The present disclosure relates to a battery charger (100). The battery charger (100) includes a charging circuit (110) which comprises a primary transformer circuit (200) connectable to a power source (120) to receive charging current from the power source (120) and a plurality of secondary transformer circuits (210,220). At least one of the plurality of secondary circuits (210, 220) is arranged to cooperate with the primary transformer circuit (200) to provide a charging voltage to at least one battery (130), and the plurality of secondary transformer circuits (210,220) are connected in series with each other. A first secondary transformer circuit (210) is configured to provide a first charging voltage to the at least one battery (130) by means of a first associated output (10). At least one second secondary transformer circuit (220) is configured to provide an additive charging voltage, which is added to the first charging voltage from the first secondary transformer circuit (210) to form a second charging voltage. The second charging voltage is provided to the at least one battery (130) by means of a second associated output (20).