From Cell to Batteries Pack Monitoring State-of-Charge for Electric Buses Technologies

The battery's state-of-charge (SOC) is an important aspect in battery management systems since it is considered as the battery's energy gauge and the image of the battery's voltage and its open circuit voltage (OCV). This latter is widely used for characterizing battery's properties under different conditions such as temperature. This paper proposes a SOC calculation method based on an OCV model for a cell and a pack in electric buses technologies. To verify the proposed model, a Lithium iron phosphate battery is characterized under three different operating temperatures. Experimental results highlight the high estimation accuracy of the proposed model in various operating conditions.