BATTERY MANAGEMENT SYSTEM AND METHOD

A battery management system for determining a time series of normalised voltage of at least one battery cell corresponding to a time period during which a first current flows through the at least one battery cell. The battery management system comprises a cell monitoring device configured to measure a current flowing through the at least one battery cell and a voltage of the at least one battery cell at a plurality of different times during the time period; and a controller configured to determine a normalised voltage of the at least one battery cell for each of the plurality of different times, in dependence on the measured current and measured voltage corresponding to that time, wherein the determined normalised voltages at the plurality of different times form a times series of normalised voltage, wherein the normalised voltage at each of the plurality of different times corresponds to an estimate of a voltage of the at least one battery cell if a second constant current were flowing through the battery cell throughout the time period, where the second constant current is different to the first current.