A battery pack includes a frame member, first and second lithium ion cells, and an isolation plate. The frame member includes a floor, walls formed perpendicular to the floor, and an aperture defined by the walls. The frame member is formed from an electrically non-conductive plastic. The first lithium ion cell includes a first positive terminal, a first negative terminal, and a first electrically conductive housing. The first positive terminal is electrically connected to the first electrically conductive housing. The second lithium ion cell includes a second positive terminal, a second negative terminal, and a second electrically conductive housing. The second positive terminal is electrically connected to the second electrically conductive housing. The isolation plate directly contacts both the first and second electrically conductive housings and electrically isolates the first electrically conductive housing from the second electrically conductive housing. The isolation plate is formed from the electrically non-conductive plastic.