the plurality of balancing units for common mode rejection. A first balancing unit comprises a plurality of switches for transferring, on the one hand, charge from the AC signal generator or from an energy storage device assigned to another balancing unit for charging the energy storage device assigned to the first balancing unit, and, on the other hand, for transferring charge to the AC signal generator or to an energy storage device assigned to another balancing unit for discharging the energy storage device assigned to the first balancing unit.