I use hearing aid batteries in older 60s and 70s vintage bodies, the voltage is closer to old mercury batteries. With a couple of bodies, Petri, I use an adaptor, others 675, like the Miranda EE, 675 fit well. With the camera turned off, maybe a couple of months, in most cases what I do is remove the battery and put the sticky tab back over the side the air vent, batteries last a up to 6 months. In terms of air vents, I had to drill a vent through the back of the metal batter compartment cover on my EE it was so well sealed that the zink air stopped working in a few hours.