A charging system that may include a booster unit; a main charging unit that has a charging capability and is configured to use, during a first charging phase, a first part of the charging capacity for charging battery cells by providing a high-C charging current of at least 4 C. The main charging unit is further configured to use a second part of the charging capacity, during the first charging phase, to charge the booster unit. The first part of the charging capacity is limited by a first charging current limitation of the battery cells.