Bicycle lighting question

Nubo said:

Steven M. Scharf said:

If you know anything about semiconductor physics, you'll understand
why this is not likely to happen for a long time, if ever. High
power LEDs have the same issues as over-voltaging conventional
lamps, the excessive heat results in a short life. However a
conventional lamp is cheap, a 5W LED is very expensive.

The best hope for LEDs is an array of lower power LEDs, but they
don't lend themselves well to focusing into a coherent beam.

I've seen an example of a homebrew bicycle light using three 3W LED
emitters, with collimating optics for each. This was pretty close
to what I'd consider a worthy competitor to the HID I'm using now,
judging from photos. The light seemed bright enough and color
rendition appeared good, though again based only on a photograph.
The other nice thing would be the redundancy of 3 emitters, where
sudden failure of one does not put you in the dark.

I've seen some positive stuff about these, but I've never seen them in
person. The Web site is unfortunately very hype-laden and short of
real information.

http://www.exposurelights.com/

"Tim McNamara" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Nubo said:

Steven M. Scharf said:

If you know anything about semiconductor physics, you'll understand
why this is not likely to happen for a long time, if ever. High
power LEDs have the same issues as over-voltaging conventional
lamps, the excessive heat results in a short life. However a
conventional lamp is cheap, a 5W LED is very expensive.

The best hope for LEDs is an array of lower power LEDs, but they
don't lend themselves well to focusing into a coherent beam.

I've seen an example of a homebrew bicycle light using three 3W LED
emitters, with collimating optics for each. This was pretty close
to what I'd consider a worthy competitor to the HID I'm using now,
judging from photos. The light seemed bright enough and color
rendition appeared good, though again based only on a photograph.
The other nice thing would be the redundancy of 3 emitters, where
sudden failure of one does not put you in the dark.

I've seen some positive stuff about these, but I've never seen them in
person. The Web site is unfortunately very hype-laden and short of
real information.

http://www.exposurelights.com/

Ask me.
I have two 5 Watt Luxeons on my mountain bike and one 5 Watt Luxeon on my
road bike.

Marty

Tim McNamara said:

Nubo said:

Steven M. Scharf said:

If you know anything about semiconductor physics,

And you do? My, you're feeling grand today. Please spare us, for once!

Quoted message said:

Quoted message said:

Quoted message said:

you'll understand
why this is not likely to happen for a long time, if ever. High
power LEDs have the same issues as over-voltaging conventional
lamps, the excessive heat results in a short life. However a
conventional lamp is cheap, a 5W LED is very expensive.

They are now, but they'll come down in price. Demand for these for
architectural lighting, etc., will be high. Ask an architect or property
manager who's been sued by someone who tripped on a sidewalk, because a light
bulb was burned out.

Quoted message said:

Quoted message said:

Quoted message said:

The best hope for LEDs is an array of lower power LEDs, but they
don't lend themselves well to focusing into a coherent beam.

Cateye has no trouble with this -- check out their 5 LED design. Its beam
pattern is fine, it just doesn't put out enough light. LED or not, it's still
only a watt or so.

Quoted message said:

Quoted message said:

I've seen an example of a homebrew bicycle light using three 3W LED
emitters, with collimating optics for each. This was pretty close
to what I'd consider a worthy competitor to the HID I'm using now,
judging from photos. The light seemed bright enough and color
rendition appeared good, though again based only on a photograph.
The other nice thing would be the redundancy of 3 emitters, where
sudden failure of one does not put you in the dark.

I've seen some positive stuff about these, but I've never seen them in
person. The Web site is unfortunately very hype-laden and short of
real information.

http://www.exposurelights.com/

I look forward to the new 3W LEDs hitting the mainstream, for battery and
generator powered lights alike. The ones being used now are very promising, but
they're still in the realm of tinkerers. The only system I know of being
produced by a major company is the Vega from L&M -- which I don't think is even
out yet. It's expensive too.

Matt O.

Matt O'Toole said:

Tim McNamara said:

Nubo said:

Steven M. Scharf wrote:

> If you know anything about semiconductor physics,

And you do? My, you're feeling grand today. Please spare us, for once!

Quoted message said:

Quoted message said:

> you'll understand
> why this is not likely to happen for a long time, if ever. High
> power LEDs have the same issues as over-voltaging conventional
> lamps, the excessive heat results in a short life. However a
> conventional lamp is cheap, a 5W LED is very expensive.

They are now, but they'll come down in price. Demand for these for
architectural lighting, etc., will be high. Ask an architect or property
manager who's been sued by someone who tripped on a sidewalk, because a light
bulb was burned out.

[snip]

Quoted message said:

Matt O.

Dear Matt,

Why will LED lights come down in price?

As I understand it, increased demand by itself only
increases prices. The people that you say are being sued for
burnt-out conventional lights would only seem to be paying
more for LED lights in hopes of paying less in lawsuits.

Our desire to save money, by itself, will not lower the
price of LED lights.

So what I'm wondering is what do you see that will make LED
lights cheaper to manufacture, distribute, and sell in the
future? Have their prices been cut in half every year
recently, leading to your prediction? Or what?

Carl Fogel

Quoted message said:

So what I'm wondering is what do you see that will make LED
lights cheaper to manufacture, distribute, and sell in the
future? Have their prices been cut in half every year
recently, leading to your prediction? Or what?

Well, their prices have certainly dropped in the past three years. And
the general trend in semiconductors of any kind is for prices to drop
over time. Can anyone think of a significant exception?

LED lighting seems to be growing in consumer attention and production
volume as much as, say, LCD computer screens. It's rare indeed for
increasing production and the competition for sales to NOT cause a price
drop, no matter what the production difficulties!

--
--------------------+
Frank Krygowski [To reply, remove rodent and vegetable dot com,
replace with cc.ysu dot edu]

Quoted message said:

So what I'm wondering is what do you see that will make LED
lights cheaper to manufacture, distribute, and sell in the
future?

Volume, volume, and volume.

Quoted message said:

Have their prices been cut in half every year
recently, leading to your prediction?

Something like that, yes.

Matt O.

Matt O'Toole said:

Quoted message said:

So what I'm wondering is what do you see that will make LED
lights cheaper to manufacture, distribute, and sell in the
future?

Volume, volume, and volume.

Quoted message said:

Have their prices been cut in half every year
recently, leading to your prediction?

Something like that, yes.

Matt O.

Dear Matt,

Something like that? If the price for a $16 LED had been cut
in half every year for the last five years, it would have
dropped to $1.

What kind of volume increases would lead to a 94% price
reduction in something like LED lights, which are basically
striving to become a commodity in competition with the
well-established existing commodity of conventional lights?

I'm willing to believe that there's a bright future for LED
lights (sorry, couldn't resist it), but I haven't noticed
much rise in volume--the ones that I see are in new traffic
lights, on keychain flashlights, and blinking on bicycle
accessory lights.

Do any bicycles even come with lights (conventional or LED)
included from the factory?

Are street lamps or indoor lights (as opposed to safety
glow) switching to LED's?

Carl Fogel

Sometimes things drop in price after a few years because the company has
gotten it's R & D costs out of it. The first handheld calculator I bought,
I paid over $100 for it. With more competition and refinements, etc., the
price soon dropped.

Pat in TX

: I'm willing to believe that there's a bright future for LED
: lights (sorry, couldn't resist it), but I haven't noticed
: much rise in volume--the ones that I see are in new traffic
: lights, on keychain flashlights, and blinking on bicycle
: accessory lights.
:
: Do any bicycles even come with lights (conventional or LED)
: included from the factory?
:
: Are street lamps or indoor lights (as opposed to safety
: glow) switching to LED's?
:
: Carl Fogel

How about car tail lights? More manufacturers are using them for more
applications. I am seeing price drops in the hand-held flashlights. I think
some Bianchi bikes come with lights included...but I don't know if they use
LED lights. Also, children's toys are using LED lights quite a bit.

Pat in TX

On Thu, 16 Dec 2004 21:33:11 -0600, "Pat" <[email hidden]>

Quoted message said:

Sometimes things drop in price after a few years because the company has
gotten it's R & D costs out of it. The first handheld calculator I bought,
I paid over $100 for it. With more competition and refinements, etc., the
price soon dropped.

Pat in TX

Dear Pat,

What you're saying helps me see what makes me dubious about
the future predicted for LED lights.

Research and development, costs of production, manufacturing
improvements, and so forth have greatly reduced the prices
of extremely complicated devices like calculators and the
amazingly finicky chips that run them.

Most of the arguments for the wonderful future of LED lights
involve the logic that computers have dropped fantastically
in price while increasing immensely in power, so LED lights
should do the same.

But LED lights aren't complicated in the sense of a micro
processor. As far as I can tell, they're more like old
fashioned light bulbs--simple devices, just more finicky
about the quality of materials and demanding more care in
production. So what's going to make them significantly
cheaper and brighter?

And LED lights aren't filling a new role in the way that
computers did, making new things possible by the sheer speed
of calculation. A slide-rule isn't a spreadsheet, nor can a
typewriter search a million words of text. LED's are
competing directly with well-established conventional
lights, but they lack the kinds of overwhelming advatnages
that drove the computer explosion.

It would be nice if WalMart sold a $5 100-watt LED light
that would outlive me after I screwed it into the ceiling
fixture--but what kind of improvements in light output and
cost of production are needed for this to happen? And why
won't the ordinary filament bulbs improve just as much?

In a way, the situation reminds me of the hopes for electric
cars. Despite all the effort, it seems to be awfully hard to
find something that works as well as a gasoline engine.

Carl Fogel

Quoted message said:

On Thu, 16 Dec 2004 21:45:11 -0500, "Matt O'Toole"
<[email hidden]> wrote:

Quoted message said:

Quoted message said:

[email hidden] wrote:

Quoted message said:

Quoted message said:

Quoted message said:

Have their prices been cut in half every year
recently, leading to your prediction?

Something like that, yes.

Quoted message said:

Something like that? If the price for a $16 LED had been cut
in half every year for the last five years, it would have
dropped to $1.

More like the $100 LEDs now cost $16.

A few years ago, I tried to get a couple of samples for bike light experiments.
These were the 1-watters which are common as dirt now, in bike lights selling
for under $20. I got them alright, but they wanted them back, or $54 apiece if
I wanted to keep them. Sheesh.

Quoted message said:

What kind of volume increases would lead to a 94% price
reduction in something like LED lights, which are basically
striving to become a commodity in competition with the
well-established existing commodity of conventional lights?

I'm willing to believe that there's a bright future for LED
lights (sorry, couldn't resist it), but I haven't noticed
much rise in volume

Well, how would you know, unless you're actually selling them?

The growth in LED sales is explosive. I do some communications work for an LED
manufacturer, and they're back every year for more and more marketing material.

--the ones that I see are in new traffic

Quoted message said:

lights, on keychain flashlights, and blinking on bicycle
accessory lights.

Don't forget tailights and turn signals on all new buses and trucks. The Volvo
truck plant is just down the road from here. All the new trucks I see cruising
down I-81 have LEDs all over them.

Quoted message said:

Do any bicycles even come with lights (conventional or LED)
included from the factory?

Not too many in the US, but in Europe and Japan they sure do. As for LEDs, give
it a couple of years. As far as I can tell, Cateye doesn't even make the
venerable Micro II Halogen anymore, having replaced it with a couple of LED
models.

Quoted message said:

Are street lamps or indoor lights (as opposed to safety
glow) switching to LED's?

Yes. I'm seeing them all over the place. We have a bunch of new ones right
here in Blacksburg. Residents of Los Angeles can see similar ones on Figueroa
through Highland Park. No bulbs to change for a long, long time. The labor to
change bulbs is often more expensive than the bulb itself.

For indoor lighting, they're showing up in the marine market where efficiency
matters. Also, newer boats have dozens of little lights everywhere. Keeping
all these bulbs working is just another maintenance headache.

None of this matters much at home, so the cost is still not competitive with
halogens. Nor do most people find the color attractive. My guess is they'll
find a way to market them anyway, selling the bluish color as a cure for
seasonal affective disorder or something, besides harping on efficiency and long
life. If nothing else, there's plenty of gimmick value.

Matt O.

Quoted message said:

I'm not arguing against the claim that LED lights will
become much cheaper and more popular. I just want to know
what I'd say to someone who asked why he should actually
invest in an LED light company.

Which one? Most LED companies are subsidiaries of huge corporations. A really
good year for LEDs could be offset by a really bad year for inkjet cartridges,
for example.

Quoted message said:

For the same electrical input, do LED's produce as much
light as conventional lights?

More.

Quoted message said:

What do they cost to produce
compared to conventional lights--including expected lifetime
and replacement costs? Should we expect to see LED lights
replacing car headlights, street lamps, and the familiar 1
watt bulbs and fluorescent tubes in buildings?

Yes, at least partially.

Quoted message said:

Or will LED's remain a niche product, good for special uses
like traffic lights, blinking safety signals, keychain
flashlights, and night bicyclists?

What's a few hundred million to a few billion dollars anyway...

Matt O.

Matt O'Toole said:

Quoted message said:

On Thu, 16 Dec 2004 21:45:11 -0500, "Matt O'Toole"
<[email hidden]> wrote:

Quoted message said:

Quoted message said:

[email hidden] wrote:

Quoted message said:

Quoted message said:

> Have their prices been cut in half every year
> recently, leading to your prediction?

Something like that, yes.

Quoted message said:

Something like that? If the price for a $16 LED had been cut
in half every year for the last five years, it would have
dropped to $1.

More like the $100 LEDs now cost $16.

A few years ago, I tried to get a couple of samples for bike light experiments.
These were the 1-watters which are common as dirt now, in bike lights selling
for under $20. I got them alright, but they wanted them back, or $54 apiece if
I wanted to keep them. Sheesh.

Quoted message said:

What kind of volume increases would lead to a 94% price
reduction in something like LED lights, which are basically
striving to become a commodity in competition with the
well-established existing commodity of conventional lights?

I'm willing to believe that there's a bright future for LED
lights (sorry, couldn't resist it), but I haven't noticed
much rise in volume

Well, how would you know, unless you're actually selling them?

The growth in LED sales is explosive. I do some communications work for an LED
manufacturer, and they're back every year for more and more marketing material.

--the ones that I see are in new traffic

Quoted message said:

lights, on keychain flashlights, and blinking on bicycle
accessory lights.

Don't forget tailights and turn signals on all new buses and trucks. The Volvo
truck plant is just down the road from here. All the new trucks I see cruising
down I-81 have LEDs all over them.

Quoted message said:

Do any bicycles even come with lights (conventional or LED)
included from the factory?

Not too many in the US, but in Europe and Japan they sure do. As for LEDs, give
it a couple of years. As far as I can tell, Cateye doesn't even make the
venerable Micro II Halogen anymore, having replaced it with a couple of LED
models.

Quoted message said:

Are street lamps or indoor lights (as opposed to safety
glow) switching to LED's?

Yes. I'm seeing them all over the place. We have a bunch of new ones right
here in Blacksburg. Residents of Los Angeles can see similar ones on Figueroa
through Highland Park. No bulbs to change for a long, long time. The labor to
change bulbs is often more expensive than the bulb itself.

For indoor lighting, they're showing up in the marine market where efficiency
matters. Also, newer boats have dozens of little lights everywhere. Keeping
all these bulbs working is just another maintenance headache.

None of this matters much at home, so the cost is still not competitive with
halogens. Nor do most people find the color attractive. My guess is they'll
find a way to market them anyway, selling the bluish color as a cure for
seasonal affective disorder or something, besides harping on efficiency and long
life. If nothing else, there's plenty of gimmick value.

Matt O.

Dear Matt,

I may not yet have seen the light, but thanks for the best
answers to my questions so far.

A quick look at the Cateye site shows the HL-500ii halogen
model (and HL-500 and HL-330) as a current product:

http://www.cateye.com/en/products/viewProduct.php?modelId=24&catId=7&subCatId=2

Are any of these the model that you had in mind?

Carl Fogel

Quoted message said:

Dear Tim,

What's developing in LED lights? That is, what's changed in
the last five or ten years in light emitting diodes?

Have LED's gotten significantly more efficient, putting out
more light (or longer) for the same electrical input? Any
figures?

Or have they become significantly cheaper at the level
needed for bicycle lighting? Any prices?

Are LED's reasonably expected to expand beyond the small
niche of bicycle accessories, traffic lights, and guide
lights?

I'm willing to believe that there's been the kind of
progress that people seem to be assuming in their
predictions, but I'm looking for some figures, such as a
150% increase in light output per amp/hour since 200x or a
75% reduction in cost per unit since 199x.

What new materials will be used to create brighter or
cheaper LED lights? What hasn't been tried?

The only figure that I see in your post is a 90% figure--you
firmly believe that the old 3-speed is the optimal gear
system for about 90% of the public. Since (at least in the
U.S.) 90% of the bicycle public shifted (sorry, couldn't
resist it) to a different gear system years ago, that would
raise some questions in any intro to economics class,
wouldn't it?

Carl Fogel

Carl, a quick glance at the luxeon.com site found this:
http://www.luxeon.com/pdfs/TP40_IESNA_July%202004_LED_Paper.pdf

The first page alone gives some perspective, scanning several pages
addressed several of your questions.

From the first page: In the early 60's, "GE distributed red LEDs
through the Allied radio catalog for $260 US. Obviously, LEDs were quite
expensive and sold only in low volumes."

Given that red LEDs are now available several for a dollar, that's
halving the cost, say, 10 times in 40 years - maybe not the dramatic
plunge you were expecting, but a four-year halflife for price isn't too
radically different than the ~18 months for computers.

Mark "Data beats speculation" Janeba

Quoted message said:

Quoted message said:

Quoted message said:

So what I'm wondering is what do you see that will make LED
lights cheaper to manufacture, distribute, and sell in the
future? Have their prices been cut in half every year

-snip-

Quoted message said:

Frank Krygowski said:

Well, their prices have certainly dropped in the past three years. And
the general trend in semiconductors of any kind is for prices to drop
over time.

-snip-

[email hidden] wrote:
-snip-
Should we expect to see LED lights

Quoted message said:

replacing car headlights, street lamps, and the familiar 100
watt bulbs and fluorescent tubes in buildings?

Or will LED's remain a niche product, good for special uses
like traffic lights, blinking safety signals, keychain
flashlights, and night bicyclists?

Commercial vehicle taillamps/signals and stoplights/walk
signs are already LED. The unit cost can keep dropping and
the manufacturers can stay profitable if the volume
increases and/or the manufacturing process gets more efficient.

--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

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

Quoted message said:

Matt O'Toole said:

Tim McNamara said:

Nubo <[email hidden]> writes:

> Steven M. Scharf wrote:
>
>> If you know anything about semiconductor physics,

And you do? My, you're feeling grand today. Please spare us, for once!

Quoted message said:

>> you'll understand
>> why this is not likely to happen for a long time, if ever. High
>> power LEDs have the same issues as over-voltaging conventional
>> lamps, the excessive heat results in a short life. However a
>> conventional lamp is cheap, a 5W LED is very expensive.

They are now, but they'll come down in price. Demand for these for
architectural lighting, etc., will be high. Ask an architect or property
manager who's been sued by someone who tripped on a sidewalk, because a

light

Quoted message said:

Quoted message said:

bulb was burned out.

[snip]

Quoted message said:

Matt O.

Dear Matt,

Why will LED lights come down in price?

As I understand it, increased demand by itself only
increases prices. The people that you say are being sued for
burnt-out conventional lights would only seem to be paying
more for LED lights in hopes of paying less in lawsuits.

Our desire to save money, by itself, will not lower the
price of LED lights.

So what I'm wondering is what do you see that will make LED
lights cheaper to manufacture, distribute, and sell in the
future? Have their prices been cut in half every year
recently, leading to your prediction? Or what?

Carl Fogel

Ha ha ha

"I think there is a world market for maybe five computers"

Marty

Quoted message said:

A quick look at the Cateye site shows the HL-500ii halogen
model (and HL-500 and HL-330) as a current product:

http://www.cateye.com/en/products/viewProduct.php?modelId=24&catId=7&subCatId=2

Quoted message said:

Are any of these the model that you had in mind?

Yes, those are the ones. But no one seems to stock the HL-500II anymore. I
asked a bike shop owner about this recently. He said they're no longer
available.

Matt O.

Matt O'Toole said:

Well, you can do the math for yourself -- how often will you be replacing
lamps,
how much will this cost, and is it acceptable *to you.*

Don't forget that the Luxeon 5 LED has a rated life of only 500
hours,and that's with an ideal thermal solution. A convection cooled
design with a Luxeon 5 LED is unlikely to have an ideal thermal
solution, since there is necessarily no air-flow across the LED.

An over-voltaged MR16 is better from many standpoints. It is more
efficient, it is MUCH less expensive, and you get a highly matched and
focused lens as part of the package.

The HID system is the most efficient, but an over-voltaged
quartz-halogen bulb is very close.

Matt O'Toole said:

And you do? My, you're feeling grand today. Please spare us, for once!

A great deal. Especially about thermals and leakage. I probably spend
more time at work dealing with this than anything else. If you don't
want to learn anything about the subject then just don't read my replies.

Quoted message said:

They are now, but they'll come down in price. Demand for these for
architectural lighting, etc., will be high. Ask an architect or property
manager who's been sued by someone who tripped on a sidewalk, because a
light
bulb was burned out.

This is the great thing about the fluorescent replacements, or even
those PAR-90 replacement lamps with ninety 1 watt Luxeon LEDs. They last
a very long time.

But using high power LEDs (3W-5W) presents a lot of problems. You can't
cool the bulb with natural air flow because the fixture has to be
sealed. Collimating the beam is inefficient.

Quoted message said:

Cateye has no trouble with this -- check out their 5 LED design. Its beam
pattern is fine, it just doesn't put out enough light. LED or not, it's
still
only a watt or so.

Scaling up to provide enough light is not easy. You don’t just replace
the LEDs with higher power LEDs, you need to redesign the whole thermal
solution. It’s a very difficult problem because unlike a regular PC
board you can’t simply position the components wherever you want in
order to have the best thermal solution, the LEDs MUST be in specific
positions. You could get fancy with heat pipes, but this gets expensive.

Quoted message said:

I look forward to the new 3W LEDs hitting the mainstream, for battery and
generator powered lights alike.

3W is more manageable than 5W take three 3W LEDs, collimate the beam,
figure out a way to manage the thermals, and you'll be close to the
brightness of a 5W quartz-halogen bulb. Not saying it’ll never happen,
but that it’s more of a challenge than you realize.

"Steven M. Scharf" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Matt O'Toole said:

And you do? My, you're feeling grand today. Please spare us, for once!

A great deal. Especially about thermals and leakage. I probably spend more
time at work dealing with this than anything else. If you don't want to
learn anything about the subject then just don't read my replies.

Quoted message said:

They are now, but they'll come down in price. Demand for these for
architectural lighting, etc., will be high. Ask an architect or property
manager who's been sued by someone who tripped on a sidewalk, because a
light
bulb was burned out.

This is the great thing about the fluorescent replacements, or even those
PAR-90 replacement lamps with ninety 1 watt Luxeon LEDs. They last a very
long time.

But using high power LEDs (3W-5W) presents a lot of problems. You can't
cool the bulb with natural air flow because the fixture has to be sealed.
Collimating the beam is inefficient.

Quoted message said:

Cateye has no trouble with this -- check out their 5 LED design. Its
beam
pattern is fine, it just doesn't put out enough light. LED or not, it's
still
only a watt or so.

Scaling up to provide enough light is not easy. You don’t just replace the
LEDs with higher power LEDs, you need to redesign the whole thermal
solution. It’s a very difficult problem because unlike a regular PC board
you can’t simply position the components wherever you want in order to
have the best thermal solution, the LEDs MUST be in specific positions.
You could get fancy with heat pipes, but this gets expensive.

Quoted message said:

I look forward to the new 3W LEDs hitting the mainstream, for battery and
generator powered lights alike.

3W is more manageable than 5W take three 3W LEDs, collimate the beam,
figure out a way to manage the thermals, and you'll be close to the
brightness of a 5W quartz-halogen bulb. Not saying it’ll never happen, but
that it’s more of a challenge than you realize.

I have a 3W Luxeon 2AA flashlight, and its brightness is a little bit
disappointing compared to what I was expecting. Its runtime is about 1.5
hours with 1800mAH NiMH cells. It's very close to a 2.4W conventional
halogen, but the halogens all take 4AAs, and the runtime is slightly lower
for the 3W. I would guess efficiency is about 1.5 times as good as the
halogens.

The problem with the 3W and 5W is the inefficiency of the circuit as
currents go up. The LED flashlight is supposed to draw 600mA at 3V, but
only about 70% of that gets through to LED itself due to the current
regulation circuit.

As currents go up, the LED gets brighter, but not not linearly with the
power consumption, so arrays make more sense.

--
Phil, Squid-in-Training