Using transient electrical measurements for real-time monitoring of battery state-of-charge and state-of-health

This paper describes a transient-based approach for estimating the state-of-charge (SOC) and state-of-health (SOH) of a lithium-ion battery. 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 non-linear least-squares routine is used to estimate the impedance parameters of the battery model. These parameter values are then passed to an H_∞ filter that estimates the open-circuit voltage while the battery is under load. Experimental results are presented. The approach requires minimal hardware and could be used to form the basis of a robust on-line monitoring system.