A battery system capable of inhibiting a reverse voltage applied to a unit cell that has lost the electromotive force without active control is provided. The exhaust muffling device of the present invention comprises a muffler having an expansion chamber whose length is L in an exhaust direction, and an outlet pipe being in communication with the expansion chamber and whose pipe length is approximately 2nL in which n is a natural number. The mass air flow sensor is mounted to sense an air flow caused by movement of the air vehicle. Additionally, the cermet material may be reinforced with fibers or screens. The RESURF region has a comb-like planar shape with repeatedly-formed teeth having tips facing the end portion of the terminal region. Each nozzle has a displaceable actuator arm, a paddle for ejecting ink through an aperture defined in a roof of the nozzle, and a motion-transmitting structure interconnecting the actuator arm and the paddle, the motion-transmitting structure comprising a lever arm formation interposed between effort and load formations.