Patent ID: 7638980

Claim:
Method to determine an effect of temperature during a period of vehicle inactivity on life expectancy of an electrical energy storage device operative to exchange electrical energy with a hybrid vehicular powertrain including first and second electric machines each machine operable to impart torque to a two-mode, compound-split electro-mechanical transmission having four fixed gear ratios and two continuously variable operating modes, comprising: determining a weighted average temperature of the electrical energy storage device during the period of inactivity based upon an average temperature of the electrical energy storage device during the period of inactivity and a temperature of the electrical energy storage device substantially contemporaneous with a vehicle shut-down; determining a resting temperature factor for the electrical energy storage device based upon the weighted average temperature of the electrical energy storage device during the period of inactivity; and determining a life expectancy for the electrical energy storage device based on the resting temperature factor.