A vehicle is disclosed comprising a battery and a controller. Projected battery impedance parameters are calculated based on predetermined parameter values and historical parameter values generated by a battery parameter estimation model. The values may be weighted according to time data associated with the historical impedance parameter values and a temperature of the battery. Recent historical impedance parameter values may affect the projected battery impedance parameter values more than older historical impedance parameter values. The model is initialized with projected parameter values at vehicle initialization. Battery power capability is calculated using the projected parameter values for a period of time following vehicle initialization. After the period of time following vehicle initialization, battery power capability is calculated using impedance parameters generated by the model. The period of time following vehicle initialization may end when the model output has converged to a stable solution.