Well, the datasheet didn't say, so I hooked it up to a 9v. There was no perceptible difference from 12v. So that's my recommendation, run it off a 9v, either alkaline or rechargeable. If you're dissatisfied with the run time, you can hook up two or three batteries in parallel -- the connectors are three for a dollar, you'll get three. It's still red to red, black to black. Then you just have to figure out how to attach this un-lovely thing to your bike.

For ten bucks you can't do better.