LED Headlight and Generator?

E Willson said:

Is it acceptable to run a 3 watt, 6 volt LED headlight with an ordinary
6v 3 watt generator? Do LED's have different requirements than normal
incandescent bulbs for a bicycle application? I assume that polarity an
issue. What about actual system voltage? Would voltage be different with
an LED compared to a standard bulb?

Most if not all bike generators are actually alternators - they make
AC, not DC, and their voltage is all over the place. You probably need
a rectifier and regulator for the LED.

Brian Huntley said:

E Willson said:

Is it acceptable to run a 3 watt, 6 volt LED headlight with an ordinary
6v 3 watt generator? Do LED's have different requirements than normal
incandescent bulbs for a bicycle application? I assume that polarity an
issue. What about actual system voltage? Would voltage be different with
an LED compared to a standard bulb?

Most if not all bike generators are actually alternators - they make
AC, not DC, and their voltage is all over the place. You probably need
a rectifier and regulator for the LED.

Or you could buy one of the LED lights now being made for generators if
one is not up to the DIY project.

- rick

E Willson <[email hidden]> sd / msg
<[email hidden]> dtd Thu, 13 Oct 2005
07:54:59 -0400:

Quoted message said:

Is it acceptable to run a 3 watt, 6 volt LED headlight with an ordinary
6v 3 watt generator?

Reportedly so, since Busch & Muller sell LED headlights for their
generators now. It would be worth checking that the light is designed
for use with a generator before buying.

Guy
--
May contain traces of irony. Contents liable to settle after posting.
http://www.chapmancentral.co.uk

85% of helmet statistics are made up, 69% of them at CHS, Puget Sound

On 13 Oct 2005 07:15:05 -0700, "Brian Huntley" <[email hidden]>

Quoted message said:

Most if not all bike generators are actually alternators - they make
AC, not DC, and their voltage is all over the place. You probably need
a rectifier and regulator for the LED.

No, they're not alternators, they're dynamos. Dynamos spin a permanent
magnet in a bunch of stationary coils, inducing current in those coild due
to the rotating magnetic field. Alternators do the same thing, but instead
of a permanent magnet they use an *electro*magnet, which means that for
any given rpm you can vary the current through the rotor such that you get
a given amount of power out of the main coils. Cars use alternators. Both
alternators and dynamos are generators, and both will produce AC (in the
case of car alternators, the rectifier bridge is usually included on the
package).

Jasper

I want to thank everyone who participated in this discussion. I'll keep
you posted about how the project turns out.

Thanks again,
EJ in NJ

E Willson said:

Is it acceptable to run a 3 watt, 6 volt LED headlight with an ordinary
6v 3 watt generator? Do LED's have different requirements than normal
incandescent bulbs for a bicycle application? I assume that polarity an
issue. What about actual system voltage? Would voltage be different with
an LED compared to a standard bulb?

TIA,
EJ in NJ