BATTERY DIAGNOSING APPARATUS, BATTERY DIAGNOSING METHOD, BATTERY PACK AND ELECTRIC VEHICLE

Disclosed is a battery diagnosing apparatus for a cell group, which includes a plurality of battery cells connected in series and is mounted in an electric vehicle, and the battery diagnosing apparatus includes a voltage sensing circuit configured to periodically generate a voltage signal representing a cell voltage of each battery cell while the electric vehicle is operating; and a control circuit configured to accumulatively store the cell voltage determined from the voltage signal in a memory unit and generate time series data representing the change over time in the cell voltage of each battery cell by using the accumulated cell voltage of each battery cell. The control circuit is configured to (i) determine a first average cell voltage and a second average cell voltage of each battery cell based on the time series data [where the first average cell voltage is a short-term movement average, and the second average cell voltage is a long-term movement average], and (ii) detect a voltage abnormality of each battery cell based on the difference between the first average cell voltage and the second average cell voltage.