Originally Posted by
Milton Keynes
Most LED's operate on 1.5V. Running 6V through them without a current limiting resistor runs the risk of burning out the LED. That being said, many LED systems run on 3 to 6V, so my opinion is, it depends on the power requirements of your light.
The question was something other than the one you appear to be answering. He asked if he can power lights designed for a hub dynamo with a bottle dynamo. And you can. Both kinds of dynamos produce a wide range of voltages, so the lights are designed to expect that. Dynamos don't produce a steady 6v. That's just a nominal rating.