It consists of three phases (or stages), to be executed by a battery charger. Battery packs can replaced or upgraded while keeping the existing battery charger. The batteries and battery charger are air-cooled. A smart battery pack must be charged by a smart battery charger. Microchip Technology provides an application note for a smart battery charger based on the PIC16C73. The F2H set included the Nikon MH-100 battery charger. When purchased the basic system includes the platform, the control unit, and battery charger. Additional handsets have a battery charger station that does not plug into the telephone system. The battery charger was discontinued on January 15, 2016. A battery charger can work as a DC power adapter for experimentation. The battery charger can be on-board or external to the vehicle. The Apple Battery Charger is a battery charger formerly made by Apple Inc. Adapters for battery-powered equipment may be described as chargers or rechargers (see also battery charger).