A novel two-steps method for estimation of the capacity imbalance among in-pack cells

•A two steps strategy for capacity imbalance estimation is proposed.•The rough estimation result turns out to be smaller or equal to the true SOD.•The precise estimation error can be hold within 1% for the pack in service.•Rough and precise estimations are combined to ensure accuracy and simplification.•A novel alarm function against capacity imbalance is established.