Abstract: Now a days, lithium-ion batteries are the most used to power electronic devices and electric vehicles. Lithium-based electrochemical accumulators have better energy density and reliability than any other energy storage method. To use a battery effectively, it is necessary to understand its operation, its dynamics and to know the parameters that can affect its performance. In this study, we propose a model of a lithium-ion battery, the parameters of this model are identified by a Levenberg-Marquardt nonlinear algorithm. The parameter output is a lookup-table of element values that depends on the state of charge of the battery. A pulses discharge test is performed on a commercial 16 Ah lithium-ion battery in order to identify the parameters and validate the model, results are presented and validated.