Electrical Thermal and Degradation Measurements of the LEAF e-plus 62-kWh Battery Pack

The paper provides a detailed description of the 62-kWh battery pack of the Nissan LEAF e-plus. Experimental measurements are collected and analyzed to identify electrical and thermal properties. The parameters identified are open circuit voltage, polarization resistance, diffusion resistances and capacitances. Measurements are carried out for different State-of-Charge and temperatures values. The current interruption method is used to identify the properties of the battery, since it is an effective way to analyze the whole battery pack without disassembling the vehicle. Afterwards, a cooldown analysis is described to identify thermal properties such as thermal capacitance and resistance. The paper is concluded with an early-stage assessment of the degradation of the battery pack after 1.5 years by using on-board readings of State-of-Health, temperature, and State-of-Charge. Stepwise changes in the State-of-Health are observed every 90 days superimposed to the expected degradation trend.