Abstract: A system of charging a battery pack with single charger includes a battery module, a main charging module, and a balance charging module. The battery module has a battery pack, and the battery pack has a plurality of cells in series. The main charging module has a main charger. The balance charging module has a balance charger. All the cells of the battery pack of the battery module are charged at the same time by the main charger of the main charging module. After the charging task of the main charging module is completed, the cells of the battery pack of the battery module are charged in sequence by the balance charger of the balance charging module.