A system includes a charger having one or more receptacles for charging one or more removable battery packs, where the charger is capable of being electrically coupled to an electrical bus of a prime mover. The charger is capable of operating in multiple different charging modes. The charger is capable of discharging energy from the removable battery packs to the electrical bus to charge one or more components electrically coupled to the electrical bus and/or drawing energy from the electrical bus to charge one or more of the removable battery packs.