DEVICE AND METHOD FOR ENABLING SOC CALIBRATION IN AN ELECTRICAL ENERGY STORAGE SYSTEM OF A HYBRID ELECTRIC VEHICLE

A device for enabling SOC estimation of at least one battery cell in an electrical energy storage system of a hybrid electric vehicle. The device initiates charging of the battery cell to a first voltage level. The battery cell is charged by an electric machine powered by a combustion engine. The device detects that the first voltage level is reached, initiates stop of fuel injection to the combustion engine. The device initiates discharging of the at least one battery to a second voltage level. The device detects that the battery cell has been discharged to a second voltage level. SOC estimation of the battery cell is enabled when the second voltage level has been reached.