Impact of Cell Replacement on the State-of-Health for Parallel Li-Ion Battery Pack

This paper addresses the effect of replacing damaged cells in a battery pack on the total State-of-Health (SoH) using a new technique in where the SoH of a Li-Ion battery pack is accurately determined. The new method is based on relating the parameters of a single-cell battery to determine the SoH in a multi-cell battery pack of the same type. This technique is applicable to the battery pack as it uses the battery pack impulse response to estimate the impact of replacing damaged cells on the battery pack. The time-consuming and expensive standard SoH measurement process can be avoided by this new method. The reference SoH function of the single cell can accurately and quickly estimate the SoH of the individual cells within the battery pack in order to identify the damaged ones. The obtained results have shown possible improvement in the SoH for the nonreplaced cells as well as the improvement in the life of the whole battery pack.