@kevin AAAA is also a battery believe it or not.

They aren't used in a lot of consumer electronics, but you'll find them hidden inside a few things, often soldered in. I've seen a few mini remotes for various devices (not TV remotes) that used them though. Also, these days manufacturers are so cheap that you'll also find them in most 9V batteries. They literally just wrap up six metal cased batteries with another metal case so you can't tell.