Implementation of an Improved Coulomb-Counting Algorithm Based on a Piecewise SOC-OCV Relationship for SOC Estimation of Li-IonBattery

Considering the expanding use of embedded devices equipped with rechargeable batteries, especially Li-ion batteries that have higher power and energy density, the battery management system is becoming increasingly important. In fact, the estimation accuracy of the amount of the remaining charges is critical as it affects the device operational autonomy. Therefore, the battery State-Of-Charge (SOC) is defined to indicate its estimated available charge. In this paper, a solution is proposed for Li-ion battery SOC estimation based on an enhanced Coulomb-counting algorithm to be implemented for multimedia applications. However, the Coulomb-counting algorithm suffers from cumulative errors due to the initial SOC and the errors of measurements uncertainties, therefore to overcome these limitations, we use the Open-Circuit Voltage (OCV), thus having a piecewise linear SOC-OCV relationship and performing periodic re-calibration of the battery capacity. This solution is implemented and validated on a hardware platform based on the PIC18F MCU family. The measured results are correlated with the theoretical ones; they have shown a reliable estimation since accuracy is less than 2%.