Cree LED lamp 200 lumens per watt

[russ]

An article from Extreme Tech about Cree's latest LED lamp

http://www.extremetech.com/electroni...n-per-watt-led

From the Cree site the specifications http://www.cree.com/led-components-a...g/XLampMKR.pdf

[SunEagle]

An article from Extreme Tech about Cree's latest LED lamp

http://www.extremetech.com/electroni...n-per-watt-led

From the Cree site the specifications http://www.cree.com/led-components-a...g/XLampMKR.pdf

I have seen that article before and it looks like a breakthrough in LED technology. I believe that Sylvania is working on a version to be used in homes that will just screw into an existing fixture.

[Sunny Solar]

Philips are just about to release into the consumer market a 200 lumens per watt lamp thats a direct replacement for CFLs.

[Sunking]

Well the new CREE lamps do set records of 200L/W in the lab but in practice are only 100W/L. Unless you live in the Artic and sub zero temps you are not going to be able to get that efficiency. The article clearly points that out. Of course the other thing that most folks over look when looking at L/W in LED's is the focal angle is vary narrow, unlike spherical like a Florescent or Incandescent and that makes a HUGE DIFFERENCE.

Give you an example using T5HO Fluorescent. T5HO has a true Efficacy of 90 to 105 L/W spherical measurement . Put them in a reflector to match LED focal angles and you jump up to 400 L/W when using LED tricks of stating Efficacy. You have to compare Apples to Apples. So in reality LEDs are not much better than incandescent and have a long way to go. Right now it is all Hype, Smoke, and Mirrors.

[SunEagle]

Well the new CREE lamps do set records of 200L/W in the lab but in practice are only 100W/L. Unless you live in the Artic and sub zero temps you are not going to be able to get that efficiency. The article clearly points that out. Of course the other thing that most folks over look when looking at L/W in LED's is the focal angle is vary narrow, unlike spherical like a Florescent or Incandescent and that makes a HUGE DIFFERENCE.

Give you an example using T5HO Fluorescent. T5HO has a true Efficacy of 90 to 105 L/W spherical measurement . Put them in a reflector to match LED focal angles and you jump up to 400 L/W when using LED tricks of stating Efficacy. You have to compare Apples to Apples. So in reality LEDs are not much better than incandescent and have a long way to go. Right now it is all Hype, Smoke, and Mirrors.

There light in there somewhere between the smoke and mirrors.

[inetdog]

Of course the other thing that most folks over look when looking at L/W in LED's is the focal angle is vary narrow, unlike spherical like a Florescent or Incandescent and that makes a HUGE DIFFERENCE.

Give you an example using T5HO Fluorescent. T5HO has a true Efficacy of 90 to 105 L/W spherical measurement . Put them in a reflector to match LED focal angles and you jump up to 400 L/W when using LED tricks of stating Efficacy.

i have to take exception to that statement. The lumen is a measure of the light output (luminous flux) of a source and is totally independent of the spatial distribution of that light. So purely in terms of light output, for a given lumens/watt figure (luminous efficiency) the amount of light produced by two light sources with the same lumens/watt rating and the same power input will be the same.

Now it is absolutely true that for actual practical amount of light where you want it, you have to look at the distribution of that light output. But that does not affect the lumens/watt rating, just what sort of fixture or application a particular bulb is best for.

A T5, or any linear fluorescent, is best for delivering uniform light over a wide area, and without distinct shadows like you would get from a point source. To the extent that light from the "back side" of the tube is not delivered to where you want it, it will produce less usable light, but that will not change the lumens/watt figure, and potentially makes the linear fluorescent appear better than it really is.

Most CFLs produce something like a uniform light output over more than a half-sphere. Only off the very back of the CFL where the socket and the ballast block the light will you get low delivery of light. Because of that CFLs make a good replacement in a fixture designed for a type A (round) incandescent bulb.

An LED bulb that delivers light mostly in one direction (directional but not narrow, like the beam of a reflector-flood type incandescent) will not work well in a table lamp or other fixture that depends on light output in all directions (and in particular downward past the base.) An LED bulb that delivers light from a band of LEDs around the bulb axis will illuminate the shade of a table lamp, but deliver almost no light out the top or the bottom of the shade.

It is indeed harder to get an LED replacement bulb to deliver light uniformly in all directions that way a round incandescent bulb would, but that just means that you will have to choose carefully what kind of fixture you use them in. For use in a gooseneck desk lamp, with a not particularly good white reflector and for use as a work light on a a desk surface, a half-sphere or less LED may be exactly what you want, and better than either a CFL or an incandescent.
For a base-up globe lamp in a chandelier high above a floor, a half-sphere LED bulb may give plenty of light down to the floor, but not be nearly as aesthetically pleasing.
When used base-down, that same LED bulb will be a disaster unless you only want to light up the ceiling.

Now where the big smoke and mirrors trick really comes in, in my opinion, is when, instead of luminous efficiency (measured lumens/watt), the figure luminous efficacy (perceived lumens/watt) is used. (And I did notice that you used the word "efficacy" but without explaining.)
That figure assumes that light delivered at a frequency to which the eye is most sensitive will be more valuable than light delivered over a broad spectrum. That may be true if all you are interested in is distinguishing shapes or detecting motion. (Security lights maybe) But, again, for real world lighting where perceived glare, color fidelity, and many other factors are important, that figure is truly, in my opinion, a crock.
At this time fluorescents seem to have the edge in color fidelity, if made for that purpose with proper phosphor combinations. And even fluorescents or LEDs with a high Color Rendition Index (CRI) can be very poor for particular applications such as digital or traditional film photography.

[Sunking]

Now it is absolutely true that for actual practical amount of light where you want it, you have to look at the distribution of that light output. But that does not affect the lumens/watt rating, just what sort of fixture or application a particular bulb is best for.

A T5, or any linear fluorescent, is best for delivering uniform light over a wide area, and without distinct shadows like you would get from a point source. To the extent that light from the "back side" of the tube is not delivered to where you want it, it will produce less usable light, but that will not change the lumens/watt figure, and potentially makes the linear fluorescent appear better than it really is.

Well MR Prosecutor you just made my case and point. I rest my case and turn it over to the Jury.

You just said what I have always said about LED's. They are great for task specific applications like flashlights, signal lights (not head lights), and reading lights, but still no where close to be used in area lighting. Th eUS Fed still prohibits their use in any public building for area lighting because they are too inefficient.

[SunEagle]

Well MR Prosecutor you just made my case and point. I rest my case and turn it over to the Jury.

You just said what I have always said about LED's. They are great for task specific applications like flashlights, signal lights (not head lights), and reading lights, but still no where close to be used in area lighting. Th eUS Fed still prohibits their use in any public building for area lighting because they are too inefficient.

And yet they are being used in Casinos, hotels, street lighting and my home.

I understand your position but I believe there will be a place for these type lamps. There was the same thinking when HID first came out that they would never replace fluorescent. But the Mercury were replaced with Metal Halide and Sodium which easily showed they were more efficient than the older hi output fluorescent. Now the T5 took back first place as a general lighting type fixture. Whose to say that LED's won't pass them in time.

[inetdog]

Well MR Prosecutor you just made my case and point. I rest my case and turn it over to the Jury.

You just said what I have always said about LED's. They are great for task specific applications like flashlights, signal lights (not head lights), and reading lights, but still no where close to be used in area lighting. Th eUS Fed still prohibits their use in any public building for area lighting because they are too inefficient.

I think that you will either be tarred and feathered on general principles or be the beneficiary of jury nullification, depending on how the jury selection goes.

Even from you, I will not go along with incorrect statements of fact, no matter how much I agree or disagree with the conclusion you reached.

Oh, and on another digression:

still nowhere close to be used in area lighting.

For the most part neither are CFLs, but for areas where there are already fixtures for linear lamps, fluorescents certainly seem to be the way to go. They just will not be screw-in replacements for incandescents in the typical home.
(And, no I am not going to branch out into light bulb jokes.)
The only two legitimate reason I can see for replacing linear fluorescents with LED strips.
One is if you want the color control of RGB fixtures for mood lighting, and the other is if you need flicker free dimming.

[SunEagle]

I think that you will either be tarred and feathered on general principles or be the beneficiary of jury nullification, depending on how the jury selection goes.

Even from you, I will not go along with incorrect statements of fact, no matter how much I agree or disagree with the conclusion you reached.

Oh, and on another digression:

For the most part neither are CFLs, but for areas where there are already fixtures for linear lamps, fluorescents certainly seem to be the way to go. They just will not be screw-in replacements for incandescents in the typical home.
(And, no I am not going to branch out into light bulb jokes.)
The only two legitimate reason I can see for replacing linear fluorescents with LED strips.
One is if you want the color control of RGB fixtures for mood lighting, and the other is if you need flicker free dimming.

I actually replaced a number of 2 foot and 4 foot fluorescent lamps with LED tubes that fit perfectly into the tombstones. I just cut out the ballast and run the 120volt directly to the LED tube. The 4 foot are 18 watts and the 2 foot are 8 watts. I only use one 4 foot lamp instead of two in the fixture. The 4 foot fixtures had 2 34 watt lamps and ballasts so a total of about 80 watts down to 18 is still a great deal.

The original 2 foot were 20 watts so with the ballast about 22 total. Going down to 8 watts and getting plenty of light.

[inetdog]

The original 2 foot were 20 watts so with the ballast about 22 total. Going down to 8 watts and getting plenty of light.

Glad to hear that it worked out for you. What kind of fluorescents were you replacing?
I am not stating the following as fact, or saying that I feel it is a show stopper, but on another forum it was pointed out that removing the ballasts and/or modifying the wiring to the tombstones voids the UL listing of the fixture.

[SunEagle]

Glad to hear that it worked out for you. What kind of fluorescents were you replacing?
I am not stating the following as fact, or saying that I feel it is a show stopper, but on another forum it was pointed out that removing the ballasts and/or modifying the wiring to the tombstones voids the UL listing of the fixture.

The old lamps were your run of the mill 4 foot 34 watt fluorescent lamps used in a 2 lamp surface mounted fixture. The 2 foot were the 20 watt in a surface mount fixture in my closets and pantry. The ballasts were the older oil type installed in 1988.

As for voiding the UL listing, not something that I wanted to do but at the time I did it back in 2009 there wasn't any reference to that. The tombstones can handle more than the 120volts and all wiring had 600volt insulation rating along with all wire terminations so the fixtures are acceptable to me.

[Sunking]

I understand your position but I believe there will be a place for these type lamps.

There already is a place for them and right now, Task Specific. I am certain in due time LED's will be used widely for area lighting. Right now in the home some excellent uses are under counter lighting, reading lamps, accent lighting, security, and landscaping are a few that come to mind.

The two benchmarks I look for as a Professional is when the day comes when the ILS association and the EIA adopt them for area lighting in both private and public buildings. As of now that day has not come. But FWIW I think that day will come within 5 years.

[Sunking]

The only two legitimate reason I can see for replacing linear fluorescents with LED strips.
One is if you want the color control of RGB fixtures for mood lighting, and the other is if you need flicker free dimming.

Well I can tell you one other already in commercial operation. Go to any Walmart, walk to the refrigerator units like the Frozen Food section or Milk Fridge and you will see LED strips used. There is one catch you should take note of with that. As you know heat is the killer of LED lighting, and those LED strips are kept cold.

Heat is one of the tricks LED manufactures use to make their LED's look better than what the real application L/W efficiency is. When they test, they use full forward current in very short pulses in a controlled environment so as not to allow the LED to heat up. When a LED heats up, it intensity decreases significantly and kills the operating life time. Keeping LED cool is a major challenge, and in some cases warm enough like when used in Auto Head Lamps not to get too bright in winter or too dim in summer.

[SunEagle]

Well I can tell you one other already in commercial operation. Go to any Walmart, walk to the refrigerator units like the Frozen Food section or Milk Fridge and you will see LED strips used. There is one catch you should take note of with that. As you know heat is the killer of LED lighting, and those LED strips are kept cold.

Heat is one of the tricks LED manufactures use to make their LED's look better than what the real application L/W efficiency is. When they test, they use full forward current in very short pulses in a controlled environment so as not to allow the LED to heat up. When a LED heats up, it intensity decreases significantly and kills the operating life time. Keeping LED cool is a major challenge, and in some cases warm enough like when used in Auto Head Lamps not to get too bright in winter or too dim in summer.

You are correct about the heat. All of my screw based or GU10 base type LED's have radiator fins built into the lamp. They do stay very cool though, enough for me to easily unscrew or twist off without burning my fingers like an incandescent or CLF type lamp. Of course they are only about 2 to 4 watts each.