State-of-health monitoring of lithium-ion battery modules and packs via incremental capacity peak tracking

•A new framework based on ICA is used to monitor SOH on-board for battery packs.•The applicability of the framework is validated through simulation and experiment.•The method can monitor SOH for pack consisting of cells with various aging paths.•On-board incremental capacity analysis is realized by support vector regression. Incremental capacity analysis (ICA) is a widely used technique for lithium-ion battery state-of-health (SOH) evaluation. The effectiveness and robustness of ICA for single cell diagnostics have been reported in many published work. In this study, we extend the ICA based SOH monitoring approach from single cells to battery modules, which consist of battery cells with various aging conditions. In order to achieve on-board implementation, an IC peak tracking approach based on the ICA principles is proposed. Analytical, numerical and experimental results are presented to demonstrate the utility of the IC peak tracking framework on multi-cell battery SOH monitoring and the effects of cell non-uniformity on the proposed method. Results show that the methods developed for single cell capacity estimation can also be used for a module or pack that has parallel-connected cells.