SECONDARY BATTERIES – LEAD– ACID SYSTEMS | State-of-Charge/Health

Abstract

This article deals with two important figures of merit (state-of-charge (SoC) and state-of-health (SoH)). that describe the state of lead–acid batteries (LABs). The SoC is generally defined as an available amount of charge in a given battery related to the full amount of charge, which can be stored in this battery and is usually expressed as a percentage. The SoH describes a degree of degradation of the battery (mainly capacity loss). Since ‘actually available amount of charge’, ‘total amount of charge’, and ‘degree of degradation’ can be defined in different ways, these definitions of SoC and SoH are not very clear. The first part of the article discusses more precise definitions of the figures of merit for LABs. The second part presents possible methods for measuring SoC and SoH in the laboratory as well as their determination in field applications under real-world conditions.