A battery charging system (15) and method for state controlled charging of a battery (12). The battery charging system comprises two parallel paths (16, 17) for supplying charging current to the battery (12) from two parallel sources of charging current, an energy source (13) and a controlled charging device (14). A control unit (18) is adapted to control the supply of charging current along the two paths in response to a detected state of the battery (12). If a state above a predetermined threshold is detected, the control unit (18) controls the supply of charging current such that the battery (12) receives charging current from the controlled charging device (14), but not directly from the energy source (13). The detected state of the battery may e.g. be a temperature state. The present invention allows for balancing the demands of high charging rate and long expected lifetime of the battery (12).