A system (1, 16) for discharging a defective battery cell having an internal short circuit of a rechargeable battery unit (3, 17) having at least two battery cells (2, 4) connected in series, comprising a balancing circuit (5, 18) for balancing said battery cells (2, 4), a control unit (9, 21) for controlling said balancing circuit (5, 18) and at least one sensor unit for detecting, if a short circuit exists in at least one of the battery cells (2, 4), wherein the control unit (9, 21) is configured to control the balancing circuit (5, 18) such that, after detection that a short circuit does exist in a battery cell (2, 4), charge of this defective battery cell is successively transferred to other battery cells by means of the balancing circuit (5, 18), wherein the balancing circuit comprises at least two power switching converters each being dedicated to one of the battery cells (2, 4) and sharing at least one inductor, and at least two diodes each being dedicated to one of the battery cells (2, 4) and each allowing a charge current to flow through the respective battery cell (2, 4), and the control unit is configured to control the balancing circuit such that, after detection that a short circuit does exist in a battery cell (2, 4), charge of this defective battery cell is transferred to the battery cell whose dedicated power switching converter shares the inductor with the power switching converter being dedicated to the defective battery cell; or the balancing circuit comprises at least two power switching converters each being dedicated to one of the battery cells (2, 4) and being inductively coupled with each other, and the control unit is configured to control the balancing circuit such that, after detection that a short circuit does exist in a battery cell (2, 4), charge of this defective battery cell is transferred to the battery cell whose dedicated power switching converter is inductively coupled with the power switching converter being dedicated to the defective battery cell, wherein the control unit is configured to control the balancing circuit such that, after detection that a short circuit does exist in a battery cell (2, 4), the power switching converter (6, 19) being dedicated to this defective battery cell is operated with a changed switching duty being different from a switching duty provided when no internal short circuit is detected, and that the power switching converter (6, 19) sharing the inductor with the power switching converter being dedicated to the defective battery cell or inductively coupled with the power switching converter being dedicated to the defective battery cell is kept switched off. wherein the control unit (9, 21) is configured to control the balancing circuit (5, 18) such that, after detection that a short circuit does exist in a battery cell (2, 4), charge of this defective battery cell is successively transferred to other battery cells by means of the balancing circuit (5, 18), wherein the balancing circuit comprises at least two power switching converters each being dedicated to one of the battery cells (2, 4) and sharing at least one inductor, and at least two diodes each being dedicated to one of the battery cells (2, 4) and each allowing a charge current to flow through the respective battery cell (2, 4), and the control unit is configured to control the balancing circuit such that, after detection that a short circuit does exist in a battery cell (2, 4), charge of this defective battery cell is transferred to the battery cell whose dedicated power switching converter shares the inductor with the power switching converter being dedicated to the defective battery cell; or the balancing circuit comprises at least two power switching converters each being dedicated to one of the battery cells (2, 4) and being inductively coupled with each other, and the control unit is configured to control the balancing circuit such that, after detection that a short circuit does exist in a battery cell (2, 4), charge of this defective battery cell is transferred to the battery cell whose dedicated power switching converter is inductively coupled with the power switching converter being dedicated to the defective battery cell, wherein the control unit is configured to control the balancing circuit such that, after detection that a short circuit does exist in a battery cell (2, 4), the power switching converter (6, 19) being dedicated to this defective battery cell is operated with a changed switching duty being different from a switching duty provided when no internal short circuit is detected, and that the power switching converter (6, 19) sharing the inductor with the power switching converter being dedicated to the defective battery cell or inductively coupled with the power switching converter being dedicated to the defective battery cell is kept switched off.