US Patent 9065280 System and method of using high energy battery packs

An energy storage system having one or more battery packs and a system controller for controlling the battery packs. Each battery pack has rechargeable storage cells and a battery pack controller in communication with the system controller. Through the operation of the system controller, battery packs with different initial charge states can be operated in parallel during a charge process and a discharge process. Discharging multiple battery packs in parallel offers not only a higher capacity and a longer run time than is available from a single battery pack, but also offers higher peak currents than available from a single battery pack, which are important in motor control applications. A battery pack design including a battery pack connector with both power and control contacts supporting user replacement of the battery packs.