Charging method for battery packs

The method involves passing an effective charging current through each of at least 2 cells connected in series for a charging period in a charging cycle and passing a lower refresh current in an at least occasionally following refresh cycle. The refresh cycle follows a number of charging cycles after a period. The number of charging cycles and optionally a flag for complete last refresh cycle termination is stored in a memory in the battery pack. The method involves passing an effective charging current through each of at least two cells connected in series for a charging period in a charging cycle (1) and passing a lower refresh current in an at least occasionally following refresh charging cycle (2). The refresh cycle follows a number (M) of charging cycles after a period (K). The number of charging cycles and optionally a flag (F) for complete termination of the last refresh cycle is stored in a memory in the battery pack