Diagnosis of the aging mechanism of lead-acid batteries using an empirical equation

Abstract

The growing use of batteries in vehicles, energy storage and distribution systems has led to an intensive research of the estimation of their states of charge and of health, which are fundamental parameters for their safe and reliable use. As systems that exhibit nonlinear behavior and are subject to irregular operation conditions including charge and discharge, many methods and models of these systems have been proposed to improve their estimation. In addition, the identification of the degradation mechanisms of the active material, which lead to the aging of batteries, is an additional challenge and this diagnosis can be used to increase its life cycle and decrease its maintenance costs. In this work, we employ an electrochemical model for simulating the discharge of lead-acid battery cells in different aging stages and with different degradation mechanisms, and we present an empirical equation that models the behavior of the capacity of these cells with the discharge current. Therefore, it can be employed to estimate their states of charge and of health. In addition, it is shown that the analysis of the parameters of this equation reveals the cell's aging mechanism, being a potential diagnosis tool.