Thermal management system for rechargeable batteries

A thermal management system for a rechargeable battery comprising:

• a metal case having an exterior surface and an interior surface lined with an electrically insulating material;
• a cell pack made from individual battery cells arranged within end frames and disposed in said metal case on isolation mounts which support and space the cell packs from the interior surface;
• and
• a thermally conductive granular filler in the form of free-flowing granules introduced into the free spaces within the battery to occupy the interstices between said individual cells and occupy the space between the cell pack and the electrically insulating material lining, wherein said thermally conductive filler decreases the thermal impedance from the cell pack to the exterior surface of the metal case to reduce cell pack temperature and increase battery life.