A METHOD AND SYSTEM FOR STATE OF CHARGE CALIBRATION FOR AN ELECTRICAL ENERGY STORAGE SYSTEM

The invention relates to a method for performing SOC calibration (SOC) for a electrical energy storage system (2) of an electrified vehicle (1), the method comprising: determining (S102) a predicted time duration needed to complete a SOC calibration, scheduling (S104) a time slot sufficient for completing the SOC-calibration according to the predicted time duration, the scheduled time slot being during a predicted downtime for the electrified vehicle, wherein when at the scheduled time slot: discharging (S106) the electrical energy storage system to a steep part (5) of an open circuit voltage versus SOC curve of the electrical energy storage system by an on-board discharge circuit within an acceptable time duration without connecting the electrical energy storage system to a discharging system external to the vehicle; once at an open circuit voltage with gradient with respect to SOC exceeding a threshold indicative of a steep part of the open circuit voltage versus SOC curve, measuring (S108) an electrical energy storage system voltage to re-calibrate the SOC of the electrical energy storage system.