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

A battery diagnosis apparatus includes a battery monitor to detect a voltage of each of a plurality of battery cells included in a battery module; and a control circuit to determine a latest value of a first voltage deviation indicating a difference between a voltage behavior of each battery cell and an average voltage behavior of the plurality of battery cells over a relaxation period from a start time of a resting event. For each battery cell, the control circuit determines a latest value of a second voltage deviation by applying a smoothing algorithm to the latest value of the first voltage deviation, determines a latest value of a third voltage deviation indicating a difference between the latest value of the first voltage deviation and the latest value of the second voltage deviation, determines a latest value of a fourth voltage deviation indicating a difference between the latest value of the third voltage deviation and a previous value of the third voltage deviation, determines a latest value of a threshold deviation using a distribution of a time series of the fourth voltage deviation having a predetermined size, and determines whether the corresponding battery cell has a micro short circuit by comparing the latest value of the third voltage deviation with the latest value of the threshold deviation..