State of health determination: Two pulse load test for a VRLA battery

State of Health (SOH) is an important characteristic in determining the overall profile of a battery. SOH is a measure of the remaining full charge capacity of a battery with respect to its nominal or rated capacity. As a battery ages and is continuously charged and discharged, the chemical composition starts to degrade. Sulphation of the plates starts to occur and the condition of the battery deteriorates which leads to a decrease in capacity. SOH determination can aid in the optimisation of the battery and prevent the battery being over charged and over discharged. This paper describes a novel two-pulse load test to determine the SOH of a Valve Regulated Lead Acid (VRLA) battery. The measurement of the change in battery terminal voltage (ΔV) in the second pulse will alter as the battery ages in relation with the change in the maximum available capacity and this in turn allows the determination of SOH. Experimental validation of this new methodology is described in detail in the paper.