Abstract: An internal combustion engine in a hybrid electric vehicle powers an alternator or generator, providing current while the engine's cooling system supplies heat to warm or cool the batteries in a thermostatically controlled manner. Further embodiments utilize heat from the exhaust and catalytic converter to maintain the engine's temperature at an efficient level, and increase the amount of usable heat energy within the system. Organized compartmentalization and insulation of system components controls storage, distribution and release of heat energy during operation and shut-down for increased efficiency and reduced pollutant emissions.