Patent ID: 8598847

Claim:
A method for balancing voltage for a multi-cell battery system, the battery system including at least two parallel groups of cells connected in series and the parallel group of cells including at least one cell, comprising: charging the battery system by keeping a voltage of all parallel groups of cells less than or equal to a second threshold voltage while: (a) at least the voltage of one group of parallel cells is less than or equal to a first threshold voltage; (b) all voltages of the group of parallel cells are less than or equal to a second threshold voltage; and (c) a charging current is above a predefined minimal current; while electrical loads are shut off, measuring the voltage of each parallel group of cells; and dissipating energy in at least one of the parallel group of cells of an amount that is represented by a voltage difference between the individual parallel group of cells and the parallel group of cells with the lowest voltage.