A method for balancing voltage for a multi-cell battery system, the battery system including at least two groups of cells (203, 213, 223, 233) connected in series, each group comprising either one cell or a plurality of parallel cells, comprising: charging (301; 601) the battery system until the lowest voltage of the group of cells (203, 213, 223, 233) is greater than or equal to a first threshold voltage (V thres1); or until the highest voltage of the group of cells (203, 213, 223, 233) is greater than or equal to a second threshold voltage value (V thres2), charging the battery system by keeping the lowest voltage of the groups of cells (203, 213, 223, 233) constant (304; 604), while at least the voltage of one group of cells (203, 213, 223, 233) is less than or equal to the first threshold voltage (V thres1); all voltages of the group of cells (203, 213, 223, 233) are less than or equal to the second threshold voltage (V thres2); and the charging current (I charge) is above a predefined minimal current (I min), charging (401; 701) the battery system, while: (a) at least the voltage of one group of cells (203, 213, 223, 233) is less than or equal to the first threshold voltage (V thres1); (b) all voltages of the group of cells (203, 213, 223, 233) are less than or equal to the second threshold voltage (V thres2); and (c) the charging current (I charge) is above the predefined minimal current (I min); while electrical loads are shut off (405; 705), measuring (409; 709) the voltage of each group of cells (203, 213, 223, 233); and dissipating energy in at least one of the group of cells (203, 213, 223, 233) of an amount that is represented by a voltage difference (ΔV P-Group(n)) between the individual group of cells and the group of cells with the lowest voltage. charging (301; 601) the battery system until the lowest voltage of the group of cells (203, 213, 223, 233) is greater than or equal to a first threshold voltage (V thres1); or until the highest voltage of the group of cells (203, 213, 223, 233) is greater than or equal to a second threshold voltage value (V thres2), charging the battery system by keeping the lowest voltage of the groups of cells (203, 213, 223, 233) constant (304; 604), while at least the voltage of one group of cells (203, 213, 223, 233) is less than or equal to the first threshold voltage (V thres1); all voltages of the group of cells (203, 213, 223, 233) are less than or equal to the second threshold voltage (V thres2); and the charging current (I charge) is above a predefined minimal current (I min), at least the voltage of one group of cells (203, 213, 223, 233) is less than or equal to the first threshold voltage (V thres1); all voltages of the group of cells (203, 213, 223, 233) are less than or equal to the second threshold voltage (V thres2); and the charging current (I charge) is above a predefined minimal current (I min), charging (401; 701) the battery system, while: (a) at least the voltage of one group of cells (203, 213, 223, 233) is less than or equal to the first threshold voltage (V thres1); (b) all voltages of the group of cells (203, 213, 223, 233) are less than or equal to the second threshold voltage (V thres2); and (c) the charging current (I charge) is above the predefined minimal current (I min); (a) at least the voltage of one group of cells (203, 213, 223, 233) is less than or equal to the first threshold voltage (V thres1); (b) all voltages of the group of cells (203, 213, 223, 233) are less than or equal to the second threshold voltage (V thres2); and (c) the charging current (I charge) is above the predefined minimal current (I min); while electrical loads are shut off (405; 705), measuring (409; 709) the voltage of each group of cells (203, 213, 223, 233); and dissipating energy in at least one of the group of cells (203, 213, 223, 233) of an amount that is represented by a voltage difference (ΔV P-Group(n)) between the individual group of cells and the group of cells with the lowest voltage.