I've asked this elsewhere and gotten no answers:
My '96 Ford Ranger has one of those remote unlock doohickeys. It still works flawlessly after 12 years. I assume it's infrared, but what provides the power?

There is a battery inside the remote unit.

There is a battery inside the remote unit.

What kind of battery lasts 12 years?

A very good one :D. They do not draw a lot of power and it's not as if one keeps the button pushed all day long.

no your both wrong its fairies that live inside the key fob and provide a magical power!!

only jokin it will be a battery and some recharge themselves using the cars power when the key is in the ignition meaning they can last for ages!!!