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  • LED Lights Are You Ready?

    Well if so you might want to tap the brakes and take a closer look at the numbers and see what they mean before you shell 5 to 10 times more money for them over CFL and Florescent tubes. With all lighting the two numbers to look at are Lumens per Watt (L/W), view angle, and to a lesser degree light color temperature.

    Lumens/Watt is the measure of the efficiency of a light and is really easy to grasp. It tells you how much light the luminaire produces for each watt of power being consumed. The higher the Limens per watt the better. For example 100 L/Watt is twice as efficient as 50 L/Watt. It is a 100% difference. The Lumens measurement is made at 1 meter from the light source in the middle of the view angle if less than 360 degrees. If view angle is 360 degrees the light is measured at 1 meter distance in any direction around the circumference of the source.

    Next is view angle. All incandescent, CFL, and fluorescent tubes emit light 360 degrees around the circumference of the fixture, while all flood lights have a view angle or beam width where 140 degrees is typical. This becomes very important as you start to compare light sources which I will now demonstrate.


    [FONT=&quot][B]Ok one of the most efficient LED lights for sale today is PAR38 42 White SMD LED Flood Light Bulb, 1314WH-CV. The Specs are: Lumens = 650, Power = 9.5 watts, View Angle = 140 degrees. Just from the numbers we can ascertain the efficiency is 650 Lumens / 9.5 watts = 66 L/W. Sounds great huh as an old tungsten incandescent is only around 18 L/W. But wait a minute the view angle is 140 degrees, not 360 of an incandescent bulb. Factor out view angle and you end up with [140/360] x 66 L/W and you get roughly 26 L/W which is still better than an incandescent right. Problem is we are not comparing apples to apples as we would not use incandescent for a flood light. Assuming we are looking for a similar light color we would probable use Quartz Halogen which has an efficiency of 22 to 26 L/w or roughly the same efficiency as a LED flood light? Interesting huh?[/B][/FONT][FONT=&quot][B]
    [/B][/FONT]
    [B][FONT=&quot][B]Take it another step let
    MSEE, PE

  • #2
    OK not doubting your figures BUT we have 16x3 w LED MR16 lights around the outside of my building/house that give excellent security light from building to well part the outer fence,
    Each 3w LED draws 9w at 12v 16times 9w =144w ,I be interested to know how this could be done on less power using any other lighting device ???
    Our ice making room now has 6 of these lights that provides to our eyes(nothing instrument measured) more even and brighter lighting than the 4x 20w flourescent tubes we used previously The LEDs 6x9 = 54 w at 12v. the 4 flourescent lights ran of an inverter so inverter losses have to be added.
    All in use now 3 years no failures ,same goes for other similar security installs I have done. All security lights run 10 hours every day of the year.
    All of us are 110% happy with the LEDs.
    Reasons. long term reliable, run direct off 12v battery, much harder to vandalize than flourescent tubes. give visually good bright even lighting.

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    • #3
      Originally posted by john p View Post
      OK not doubting your figures BUT we have 16x3 w LED MR16 lights around the outside of my building/house that give excellent security light .....
      What is mfg & model # of those ? I'm looking for something like that.
      Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
      || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
      || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

      solar: http://tinyurl.com/LMR-Solar
      gen: http://tinyurl.com/LMR-Lister

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      • #4
        they are made by CREE they operate on 12v DC(11 to 15 is ok)and can be connected without regard to polarity. available in 1w and 3w (6w is wasted) so the total draw is 7w and 9w ,availabe in narrow and wide angle. are direct plug in for MR16 s. get daylight or cool white NOT warm white, the colour of warm white is terrible.
        I buy mine here from an electronics parts chain Jaycar.. a bit over priced I think but worth it in long term.

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        • #5
          John my only point here is LED may not be as efficient as you may have been lead to believe. It is just info and nothing more.
          MSEE, PE

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          • #6
            Sunnyking I understand that its information you giving only.
            I was just giving an example that they can be the best(in my opinion) to be used in some situations.
            I think it be hard to find anything that can light up the whole perimeter of a building and use less than the 144 w im using.
            Measured light and apparent light are different. A lot depends on how bright it seems by the colour of the light. As its well known that a green laser beam to the eye looks many times brighter than a red laser beam looks. but if you measure them they both the same intensity.
            Sometimes figures get in the way of the facts.. but I didnt say that.

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            • #7
              Received several different LED lights from Deal Extreme last night. Some of the newer LED lights are pushing the lumen's per watt ratios of the T5 & T8 bulbs. Of the bulbs I received the one I like the best is the E27 HA006 6W 128-LED 700-Lumen 4000K Warm White Light Bulb (110V). It has a real natural color and looks great in lamps and fixtures using the E27 socket.

              Hard to say if it is hitting the specs it is listed at since I haven't had a chance to put it on the Killawatt & I don't have a light meter. They do look brighter and with a nicer color than the 14watt CFLs I replaced.

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              • #8
                Originally posted by yyzdnl View Post
                Received several different LED lights from Deal Extreme last night. Some of the newer LED lights are pushing the lumen's per watt ratios of the T5 & T8 bulbs. Of the bulbs I received the one I like the best is the E27 HA006 6W 128-LED 700-Lumen 4000K Warm White Light Bulb (110V). It has a real natural color and looks great in lamps and fixtures using the E27 socket.
                Be careful because this is where the LED manufactures like to play number games:
                [LIST][*]They do not include driver power consumption.[*]They spec it at a micro-second full power pulse so it does not heat up an loose brilliance. If you tried to run at full power, as it heats up it looses intensity and will only last a very short period of time before it burns out[/LIST]
                So once you put them in the real world and run at sustainable power levels and include driver cuts the claimed efficiency 50 to 80%. With all the work going into LED's I think they will be become the leader at some point, but what is on the market right now just falls short.

                There are some nice niche applications like a project we did for Walmart. We changed out all their meat counters, display freezer and coolers with very high efficiency refrigeration and the units used LED's With the cold climate they are able to run at high power level to get the efficiency without over heating the base, and directional nature of LED's are able to put the light on the product. But for room and area lighting, not yet.
                MSEE, PE

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                • #9
                  Sunking is right thay never include driver power used for LEDs but then they never do either for CFLs or tube fluros.
                  The 3w and 1w Led lights I use "waste" 6 w
                  CFLs I have measured all good ones like Philips "waste" 6w some bad ones as much as 9w
                  Tube fluros that use the non electronic ballast "waste" 40w it makes no difference I have found if using a 20w or 40 w tube,(I know this may not be relevent in USA as only the electronic ballast is used but the old "get very hot" ones are still used in the millions in many countries.)

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                  • #10
                    Well John you cannot buy any magnetic ballast in the USA, they did away with those decades ago. Even more significant is LED's cannot be used in any federal buildings, they do not meet minimum efficiency guidelines.
                    MSEE, PE

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                    • #11
                      Sunking I know that, and that is why I specifically noted that in USA only electronic ballasts are used. BUT most of asia about 3 billion (a few more than in USA)people still use and buy the magnetic ballast.Because its a fact for some reason the electronic ones are more expensive, and thinking in most of Asia is a bit different. They buy on price only. Explaining to them its false economy gets same result as trying to teach a cat to bark.

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                      • #12
                        Originally posted by john p View Post
                        trying to teach a cat to bark.
                        I taught a parrot to bark when I was a kid.
                        MSEE, PE

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                        • #13
                          Sunking you only get 4 out of 10 for that. You are not a great animal teacher until you can teach a cat to bark

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                          • #14
                            I have frogs that bark
                            Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
                            || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
                            || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

                            solar: http://tinyurl.com/LMR-Solar
                            gen: http://tinyurl.com/LMR-Lister

                            Comment


                            • #15
                              Originally posted by Sunking View Post
                              Be careful because this is where the LED manufactures like to play number games:[LIST][*]They do not include driver power consumption.[*]They spec it at a micro-second full power pulse so it does not heat up an loose brilliance. If you tried to run at full power, as it heats up it looses intensity and will only last a very short period of time before it burns out[/LIST]
                              So once you put them in the real world and run at sustainable power levels and include driver cuts the claimed efficiency 50 to 80%.
                              Great to know, but how would I test this real world? I tested the three bulbs I have and they consistently pull 4.4-4.5 watts thats better than the spec of 6 watts.

                              I put them in the bathroom against a Sylvania 13 watt CFL rated at 800 lumens and a GE soft white 60 watt incandescent. It is a multi exposed bulb fixture so I could quickly switch between bulbs the incandescent and CFL where indistinguishable. The LED bulb was slightly dimmer but really hard to detect after I removed the plastic diffuser/cover.

                              The LED is rated at 700 lumens I don't have a clue what a difference of 100 lumens should look like to the eye.

                              Even if it is only 500 lumens with the diffuser on it is running 100+ lumens/watt. That seems real good for the standard the E27 sockets my house is full of.

                              I slipped one into our bedroom ceiling fan without diffusser since it has a frosted globe. Will be interesting to see if my wife even notices.

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