Abstract: A battery pack includes a cell holder to which a plurality of battery cells are assembled and a bus bar assembly including a bus bar electrically connecting the plurality of battery cells to each other, and a protrusion protruding from the bus bar to at least a portion of a thickness of the cell holder. The plurality of battery cells are arranged on a first side of the cell holder, and the bus bar assembly is located on a second side of the cell holder opposite the first side of the cell holder. The cell holder integrated with the bus bars, which are firmly fixed at appropriate positions on the cell holder, may be provided through insert injection molding.

Abstract: A battery pack includes a spacer. The spacer for the battery pack can be used by being cut according to the number of batteries received in the battery pack, and can thus be applied to multiple battery packs in which different numbers of batteries are received, and can be easily separated manually. In one type of spacer, a first plurality of concave battery receiving parts corresponding to portions of outer surfaces of the cylindrical batteries are formed on a first surface of a rectangular frame, and cutting grooves are formed in the respective battery receiving parts in a direction corresponding to the center axes of the cylindrical batteries to facilitate cutting of the spacer.