NOVELTY - Cells temperature within battery module (10) is managed by directing gas past a gas temperature modifying device (220), and directing the gas into inlet (76) of battery module such that the gas flows the cells (211-214) to modify the cells temperature. The gas enters the inlet at a temperature during a one period and at another different temperature during another period. The temperature difference between the two groups of cells furthest from the inlet is less than it would be if the gas were provided into the battery module at constant temperature.    USE - Method for managing cells temperature within battery module for use in vehicles.    ADVANTAGE - The method utilizes a system that efficiently and effectively cools and/or heats battery cells used in the module.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a method for controlling the temperature of cells in battery module, comprising thermally conditioning a gas using thermal management device, forming the gas over the cells using a fan (230), and changing the speed of the fan at predetermined intervals and by predetermined amounts to change the temperature of the gas. The gas temperature modifying device turns on and off at scheduled intervals, cycles between two temperatures; and can be heater or cooling device. The temperature of the gas provided to the inlet is less or greater than ambient temperature when the device is turned on. The fan speed is continuously changed in smooth or stepped fashion. The fan speed is changed such that the temperature of the thermally conditioned air is changed approximately 5 degrees C every 40 minutes. The temperature of the thermal management device and the fan speed are controlled simultaneously to reduce the variation in temperature between individual cells.    DESCRIPTION OF DRAWING(S) - The drawing shows a perspective view of the battery module including a fan and thermal management device.    Battery module (10)    Inlet (76)    Cells (211-214)    Gas temperature modifying device (220)    Fan (230)