Development of a battery real-time state of health diagnosis based on fast impedance measurements

The capability to assess and monitor the state of health (SOH) lithium-based cells is a highly demanded feature for advanced battery management systems. Due existing relation between SOH internal impedance, electrochemical impedance spectroscopy (EIS) methods are adopted diagnosis. Nevertheless, accurate EIS tests demand expensive facilities, long time test procedures, algorithms with high-computational efforts, which makes them almost unsuitable on-board This paper presents new diagnostic method aimed at detecting using fast measurements. Key factor application broadband current signal excitation on battery; here presented, pseudo-random binary sequence (PRBS) adopted. To demonstrate functionalities prototype testbed, several same manufacturer but presenting different SOHs, due their past load history, have been subjected test, acquiring voltage response under imposed excitation. Finally, results processed: key step being clustering measurements (represented in Nyquist diagram) rectangular areas, related actual SOH. performed experimental showed possibility determine frequency points dramatically change cell SOH; as consequence, these peculiar frequencies can be reference cluster separation. According proposed sufficiently promising solution real-time