New 10-watt(?) LED Light

Quoted message said:

The new Summer Performance catalog is featuring their
new "ViewPoint GEN3" single Luxeon LED headlight.
They claim "10 watts plus" coming out of 4 AA
NiMH batteries that run 5 hours.

Here's why their claim is hard to believe:

(10 watts) x (5 hours) / (4 cells) = 12.5 watt-hours per cell

Four watt-hours per AA cell is about the best you can expect. I'm
thinking they're using a Luxeon 5-watt LED [URL below] and running the
batteries dead flat, long after the light dims below full output (in
about three hours), to get five hours out of them.

Quoted message said:

I think what they really mean is the LED light is equivalent
in brightness to a typical 10-watt halogen light.

From my experiments with bike lights, I'd say there seems to be about a
two-to-one ratio of apparent brightness between LED and halogen lights,
so the 5-watt LED may well look as bright as a 10-watt halogen.

luxeonstar.comsub category.phpOpen ↗

I thought this was reaching a bit in the 10-watt claim as well. For
comparison, here is a discussion on the performance of a caving lamp
using a similar Luxeon LED. They claim it's 5 watts. It may be the same
emitter.

http://www.caves.org/imo/pdf/Nova%20discharge.pdf

It's kind of vague, but in general it demonstrates that Speleotechnics
claims about half the life for half the wattage of the Performance
light. Also there are some instruction for its use.

http://www.caves.org/imo/pdf/NOVA%20instructions.pdf

Then again, it would be really nice if companies would start describing
their lights in comparable terms, like using "Lux" or "lumens" to
describe the actaul amount of light output by the light. Not many
people understand these terms (I have to look it up all the time because
I forget), but many companies are now using fake "Wattage" values in an
attempt to compare LEDs with filament bulbs.

Incidentally, the digital versions are the best thing in the world for
caving. They do such a good job of flattening out the voltage curve
that you never notice a drain on the battery, and you get maximum life
out of the battery as well.

-Collin

LioNiNoiL_a t_Ne t s c a pE_D 0 T_Ne T said:

Quoted message said:

The new Summer Performance catalog is featuring their
new "ViewPoint GEN3" single Luxeon LED headlight.
They claim "10 watts plus" coming out of 4 AA NiMH batteries that run
5 hours.

Here's why their claim is hard to believe:

(10 watts) x (5 hours) / (4 cells) = 12.5 watt-hours per cell

Four watt-hours per AA cell is about the best you can expect. I'm
thinking they're using a Luxeon 5-watt LED [URL below] and running the
batteries dead flat, long after the light dims below full output (in
about three hours), to get five hours out of them.

Quoted message said:

I think what they really mean is the LED light is equivalent
in brightness to a typical 10-watt halogen light.

From my experiments with bike lights, I'd say there seems to be about a
two-to-one ratio of apparent brightness between LED and halogen lights,
so the 5-watt LED may well look as bright as a 10-watt halogen.

luxeonstar.comsub category.phpOpen ↗

For a *real* 10w equivalent LED headlight, see
http://www.nova-factory.com/headlight.html. Not cheap though.

Nick

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

Quoted message said:

The new Summer Performance catalog is featuring their new "ViewPoint GEN3"
single Luxeon LED headlight. They claim "10 watts plus" coming out of 4 AA
NiMH batteries that run 5 hours. There's a "Digital" model with 6 power
modes and 5 flashing modes ($140) and a "Non-Digital" model that runs 8
hours on "high" and 4 day on "low" ($60). The lights are made by Nite

Hawk.

Quoted message said:

I think what they really mean is the LED light is equivalent in brightness
to a typical 10-watt halogen light. By my math 4 NiMH AA at 1.2 volts each
will put out about 0.4 amps for 5 hours, which is really about 2 watts of
power.

Watts, in this application, is a unit of heat dissipation. The average LED
at maximum brightness produces about 1.4 milliWatts. You'd need over 7000
LED's to produce 10 Watts. Another draw-back is the light produced by an LED
is very directional. The trick designers use to make them good headlights is
reflector and lense design. I've got a Cateye Opticube and I love it. The
other posts had it right about rating output in Watts as deceptive. They
should rate them by lumens or candlepower.

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

Quoted message said:

For a *real* 10w equivalent LED headlight, see
http://www.nova-factory.com/headlight.html. Not cheap though.

Nick

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

Quoted message said:

The new Summer Performance catalog is featuring their new "ViewPoint

GEN3"

Quoted message said:

Quoted message said:

single Luxeon LED headlight. They claim "10 watts plus" coming out of 4

AA

Quoted message said:

Quoted message said:

NiMH batteries that run 5 hours. There's a "Digital" model with 6 power
modes and 5 flashing modes ($140) and a "Non-Digital" model that runs 8
hours on "high" and 4 day on "low" ($60). The lights are made by Nite

Hawk.

Quoted message said:

I think what they really mean is the LED light is equivalent in

brightness

Quoted message said:

Quoted message said:

to a typical 10-watt halogen light. By my math 4 NiMH AA at 1.2 volts

each

Quoted message said:

Quoted message said:

will put out about 0.4 amps for 5 hours, which is really about 2 watts

of

Quoted message said:

Quoted message said:

power.

El Calaverada said: "Watts, in this application, is a unit of heat
dissipation. The average LED at maximum brightness produces about 1.4
milliWatts. You'd need over 7000 LED's to produce 10 Watts. Another draw-
back is the light produced by an LED is very directional. The trick
designers use to make them good headlights is reflector and lense
design. I've got a Cateye Opticube and I love it. The other posts had it
right about rating output in Watts as deceptive. They should rate them
by lumens or candlepower."

P = IE Power equals current in amps times Voltage in Volts. Heat
disapation isn't part of the equation. There are many different rated
Light Emitting Diodes... some up to 5 Watts. Since they disapate very
little heat, most of the energy is radiated in light. Yes, designers
need to make the reflector aim the light in a most useful pattern.
Lumens or candlepower can help understand the light output, but you also
need to know the intensity across the pattern.... like a pencil beam or
a wide angle beam.

--

daveornee said:

P = IE Power equals current in amps times Voltage in Volts. Heat
disapation isn't part of the equation.

Unfortunately it is very much part of the equation. Even the best LEDs are
not much more efficient than high-efficiency filament lamps and to a first
approximation all of their power input is given out as heat.

One of the reasons there has just been such a quantum leap in LED light
output, is that in newer LEDs, the LED die (semiconductor part) is mounted
on a metal die that conducts heat away from the die much more efficiently
than can happen in old-style plastic-packaged LEDs that we are so
familiar with. They still have a plastic window to let the light out, of
course. New LEDs typically need to be mounted on metal heatsinks - like
power transistors.

Quoted message said:

There are many different rated
Light Emitting Diodes... some up to 5 Watts. Since they disapate very
little heat, most of the energy is radiated in light.

Red LEDs are typically much brighter than green LEDs with the same
wattage, even though our eyes are more sensitive to green - yellow light.

AC

Is there really such a thing as a 5 Watt LED? What materials are they made
from? Has someone come up with a new junction material capable of producing
5 Watts without applying a huge current? I haven't been involved in design
in quite a while, now I'm curious.

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

Quoted message said:

daveornee said:

P = IE Power equals current in amps times Voltage in Volts. Heat
disapation isn't part of the equation.

Unfortunately it is very much part of the equation. Even the best LEDs are
not much more efficient than high-efficiency filament lamps and to a first
approximation all of their power input is given out as heat.

One of the reasons there has just been such a quantum leap in LED light
output, is that in newer LEDs, the LED die (semiconductor part) is mounted
on a metal die that conducts heat away from the die much more efficiently
than can happen in old-style plastic-packaged LEDs that we are so
familiar with. They still have a plastic window to let the light out, of
course. New LEDs typically need to be mounted on metal heatsinks - like
power transistors.

Quoted message said:

There are many different rated
Light Emitting Diodes... some up to 5 Watts. Since they disapate very
little heat, most of the energy is radiated in light.

Red LEDs are typically much brighter than green LEDs with the same
wattage, even though our eyes are more sensitive to green - yellow light.

AC

El Calaverada said:

Is there really such a thing as a 5 Watt LED?

Yes - look up www.lumileds.com and www.roithner-lasertechnik.de

Quoted message said:

What materials are they made from?

Pretty much the same materials as the old LEDs. One point is that these
LEDs actually contain multiple junctions on each die. So in one sense
they're parallel LEDs. I think the major innovations are in the packaging
and thermal management.

Quoted message said:

Has someone come up with a new junction material capable of producing
5 Watts without applying a huge current?

No... LEDs used to use such a small current, because their light output
was quite low. They were bright enough to see, but not bright enough to
be seen by... Now that they produce a lot of light, they use a lot of
current to match. Power (watts) = Volts x Amps. 'owt for nowt, alas.

Quoted message said:

I haven't been involved in design in quite a while, now I'm curious.

They will take over the world. (I use them, but have no connection with
the company).

AC

Anonymous Cowar said:

daveornee said:

P = IE Power equals current in amps times Voltage in Volts. Heat
disapation isn't part of the equation.

Unfortunately it is very much part of the equation. Even the best LEDs
are not much more efficient than high-efficiency filament lamps and to a
first approximation all of their power input is given out as heat.
One of the reasons there has just been such a quantum leap in LED light
output, is that in newer LEDs, the LED die (semiconductor part) is
mounted on a metal die that conducts heat away from the die much more
efficiently than can happen in old-style plastic-packaged LEDs that we
are so familiar with. They still have a plastic window to let the light
out, of course. New LEDs typically need to be mounted on metal heatsinks
- like power transistors.

Quoted message said:

There are many different rated Light Emitting Diodes... some up to 5
Watts. Since they disapate very little heat, most of the energy is
radiated in light.

Red LEDs are typically much brighter than green LEDs with the
same wattage, even though our eyes are more sensitive to green -
yellow light.
AC

P = I*E are all electrical terms that do NOT include heat in the
equation. The input power... power required from the source is measured
in Watts. You arrive at the input power by multiplying Volts times Amps.
The frequency of the light and human perception of the brightness are
also important, but not part of the input power equation. Distribution
of the light is also important, but not part of the input power
equation. Point taken on LED efficiency compared to incandescents, and
the need to disapate heat. Light output and heat disapation are very
important, but not part of the equation.... that's my point. I stand
ready for more "illumination" on the subject.

--

AC,
Thank you for the info. Take care -

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

Quoted message said:

El Calaverada said:

Is there really such a thing as a 5 Watt LED?

Yes - look up www.lumileds.com and www.roithner-lasertechnik.de

Quoted message said:

What materials are they made from?

Pretty much the same materials as the old LEDs. One point is that these
LEDs actually contain multiple junctions on each die. So in one sense
they're parallel LEDs. I think the major innovations are in the packaging
and thermal management.

Quoted message said:

Has someone come up with a new junction material capable of producing
5 Watts without applying a huge current?

No... LEDs used to use such a small current, because their light output
was quite low. They were bright enough to see, but not bright enough to
be seen by... Now that they produce a lot of light, they use a lot of
current to match. Power (watts) = Volts x Amps. 'owt for nowt, alas.

Quoted message said:

I haven't been involved in design in quite a while, now I'm curious.

They will take over the world. (I use them, but have no connection with
the company).

AC