A time-domain approach for monitoring battery state of health (SOH) and remaining useful life (RUL)

This paper describes a time-domain approach for estimating the state of health (SOH) and remaining useful life (RUL) of a battery, with particular emphasis on LiFePO₄ cells. In this methodology, a small test signal is superimposed on top of the battery load to trigger its transient dynamics. The resulting terminal voltage and current are measured, and a nonlinear least-squares routine is used to estimate the impedance parameters of the battery model. These parameter values are then used to track the SOH and RUL over time. Experimental results are presented. The approach requires minimal hardware and could be used to form the basis of a robust on-line monitoring system.