Ok, so now I have a cool bike, a Dahon Speed TR, with a dynamo hub. But my rear-light isn't connected to it, but has to be battery powered. So I still need to carry spare batteries, because they always run out of power when needed most. I'd like to connect a non-battery taillight to my Joule II dynomo hub. I've heard it has been done, but how exactly do I go about it?