A battery module for an electric vehicle includes an auxiliary power module (APM) and at least one battery pack assembly. The battery pack assembly includes a plurality of battery frames, each with at least one battery cell disposed within it, and a plurality of cooling plates, each in thermal communication with at least one battery cell. The cooling plates have an inlet and an outlet connected by at least one coolant channel through which coolant is circulated to cool the battery cells. The APM may also require cooling, in which case the battery module may further include at least one additional cooling plate in thermal communication with the APM. The APM and the battery pack assembly are held together under compression such that they may share a common cooling system, and coolant may flow through the APM and/or the battery pack assembly to the cooling plates.