A battery pack including a housing having a first housing portion and a second housing portion. The first housing portion is secured to the second housing portion and defines an interface for receiving a power tool. The battery pack also includes a frame received within the second housing portion, the frame including opening to secure a plurality of battery cells. The battery pack further includes a pair of battery cells of the plurality of battery cells stacked vertically in each of the openings. A wedge is positioned in each of the openings between the pair of battery cells. The battery pack also includes a printed circuit board positioned between the frame and the first housing portion.