BATTERY PACK WITH FLEXIBLE BUSBAR FRAME JOINT

A battery pack assembly includes a cell stack assembly including a plurality of battery cells disposed along a cell stack axis. A busbar frame is joined to the cell stack assembly. The busbar frame includes at least one relief notch that accommodates movement of the cell stack assembly relative to the frame. At least one joint can connect the busbar frame to the endplate. The at least one relief notch can be configured to accommodate movement of the at least one joint when the endplate is moved axially relative to the busbar frame.