An EV-Scale Demonstration of In-Situ Battery Electrochemical Impedance Spectroscopy and BMS-Limited Pack Performance Analysis

State-of-power (SOP) and state-of-charge (SOC) estimation inaccuracy manifests throughout the electric vehicle (EV) battery lifetime due to the nonlinear degradation trajectory that is unique to each use-case. The inaccuracy leads to premature termination of charge and discharge operations, which results in the virtual loss of battery performance. In-situ electrochemical impedance spectroscopy (EIS) has been proposed to provide real-time battery impedance measurements, which can theoretically improve the SOP/SOC estimation accuracy. In this work, an EV-scale in-situ EIS system is demonstrated experimentally, from impedance measurement to equivalent circuit model (ECM) extraction. The pack-level discharge energy versus SOP/SOC estimation errors is also simulated, which quantifies the virtual loss of battery performance. The measured-impedance error tolerance of three common ECM extraction techniques is then examined through a randomized set of simulated EIS tests with injected measurement noise. Finally, in-situ impedance measurement is performed on 20 battery submodules using an electric pickup truck EIS system. The ECM-predicted voltage output is compared against measured driving data. Experimental results indicate approximately 8%–9% improvement in SOP estimation accuracy at 3$^{\circ }$C and 10$^{\circ }$C between the in-situ extracted models and a representative baseline.