Originally Posted by rhm
Thanks for all that!
Have you tested the voltage that wheel gives you? I ask because I built up a pair of wheels for a Moulton Stowaway, ISO 349 rims and the new SA drum brake / dynamo hub. At very moderate speeds (like, maybe 10 mph) it was putting out 15 volts!
What electrical load did you have on it when you measured 15 volts? The load makes a huge difference.
Originally Posted by rhm
I realize your Schmidt hub is built for relatively small wheels, but not THIS small, right? I ran mine through a voltage regulator to give a uniform 12 volts, powering a 12v 5w halogen bulb, and that setup gives me a LOT of light.
What kind of regulator? Do you rectify the current to DC? Years ago I used to use a pair of zener diodes to limit AC current, but nowadays modern generator headlights like the LED Inolight on my Mobiky, or the halogen Schmidt E6 have zener diodes and other circuitry built in. The more usual way to get 12 volt output from a hub generator is to use two 6 volt headlights in series and keep one of them shorted out at low speeds. At low speeds and voltages a single 6 volt light is brighter than two of them and I suspect much brighter than a 12 volt one.
The Schmidt SON20 is intended for 16 to 20 inch wheels. A typical 406mm wheel is actually 18" in diameter. The Mobiky wheels are 12" so the generator and light act as if the bike were going half again as fast - about the same effect as your hub made for full size wheels used with the 349 rim.