In this document, a powerful approach is presented to model the performance of Li-ion batteries, specifically designed for battery electric vehicles and hybrid electric vehicles. The chosen model is a second-order equivalent electrical circuit that includes an open-circuit voltage source OCV, a resistor Rint, and two parallel RC circuits. This model, called dual polarization (DP), presents the best choice for tolerable levels of precision and intricacy. The model elements depend on the value of the state of charge SOC. To ascertain the model parameters, short-duration current pulse measurements are conducted during discharge at various state of charge levels. The SOC and model components were correlated using the least squares approach. Discharge tests of the lithium-ion cell were used to calculate the Rint, Rl, Cl, Rs, and Cs values. Once the different parameters of the model have been identified, the validation of this established battery model is carried out by comparing the results obtained from the model to the experimental discharge test.