Estimating the Internal Resistance of Li-Ion Battery with Joule's Law to find the Open Circuit Voltage

This paper explores the electrical equivalent model of a Li-Ion battery and its resistance estimation. The energy loss in the battery in one cycle of charging and discharging is used to calculate the internal resistance of the battery by application of Joule's Law of Heating. The potential drop across the resistance thus obtained is compounded with the measured terminal voltage to predict the Open Circuit Voltage (OCV) of the battery. The tabulated OCV and State of Charge (SoC) values are fed into a Deep Neural Network model in MATLAB/Simulink to establish a relationship between the SOC and OCV. Further a Simulink model was developed to verify the accuracy of the Neural Network. The results obtained through the simulation closely follow the estimated OCV values.