Re: dynohub chargeing a battery
Just lurking but I will add that a solid state voltage regulator couldn't be that hard to find, or make. Almost every small and large battery charger I've seen, except for very old ones, have a regulator built in that will reduce the charging rate as the battery voltage approaches full charge.. WayneC is correct in that the white wire produces 6 volt AC (alternating current) and that will need to be rectified to DC to charge a battery. As he said, a full bridge rectifier wired in series with the charging circuit will take care of that. I would think a little searching would come up with a small unit that would do both regulate and rectify; probably no bigger than a matchbox.
Radio Shack used to have a project book for hobbiest to build small electronic devices and circuits. I think I have an old copy. If I find anything I'll get back here.
Age and Treachery Will Always Triumph
Over Youth and Skill & "Charlie Don't Ride"