Originally Posted by
Juha
First off, I'm not sure the 2nd "auxiliary lead" actually puts out any current. Are you sure it's not a ground/earth wire? B&M products are built to the German specs for dynohub/lights, and when you use both front light and rear light, there's no extra power output left from the dynohub. I wonder why they'd put an extra wire there.
I think there is a B&M light that has USB output capability. Don't know about the Topal. I am trying to find where I saw that, probably Peter White site.
** EDIT ** It's the Luxos U model with the USB output:
http://www.peterwhitecycles.com/b&m-hl.asp
BTW, and to the OP's questions, I am able to run B&M head and tail lights off my Dynamo hub, AND charge my Biologic Reecharge battery pack at the same time. The wire pairs from the headlight and the Biologic charging device ($100) are simply twisted together before plugging into the dynamo.