A system includes a sensing module and a switching module. The sensing module is configured to sense output voltages of first and second cells connected in series in a rechargeable battery stack. The switching module is configured to alternately connect a capacitance across the first cell and the second cell at a switching frequency when a difference in the output voltages is greater than or equal to a first threshold. The switching module is further configured to stop alternately connecting the capacitance when the difference is less than or equal to a second threshold, wherein the first threshold is greater than the second threshold.