Abstract: According to the dynamic operating conditions of traction batteries,an equivalent circuit model is selected to simulate electro-chemical characteristics of the battery.A pulse current test method is proposed to derive the internal parameters.Data analysis results indicate that these parameters vary with the state of charge.According to these disciplines,the dynamic working range of batteries can be chosen for the high energy transfer efficiency.Also these parameters can provide the calibration for the on-board state of charge and state of health identification with Kalman filter techniques.