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  1.  
    On the discussion below 'LED testing' we finished by talking about LEDs direct from China. I thought many might have missed the tail-end so whilst 'owing' a follow up post I thought I would give it a more appropriate title on a new post.

    http://www.greenbuildingforum.co.uk/forum114/comments.php?DiscussionID=7769&page=4#Item_26

    With a new dream kitchen to DIY I needed at low energy solution to the kitchen's task lighting. Complicated by the fact that the ceiling is solid and the budget horrid. I opted for GU10 spotlight fittings 'cos they are dead cheap and an LED bulb is a lot cheaper than an LED luminary. I hardly need mention the cost of 16 LEDs from the UK. In the discussion above AliExpress was suggested as a way of buying LEDs much cheaper. On this site one can buy very small quantities of LEDs 10 or even less at crazy prices. My first purchase was twenty 3x1w, CREE chip, GU10 bulb, CE, 50,000 hrs, 290 lumen, natural white. Cost incl delivery by courier and Italian VAT/charges was £4 each. My second purchase was 30 3x3w, CE, CREE chip, cool white, 810 lumen, 50,000 hour at £4.60 each.

    I couldn't have done it without JSHarris and others on the thread above - so thanks guys. My advice on using Alixpress is:

    When searching start with reasonably generic searches 3w LED GU10 and use the criteria to bring down the number of choices to something manageable (under 500 choices!) - try changing the order in which you select each criterion. It shouldn't make a difference but it has.

    The system of 'Escrow' means you pay a 3rd party who doesn't release your funds to the supplier until you confirm satisfactory delivery. It seems professionally run to me and I felt my money was safe.

    Check the whole of the page for contradictory info especially regarding lumen.

    Always read all the feedback - usually less than 30 or so for any gotchas.

    If you get a good feeling about the info on the site but they don't appear to offer a detail you want, for example a 30 deg angle or the colour you want, don't give them up ask them - my experience was that they always had what I wanted but that their site was rubbish.

    JS' experience of delivery to the UK was that with EMS one often escaped the VAT. My experience was that this will never happen in Italy.

    Some sites actually state in their terms that they will complete the customs doc with a much lower value of goods than is the case - potentially saving you most of your VAT. Another site agreed to do this for me when I asked. Doesn't help in Italy because I had to scan in proof of what I paid - can't argue given where Italy is right now!

    Get stuck into the 'chat' choice - seems to always be someone at work even 8pm Sat local but always close the tab within the chat panel of the PERSON you are talking to when you are finished, otherwise you will end up chatting to them again and getting well confused!

    Don't assume check - after my 20 3w LEDs arrived I was straight onto them again and ordered ten 9w LEDs, same company, same spec, everything looked good. The next day whilst gloating to myself I wondered what the lumen they produced - not listed, how did I miss that, oh well, will be good - no it wasn't - get this: 1x3w = 290 lumen, 3x3w = 300, yes that's three hundred lumen. Fortunately they agreed to refund me, not my right though.

    Don't be afraid to bargain - whilst chatting to one company live I decided I was happy and I started to make my order. But there was no option to use a courier (China Air mail up to 45 days delivery maybe - as in they warn you 'maybe'). The chap(ess) immediately sent me a link for courier choices that at least doubled the price of the goods - OK sorry I said goodbye - wait, how many, if you buy 30 not ten, delivery by courier free.

    Make sure you have time and energy: the sites are hugely numerous and all dire, the English in E Mail/chatting dire, contradictions in spec occur on most sites (especially about the colour temperature), missing info normal too (especially lumen). You have to decide whether to trawl through for hours looking for a perfect spec or bottom the spec out through chat/e mail. And the searches never seem to give the same results the next time you look.

    You MUST state the spec you want in the dialogue box at the time of ordering, angle, colour, supply voltage, everything, otherwise they will send you a default spec. Even if you want the default spec don't omit this info.

    My 3w LEDs had not a mark on them or the box - in comparison with LP's LEDs the colour looked good, the output as right as it is possible to tell by eye and the angle was correct. As for the lifespan, ask me later....but order some spares!

    I think that's it but the other thread may have some other stuff. Good luck all
    • CommentAuthorjamesw
    • CommentTimeDec 7th 2011 edited
     
    Thanks very much for the summary. Having just installed my first ebay LED bulbs, I'm trying to work out how to source LEDs for my own upcoming extension.

    One thing that I'm not clear about is where you say "get this: 1x3w = 290 lumen, 3x3w = 300, yes that's three hundred lumen." Do you mean that one of your supposedly 3W bulbs gave out 290 lumen, and that a further three such bulbs gave out 300 lumen each? I know you are making the point that their light output is bad, but I just want to be clear how bad.

    If it is that bad, does that not mean that, of your two purchases to date, one ended up being fairly disastrous (even though they did refund you)?
  2.  
    Sorry, need to be more explicit. I bought some 3w LEDs, each LED is actually 3x1w LEDs in one 'bulb' - the std terminology for this appears to be 3x1w. Each 3w (total) LED had an output of 290 lumen - this is very good. I then started to buy some 9w (total) LEDs, each 'bulb' containing 3x3w 'bulblets'. Despite being rated for 300% more wattage they only produced 300 lumen ie about 3% more light output - anything under 50 lumen per watt is BAD. I found at least one other company offering similar spec 9w (total) LEDs and a few at around the 450 lumen mark, then a gap and 800 or 810 lumen was the usual output. Hope that helps.
    • CommentAuthorCWatters
    • CommentTimeDec 10th 2011 edited
     
    Forget the wattage (W) when it comes to selecting an LED. The wattage is the amount of electrical power going into the bulb. The Lumen figure tells you how much light is coming out. When it comes to brightness the figure that only really matters is the Lumens (Lm), if they can't provide it go elsewhere.

    As LEDs improve the ratio of Lumens to Watts changes. So this years 3W LEDs produce more light than last years 5W or 7W. It's not safe to look at the wattage only because you have know way of knowing if you are buying last years or this years technology.

    The problem is that few people know how many Lumens ordinary incandescent or halogen bulbs produce so they aren't used to using Lumens to compare them. The EU have produced a table to help which I've posted on other threads. In short anything over 400L from a GU10 downlight bulb shape LED is very usable in my opinion.

    To be complete you actually need at least four figures to compare lamps:

    Brightness (in Lumens)
    Beam Angle (in degrees).
    Energy Consumption (in Watts)
    Colour Temperature (in Kelvin)

    The beam angle and colour can also have a big effect.
    •  
      CommentAuthorDamonHD
    • CommentTimeDec 10th 2011
     
    The unit is, AFAIK, "lm", not "Lm" or "L", for lumens.

    Anything over 60lm/W is basically beating CFL and is very decent efficiency.

    (I've just bought a 2W nightlight for in-laws to try out rated at 135lm, and which may be too bright compared to the 15W incandescent it is replacing. With the small number of watts involved (it may be up to 2.49W actual, for example), it is impossible to tell exact efficiency, but it could save ~£10/year which would be a 1 year payback, maybe 2 years to be conservative.)

    Rgds

    Damon
  3.  
    Well CW I didn't want this to be a lecture in how to asses an LED, there's plenty of that on this site already though it could perhaps be summarised into a good for newbies thread. And I reckon telling anyone on this site that lm and beam angle are important is trying to teach them to suck eggs. In addition, you can't say "Forget the wattage (W) when it comes to selecting an LED." as a sentence because, as you say, it is one of the 2 critical numbers you need. Neither can you say as a sentence: "In short anything over 400L (sic) from a GU10 downlight bulb shape LED is very usable in my opinion." without mentioning how many watts this usable bulb would have. Finally, since I mentioned that under 50lm/W is BAD I guess people can work out that over 60 lm/W is good.

    In short: if anyone has any experiences that might help others in buying LEDs direct from China (or equiv Taiwan?) then this is the place to put it. I know one can buy LEDs from EBayers, are they just commercialising what I have done privately I wonder?
    •  
      CommentAuthorJSHarris
    • CommentTimeDec 10th 2011 edited
     
    <blockquote><cite>Posted By: Gotanewlife</cite>I know one can buy LEDs from EBayers, are they just commercialising what I have done privately I wonder?</blockquote>

    Most of the time, yes, they are.

    Until fairly recently it has been difficult to transfer money to Chinese companies which has seriously hindered direct purchasing. Many companies insisted on fairly risky payment methods, like direct bank transfer. Ebay offers PayPal, so a whole new generation of Chinese entrepreneurs arose, buying stock from Chinese companies and reselling it, or just offering a drop shipping service (which is all that Deal Extreme is).

    Now that Alibaba have put in place the escrow system, it's a reasonably safe way to transfer money to China, and probably cheaper than either PayPal or bank transfer. it certainly opens up munch greater choice for us.
    • CommentAuthorGotanewlife
    • CommentTimeDec 10th 2011 edited
     
    Hmm then LEDs could come down much more in price. Quality LED suppliers like Light Planet's LEDs are 3-4 times more expensive with the same specifications - OK the quality is for sure better and the 2 year guarantee offered by most Chinese companies requires you to send them back at your own expenses but their lights have 50,000 even 100,000 hour theoretical lifespans and don't tell me LP's actual life span will be 300% greater than an equivalent spec unbranded LED. I doubt there is even 1 in 10,000 people who could not save a lot of electricity and money if they had some some more LEDs. Surely now the market (thanks to escrow) will drive this thing. In fact maybe I'll chat to some of the Chinese people about buying some LEDs with writing on myself, stick a DIY sticky label on the box and Yu Lin Mie's your uncle - BTW prices for LEDs here in Italy make LP's look cheap!
    • CommentAuthorTonyt
    • CommentTimeDec 10th 2011
     
    Buy some halers h2 lights if you are looking for downlights, or philips 7 watt master leds as direct replacement for 50 watt halogens

    Tony
    • CommentAuthorGotanewlife
    • CommentTimeDec 11th 2011 edited
     
    Tonyt. Why oh why oh why would I want to spend £30 on one LED producing 270lm, avg life 45,000 hrs, when I can (and have) spend £5.50 on an 810lm LED lasting on avg 50,000 hrs. Your recommended LED has less than 40lm/W and whilst there may be some debate about many aspects of LEDs there is no doubt whatsoever that less than 50lm/W is BAD. So please take note of what has been written above and on every other thread on this Forum to do with the basics of LED lighting before giving terrible advice on a well respected forum.

    To put this another way your £30 buys you 270lm of light from your LED OR buys 4418 lm (yes that's over four thousand) lumen from my LEDs.

    I note some of the adverts for this Phillips 7 watt master LED mention the highly misleading "is a direct replacement for 50w halogen..." I think it is about time this sort of language is banned under the Trade Descriptions Act, or at least heavily caveated. God help us all.
    • CommentAuthorTonyt
    • CommentTimeDec 11th 2011
     
    Sorry, just speaking about 2 products i have fitted at work. I have no connection with these companies.

    Can you provide a link for your purchase?

    I was going to buy 7 philips master leds for my kitchen to replace the megaman cfl as the light at work was good.
    My work clearly just buys from reps as they i imagine they dont fancy buying direct from china, but i dont have that problem for my house
    • CommentAuthorbillt
    • CommentTimeDec 11th 2011
     
    I'd treat those life time figures with a very large pinch of salt. I've been using about a dozen LED GU10s and 4 of them have failed; other people have had even worse failure rates. Some of mine were cheapish chinese ones from a UK importer, and some were more expensive. Unfortunately you have no chance of knowing what sort of quality control, if any, is used.
    •  
      CommentAuthorJSHarris
    • CommentTimeDec 11th 2011
     
    My worry with reliability isn't the LEDs themselves, as in my experience they are very reliable, even the cheap ones. The failure mode seems to be mainly the 240V AC current driver circuitry built in to the base of the light. It has a tough job to do and is always running pretty hot.

    Low voltage LEDs have a much better prospect of long term survival in my view. Then run much, much cooler, because they don't have to deal with dropping 240V AC to the LED operating voltage of typically 3.5V per LED. The 78 LED MR16 units I have in my workshop are a good example (although not individually very bright). The current limiting function on those is a small resistor in line with each of the 3 LED strings (there are 26 paralleled strings of three LEDs in each light). Even if one or two of the LEDs or resistors were to fail, the light would carry on working with just a few less LEDs operating, although I've not had a single failure yet.

    I think it would makes sense in a new house to include a 12V lighting circuit, so that low voltage LEDs could be used everywhere. The chances are that an efficient 240V to 12V switched mode converter, situated somewhere cool, would be very reliable. Such a system would also offer the opportunity to include battery back up, so the lights would still work in the event of a power cut.
    • CommentAuthorborpin
    • CommentTimeDec 11th 2011 edited
     
    Posted By: JSHarrisI think it would makes sense in a new house to include a 12V lighting circuit, so that low voltage LEDs could be used everywhere. The chances are that an efficient 240V to 12V switched mode converter, situated somewhere cool, would be very reliable. Such a system would also offer the opportunity to include battery back up, so the lights would still work in the event of a power cut.
    I like this idea. The other benefit would be that as it is not 'mains' I suspect it is outside the 17th (latst?) regs. Have you any thoughts on design details of how to do this. It has rather sparked a thought train. Wonder what the BCO would say! Does a house have to have a lighting circuit? Perhaps a new thread..........
    •  
      CommentAuthorJSHarris
    • CommentTimeDec 11th 2011
     
    It's already allowed for in the regs, as many of the halogen systems are 12V. Older halogen systems used transformers, which were a bit heavy and sometimes hummed a bit, but the newer 12V lighting systems use electronic switched mode supplies that are efficient and silent.

    My workshop lighting now runs on 12V, with a couple of old batteries charged from a small solar panel, with a mains charger that only triggers when the battery voltage drops. Most of the time the workshop lights are run entirely on solar power.

    My intention is to do something similar in the new house, and have all the lighting circuits wired for 12V. The snag is that there are only a limited range of 12V light types available, mainly things like MR16 spots and floods.
    • CommentAuthorGotanewlife
    • CommentTimeDec 11th 2011 edited
     
    Posted By: billt'd treat those life time figures with a very large pinch of salt.


    Yup couldn't agree more and you pays your money and takes your chances; nevertheless, at £5.50 I have a lot of scope for early failures and to still remain quids in, and I have ordered plenty of spares, which if I don't need I can use later in the renovation.
    •  
      CommentAuthorjoe90
    • CommentTimeDec 11th 2011
     
    Dick Strawbridge (of its not easy being green on BBC some years ago) had a 12 volt lighting circuit for his house and it was powered by a water wheel he constructed. Thats something I would love to do.

    There has been a discussion on here sometime ago about a low voltage ring to save having so many chargers around the house and the main question was cable size due to the current required but I guess LED use such low power this would not come into question.
    • CommentAuthorEd Davies
    • CommentTimeDec 11th 2011 edited
     
    Posted By: JSHarrisI think it would makes sense in a new house to include a 12V lighting circuit,


    LEDs don't need voltage, they need current. How about a constant-current circuit?

    You could really mess with a sparky's brains: switch wired in parallel; open switch, light comes on... The constant current source ought to be clever enough to notice when its output voltage is zero and turn itself off most of that time.
    •  
      CommentAuthorJSHarris
    • CommentTimeDec 11th 2011 edited
     
    <blockquote><cite>Posted By: Ed Davies</cite>

    LEDs don't need voltage, they need current. How about a constant-current circuit?

    You could really mess with a sparky's brains: switch wired in parallel; open switch, light comes on... The constant current source ought to be clever enough to notice when its output voltage is zero and turn itself off most of that time.<div id="Attachments_125878" class="Attachments"><ul><div><img alt="cc-leds.jpg" src="/forum114/extensions/InlineImages/image.php?AttachmentID=2398"></img></div></ul></div></blockquote>

    The problem with a constant current circuit is that it only works for a single LED or a daisy chain switching arrangement which would be inconvenient to wire into a house. It also requires all the LEDs to be identically rated. If you fitted a dozen LEDs with a typical star type lighting circuit then you'd need a constant current circuit for each, which is what is already built in to the base of the 240V AC LEDs anyway.

    The nice thing about a low voltage lighting circuit is that there is less voltage to drop locally at each LED. A typical 3 LED light requires a Vf of around 10.5V with an If of anything from about 0.85A for a "3W" LED to maybe around 1.4A for a "5W" LED. If you have a 12V supply, then the voltage drop at each LED is only around 1.5V to run them at the required constant current, which makes for low losses, even with a simple resistive current limiter. If you run them at 240V AC, then you're looking at a much bigger voltage drop, and even with a switched mode constant current supply (which is what most use) you are still looking at losing around 15% to 20% of the power in the converter, which adds to the heat load.
    •  
      CommentAuthordjh
    • CommentTimeDec 11th 2011
     
    Posted By: Ed DaviesYou could really mess with a sparky's brains: switch wired in parallel; open switch, light comes on

    I'd expect the switches to be solid-state and incorporated in the power circuit at the lamp's position. Controlled by a wireless battery-powered unit stuck to a wall somewhere. Or a self-powered enocean controller or whatever. So all just lumps of plastic as far as the mythical sparky sees it. I do like the idea of a constant-current ring!
    • CommentAuthorborpin
    • CommentTimeDec 11th 2011
     
    So is a 12V circuit theoretical or a practical possibility? Are you limited by distance? Could you drive such a circuit from a single point in a house or do the voltage drops get too large?
    • CommentAuthorwookey
    • CommentTimeDec 12th 2011
     
    A lot of LED stuff is 12V, and it does seem to be becoming something of a standard, but picking '12V' gear may well stop you dimming your LEDs, because in fact they are '350mA' or '700mA', or '1A' devices, and they make them work on 12V by adding a resistor network or a switcher driver, which may prevent dimming and generally be at least slightly wasteful. I need to do some tests to quantify this effect as I have a '12V' strip here, which is also a '700mA' device. In practice it seems to dim OK.

    The other problem with a 12V 'main' is that the 12V supply is always on but sized for the largest load you might want to use it for (200W for every LV light in the house?). If it's not very well designed it'll be using 5W permanently even when all the lights are off. On the other hand you can afford to buy a very efficient supply, rather than lots of smaller, cheaper units which won't be as good. I should do the numbers, but I reckon small, switched-with-the-lights units will come out better so long as they are at least 80% efficient.

    I'm currently using these (one per room): http://www.leds.de/en/Accessories/Power-supplies/Constant-current-supply-700mA-IP20.html but the efficiency is only '> 60%', which isn't good enough IMHO.

    Lumitronix have got these funky 'Matrix' LEDs now, which are modular with same connectors as the strips (and 88lm/W). Lots of possibilities here, but not 'chinese cheap' as still 17€/per 320lm.
    http://www.leds.de/en/LED-strips-modules-oxid-oxid-oxid-oxid-oxid/LED-Cluster/LED-Matrix-white-2x2-45-LEDs-900lm.html

    I'll scour alibaba and see if I can find something that is both good and cheap. I'll post some pics of my lights and pricing too by way of comparison.
    • CommentAuthorCWatters
    • CommentTimeDec 12th 2011 edited
     
    Posted By: JSHarrisIt's already allowed for in the regs, as many of the halogen systems are 12V.


    Interestingly the regs reguire 12V lights to be professionally installed in situations where you can DIY install 230V versions. Thats because the regs assume 12V lighting requires high currents with the potential for fire if the wrong size wire is used.
    •  
      CommentAuthorJSHarris
    • CommentTimeDec 12th 2011
     
    <blockquote><cite>Posted By: CWatters</cite>Interestingly the regs reguire 12V lights to be professionally installed in situations where you can DIY install 230V versions. Thats because the regs assume 12V lighting requires high currents with the potential for fire if the wrong size wire is used.</blockquote>

    Yes, that's why I mentioned it. The regs were intended to reduce fire risk from the high current supplies needed for multiple 12V halogen lights. It's pretty easy to get a few tens of amps flowing in one low voltage lighting circuit, with the risk of wiring overheating if it's not sized appropriately.

    The situation with LEDs should be a lot different, because the current is much lower.

    Dimming 12V LEDs works fine. I made a replacement bedside lamp a while ago, using four 19 LED arrays (purchased very cheaply via ebay) mounted on a small fabricated "pyramid" and fitted to a home made lamp base with a conventional lamp shade. These LED modules were intended to run on 12V AC, as they have a bridge rectifier and current limiting resistors on the circuit board. I fitted a small switched mode power supply in the base of the lamp, modified so that the voltage adjustment was an externally mounted pot that acts as a dimmer. I was surprised at just how linearly the LEDs dim, better by far that conventional AC phase angle dimmers. As a bedside light it works very well, as turned to its lowest brightness it can be turned on and almost act like a night light.

    Similarly, my homemade reading light uses a 3W Lumiled LED, fitted with a diffusing lens, and that can be dimmed with the same method very nicely. In the case of the reading light I didn't use a switched mode supply (only because I happened to have a transformer lying around that would do the job) so the dimmer is just a simple PWM circuit with a 555 and FET switching the supply.
  4.  
    watts are meaningless. Its all about the lm's. The output of poor to great LED's varies greatly so you only need the lm value (inc beam, colour etc).
    I imported some units from Taiwan. They are the same units as I can purchase here but at approx 50-60% of the cost. Great lm values.
    Ebay for LED's? I think it depends what you are looking for. The quality of most of the multi packs is poor. Just look at sellers feedback. The only units I could see that I would even consider would have been Kosnic.
    As for my units from Taiwan, top drawer,
    Gusty.:tooth:
  5.  
    Seems to me the great info on this thread about 12v circuits would help far more people if on its own correctly titled thread - even a quick and dirty cut and paste of the divergent posts above would do it. Not that I care about my thread as I only stuck it up to help others, not needing something for me, but the irony of starting this thread because it was too far away from the Testing LED thread to make sense, only to watch yet more great info go 95% to waste is great.:wink:
  6.  
    Gusty what are you on: "watts are meaningless...you only need the lm". Grief man, I think I'll give up - except because its you I'll blame it on a bad hair day - you do have some hair I presume......

    2 LEDs, identical specs, manufacturer, certifications etc, identical aside from from Watt value. First LED has 290lm second has 300lm - which one is best Gusty? Can't tell can you? The answer is in one of my posts above as these 2 bulbs actually exist.
  7.  
    Hey just hold it big fella.

    Firstly, the increasing gap between my nose and hair line is no business of yours (Baldy, cough, cough)
    Secondly, if you have got a new life already I would look for another new one!!!! CHILLAX man.
    Thirdly, I can't think od a thirdly just yet.......

    OHHH yes. When you look for LED's I would assume you have an idea of the lm value you want and how much you think you should spend??? I do anyway.
    So, if 2 units are identical apart from wattage then the price should be very different. Are you looking for the new technology or yesterdays technology? Price should tell you what you are looking at if you have any idea at all,
    Gusty.
    •  
      CommentAuthorJSHarris
    • CommentTimeDec 12th 2011 edited
     
    I've started a "low voltage" thread here: http://www.greenbuildingforum.co.uk/forum114/comments.php?DiscussionID=8267&page=1#Item_2 to shift the chat on this away from this thread.
    • CommentAuthorTonyt
    • CommentTimeDec 12th 2011
     
    Will some post a link to all these great leds they are buying?
   
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