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

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.

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

<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.

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

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

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.

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.

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.

<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.

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?

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.

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.

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.

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.