PDA

View Full Version : The Latest on LED Lights


steveparrott
05-13-2007, 07:37 PM
Hi Gang,

Just came back from LightFair where I attended all the LED workshops and seminars and got the low-down from researchers and manufacturers. Here's a few points that might interest you.

1. LED research has progressed very rapidly and LED manufacturers have suceeded in creating highly efficient, very bright and long-lasting LED's. From an efficiency stand-point they are now equivalent to compact flourescents. In brightness, they are making LED arrays comparable to 35w MR-16's. Lamp-life is expected to approach 100,000 hrs. But. . .

2. Heat. Heat is the number one problem with LED's. One early LED fixture from a major manufacturer has already been pulled from the market because of failures. It takes some pretty sophisticated engineering and a lot of metal to conduct heat away from LED components. Many fixtures on the market today will have lamp lives in the range of 10,000 to 20,000 hrs. instead of their promised 100,000 hrs because they fail to dissipate heat sufficiently. Contractors and Architects purchasing LED fixtures today have no guarentee that the fixtures will perform anywhere near the specifications.

3. Color. LED manufacturers have succeeded in developing a fairly good white light from LED's. They do this by starting with a blue LED chip and coating it with a phosphor. Unfortunately, the phosphor coating tends to be inconsistant resulting in slightly different colors from chip to chip. Also, the blue LED varies in color from batch to batch. To address these variables, manufactures measure the LED colors and put matching chips into certain bins. When they sell a bunch of LED's, they try to take them all out of the same bin so the colors will be fairly close. But when you as a contractor go to buy say, 20 LED fixtures, the lamps may have come from different bins and the resulting light may be noticably different from fixture to fixture. One designer showed us photos of projects where LED's where used as wall washes; the beam colors varied haphazardly and the result was awful. As the technology develops, these color inconsitencies will become less, but researchers seem to be years away from that time.

4. Throw-away's. You may not have noticed, but lighting manufacturers selling LED fixtures do not also sell replacement LED's for those fixtures. Why? Because the LED's are supposed to last over 10 years. Why does this bother me? First, no one really knows how long the LED will last. (Note: LED's are only tested for 6,000 hrs. The lumen deprication curve is then extrapolated to 70% to estimate the life.) LED's can also break and need replacement. LED's are also getting better; maybe you'll want to swap out this years LED's for the next years. Also, remember that LED's don't burn out, they get dimmer. How many homeowners will want to discard their expensive fixtures just because they're a little dimmer? More likely, the homeowner will gradually get more and more dissatisfied with the lighting design; she will live with the diminished lighting for a long time. It would bug me as a designer to think that many of my designs will gradually degrade instead of maintaining the same level of brightness.

In conclusion, one of the researchers put it this way to the group of manufacturers and designers in the room (I'm paraphrasing). "You are the early adopters and I commend you for that. Understand, however, that you will not get the results you expect. It will take 5 to 10 years for LED's to become standardized to the point where they can be specified for lighting with confidence."

My advice to contractors at this point is to be very very wary of these new LED fixtures. I would certainly never use them in a big or important project.

Chris J
05-13-2007, 08:15 PM
Very interesting. It leaves one to ponder whether or not he/she will delve into this area heavily and market the technology, or wait until the technology is more consistent and marketable without hurting ones reputation. Did you happen to talk to any of the Kichler people about their LEDs? Were any of the Nichia reps there? Nichia, in case you didn't already know, is the company responsible for developing the LED's for Kichler. They are also the people responsible for the back-lights in most cell phones on the market.
Thanks for the great insight on the subject.

NightScenes
05-13-2007, 08:41 PM
Steve, I'm glad to hear someone actually talking frankly about LED. I know that LEDs will someday be ready to use in professional lighting but I also know that it's got a long way to go. I have yet to use any in my projects and was thinking about using a couple in a water feature. I think I will probably use fiber optics or MR11s as I know what to expect from them.

steveparrott
05-13-2007, 08:44 PM
Nichia is one of the key LED innovators that's been making breakthroughs left and right; Cree, Seoul Semiconductors, Lumileds and Osram and others are right up there. I spoke with all of them. One of the problems they face is that all this new technology is proprietary and they are rushing to patent every new design and advancement.

As a result, all the LED structural configurations are different and fixture manufacturers need to marry with one of these LED manufacturers and one of their LED designs to engineer their fixtures.

Do you remember 8-tracks vs. casettes? Just as 8-track dissapeared leaving manufacturers with obsolete 8-track players, certain LED designs and manufacturers will fall out of favor and fixture manufacturers may need to write off their engineering investment as they retool for whatever rises to the top.

Eventually LED's may become standardized in the same way that incandescents did, but some forecasters say they may not (because of their long lives).

Frog Lights, LLC
05-14-2007, 10:47 PM
Steve
Our company has been selling LED's for 3 years now. We have found that the voltage regulation has been the main failure facture. This has not been a major problem, however. We have not had a problem with heat. If it is configured for 12VAC , that is the voltage not more or less. Our new LED Paver Bricks that are sold in shapes to avoid cutting the pavers, have a life of 100,000 hours ! We warranty that! Low power drain average 1.3 watts, completely sealed , waterproof, stainless steel body, UV stable frosted glass with no "hot" spots or glare like a tail light. Please watch for ads in upcoming trade magazines. LED's are here now and they have their place. We stock direct replacement LED MR 16 bulbs, if any of you would like to try them.
For the record the NY lightfair was not very impressive as compared to the Hong Kong or European shows.

ChampionLS
05-15-2007, 04:14 AM
Oh... I'm sorry. Did I miss something? :dizzy:
You mean this stuff? I think you left out one very important fact. NONE of this stuff is UL listed. Since this junk is manufactured with no design protocol, these items usually have inferior wiring, ratings, safety concerns and lack of manufacturer support. It is up to the end user to guess at what wire and transformer will work best, or how to connect 28 Gauge "headphone" wire to standard LV circuit cable. I really like the paver light with the red fuzzies on it.:laugh:

ALL Evening Star Lighting's products are cULus listed, can be installed into any paver- not just limited to geometric shapes, and the same unit is available for wood or composite decking and docks. Our down loadable brochures and instruction sheets are available on the website, or in print form from any of our dealers. Everything we sell and manufacture is proudly made in the USA :usflag:

Visit the Hardscaping threads to see the Evening Star difference. Decide for yourself :rolleyes:

www.eveningstarlighting.com

Chris J
05-15-2007, 06:33 AM
Now, now boys... Let's not get fussy. Since everybody has a disco-dance floor, why don't we all just get jiggy?

steveparrott
05-15-2007, 07:25 AM
I think all manufacturers of outdoor LED fixtures should think twice about providing any warranty for their devices. Two major manufacturers (beginning with H and K) have already pulled their early LED models due to early failure.

I have to chuckle when manufacturers claim their LED fixtures will last 10 to 15 years. Forget about what happens to the LED; powder coated aluminum, copper and even brass won't last 10 years in a corrosive environment - they will be chipped, pitted, cracked, broken etc. Also, don't forget that the LED circuit and power supply have connections that corrode with time.

Also, keep in mind that LED life is set at the time when luminosity diminishes to 70% of the the initial level. If a manufacturer claims that their fixtures have been operating fine over a period of years, I'd like to know if they used a light meter to measure footcandles initially and as time progresses.

LED warranties are meaningless unless manufacturers provide an initial footcandle reading and if homeowners have a light meter to determine when the 70% level is reached - pretty ridiculous, don't you think?

Frog Lights, LLC
05-15-2007, 11:48 AM
This is not our merchandise! But nice pictures!!!!!

Duekster
05-15-2007, 12:25 PM
I like LED's too but the price is high. They need to make a DC Transformer and keep the rectifier in one location and IMHO this will bring down the fixture cost.

David Gretzmier
05-15-2007, 01:50 PM
my problem with led's is the color. I've yet to see an led that did not seem harsh to the eye, whereas low voltage halogens seem to look pleasing to the eye. I have heard about "warm white LED's" but never seen one. maybe they are better.

aside one- led's do work great for flashlights. I have a cree 1watt LED fenix p1-d, about the size of a tube of lipstick, and it is an awesome light, actually brighter than a 20 watt mr16 !

aside two- those brick lights look kinda funky, and break my rule for landscape lighting, don't see the source, see the effect. the effect of brick lights are??? a lit up brick? my goal is to light the path or drive. and not see the bulb. I'm sure they have thier place, but LED brick lights are like two negatives in one for me, but remember- THIS IS JUST DAVE'S OPINION.

steveparrott
05-16-2007, 09:21 AM
The bluer white LED's (higher color temps) have better color rendering indexes (CRI). They are also more efficient and have higher light output.

The warmer LED's that approximate incandescent color temp, have lower CRI, meaning that objects they illuminate look slightly off-color. They also tend to show color inconsistancy at the edges of the beam (brownish).

I haven't seen a side-by-side comparison of LED vs. incandescent on plant material, but I'm guessing that the greens will look significantly different. This is because LED chromaticity curves have a sharp spike in the blue region, a dip in the blue-green, then increase to a wide swell in the yellow-orange-red region. This compares to incandescent that starts low in the blues then steadly increases to max out in the reds.

When I get a chance I'll take some side by side photos to compare.