Abstract: Inconsistency is one of the important factors restricting the available capacity of battery packs. The difference in the parameters of the battery pack is an important indicator for describing the performance of the battery pack, and the difference in capacity is causally related to the available capacity and optimized control of the battery pack. A reasonable assumption for simple scaling of the voltage curve when the charging current changes was proposed. Based on this assumption, a fast capacity difference identification method was established. The rationality and adaptability of the method was analyzed and verified in various situations. The incremental capacity analysis method was used to correct the estimation error caused by SOC and internal resistance. This method was applied to battery pack charging data with high voltage sampling accuracy and wide SOC operating range. The basic algorithm error is less than 2.5%, and the identification error can be less than 1.5% after correction. The method proposed in this paper can be used to describe the inconsistency of the battery capacity within the battery pack and provide a reference for the balance and maintenance of the battery pack.