Study of the Temperature and Aging Impact on an Enhanced Coulomb Counting Method for Estimating SOC of Lead-Acid Batteries.

Abstract

Lead-acid batteries are widely used in power wheelchairs due to their safe and reliable operation. To ensure optimal performance, longevity, and reliability, Battery Monitoring Systems (BMS) play a critical role in monitoring and controlling the charging and discharging of the batteries. State-Of-charge (SOC) estimation is the most crucial part of the BMS, as it enables the BMS to accurately track the battery's capacity and prevent overcharging or over-discharging of the batteries. As batteries age, factors like electrode degradation and electrolyte breakdown decrease capacity, leading to aged batteries being unable to provide as much charge as new ones even when fully charged. Temperature also plays a significant role in altering batteries' characteristics, affecting performance and capacity. Temperature variation can affect the rate of chemical reactions within the battery, cause it to age more rapidly, and affect its ability to hold a charge. This empirical study focuses on investigating the impact of temperature and aging on the Enhanced Coulomb Counting (ECC) method used to determine the SOC of sealed lead-acid batteries used in power wheelchairs. Considering temperature changes, the proposed method shows a very accurate SOC estimation for both aged and new batteries. In particular, the SOC estimation is significantly more precise for aged batteries, achieving about 32% improvement in accuracy.