The invention is directed to a protective circuit for a multiplicity of individual cells arranged in a rechargeable battery pack, wherein a predefined number of individual cells forms a cell network. A monitoring circuit for the state of charge of the individual cells in the cell network is provided wherein the voltage at an individual cell is detected and the detected voltages of a plurality of individual cells are compared among one another to output a signal when an unbalancing limit is exceeded unbalancing limit indicates a permissible voltage difference between two selected individual cells of the cell network. The unbalancing limit of the cell network is provided as a characteristic curve variable over its state of charge. To alter the unbalancing limit, the characteristic curve is altered in dependence on a correction value.