Patent ID: 7656131

Claim:
A method of charging a battery pack having a plurality of battery cells, comprising: inserting the battery pack into a charger, performing an initial set of checks of cell voltage and pack temperature, charging the cells at a first substantially constant current level once the initial set of checks are satisfied, adjusting the first constant current level to one or more lower levels of substantially constant current until cell voltages of all the cells are within a full charge voltage window between a minimum full charge cell voltage level and a maximum full charge cell voltage level wherein during the charge, after the initial set of checks are performed, all of the subsequent change levels applied to the cells are substantially constant charge levels and are lower than the immediately proceeding substantially constant current level except if the charge is interrupted, then the substantially constant current level following the interruption is brought to the substantially constant current level immediately before the interruption, and terminating the charge once all cells are within the full charge voltage window.