Originally Posted by Tomwilllight
First: A WATT is a measurement of heat and describes an amount of increase. A watt of steam is the same increase as a watt in solid-state electronics. The higher the watts, the greater the heat produced. Sorry but that is not 100% accurate. A watt is not a measure of heat. A watt is standard unit of power (energy over time). The watt is used to specify the rate at which electrical energy is dissipated
Second: The problem for higher wattage LEDs is heat management. IC boards don't like heat. LEDs are mounted on IC boards. No, not all LEDs are mounted directly to the IC/PC boards that carry the power management circuits. Many LED chips are mounted directly to heat sinks and have the IC/PC boards mounted remotely. The Luxxo Lamp is built like this.
Third: The heat generated by an LED is located in the IC board and must be removed to avoid damaging the circuitry. This damage, if allowed to continue, leads to rapid deterioration in the LED performance. No not 100% true. See my note above. Also, the heat produced at the junction of the LEDs and their mounting can be problematic to the phosphors that are used to shift the colour output to the white spectrum. In fact, the heat issue (if you will call it that) is more problematic for phosphors than it is for IC circuits.
The Problem: How to wick the heat away from the IC board? Obviously, water works well as do fans, particularly if you have the amount of room an automobile engine has to work out it's heat production problem. Fans can work, and I have some fan cooled LED A-Lamps here that are amazing. I am also working with closed circuit nitrogen filled cooling systems for very high output LEDs. Very cutting edge stuff, and much more effective than H2O.
I sat in on a meeting last week where a LED engineer briefly considered cooling LEDs with water in Industrial and Theatrical lighting applications. He admitted that water and solid-state circuitry do not mix very well and that the amount of plumbing necessary to cool LEDs in those applications didn't make much sense either. Watch what happens in that segment with nitrogen and other super conductive liquids.
... The way to make heat sinks more efficient is to make them BIGGER and to assist them with MOVING AIR. Not necessarily, special alloys are effective as well as other techniques. The air takes away the heat from the larger service and cools the heat sink which can then take up more heat and so on. There is also the ability to transfer heat away from the body of the lamp with physical conduction. Where the body of the lamp comes into contact with the body of the fixture. Most of our discussion, to this point, has been about the use of RETROFITTED MR16 sized LED lamps in existing MR16 landscape fixtures.
Please correct me if I am wrong, but I don't recall ever seeing a MR16 fixture designed for the landscape that was not sealed against the elements. The goal is: NO exchange of hot air inside with moist air from the outside. There are a few MR16 fixtures on the market that are open design. Nighscaping, Kichler and Unique all have them.
Landscape lighting fixtures are designed to handle very high heat. Why? Halogen lamps love heat. They are designed to run hot, because the heat makes the Halogen Cycle work. If you want to use a LED Retrofit MR16 lamp in a landscape fixture you must deal with the heat build up inside the sealed fixture. Or you have to use a lamp that is capable of operating in those conditions, like the Luxxo LED MR16 lamp is. Also the CRS products work find in enclosed fixtures.
In a sealed landscape lighting fixture, there is no cooling air flow over the heat sinks which makes the built in heat sinks virtually useless. Not entirely true. It all depends on the heat sinks, conductivity between lamp and fixture, volume of internal atmosphere, and the materials that the fixture is made of. Slowly the air inside gets hot, there is no exchange of cool air for hot air and the inside gets hotter. Add a hot day followed by a hot night and you have a hot fixture which will eventually exceed the design limits of the LED MR16 IC board. Again, it is not necessarily the case that the LED chips are mounted to the driver's IC board. This is NOT the case with the Luxxo LED MR16.
How to fix the problem?
And we have a market share problem too. We just donít buy enough lamps to interest major lamp manufacturers. Really?? I think that outdoor lighting makes up a significant share of the MR16 lamp market, certainly enough to be noticed. Also, these lamps are not ONLY suitable for use in outdoor lighting systems. They fill many niches in many categories and will become more suited to more applications as the technology is advanced and improved.
As I understand it, by far the greatest use of MR16's is for commercial Retail and Display applications. Landscape Lighting is a relatively minor segment of the MR16 lamp industry. We are a sideshow in the lamp manufacturing world. MR16s are a very common lamp for residential interior applications too. As a whole, they are a very common spec. throughout the world.
The designer/engineers of the LED MR16 retrofit lamps have a number of serious problems to deal with. The LED manufacturers' want a piece of the giant MR16 market. The retail managers want to save money and labor. The LED manus need to produce lumen and life numbers that suggest that it makes economic sense to spend 10 to 15 times more than the cost of a generic MR16 that will last a year. They are most certainly not that expensive! New ratings and measures are being introduced by IES and others that will help in leveling the playing field when it comes to listing efficacy, output, efficiency, etc. (The L70 is but one example)
In addition, everybody likes the small size of the MR16. We certainly do.
All of the recently released MR16 LED retrofits Iíve seen have integral heat sinks. The heat sinks canít be too big because the retrofits could quickly become too large to replace the MR16. If they are too small, the LEDs fail prematurely. Not ALL fail prematurely! Some actually operate, while in enclosed fixtures, at or significantly below the LED chip manufacturers max operating temperature. It is possible to make these things function.
Even in those applications, we are hearing a lot about very early failures. Why are they predictions for long life and increased output so far off the reality? Mostly because a lot of the product on the market is clone and 'no-name' product from unknown SE Asian factories. Just like the first wave of popular CFL products, these manufacturers are long on claims and short on quality control. They play fast and loose with the numbers and flood the market with junk. That does not mean that Quality product is not available. Kumho & CRS are on the leading edge of engineering and manufacturing in this category.
The LED designer/engineer test their designs in a lab and use meters to prove what their bosses want to hear. It works in the air-conditioned labÖ it should work in the real worldÖ Right? Wrong!!! How would you know? How many years of shop testing have you done? How many hundreds of LED lamps have you tested and vetted? How many thousands of LED lamps have you installed? Is your opinion based on any real life experience, or simply conjecture and vague, outdated reports?
The Manufacturer, certain they will make a sell a gazillion, advertise the best possible lumen, life and cost numbers. They need the inflated results to compete with a very mature technology that works very well - the MR16 Halogen lamp. I won't argue that the MR16 Halogen lamp is not an excellent product, I still use them by the thousands every year. But to say that ALL LED lamp manufacturers have it wrong, inflate their numbers, mislead and misrepresent is a very negative, and wrong generalization.
Solution - from what I hear and read - the manus and their engineers haven't come up with a solution that is proven to hold up in the real world of retail/display applications or in the landscape. I guess you have not spent much time with Kuhmo, CRS, and (suitable for interior fixtures) Lamina & Ushio then. They all have fantastic products that have unique solutions.
James, a courageous innovator by any measure, (Thank you Tom,) is reporting his success with a particular line of retrofit LEDs. He is the only user of retrofit LEDs in North America I know of who gets such good results. I assure you there are others! He lives and works in Canada, in a resort community that has a relatively short season (compared to Florida or North Carolina or even NY's Hamptons). Our climate here is not at all different from anywhere in the Northern Half of the United States! Heck it is pretty much Identical in climatic and weather conditions to where you are from Tom. I believe itís because his short season Same length of season as anywhere else Tom... 365 days in the year even here in Canada! and relatively low ambient temps at night Again, same temperatures here as in most of the United States, even in the summer, reduce the stress on his LED products and significantly delays their failure. The product I use is not only being produced for and used here in North America. In fact the lions share of the product is used throughout all of Asia and Europe, in all climatic zones. Lets not for a moment suggest that I live in some micro-climate zone that is uniquely adapted to the operation of LED lamps! The things work... period... why do you have such a hard time accepting that fact?
I believe the challenge for our industry is to create fixtures that work with LEDs. I believe the answer to LEDs in the landscape is in very well designed and dedicated LED fixtures. We need to make them to match our environmental and economic challenges, not the retail marketís. I believe that there is a place for LED fixtures too, but significant hurdles will have to be overcome. They need to be field serviceable for one and their designers and engineers need to accept that function cannot over ride form at every turn.
The market for LED lamps far outstrips that of LED fixtures, and it is this potential market that will continue to drive the research and development into successful LED lamps for years to come.
Of course, this will change the design/install industry. The MR16 is difficult to give up for many reasons: their small size and low unit cost. The good profit from replacing the dead, the quality of their light, and the incredible number of ways we've learned to modify their output to match our design goals. I will miss the MR16.