METHOD AND SYSTEM FOR ESTIMATING REMAINING BATTERY PACK ENERGY USING CELL-GROUP STATE OF CHARGE SPREAD

A method for estimating remaining energy in a battery pack having series-connected cells/cell groups includes measuring battery parameters, including a battery voltage, current, and temperature. The controller estimates a static state of charge difference ( ΔSOC) value and a current-dependent ΔSOC value in real-time using the parameters, including calculating the static ΔSOC value as a difference between an average SOC of the battery pack and an SOC of a weakest/lowest energy cell group. The current-dependent ΔSOC value is a percentage SOC per unit of the current. The static ΔSOC value and current-dependent ΔSOC values are filtered via a multi-parameter state estimator block. Using the filtered state values, the controller executes a control action responsive to the estimated remaining energy, including displaying the remaining energy and/or a quantity derived from the remaining energy via a display device. A powertrain system includes the controller, electric machine, and battery pack.