Frazer Monks of Exhibitas Design recently wrote to LEDs Magazine to explain his decision to stop specifying lamps based on white LEDs.
Read the Letter in full.
"As an exhibition designer and lighting specifier I have been a keen advocate of white LED lighting in exhibitions, but recently I have had to reconsider this decision," says Monks.
"There is an urgent need for the white LED lighting industry to develop a more transparent and meaningful framework for the specification and performance rating of white LED-based lamps.
"If this is not done then I believe that many of the developmental gains of the last few years may be squandered as users are put off by the poor performance of some products...
"I have been forced to replace whole lighting systems at my cost and consequently I have had to take the decision to not specify white LED lighting until such time as I can be confident in the specifications and lamp life.
"Unless the true performance of white LEDs can be dramatically improved or costs substantially reduced then this technology may yet prove to be a dead man walking."
Your comments on this subject are very welcome.
Wednesday, January 28, 2009
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17 comments:
I think the key is heat sink. I have made accelerated life tests for 1000 hrs at +55°C ambient, 120°C juncion temperature, on white light fixtures. The design allowed the LED work under the maximum junction temperature specified by the manufacturer. After the we coud not measure any decrease in light output grater than the measurement errors, 2%.
We manufacture LED light units for avionic applications, where reliability is one of the must and I can say that using white LEDs there is no criticality, but just in case that proper care is taken about heat dissipation, as I already mentioned in my presentation at LED 2004.
I see that You have used LED lamps with LEDs packaged in standard halogen lamp package and that's one of the big errors made by a big number of LED lamp manufacturers without sufficient technical knowledge of LED technology. For the best of its use LED lighting shall be apply differently to the standard lighting technologies, LEDs shall be properly packaged taking into account the heat dissipation criticality.
The same happened with CFL's, if there is one lesson to be learned in my opinion: stick with a brand/manufacturer you know and trust (have done business with before and who gives you good service/guarantee); if you "bet" on the new cowboys in town, realise you are in fact making a bet and might loose;
reliable manufacturers will also show you real testing data and can at least for some products give testresults from an independent test lab;
You failed to mention what you paid for the lamp and which manufacturer made the product. I think I can take a guess though. I'm constantly surprised that folks are irritated when they find out that the cheap lamp they bought from a no-name company from a third world nation doesn't meet their expectations. Would you buy an appliance or construction equipment in this manner? At the end of the day you get what you pay for, so please "buyer beware." Buy your LED lamps from manufacturers that already have been making lamps for a century, not some unknown company that shoved cheap LEDs into a tiny housing and called it good. By making the decision to shun a new technology because you got burned for not doing your homework is sad.
Can anyone list 5 manufacturers that they have confidence in the performance and quality of their products for those of us wishing to intorduce LED's into the marketplace for energy efficiency and O&M benefits. I'm with a large public utility and this is a big topic for us as we are pushed into producing greater energy reductions.
Trust the LED technology, if you buy the right product you will be very impressed with its performance. Just don't buy Chinese! The best products I have seen on the market thus far are the Cree/LLF downlight for new construcion, and for retrofit option the Array Lamps by Nexxus Lighting. Both are very impressive.
As other posts have commented, purchasing LEDs from well-known, well-respected, established manufacturers is much different from purchasing no-name LEDs from some fly-by-night company. There are hundreds of companies all over the world slapping cheap LEDs into cheap housings with cheap electronics. Most of these companies have given no thought whatsoever to heat dissipation and other issues that will affect LED lamp life, and use second rate LEDs to begin with. They are simply trying to grab a quick buck by taking advantage of the popularity of LED lighting. With LEDs, you really do get what you pay for. If the LEDs you are purchasing are really cheap, there are almost certainly reasons for that – and they are not reasons that will make your clients happy in the long run! Purchase from a reputable company like Color Kinetics; their equipment is more expensive, but well worth the premium compared to the cheap knockoffs I have seen.
Almost all of these comments are negative about chinese LEDs. I certainly understand the trouble that cheap components can get you into. Are there no trustworthy smaller companies that make reliable components that can be deployed in high quality lamps. Also most of these comments are not about failure rates of white LEDs. Am I to assume that the writer of the original letters experience with white LEDs is a fluke.
Doubt about performance of White LEDs or for that matter any LEDs for lighting are correct.Besides Phosphor Degradation,Power supply issues are equally ignored especially when the Supply Voltages are variable.In third world countries LEDs and CFLs face this problem.Clearly,Best brands of LEDs with best heat sinks will fail when Power Supply or the Electronic Ballast is not properly designed to ensure that lamp currrent and voltage demands are met within parameters permitted by lamp standards.
Last year I bought some white LED units with a standard E27 screw base from an unspecified supplier in China. I have had overheating failures with these fixtures, but I don't think that the entire technology is necessarily busted. These fixtures were poorly designed using existing parts. I suspect a better original design would mitigate the heat failure.
I also have some white LED accent strips I bought (from IKEA, of all places) around the same time. They have not suffered any visible degradation.
Name and shame. Who supplied your lights Frazer? Did they offer a warranty?
In 2008 I retrofitted GU10 1.8W LED`s from various suppliers [many Chinese] as recessed accent spots to a number of my customers. Within six months of normal domestic use the light output had degraded by some 30 to 60% I had to replace with GU10 CFL lamps. I now have a few 3W GU10 LED`s with improved heat sinks, these are on test, so far no conclusions. I agree that the products from established makers may be more viable with better heat sinks and electronics, but unfortunately most of these will physically not fit into the current generation of recessed spotlight fittings. So there is a huge opportunity missed to capture the large retrofit market. Perhaps some reputable suppliers will address this. I hope so.
David; UK
Pointing to a region and telling that all products originating from there are of low quality shows most of you do not really know the market, about 80% of LED dies are all made in Taiwan..and of superb quality, the next step, LED packaging, same issue..but the third step, making a workable light source out of this all is where the companies without knowledge fall from the boat, if you want to test some real quality products, made in Taiwan, and using original Cree chips..drop me a line at -henri at bit dot com dot tw- Cheers~~~
We are a manufacturer’s representative for a number of lines dealing with solid state lighting and for
the most part the biggest problem is that we (especially in North America) are addicted to “cheap”.
So we end up with products from China that are very inexpensive because a lot of corners have been cut.
I have looked into a number of lines looking to have their replacement LED bulbs marketed in North America
and the results have been shocking.
I have seen electrolytic capacitors in the power circuits which have a much lower life expectancy than the
LED, poor quality LEDs masquerading as brand names and exceptionally poor thermal management practices.
This all leads to a very disappointed consumer. If we would all realize that this is early days for this market and
shop with a more critical eye toward the quality we would be better served.
Trent Bradford makes a great point, as do others, about the quality of the electronic components used in the driver portion of the overall fixture. Let's face it people there are only a limited number of LED manufacturers out there, so we're pretty limited by the breadth of the offering. But all those other electronic components in their? Next time you're talking with your favorite LED luminaire manufacturer ask them about the rated lifetime of the electronic components in their drivers. Ask them if their manufacturer uses high quality components or if they allow substitutions to be made for components of "equal" performance. Ask them if they use MIL-SPEC components. MIL-SPEC means military specification, these are of significantly higher quality as they're designed to handle the rigors of battle.
LED lighting is still in its enfancy. There are no quality protocol throughout the value chain
and like a recent DOE report showed
a great number of LED Lamp literature is misleading or deliberate lie.
I have also rarely seen designers and engineers conducting product & process FMEAs with LED manufacturers to identify the potential failure risk at customer sides. Unless the LED industry and its customers adopt a more systematic approach to Quality, I am afraid that the " Hype" will generate frustration and dis-satisfaction.
Hello every body
I would like underline the following premise.
Any HBLED manufacturer states the following : "The lifetime of HBLEDs is primarily a function of their internal operating temperature. This is generally stated as an expectation that for a given temperature, in any batch of LEDs, 50% will have their light output degrade by 50% after 50,000 hours. The internal LED operating temperature in this application is within the bounds of a 50,000 hours life expectancy"
At LUMTEAM, our company, we are using only quality HBLED with certain origin from quality manufacturers (i.e. OSRAM-SIEMENS or PHILIPS)
Because we are concerned about life lasting of our luminaries with HBLED we are always following HBLED technology evolution to use last generation of products.
We dimension our thermal management in our products in a way that when product is working in an environment with a Ta=40°C ( for instance during the night in DUBAI) the temperature at the junction is always at least 30% lower than the limit.
So in a normalized environment with Ta=25°C we still are far away from critical situation for the thermal management of the HBLED we use.
Francesco Biasoli
LUMTEAM - France
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