NOVELTY - The method involves measuring battery characteristics of used battery modules (a, b, c) or unit cells obtained by disassembling used assembled batteries (A, B, C). The battery modules or unit cells are selected based on the characteristics. An absolute acceptable range and a relative acceptable range are used to select the battery modules or unit cells falling within the absolute acceptable range and within the relative acceptable range. An assembled battery (D) i.e. battery pack, is reconstructed using the battery modules or unit cells.    USE - Method for reusing a flat rectangular parallelepiped shaped secondary battery utilized as a power source of an electric vehicle or a hybrid electric vehicle by reconstructing an assembled battery i.e. battery pack, from used battery modules or unit cells selected based on battery characteristics such as open-circuit voltage, internal resistance, remaining capacity, battery temperature of the battery modules or unit cells (all claimed), battery use time, resistance change rate, capacity change rate and battery use intensity of the battery modules. Can also be used for a cylindrical secondary battery.    ADVANTAGE - The method enables reconstructing secondary batteries of the battery modules or unit cells to reconstruct the assembled battery so as to select most suitable battery modules or unit cells, thus improving a rate of reuse of unit cells or battery modules, making the battery characteristics of a rebuilt assembled battery to be uniform and reusing the secondary batteries in an efficient manner. The method enables performing rebuilding of the batteries, so that ratios of numbers of battery modules of different ranks are adjusted to be same, thus eliminating waste of the battery modules and equalizing battery characteristics for battery block for the rebuilt assembled battery, and hence preventing situations in which large variations between battery blocks cause erroneous determination of abnormality.    DETAILED DESCRIPTION - The used assembled batteries are second-generation assembled batteries reconstructed from first-generation assembled batteries, which are originally sold.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view illustrating a method for rebuilding an assembled battery.    Used battery modules (a, b, c)    Used assembled batteries (A, B, C)    Assembled battery (D)