Abstract: Described herein are methods and systems for detecting variation in minor total-impedance contributors in sets of electrochemical cells. For example, a method comprises maintaining a substantially constant current through the set of electrochemical cells and obtaining multiple voltage readings of the cells while the substantially constant current is maintained. The method then proceeds with determining multiple differential capacity values from the multiple voltage readings, characterizing one or more peaks in the multiple differential capacity values, and determining the variation in the minor total-impedance contributor based on one or more peaks. More specifically, partial capacitance values can be assigned to different impedance channels based on these peaks or, more specifically, based on the separation of adjacent peaks.