I have a Sears part number 139.53879 garage door opener remote. I want to hardwire it to a button on my motorcycle so that the original remote is hidden but I have access to the button so that I can open my garage door. My problem is that the batteries in the remote would need to be replaced periodically so I'd like to wire it into the bike's 12v system somehow. The batteries in the remote are two 3v button batteries so I'm assuming it's a 6v remote. What's the simplest way to do this? I'm sure the remote dosen't pull any amps to speak of and would only be operated for seconds at a time while trying to open the door. Would 12v from the bike's battery kill this remote?

 

Odds are good that it may be damaged by the excess voltage. Your motorcycle's electrical system isn't just 12v either; it may be as high as 14v when the battery is low.

You could use a LM7806 3-terminal voltage regulator to step the voltage down. It only has three connections; input, output and ground. You should also use a small capacitor on the output of the regulator to help keep the output stable.