Development of a state of charge algorithm for batteries based on lithium chemistry

Abstract

The purpose of this report is to describe the development process of a State of Charge algorithm for low voltage battery packs built in a configuration of up to 16 cells series. The aim of this project is to obtain a good understanding on the dynamics of a lithium-based cell and with it develop a State of Charge algorithm that will be built in several battery management ICs for the company MPS. The algorithm will be coded in C to easily use it on MCU for evaluation and testing and also to easily build it in the final ICs. This project also details the battery pack testing and cell characterization automations, controlled with LabView software; the Evaluation Board that has been designed using the Altium Designer software, to act as BMS for protection and for testing the algorithm in a real system; and the simulation environment developed with Python and Docker to test the algorithm and tune it based on tests recorded with the battery testing automation. The result of this project is a robust and reliable State of Charge algorithm with less than 3% of error even for high current applications.