A battery charger and method for a rechargeable battery pack which includes various elements in series with the cells to be charged, including but not limited to current control FETs, a fuse, current sense resistor, and internal series impedance of the series connected cells to be charged. The charging current Ichg flowing through these series elements reduces the voltage applied to the cells, thus lengthening charging time. A compensation voltage Vcomp, which when added to the nominal charging voltage for the series connected cells overcomes these voltage drops, facilitates more efficient charging while avoiding over-voltage damage to the cells. Three voltages representing substantially all of the voltage drops reducing the charging voltage on the cells, are summed, and the result is a compensation voltage which is utilized to change the nominal charge voltage for the battery to overcome these voltage drops.