Re: DynoHubs: What light bulbs/LED emitters?

Peter Cole wrote:
frkrygow@xxxxxxxxx wrote:

In a bike lighting system, the efficiency of an incandescent bulb -
even a halogen one - is terrible. About 90% of the input energy goes
to heat, rather than light. If your emitter does a lot better than
that, you can afford to feed it through a 75% efficient component.
You'll still come out ahead overall.

All this is true, but the typical bike generators today are designed for incandescents. With a few design changes they would be much better (smaller, lighter, cheaper) for driving LEDs.

It's not just "a few design changes," either. It's a significant change. It's been done (or at least designed). See "http://www.wipo.int/pctdb/en/wo.jsp?wo=2006016397";. Actual production, is far in the future, if ever. It's almost chicken and egg though. Self-powered lighting continues to decrease in popularity around the world because newer battery powered lighting is so much more efficient, yet if there were good (and cheap) DC generators available that could power LEDs properly then self-powered lighting would become more viable.

My ideal bike light would be a sidewall bottle with an integrated/matched 3W LED. Something like that ought to cost $50 and put out 300 lumens.

You won't see a single 3W LED on a dynamo for now for reasons that have already been explained.

But see "http://www.kmc-drrider.com/product_info.php?id=70";

There's another option as well. If you could design a dynamo with a higher frequency output you could design a custom switching regulator that didn't first have to convert the AC to DC. At the current time you're stuck with the losses of rectifying the AC to DC, and the additional losses of a switching regulator (as used in the high end LED lights which is converting the DC to AC internally then back to DC), and as was used in the LightSpin (I believe). Eliminate one conversion and you could boost the efficiency from what's currently around 50%, up to 70-80%.
.

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