Abstract: A method and system for charging and equalizing battery packs in a battery power system by transferring charge between battery packs. The method involves determining if a battery pack is a candidate for charging, selecting a battery pack to transfer charge from, and transferring charge between the battery packs until an equalizing charge level is accomplished between the battery packs.

Abstract: A steerable vehicle that includes a drive train that is used to propel the vehicle. The steerable vehicle comprises a plurality of auxiliary power units (APUs), an electric motor, and a power controller. The APUs are operatively isolated from the drive train and electrically coupled to the electric motor to provide power to the electric motor. The electric motor is mechanically coupled to the drive train to propel the vehicle. The power controller is communicably coupled to the APUs and to the electric motor. The power controller monitors the status of the components of the vehicle to determine the power requirements of the vehicle. Each APU is associated with an efficiency profile. The power controller utilizes the efficiency profiles to control the APUs and provide power to the electric motor as efficiently as possible.