AC batteries, LOL. Some of those wall-worts are just transformers that do put out AC. I designed avionics hardware for about 40 years. One of the most fun projects I did was a cockpit audio mixer for regional jets. Lots of equipment (radios, sitcom, nav equipment, etc) put out aural alerts and they need prioritization and mixing. Ground proximity warning takes precedence over collisions and they both take priority over windshear alerts. If you get all three simultaneously, well you booked a bad flight. Many electrical engineers happen to be musicians. Makes sense since music is math....sort of. One company I worked for was called ROCK-WELL. Didn't wanna let them down.