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Are LEDs a big con?

Discussion in 'Electrics UK' started by d000hg, 4 Apr 2020.

  1. aptsys

    aptsys

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    Any LED die is typically only in the 15-25% efficacy range. For the most part you can assume the majority of power will be dissipated as heat, and there are further losses in the driver. The filament LEDs still dissipate the same amount of heat, just spread over a larger surface area.

    Heatsinks are relatively vast because the LEDs need to remain <40C for long service life, however most of the time in consumer products the temperature is likely to be at least double.
     
  2. ajohn

    ajohn

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    From what I have seen LED bulbs fail by flickering at a very irritating rate or just stop working ;) preferable. The ones we had start flickering early were by Philips but no problem with a more recent purchase of several but don't know how these fail yet.

    There was an announcement on the news a while ago that led bulb use had made the country greener than any other step that has been taken. Probably ignoring gas and a slight increase in gas usage due to their use.

    Some councils have been criticised for fitting high CRI LED street lighting - high colour temperature - as it is noticeable less efficient than lower temperatures such as warm white all down to the excess blue lighting high apparent colour temperatures need. The blue is unfortunate as our eyes aren't very sensitive to it. The true CRI of these isn't that good anyway so work is being done on 4 and more colour led lighting rather than 3.
     
  3. d000hg

    d000hg

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    Yeah we have had bulks start to flicker and fade. Fading is far preferable... a flickering light you have to take it out or you go mad!
     
  4. StephenOak

    StephenOak

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    My anecdotes agrees with those coimments. Over 10 years ago I paid a lot (£25?) for a then new 6W LED (60W light equivalent) that is a bulky as a traditional GLS bulb and has a large heat sink on it. It is in our dining room (between the hall & the kitchen) and is on quite a bit everyday.

    Also a long time ago (2008?) I bought a number of BELL G9 adaptor lamps, like this
    http://www.lampspecs.co.uk/Manufacturers-Stores/BELL_G9_Adaptors_2

    with BC, ES & SES bases and a variety of covers. When we moved in, the house used a wide variety of bulbs and my idea was that I could keep a stock of G9 bulbs rather than lots of different types.

    I have used a variety of G9 LED lights in them and none have lasted that well, some have gone in months. Also the construction seems poor, they look like this
    https://www.amazon.co.uk/gp/product/B00MJXCQ9O/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

    with eight lines of LEDs, one line on each side of the four ribs. So something like 80 individual LEDs, but they are wired in one series, so that when a single LED fails the whole bulb fails.
     
  5. AndyPRK

    AndyPRK

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    try minisun G9 leds
     
  6. ericmark

    ericmark

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    I have Minisun G9 led's had to fit load capacitors and they pulse, when a chandelier used 5 bulbs swapping lights is not cheap, so tried a few makes, and they all seem to pulse together, so I swapped the wifi switch, still pulses with G9 but old one does not pulse with E14 bulbs, so does seem to be something to do with G9 LED's not the electronic switches.

    The problem is they don't always pulse, it seems what every you do it stops pulsing for a day, then starts again, every so often the GU10 lights pulse, then stop again.

    All my E14 bulbs have the base at the bottom, I think they last longer that way as heat raises, the BA22d bulbs however base at top, standard ceiling rose.

    I think in spite of the G9 bulbs stating dimmable, they are not, and some thing in them does not like electronic switches, some day I will wire traditional two way, but wife does not complain as before we got the silly G9 chandelier I said not G9 but she insisted, so she just puts up with it.
     
  7. aptsys

    aptsys

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    Seems like a nonsense bit of info. High colour temperature LEDs are more efficient than low colour temperature as all white LEDs are based around blue dies, so the fewer losses in phosphor the better.

    CRI is a separate metric.
     
  8. SUNRAY

    SUNRAY

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    This is my experience of LEDs but I've never really had similar devices to make a direct comparison.
     
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  10. endecotp

    endecotp

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    I thought they were UV emitters, with multiple phosphors including blue.
     
  11. SimonH2

    SimonH2

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    CRI is the colour rendering index = closer to 100% the better for being able to see colour. That's a factor of the phosphor mix used to generate white from the blue LED - cheaper LEDs use "simpler" phosphor mixes and if you look at the spectrum of emitted light (which is in the data sheet any quality manufacturer makes available) then they have more peaks and gaps in the spectrum.
    Cool white LEDs are generally more efficient than warm white - I've looked at this and comparing identical emitters, the cool white ones emit more lumens that the otherwise identical warm white ones.
    I believe the big problems with the new street lights are :
    • They emit less light than the old fashioned yellow sodium lights
    • They have hard cutoffs
    The latter should be a benefit, but my wife complains that we don't get the yellow glow during the night to be able to walk around without any lights on :rolleyes: But between the two, it causes more exaggerated dark pools between the fittings.
    I also suspect that they aren't high CRI - as above, for a high CRI you generally pay more and get less lumens. So for street lighting I suspect they aren't high CRI - and don't forget that the old yellow sodium lights were effectively monochromatic, emitting a single (or was it two closely spaced, it's a while since we studied this in A level physics :whistle:) lines in the spectrum.

    Funny isn't it. If we were all used to LED lighting with moderately reasonable CRI and a hard cutoff (so light directed to where it's wanted) - would we be happy being switched to yellow lights that make anything not yellow reflective appear black and which "floodlight" our bedrooms o_O
     
  12. d000hg

    d000hg

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    I wouldn't be surprised if given the current climate on... err, climate... modern lights are simply made darker than they used to be under newer regulations to reduce power use still further?
    Of course the old sodium lamps are actually pretty good, which is why they were used - except they are just horrendously ugly :)
     
  13. SUNRAY

    SUNRAY

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    Do you think they are uglier than the LED replacements.

    My big gripe is the horrendous lack of light. When i stand at the end of my street and look down the hill the most visible things are the lamp standards (the actual posts) as they are perfectly lit by the downlighters along with a tiny pool of light on the ground but then nothing for 50metres. A few weeks ago there was a person visible on the IR CCTV camera but totally invisible to the eye which is a complete reversal of pre LED.
     
  14. d000hg

    d000hg

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    THe colour of sodium is far uglier but as you say the modern ones appear to suffer brightness wise. Although that varies, I've seen some that are great and some that are awful.
     
  15. JohnD

    JohnD

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    I have no doubt that is due to cheese-paring to buy the lowest wattage lamps that are "almost" enough.

    you can spec a lamp with the required lumens with ease.

    In my district, they first set the new lamps to a good brightness, but reducing to about half power at 2am

    Now, they run at half power, and turn OFF at 2am

    This is obviously an energy-saving (money saving) decision.
     
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  16. SimonH2

    SimonH2

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    You do realise that the purpose of street lighting is NOT to light up people (and other things) ?
    The idea is that you provide a lit background, against which objects will appear in silhouette if not directly lit. And the disjointed pools of light still provide that. I do agree though that it's not as nice to walk in when there are pools of light with dark in between.
    Oh how things have changed, remember the days when you always thought about how long you'd be out - and make sure you had a torchif it was likely to be dark :whistle: Some of my friends still do :rolleyes:
     
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