Battery Pack Inspection Method and Inspection Device

An inspection device of a battery pack, the battery pack comprising a plurality of cell groups connected in series, each of the cell groups comprising a plurality of chargeable/dischargeable cells connected in parallel, the battery pack further comprising a battery controller built therein to monitor voltages of the respective cell groups, the inspection device comprising:

• an inspection unit connected to the cells of the battery pack through a charging line and connected to the battery controller of the battery pack through a signal line;
• and
• a charging unit connected to a commercial power supply and configured to charge the battery pack at a constant current through the inspection unit,
• wherein the inspection unit is configured to:
• cause the charging unit to perform charging of the battery pack at a constant current;
• retrieve, from the battery controller, voltages of the respective cell groups at an early stage of start of the charging as first cell voltages;
• retrieve, from the battery controller, voltages of the respective cell groups at a stage where the charging proceeds to a predetermined level as second cell voltages;
• determine a first deviation value by comparing each of the first cell voltages of the cell groups with an average value of the first cell voltages of the cell groups;
• determine a second deviation value by comparing each of the second cell voltages of the cell groups with an average value of the second cell voltages of the cell groups;
• and
• judge, based on the first and second deviation values, any one of the cell groups as a group cell having a series connection anomaly when the first and second deviation values of the cell group are greater than predetermined values, and the first and second deviation values of the cell group are equal in level.