Abstract: A method of charging a battery pack is provided. The method includes: providing a charger comprising a battery interface, a set of terminals, and a power supply circuit for providing a charging current scheme; providing a set of battery packs, each battery of the set of battery packs comprising a charger interface having a physical configuration to mate with the battery interface and a set of terminals having a physical configuration to mate with the set of charger terminals; and providing a charging scheme defined by a relationship between the set of battery terminals and the set of charger terminals.

Abstract: A battery charger for charging a first battery pack and a second battery pack is disclosed. The charger includes a housing, a first and second charging circuit positioned within the housing, a first and second charging port coupled to the housing and electrically coupled the first and second charging circuits, respectively. The first charging port is configured to support the first battery pack and defines a first connection axis along which the first battery pack is movable to connect with the first charging circuit. The second charging port is configured to support the second battery pack and defines a second connection axis along which the second battery pack is movable to connect with the second charging circuit. The second charging port is configured to support the second battery pack while the first charging port supports the first battery pack.