EKF STATE RELAY STRATEGY IN BATTERY ONLINE IDENTIFICATION

A vehicle includes a battery and a controller. The controller is programmed to executed a parameter estimation strategy for the battery during time intervals when the current flowing through the battery is sufficiently dynamic. During periods of generally constant current, the parameters are derived from the last valid parameters from the parameter estimation strategy. During periods of generally constant current in which a battery temperature and/or a state of charge of the battery changes by a predetermined amount, the parameters are derived from historical parameter values.