Coming to a bike light near you?

Tim Forcer · Oct 3, 2006

Latest white LED sensation produces 131 lumens/W - which is way above
even fluorescent efficicacy.

<http://www.cree.com/press/press_detail.asp?i=1150834953712>

This company is talking (OK, its PR office is talking) about car
headlights as an application. So 2*AA superbright bike lights should
be a doddle - particularly as the higher efficiency should mean less
heatsinking than current systems.

Cree's claim overtakes advances by others:
<http://www.eetimes.com/news/latest/showArticle.jhtml?articleID=189501072>

Wiki gives what should be objective info to put this in context at
<http://en.wikipedia.org/wiki/Luminous_efficacy>

--
Tim Forcer [email protected]
The University of Southampton, UK

The University is not responsible for my opinions

rick H · Oct 3, 2006

Tim Forcer <[email protected]> wrote:
> Latest white LED sensation produces 131 lumens/W - which is way above
> even fluorescent efficicacy.
>
> <http://www.cree.com/press/press_detail.asp?i=1150834953712>
>

That site reports that the 131 lumens/W were achieved at just 20mA,
which would be about 70 to 80mW, assuming the usual 3.5-ish Volt
forward-voltage. So the device measured was presumably emitting a
feeble 10 lumens or so.

I wouldn't bet your last fiver that these parts are still 131 lm/W
when actually consuming 1W.

--
Rick

Marcus Red · Oct 3, 2006

rick H wrote:
> Tim Forcer <[email protected]> wrote:
>> Latest white LED sensation produces 131 lumens/W - which is way above
>> even fluorescent efficicacy.
>>
>> <http://www.cree.com/press/press_detail.asp?i=1150834953712>
>>
>
> That site reports that the 131 lumens/W were achieved at just 20mA,
> which would be about 70 to 80mW, assuming the usual 3.5-ish Volt
> forward-voltage. So the device measured was presumably emitting a
> feeble 10 lumens or so.
>
> I wouldn't bet your last fiver that these parts are still 131 lm/W
> when actually consuming 1W.
>
>
This post is not in the same category, but as a cheapsk////// low-cost
bicyclist, I have discovered that HyperValue are selling a torch/bicycle
lamp (it fits in a holder with clamp) for £2. It requires 3 AAA
batteries and has 3 white (with a hint of blue!) LEDs of the newer kind
(i.e. bright).

Probably nowhere near as good as a £50+ lamp, but it shows that the "new
technology" is now eminently affordable.

Zog The Undeniable · Oct 4, 2006

rick H wrote:

> That site reports that the 131 lumens/W were achieved at just 20mA,
> which would be about 70 to 80mW, assuming the usual 3.5-ish Volt
> forward-voltage. So the device measured was presumably emitting a
> feeble 10 lumens or so.

A bit like the famed 60% efficiency of a SON hub being achieved at 10mph :-\

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