A multi-stage quick charging system is proposed. The system uses an intermediate power battery as voltage supporting point so that a converter having a fraction of the output voltage may control the entire power flow towards or from the battery of a vehicle or an electrical power device. The intermediate battery comprises several stages in series, associated with respective small chargers allowing a management of the charge balancing of the stages of the intermediate battery, since the chargers may be controlled in order to separately vary the contribution of each stage.