Modeling and Identification of Batteries Parameters Using an Equivalent Electric Circuit

We present a mathematical model that describes the electrical dynamics of a lithium-ion battery associated with its state of charge and its output voltage in open circuit. The proposed model describes this dynamics considering the resistor-capacitor configurations in parallel in the battery. This model is non-linear and it depends only on battery temperature and current. We use the least squares approach to estimate the model parameters considering fits by means of a sixth-order polynomial and an exponential function, which we applied to experimental data published in 2012 and 2016 for ion-lithium batteries. We show the battery voltage as a function of its charge state when we simulate the equivalent electrical circuit of the battery considering a specific profile on current demand. Finally, we show that the proposed model maintains the charginydischarging profile of the battery according to the current demand profile.