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  • LED lighting

    Any recommendations for LED lights. I have 3 ceiling cans that I have CFL's (20 wt) now, that I would like to use LED in.
    Thanks
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  • #2
    LED's in ceiling can lighting

    I worked in the LED business for the past 3 years, there are some strides in output per watt. This field is growing with great strides. The biggest problem is cooling.
    We manufacture lights for aircraft, and while most of these were configured to run off of 28Volts DC we did make some for 120 Volts AC @ 400 Hz
    The problem is current control with each LED or string of LEDs.
    While it is true most white light LED's forward voltage is about 3.5volts the way in that the current is controlled varies a lot. There are many getting into this field but mostly it is the commercial applications is where you will find the "good stuff". These screw in LED bulbs for 120 VAC leave much to be desired and while a CFL may seem "low tech" they are still very good at converting watts to lumen's
    Color temperature is another factor to look at in selecting any lamp other than a incandescent The lower the number, the warmer the color. (2700 K is very warm and pleasing)
    White LED's are basically blue LED's with a phosphor dot that emits the white light (much like a fluorescent uses the UV spectrum to excite the phosphor coated tube.)
    If your ceiling cans are purpose built to accept only a proprietary lamp (Bi or Quad pin) then you will be waiting a long time and would need to change out that fixture for another as these have their own (ballasts) control circuitry made just for the one lamp type. If they have a standard light bulb socket, you do have some options out there, although I have yet to see any that really "shine" pun intended.

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    • #3
      Hey, thanks for the info.

      Yep, biggest problem is cooling the LED. Costco just had to to a big refund to folks who got LED bulbs, and the only lasted a couple of months.
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      • #4
        Originally posted by ed2kayak View Post
        Any recommendations for LED lights. I have 3 ceiling cans that I have CFL's (20 wt) now, that I would like to use LED in.
        Thanks
        Have a look my LED lamp. The long one is 1,2m. The shorter one is 90cm.
        Attached Files

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        • #5
          It looks very bright. Did you make it yourself? How many LED's?
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          • #6
            Led Lighting is lighting which solely makes use of LEDs, small lights, often assembled in groups of 18, 21 or more in one led light bulb. However more lamps don
            Last edited by Mike90250; 03-22-2010, 09:47 AM. Reason: remove click sig

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            • #7
              The problem with LED's are many but the 5 biggest are:

              1. Cost.

              2. Efficiency is exaggerated and does not conform to NLI standards. As mentioned the problem is with the driver circuits and heat. You will see claims as high as 100+ Lumens per watt. When the ballast or driver power is included as with all other lighting, the efficiency is not much better than incandescent

              3. Next on the efficiency hit list is LED's produce the highest output when they are cold. So when the measure the Lumen output with a very short pulse of a few milli-seconds so the light does not warm up. Once the light warms up in real use, the output drops considerable.

              4. Last on the efficiency list is the directional nature of LED light and where they take the measurement. They measure on the lights focal spot. Move a few degrees in any direction and the light falls off the cliff. Great for flashlights and effect lighting, terrible for indoor area lighting.

              5. Color Rendering Index. LED's CRI is horrible with an extreme amount of Blue light pollution.

              The most efficient lighting one can use in your home is fluorescent T5 tubes which has a true 100 Lumens per watt and excellent CRI. Next in line is CFL of 60 to 80 Lumens per watt, and then LED with a real rating of around 30 to 6 Lumens per watt.
              MSEE, PE

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              • #8
                Retail Lighting?

                [QUOTE=Demetriusalwyn;8127]Led Lighting is lighting which solely makes use of LEDs, small lights, often assembled in groups of 18, 21 or more in one led light bulb. However more lamps don

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                • #9
                  Originally posted by Sunking View Post
                  The problem with LED's are many but the 5 biggest are:

                  1. Cost.

                  2. Efficiency is exaggerated and does not conform to NLI standards. As mentioned the problem is with the driver circuits and heat. You will see claims as high as 100+ Lumens per watt. When the ballast or driver power is included as with all other lighting, the efficiency is not much better than incandescent

                  3. Next on the efficiency hit list is LED's produce the highest output when they are cold. So when the measure the Lumen output with a very short pulse of a few milli-seconds so the light does not warm up. Once the light warms up in real use, the output drops considerable.

                  4. Last on the efficiency list is the directional nature of LED light and where they take the measurement. They measure on the lights focal spot. Move a few degrees in any direction and the light falls off the cliff. Great for flashlights and effect lighting, terrible for indoor area lighting.

                  5. Color Rendering Index. LED's CRI is horrible with an extreme amount of Blue light pollution.

                  The most efficient lighting one can use in your home is fluorescent T5 tubes which has a true 100 Lumens per watt and excellent CRI. Next in line is CFL of 60 to 80 Lumens per watt, and then LED with a real rating of around 30 to 6 Lumens per watt.
                  I concour
                  Additionally, depending on the driving frequency verses pure direct current some LED drivers actually create a strobing effect and or a noise, that may be audiable and also cause radio frequency issues as well. LED's have a very fast rise time, meaning they go from an off state to full on in very short time, by comparison a filament based lamp is like waiting for the stove to cool down.
                  These inherant idiocyncries give lamps there unique qualities, and should be factored in when given a particular application.
                  Seldome, other than the inexpensive LED battery powered flashlight (torch for our UK friends) are LED's driven directly without some type of additional circuitry.
                  Indeed it is when LED's went from indicator duty to the sighnage, and now general illumination role where the quest to boost the lumen output has created some very interesting challanges!

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                  • #10
                    I know this thread is old, but I can't help myself

                    Originally posted by Sunking View Post
                    The problem with LED's are many but the 5 biggest are:

                    1. Cost.
                    Agreed.

                    2. Efficiency is exaggerated and does not conform to NLI standards. As mentioned the problem is with the driver circuits and heat. You will see claims as high as 100+ Lumens per watt. When the ballast or driver power is included as with all other lighting, the efficiency is not much better than incandescent
                    This is a terrible overstatement of the problem. LED manufactures typically DON'T MAKE the current regulators that are required to run their product. They are rating their product and not the SYSTEM you buy, and it's the SYSTEM you must compare to get apples to apples. You could well be right on the money as far as the terribly conceived and built "replacement bulbs" around that snooker people into them buying based on general LED hype and claims. But you're way off base in applying it to properly designed LED oriented enclosures and systems. It's pretty easy to maintain 100+ l/w with the latest and greatest LEDs in a properly built and executed system. Current top bin is ~143 lumens/watt @ 25C junction, which gives you a 30% margin for power supply and die heat losses before you get below 100 lumens/watt. Still costs way too much $/lumen to do though.

                    CFLs and the like have ballast losses as well, and they certainly are not on the order of 70-85% loss you are assigning to LED regulators.

                    3. Next on the efficiency hit list is LED's produce the highest output when they are cold. So when the measure the Lumen output with a very short pulse of a few milli-seconds so the light does not warm up. Once the light warms up in real use, the output drops considerable.
                    I would put heat as the #2 issue rather than 3. It's a problem. They use a small pulse because you want to compare apples to apples, 25C die temp. The efficiency over the temp range is also characterized and rated as well as the package thermal path, you can keep the output fairly good with a good thermal path. This has been one of the most focused on areas of LED development because heat ultimately limits how much power you can get through a single package.

                    You can't keep an LED at this rated level in most cases, but you can keep heat losses to 5-10% with ease. Over driving LEDs for the thermal path available is easily the most common mistake in poorly conceived systems. The need for this thermal path also means LEDs do not work very optimally in current standard lighting fixtures unless they are mostly a heat sink and very low power because they lack that thermal path, and this adds yet more cost to their adoption for well built systems. You NEED a designed thermal path and most-to-all other currently lighting systems don't have one beyond generous access to open air.

                    It is useful to note here that CFLs have the opposite problem - they struggle in the cold. Not a big deal in the house, but in a garage or outside are a different matter in the winter. Refrigerators are great candidates for LED lighting and I'm surprised more manufactures haven't figured this out.

                    4. Last on the efficiency list is the directional nature of LED light and where they take the measurement. They measure on the lights focal spot. Move a few degrees in any direction and the light falls off the cliff. Great for flashlights and effect lighting, terrible for indoor area lighting.
                    There are many different beam profiles, many are much smoother than you describe and many are quite suitable for general lighting, and I would even say that the typical LED beam profile can even be an advantage - you don't need to waste a massive amount of your light going directly back into your fixture and needing to be reflected back out (if you manage it at all) like many bulb and tube style lights do, which can easily be a 30-40% or more lumen loss that LEDs can completely avoid. I'd say this can be a solid advantage rather than a disadvantage.

                    It is true that if you concentrate all the LEDs in one spot in the same direction the light will likely not be uniform, that's a system design issue that makes it a bit more complicated than "put one in any orientation that you like in the middle of the room" but not completely unmanageably so. Even with simplicity, you can take a lumen hit to make the light uniform with a diffuser - it certainly need not be any worse than the above mentioned fixture hit.

                    5. Color Rendering Index. LED's CRI is horrible with an extreme amount of Blue light pollution.
                    CRI on some LEDs is very very good. It's even more expensive, less efficient than run of the mill, so a ridiculous candidate for general lighting. Regardless, it exists, so if this really is a problem it can be addressed.

                    While CRI is an interesting standard, many people have lived with and dealt with poor CRI bulbs before. LEDs aren't any worse than most of the CFLs out there and many people use those just fine. So I don't really see this as an impediment, it's certainly "good enough" in it's current state and much much better than it was 5 years ago.

                    Warm white LEDs have toned down the blue spike significantly and have slightly better CRI than the current cool white (80 vs 75). I would not describe the warm white LEDs I have experience with as having any "blue light pollution".

                    The most efficient lighting one can use in your home is fluorescent T5 tubes which has a true 100 Lumens per watt and excellent CRI. Next in line is CFL of 60 to 80 Lumens per watt, and then LED with a real rating of around 30 to 6 Lumens per watt.
                    I can't argue with your recommendations, they are spot on. Even if I think you tend to poo poo LED tech more than you should But perhaps you do it because there are so many poorly conceived LED products out there - and that I can certainly sympathize with that.

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                    • #11
                      Backblast we can agree to disagree, but fact is LED lights are not much better than incandescent bulbs with 40 to 60 Lumens per watt overall efficiency with driver and fixture, CFL with ballast is 60 to 90 Lumens per watt and cannot touch T5 and T8 fluorescent lighting at around 90 to 120 Lumens per watt. Our Government will not allow LED lighting in any federal building period because they are not even close to being GREEN or ENVIROMENTLY friendly.

                      LED someday might compete and become mainstream, but for now they should only be used for special task lighting like flashlights, tail lights, and landscape lighting
                      MSEE, PE

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                      • #12
                        Originally posted by Sunking View Post
                        Backblast we can agree to disagree, but fact is LED lights are not much better than incandescent bulbs with 40 to 60 Lumens per watt overall efficiency with driver and fixture,
                        Those numbers are ballpark accurate about 1.5 LED generations ago, the older lower binned Cree XR-E in a fixture would be in this ballpark, though the nicer bins could probably push 80 l/w in a fixture if anyone cared to pay a premium to get them. This is still comfortably above Incandescent levels that you inferred earlier were equivalent, which tops out around 35 l/w. With the lag to production, I actually don't doubt this is all the fixed LED lighting world has really seen yet. So I will largely buy this as the available, not the possible.

                        ...cannot touch T5 and T8 fluorescent lighting at around 90 to 120 Lumens per watt
                        I've never seen anyone claim 120 lumens per watt for fluorescent until now. Do you have a cite I'm not aware of? I'd like to see these new tubes..

                        Our Government will not allow LED lighting in any federal building period because they are not even close to being GREEN or ENVIROMENTLY friendly.
                        I would hardly call our government a sound source of judgment on anything. This is not good supporting evidence.

                        LED someday might compete and become mainstream, but for now they should only be used for special task lighting like flashlights, tail lights, and landscape lighting…

                        So my point is valid, forget LED for now.
                        I do still agree with this, it has a few nitches and nothing more.

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                        • #13
                          Originally posted by BackBlast View Post
                          This is still comfortably above Incandescent levels that you inferred earlier were equivalent, which tops out around 35 l/w. e possible.
                          Show me a quote where I said LED's are equal to incandescent. Here is what I did say:
                          Backblast we can agree to disagree, but fact is LED lights are [U][I][B]not much better [/B][/I][/U]than incandescent bulbs with 40 to 60 Lumens per watt overall efficiency with driver and fixture.

                          Originally posted by BackBlast View Post
                          I've never seen anyone claim 120 lumens per watt for fluorescent until now. Do you have a cite I'm not aware of? I'd like to see these new tubes..
                          It is an old link, or I should say graph, but 110 l/w. I would link to NLI (up to day l/w printed 2-2010) but without an username and password it will not work.
                          MSEE, PE

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                          • #14
                            Originally posted by Sunking View Post
                            Show me a quote where I said LED's are equal to incandescent. Here is what I did say:
                            Sorry, my characterization was inaccurate. But you are not being very accurate either, and if we're going to nit pick, well, lets nit pick...

                            Incandescent ranges 10-17 by your own cite, and for consumer level lighting this IS accurate. 35 is for boutique specialty lamps and I was being rather generous by citing it.

                            "Not much better than" 10-17 l/w would be somewhat less than 3 times more efficient that a typical LED setup will achieve using your own numbers. This would make LEDs more directly comparable to CFLs rather than incandescents.

                            It is an old link, or I should say graph, but 110 l/w. I would link to NLI (up to day l/w printed 2-2010) but without an username and password it will not work.
                            By this link you have overstated the case for both CFL and linear fluorescent. I was able to find a 109 l/w tube for sale (which claimed to be the best), and I noticed the wonderful "up to 109" in it's marketing literature. It would be interesting to see the performance parameters and decay present in those so I can derate the tubes properly besides the known fixture issue.

                            Anyway, I think we've run the course on this thread. Nice to be on the forum, I hope to learn some things, see you around.

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                            • #15
                              Welcome BackBlast - The object of the forum is to learn as much as possible and help others where we are able. Note that some are of much more assistance than others due to background.

                              Being from a mechanical background, I am sometimes a fish out of water with electrical thingies. After I retired and we started building homes (great timing) I learned how much I didn't know about many things to do with residential construction!

                              Lighting, insulation, solar PV and thermal, heating systems, windows and on and on all require a good deal of effort to learn what there is available, what is cost effective and to stay up to date.

                              Again, welcome and lets us see what we can accomplish!
                              [SIGPIC][/SIGPIC]

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