Abstract: A battery pack for easy access to, and uniform cooling/heating of, the individual battery modules thereof. The pack comprises stackable housing parts (i.e., top and bottom) housing multiple tiers of battery modules supported by underlying trays having openings/holes therein aligned with gaps/spaces between adjacent battery modules through which cooling/heating air is uniformly flowed in parallel between the modules from an underlying plenum. The battery modules are compressively immobilized in the housing by resilient foam pads which bear down on the tops of the modules.