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.
Maybe the LED circuitry itself is 1.5v, but dyno powered LED headlights have to be able of taking a wide range of voltages of AC because they are expected to produce reasonably good light at a speed as slow as jogging speed, but they also have to continue to work when you are going down a hill at much higher speeds. Thus, they have internal circuitry to handle that.