Patent ID: 7660694

Claim:
A method of estimating en initial value for an internal temperature of a vehicle battery using a program controlled engine control unit and a program controlled automatic calibration tool, the method comprising: using the engine control unit to determine which of a predetermined set of time zones correlates with a measured period of time for an engine of the vehicle being in an engine-off condition, wherein the time zones are categorized as four different possible time zones comprising a holding time zone, a model based estimation time zone which is greater in time than the holding time zone, a first self-adjustment time zone which is greater in time than the model based estimation time zone, and a second self-adjustment time zone which is greater in time than the first self-adjustment time zone; using the automatic calibration tool to generate a set of parameters correlated with the determined time zone; and using the engine control unit to determine an initial estimated value of the internal temperature of the battery as a function of the set of parameters.