Patent ID: 7550949

Claim:
A process for controlling temperature of a battery pack having unit cells, comprising the steps of: operating a fan to change a battery temperature to an optimal range of temperature (T opt ) when a condition is satisfied that the battery temperature is equal to or greater than a maximum acceptable temperature (T max ) or when the battery temperature is equal to or less than a minimum acceptable temperature (T min ) and, at the same time, when the difference between a battery temperature (T bat ) and an air temperature (T air ) of air is equal to or greater than a critical temperature (T crt ); operating the fan to change the battery temperature to a temperature within an optimal range of temperature variation (T opt1 ) between each unit cell when the battery temperature does not satisfy the condition, and when a temperature variation (T var ) between each unit cell is equal to or greater than a predetermined critical temperature (T crt1 ); when the air temperature (T air ) of the air is too high, mixing or replacing the air with air supplied from an additional cooling unit; and when the air temperature (T air ) of the air is too low, mixing or replacing the air with air supplied from an additional heating unit.