A mobile electronic device is described. The mobile electronic device includes a circuit board and a battery. The circuit board has opposing first and second peripheral edges. The first peripheral edge has a first cutout and the second peripheral edge has a second cutout. The battery is located adjacent to the circuit board and has opposing first and second curved end portions. The first curved end portion extends at least partially through the first cutout. The second curved end portion extends at least partially through the second cutout.