A method and battery charger for charging two or more batteries includes a pulse generator, a detector and a processor communicably coupled to the pulse generator and the detector. A charging series time period, a charging time period and a rest time period are determined based on one or more battery parameters using the processor and the detector. The charging time period is approximately equal to the charging series time period divided by the number of batteries and the rest time period is approximately equal to the charging series time period minus the charging time period. A charging pulse group having a positive pulse for the charging time period and a rest period for the rest time period is generated using the pulse generator, and sequentially applied to each of the batteries. The battery parameters are monitored and the charging pulse group may be adjusted.