A charger including a first battery pack interface that receives a first battery pack, a second battery pack interface that receives a second battery pack, the second battery pack interface being different than the first battery pack interface, and a primary driver circuit for receiving power from an external power supply, the primary driver circuit including a primary winding. The charger further includes a first secondary winding connected to the first battery pack interface for receiving power from the primary winding and generating a first nominal charging voltage for supply to the first battery pack when the first battery pack is received. The charger further includes a second secondary winding connected to the second battery pack interface for receiving power from the primary winding and generating a second nominal charging voltage for supply to the second battery pack when the second battery pack is received.