Abstract: Various embodiments of battery pack assemblies are described. In at least one embodiment, a battery pack assembly includes first and second cell carriers. At least one of the carriers is a retaining cell carrier, has a plurality of upstanding walls extending from a bottom wall thereof and defines a matrix of recesses. At least one of the carriers is a perforated cell carrier and has a wall with a plurality of openings. Battery cells, each having a plurality of cell terminals, are retained within the matrix of recesses and at least a subset of the plurality of cell terminals extend through the openings of the wall of the perforated cell carrier. Electrically conductive interconnecting members are electrically coupled to at least two of the cell terminals of the battery cells that extend through the openings of the perforated cell carrier to provide an electrical interconnection therebetween.