Operating limits of battery charge controllers

Abstract

The present work aims to show the limits when managing the state of charge (SOC) of different types of batterie. Charge control appear the most important techniques that ensure safety and a good health of batteries. The majority of charge controllers try to optimise the charging process. However, they can t prevent perfectly the fall phenomenon like sulfation. These charge controllers assume that identical cells compose the battery. Or a slight difference between cells capacities leads to a difference between their SOC. Hence, the risk of having some cells very well charged while others aren t. This phenomenon decreases significantly the battery capacity. For this purpose, we realised a data acquisition system to supervise the cell SOC. The experimental results show that controlling the SOC of the whole battery by making external measurements isn t sufficient, and a control of each cell is necessary to estimate correctly the global performance of the battery.