Implementation of an improved Coulomb-Counting Algorithm Based on a Piecewise SOC-OCV Relationship for SOC Estimation of Li-Ion Battery

Abstract

Considering the expanding use of mobile devices equipped with rechargeable batteries, especially Li-ion batteries that have higher power and energy density, the battery management function becomes increasingly important. In fact, the accuracy of the amount of remaining charges estimation is critical as it affects the device autonomy. Therefore, the battery State-Of-Charge (SOC) is defined to indicate its estimated available capacity. In this paper, a method for Li-ion battery SOC estimation based on an enhanced Coulomb-counting is proposed to be implemented for multimedia applications. Assuming that Coulomb-counting suffers from cumulative errors due to the initial SOC and the measurements uncertainties errors, we used a piece-wise linear SOC-OCV relationship and periodic re-calibration to overcome these limitations. This solution has been implemented and validated on a hardware platform based on PIC18F MCU Family. The measurement results were correlated with theoretical ones and the method has shown a reliable estimation since accuracy is less than 2%.