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.