Evaluating the accuracy of electro-thermal coupling model in lithium-ion battery via altering internal resistance acquisition methods

Predicting the heat generation and dissipation characteristics accurately is vital for the lithium-ion battery management system applied in electric vehicles. To achieve such goal, an electro-thermal coupling model is established by measuring the key parameters including the open circuit voltage, entropy coefficient and internal resistance. The internal resistance is further measured by three different methods, namely the constant-current discharge (V-I) method, the difference between the OCV and the cell voltage (OCV-V) method, and the voltage drop during the 30 s intermittent discharge (HPPC) method, which is used as the input of electro-thermal coupling model. The comparatively analysis between the output results from modeling and the testing results of lithium-ion battery, such as discharge curve, temperature distribution diagram and discharged temperature rise curves, shows that HPPC method is the best internal resistance acquisition method as compared with the others.