Online Adaptive Data-driven State-of-health Estimation for Second-life Batteries with BIBO Stability Guarantees

A key challenge that is currently hindering the widespread deployment and use of retired electric vehicle (EV) batteries for second-life (SL) applications is the ability to accurately estimate and monitor their state of health (SOH). Second-life battery systems can be sourced from different battery packs with a lack of knowledge of their historical usage. To facilitate the on-the-field use of SL batteries, this paper introduces an online adaptive health estimation strategy with guaranteed stability. This method relies exclusively on operational data that can be accessed in real-time from SL batteries. The adaptation algorithm is designed to ensure bounded-input-bounded-output (BIBO) stability. The effectiveness of the proposed approach is shown on a laboratory-aged experimental data set of retired EV batteries. The estimator gains are dynamically adapted to accommodate the distinct characteristics of each individual cell, making it a promising candidate for future SL battery management systems (BMS2).