LED headlights?

Ted Bennett said:

Pupil size is affected by much more than photons.

This is sort of off-topic, but pupil size is affected to a degree by psychology. That is, when a
person looks at another person they really, really, really "like," their pupils dilate noticeably.

I don't know if this has any applicability to bicycling. I suppose it might help you find a steady
riding partner. ;-)

--
Frank Krygowski [To reply, omit what's between "at" and "cc"]

Frank Krygowski said:

Would you say the Luxeon V is typical of most LEDs?

<Heavy sigh>

We were talking about LEDs used for bicycle lights, specifically the high brightness LEDs
from Luxeon.

As the poster stated: "the LED reputation for lasting a long time comes from its not drawing much
current, which until now has meant not much light either." No one is disputing that a low power
indicator LED is going to last virtually forever, versus a bulb with a filament which has a
relatively short life span.

There's no free lunch, whether you're dealing with a filament or a diode junction. Low power LEDs
last almost an infinite amount of time because they run at very low power and generate virtually no
heat. High power LEDs have a much shorter lifespan because they run so hot. Force more current
through a diode and the junction temperature goes up, pretty soon you go into thermal runaway,
unless you can cool the junction somehow.

The Luxeon 5W LEDs run very hot and require special attention to the thermal solution to prevent
them from quickly burning up. They also require that the voltage be fairly precise or they won't
illuminate at all.

The Luxeon DS40 (the 5 watt white LED) has a predicted lifetime of 500 hours with the proper thermal
solution. Okay for a flashlight that is only used occasionally, not great for a bicycle light,
especially at the current prices for replacement LEDs. A quartz-halogen bulb that is not over-
voltaged has a projected life of 2000 hours. Over-voltaging drastically reduces the life of the
bulb, while greatly increasing the brightness, but at least the bulbs are very cheap.

The 1W LEDs from Luxeon have a lifetime of 100K hours because they use 1/5 the power. Just as with
filament bulbs, the decrease in life with increased heat is not linear, it's exponential.

Look at an older LED traffic light sometime and count how many LEDs are burned out. It doesn't
matter because they don't all burn out at the same time. The energy savings is one advantage, but
the bigger advantage is that you can probably go for twenty years before enough of the LEDs burn out
for replacement to be necessary. The LEDs in traffic lights are not 1W either, they are closer to
100mW. Typically 121 LEDs are used, with a total power of 14W (116mw per LED). And of course it's
easier to make red, green, and yellow LEDs than it is to make white ones.

Read "eetimes.comOEG20030612S0019Open ↗"

Unfortunately, using multiple low power LEDs, while good for narrow angle "being seen" applications
such as traffic lights, brake lights, etc, is not a solution when you want to create a strong beam
to illuminate something,
i.e. a road. You're going to have to have a single light source that can be focused with the use of
a reflector and a lens.

HID lamps are the future of high-efficiency lighting for vehicle and bicycle headlights. They are
more efficient than LEDs and are easier to work with in terms of reflectors and lenses. The
electronics for them are actually very cheap to produce, in volume.

The relative efficiency figures are computed based on lumens/watt. The lumens and wattage of the
various lamps and LEDs are available on the manufacturer's or distributor's web sites. The table is
available on my web site, bicyclelighting.combicyclelighting.comOpen ↗.

Peter Cole said:

I know it can be done, but I haven't seen it done. I have a dual head

light,

Quoted message said:

but it's not simple to switch, I'd really like something like a car's high beam switch just for
high speed descents and times when oncoming lights

wash

Quoted message said:

out my vision.

Turbo Cat has a system with a convenient high beam switch.

turbocatusa.comS25.htmlOpen ↗

Steven M. Scharf said:

Frank Krygowski said:

Would you say the Luxeon V is typical of most LEDs?

<Heavy sigh>

We were talking about LEDs used for bicycle lights, specifically the high brightness LEDs
from Luxeon.

Funny, I thought we were talking about "the LED reputation for lasting a long time" (to quote Ron
Hardin's post); and I thought we were talking about LED bike lights currently on the market. Are you
saying that Cateye's LED lights use the Luxeon LEDs? Are you saying they use the Luxeon V that you
changed the subject to?

If they do, I certainly wasn't aware of that.

Quoted message said:

No one is disputing that a low power indicator LED is going to last virtually forever, versus a
bulb with a filament which has a relatively short life span.

Good. People do dispute the strangest things in this forum!

Quoted message said:

There's no free lunch, whether you're dealing with a filament or a diode junction. Low power LEDs
last almost an infinite amount of time because they run at very low power and generate virtually
no heat.

Hmmm. You don't think it has _anything_ to do with being solid state devices with no white-hot
metal? And hmmm. Can you point to a common filament light bulb which matches the life of a
common LED?

Quoted message said:

Unfortunately, using multiple low power LEDs, while good for narrow angle "being seen"
applications such as traffic lights, brake lights, etc, is not a solution when you want to create
a strong beam to illuminate something,
i.e. a road. You're going to have to have a single light source that can be focused with the use
of a reflector and a lens.

I didn't propose "low power" LEDs. I was speculating that multiple LEDs with improved integral
lenses (and, perhaps, reflectors) might be used for lighting the road in the future.

I still think that's a strong possibility. I guess we'll see.

Quoted message said:

The lumens and wattage of the various lamps and LEDs are available on the manufacturer's or
distributor's web sites. The table is available on my web site...

I'm interested in more than one brand of LED. And I prefer sources that are truthful and unbiased.

--
Frank Krygowski [To reply, omit what's between "at" and "cc"]

"Frank Krygowski" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

Funny, I thought we were talking about "the LED reputation for lasting a

long time" (to quote Ron Hardin's post). If they do, I certainly wasn't aware of that.

You responded with mis-statements to Ron Hardin, who correctly pointed out that the low heat
reputation of LEDs was due to their low current, and that high current, high brightness LEDs do not
have the same low-heat property. I think the problem may be that you do not understand how
semiconductors work, and I don't mean this unkindly. "Solid State," is not a panacea, especially in
applications requiring high current. Vacuum tubes are still popular in some high power applications,
yep, that nice old filament sitting there heating the tube.

Quoted message said:

Good. People do dispute the strangest things in this forum!

They certainly do! One more item for my Myths and Facts section has been added!

Quoted message said:

Hmmm. You don't think it has _anything_ to do with being solid state

devices with no white-hot metal?

It has everything to do with "hot," whether "white-hot" or other type of hot. This is why the high
power LEDs don't have a long life-span, despite being "solid-state." Heat is not the exclusive
territory of filament based lamps.

Quoted message said:

And hmmm. Can you point to a common filament light bulb which matches the

life of a common LED?

Sure. Any filament light bulb will last virtually forever if operated at the same current as an LED.
Of course it will not produce any light either. LEDs will illuminate at low current. That's the
great thing about LEDs and why they are used so widely in "being seen" applications where high
intensity is not required, you get a little light with a very low current and very low voltage.
Unfortunately it does not scale well, and you can't easily or cheaply make a light powerful enough
to project a beam.

What Lumileds is doing with their Luxeon 5W LED is basically over-driving them, raising the junction
temperature, trying to manage the thermal issues with heat sinks and perhaps fans, and living with
LED lifetimes that are less than that of a filament bulb. The Luxeon 1W is a good product for some
applications, but few people will accept the 500 hour limitation of their 5W LED.

Quoted message said:

I didn't propose "low power" LEDs. I was speculating that multiple LEDs

with improved integral lenses (and, perhaps, reflectors) might be used for lighting the road in
the future.

Quoted message said:

I still think that's a strong possibility. I guess we'll see.

"The future" is a pretty long time. Certainly they won't be used in headlights on motor vehicles in
our lifetime due to the cost and intensity. As to bicycle lights, it's a possibility, but the
lumens/watt will have to be magnitudes better.

Quoted message said:

I'm interested in more than one brand of LED.

I'm not aware of any other companies building LEDs as bright as the Lumileds ' Luxeon product. As
far as other brands of LEDs you can check out web sites of Vishay, Agilent, Fairchild etc. You'll
find that it terms of lumens/watt LEDs are comparable to incandescent lamps, not as efficient as
fluorescent or HID. The $/Lumen of LEDs is unfavorable, but improving and will eventually be
comparable to fluorescent.

Quoted message said:

And I prefer sources that are truthful and unbiased.

That's why I referred you to my web site. Even if you disagree with the views of myself, and others,
regarding the level of lighting needed for commuting, the table of lumens and watts is not based on
any opinions.

David Damerell said:

Zog The Undeniable said:

Dynamo lamps give out a lot more light than their electrical power rating suggests - mine has a 6V
3W bulb [1] but it's about twice as bright as a battery powered 6V 2.4W headlamp. Must be the AC
or something.

Quoted message said:

It's focussing. Dynamo headlights are of vastly superior design, and do not waste half their
output illuminating the sky and the ground three inches in front of the bicycle.

Quoted message said:

Quoted message said:

[1] the rear light is a Cateye TL-AU100BS, which is one of the very few UK *legal* LED lights - so
the full dynamo output can go to the front.

Quoted message said:

I'm afraid it is still the case that no LED light is legal in Britain (in and of itself; a steady
LED accompanying a legal light is legal.)
--
David Damerell <[email hidden]> flcl?

I'm sorry but could you clarify my understanding of this? LED lights (steady, non-
flashing) are not legal because they are LEDs despite the fact that they may be British
Standards approved?

A quick googling tells me that BS 6102 is what lights should conform to & I think this
is what the Cateye lights meet though I've not yet managed to read the regulations
requiring this.

I'm quite curious since I'm looking to replace a set of lights and was intending to fit a
combined LED rear light and reflector.

Tim.
--
Tim. /\ /\ O___O
=\__|__/= meow.
U

Tim Izod said:

David Damerell said:

I'm afraid it is still the case that no LED light is legal in Britain (in and of itself; a steady
LED accompanying a legal light is legal.)

I'm sorry but could you clarify my understanding of this?

God forbid anyone do a little background reading.

Quoted message said:

A quick googling tells me that BS 6102 is what lights should conform to & I think this is what the
Cateye lights meet though I've not yet managed to read the regulations requiring this.

The current Road Vehicle Lighting Regulations (inadvertently) require that lights conform to an
earlier version of BS 6102, which permits only incandescent bulbs.
--
David Damerell <[email hidden]> Distortion Field!

David Damerell said:

Tim Izod said:

A quick googling tells me that BS 6102 is what lights should conform to & I think this is what the
Cateye lights meet though I've not yet managed to read the regulations requiring this.

The current Road Vehicle Lighting Regulations (inadvertently) require that lights conform to an
earlier version of BS 6102, which permits only incandescent bulbs.

That's an interesting example of a badly-written law. Of course, when originally conceived, the
alternatives to incandescent bulbs may have been only carbide lamps; and perhaps the legislators
were really trying to discourage carbide lamps. (Just a guess.)

Still, it's shortsighted to assume that there will never be an alternate, "breakthrough" technology.
It would be more logical to specify the performance, rather than the technology used to produce it.

--
Frank Krygowski [To reply, omit what's between "at" and "cc"]

frkrygow said:

David Damerell wrote:

Quoted message said:

Quoted message said:

The current Road Vehicle Lighting Regulations (inadvertently) require that lights conform to an
earlier version of BS 6102, which permits only incandescent bulbs.

That's an interesting example of a badly-written law. Of course, when originally conceived, the
alternatives to incandescent bulbs may have been only carbide lamps; and perhaps the legislators
were really trying to discourage carbide lamps. (Just a guess.)

I used an inexpensive carbide lamp for commuting for a couple years and found it to work quite well.
It was especially effective on rough roads since the bumps would accelerate the flow of water onto
the carbide and create a mini-flamethrower. Eventually the carbide chamber developed a crack and I
went back to a dynamo system.

Quoted message said:

Still, it's shortsighted to assume that there will never be an alternate, "breakthrough"
technology. It would be more logical to specify the performance, rather than the technology used
to produce it.

Steven M. Scharf said:

"Frank Krygowski" <[email hidden]> wrote in message "]news:[email hidden]...

Quoted message said:

Quoted message said:

And hmmm. Can you point to a common filament light bulb which matches the

life of a common LED?

Sure. Any filament light bulb will last virtually forever if operated at the same current as an
LED. Of course it will not produce any light either.

:-) You're idea of a "light bulb" is much different than mine! I
actually expect it to produce light!

If, instead of discussing practical matters, you merely want to further your version of the
argument, I'm surprised you didn't leave your hypothetical bulb in the box. After all, if
_no_ current flows, the bulb won't be destroyed except by geological forces! The ultimate
Scharf argument!

But back here in the real world, ordinary bulbs do not last nearly as long as ordinary LEDs - again,
because solid-state LEDs don't inevitably lose their integrity in normal operation, as filaments do.
The fact that LEDs can be pushed or abused into quick destruction does not change that.

BTW, you didn't answer: _Do_ the Cateye LED units use the Luxeon V LED, as you seemed to imply? Or
was that more misinformation?

Quoted message said:

Quoted message said:

And I prefer sources that are truthful and unbiased.

That's why I referred you to my web site. Even if you disagree with the views of myself, and
others, regarding the level of lighting needed for commuting, the table of lumens and watts is
not based on any opinions.

Your website contains obvious lies such as this: "The minimum legal requirements are inadequate,
according to every expert on bicycle lighting."

Your bias is apparent to all of us, I believe, and your website apparently functions largely as a
place for you to post your nonsense without fear of rebuttal.

Given the situation, I can't trust your figures as being necessarily accurate. And even if they are
accurate for certain specific cases, I can't trust them as applying to truly representative
equipment.

Your insistence in this forum that dynamos or generators must cost many hundreds of dollars, is a
perfect example of the type of distortion I expect.

--
Frank Krygowski [To reply, omit what's between "at" and "cc"]

"David L. Johnson" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

I've been curious, from following a couple of sort-of related threads. One guy pointed to a site
that had a 1W single LED light (for $35 or so). Now, 1 watt does not seem like much. At the moment
I use a 15W Nightrider, but am interested in something that would last longer and still have
enough light.

Are there LED lights that really do the job? How many watts would it

take?

The Streamlight 51013 TT-3AA with the TwoFish holder seems like it would be good as a backup. The 3
LED half is long lasting (80 hours) and an okay "being seen light", and the xenon half can deliver
2.6 hours of adequate brightness for an emergency back-up (46 lumens). Plus the xenon half is like a
Maglite with an adjustable spot to flood reflector/lens. 46 lumens is the same as a 3W HS3 with an
3W dynamo (no 0.6W tail light). Watts is not a good measure of brightness.

David Damerell said:

Quoted message said:

The current Road Vehicle Lighting Regulations (inadvertently) require that lights conform to an
earlier version of BS 6102, which permits only incandescent bulbs.

Frank Krygowski commented:

Quoted message said:

That's an interesting example of a badly-written law. Of course, when originally conceived, the
alternatives to incandescent bulbs may have been only carbide lamps; and perhaps the legislators
were really trying to discourage carbide lamps. (Just a guess.)

Still, it's shortsighted to assume that there will never be an alternate, "breakthrough"
technology. It would be more logical to specify the performance, rather than the technology used
to produce it.

I seem to recall an analogous situation not so many years ago, when regulations called for
automobiles to have "sealed beam" headlights. As a result, the adoption of brighter, halogen
headlights was delayed for several years.

Sheldon "Unintended Consequences" Brown +--------------------------------------------------+
| Whoever you vote for, the government gets in. | John Jones--Oysterband |
+--------------------------------------------------+ Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041 harriscyclery.comharriscyclery.comOpen ↗ Hard-to-find parts shipped Worldwide
captainbike.comcaptainbike.comOpen ↗ sheldonbrown.comsheldonbrown.comOpen ↗

"rosco" <reverse-the-following"ocsor_g"@hotmail.com> wrote in message

Quoted message said:

I have one of these Planet Bike units on order,

Quoted message said:

and plan to modify it using the 3W Luxeon Star if possible ($13 from www.elekrolumens.com). If it
works out, I'll post my findings.

The Planet Bike unit arrived today. I don't have any experience with the other LED 4xAA units on the
market (e.g. Cateye) so can't really compare. I'd say the unit is OK, but far from great. The beam
pattern isn't as tight, smooth and well defined as I was hoping for. My Luxeon Star based flashlight
(Surefire E2e w/ KL1 head) has *much* better optics & beam pattern. In the end, the Planet Bike unit
is a $30 commercial product, and I shouldn't really expect it to be up to the standards of the
Surefire. I'll probably send it back to Performance. It really isn't worth trying to modify with the
3W Luxeon part.

frkrygow said:

David Damerell said:

The current Road Vehicle Lighting Regulations (inadvertently) require that lights conform to an
earlier version of BS 6102, which permits only incandescent bulbs.

That's an interesting example of a badly-written law. Of course, when originally conceived, the
alternatives to incandescent bulbs may have been only carbide lamps;

Goodness me, no. The current RVLR are quite recent, post-dating LED lights, although a revision is
in the works.

I really mean "inadvertently"; the intention was to permit anything that adhered to the then-current
BS6102, and perhaps even later versions of the standard. Bad drafting is to blame, not bad intent.

The older BS6102 that was referenced predated LED lights. Arguably it also should not be tech-
specific, but the real trouble is getting away from legislation about power inputs, and specifying
light output (both directly ahead or astern and at offset angles), minimum run times, &c.
--
David Damerell <[email hidden]> Kill the tomato!

"rosco" <reverse-the-following"ocsor_g"@hotmail.com> wrote in message news:<[email hidden]>...

Quoted message said:

My Luxeon Star based flashlight (Surefire E2e w/ KL1 head) has *much* better optics & beam
pattern.

what's the beam like? any potential for bike use? whenever i'm ever feeling fiscally irresponsible,
i think about getting a SureFire KL-3 LED head, and adapting it for use bike use. i wish they
published beam pattern info. BTW, they a pretty good info section.

Steven M. Scharf said:

optics improve, then LEDs may have a future in high brightness bicycle lighting. For now, they're
"being seen" lights only.

That's odd; when we started, you thought that one needed bright lights to be seen in urban
situations, and in the country weaker lights would suffice. What changed?
--
David Damerell <[email hidden]> Kill the tomato!

"Sheldon Brown" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

I seem to recall an analogous situation not so many years ago, when regulations called for
automobiles to have "sealed beam" headlights. As a result, the adoption of brighter, halogen
headlights was delayed for several years.

Now the problem is that headlight maximums are in watts (in the U.S.).. This led to the blindingly
bright automotive HID headlights which are legal because they are within the wattage limitations,
but really were not intended to be legal. We also have the lack of regulations for DRLs (in the
U.S.) where automkers such as GM don't bother to do the design properly and we end up with annoying
high beams at reduced brightness as DRLs on some vehicles, see nordicgroup.usdrl.htmOpen ↗. Of
course the evidence shows that DRLs don't work anyway!

Steven M. Scharf said:

intended to be legal. We also have the lack of regulations for DRLs (in the U.S.) where automkers
such as GM don't bother to do the design properly and we end up with annoying high beams at reduced
brightness as DRLs on some vehicles, see nordicgroup.usdrl.htmOpen ↗. Of course the evidence
shows that DRLs don't work anyway!

Blame Canada. DRLs are not mandatory in the US, but they are in Canada, and automakers prefer to
make one model exactly the same for sale in both countries.

Of course, it would be nice if they would stop using the high beams. DRLs might be effective if they
didn't cause accidents from glare (conjecture).

The DRLs on my pickup are dedicated DRLs, separate from all other lights, and so are aimed better
than reduced-intensity high beam DRLs; but they are pretty bright -- IMO, nearly annoyingly so.
--
Rick Onanian

"frkrygow" <"frkrygow"@omitcc.ysu.edu> wrote in message
"]news:[email hidden]...

Quoted message said:

Steven M. Scharf said:

"Frank Krygowski" <[email hidden]> wrote in message "]news:[email hidden]...

Quoted message said:

Quoted message said:

And hmmm. Can you point to a common filament light bulb which matches

the

Quoted message said:

Quoted message said:

life of a common LED?

Sure. Any filament light bulb will last virtually forever if operated at

the

Quoted message said:

Quoted message said:

same current as an LED. Of course it will not produce any light either.

:-) You're idea of a "light bulb" is much different than mine! I
actually expect it to produce light!

What I'm trying to get you to understand, and I think you do actually understand it, is that the LED
is NOT any more efficient than a filament based lamp, nor does it last longer (shorter life in fact)
when it is used to produce amounts of light sufficient for a beam for bicycling. If the efficiency
goes up, some new way of controlling thermals is discovered, and optics improve, then LEDs may have
a future in high brightness bicycle lighting. For now, they're "being seen" lights only.

"B.C. Cletta" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

"rosco" <reverse-the-following"ocsor_g"@hotmail.com> wrote in message

news:<[email hidden]>...

Quoted message said:

Quoted message said:

My Luxeon Star based flashlight (Surefire E2e w/ KL1 head) has *much* better optics & beam
pattern.

what's the beam like? any potential for bike use? whenever i'm ever feeling fiscally
irresponsible, i think about getting a SureFire KL-3 LED head, and adapting it for use bike use. i
wish they published beam pattern info. BTW, they a pretty good info section.

I'll try to take some pictures next week.