LED-bulb tearing itself down - Page 1
Forum section: electronics / projects

author: jitter
author_rank: Frequent Contributor
timestamp: September 13, 2016, 05:18:40 am
content: I'm doing a lifetime test of anIkea Ledare 13 W / 1,000 lmretrofit LED-bulb (more specifically, the LED1309G15).It's in a luminaire that's lit during the night, and does roughly 5,000 hours a year. The luminaire is reasonably well ventilated.I started this test for several reasons, one of them is because it runs pretty hot and yet has a 25,000 hours specified lifetime.After about 5,000 hours nothing remarkable had happened, just a 11% drop in light output, more or less as expected.Yesterday, after roughly 10,000 hours I tested it again. Drop in light output has increased to 21%. That's too much. If that trend doesn't taper down real fast, it's not going to make 25,000 hours and still have 70% light output left (also as specified).But more remarkable is that the casing seems incapable of dealing with the stresses caused by the heat, in the second year of testing large cracks have started to appear.At EOL, I'm going to do a teardown, but it seems the teardown is already under way...Would you agree that this bulb suffers a design flaw?

author: zlymex
author_rank: Frequent Contributor
timestamp: September 13, 2016, 05:56:59 am
content: Agreed.- Although more efficient than florescent source and especially much more efficient than incandescent types, still about 85% of input power(around 11W) is wasted as heat.- LED is sensitive to heat(lost flux quicker, less efficient at high temperature), heat must be dissipate effectively.- There is no Aluminium heat sink like other LED bulbs greater than 10 Watts- They(the vendor, the maker) may say that the test environment is not controlled, the equipment is not professional(such as no integrating sphere)- The specified parameters are probably typical value.

author: amyk
author_rank: Super Contributor
timestamp: September 13, 2016, 10:58:42 am
content: 25k hours is definitely possible in optimal conditions, i.e. not being overheated and probably overdriven.It's not a design flaw, it's planned obolescence.

author: Fungus
author_rank: Super Contributor
timestamp: September 13, 2016, 11:03:38 am
content: Quote from: jitter on September 13, 2016, 05:18:40 amYes.I've had a couple of those die on me and I think it's purely down to heat. It's a closed device with absolutely no ventilation, that's madness!When I replaced them I actually drilled a row of holes around the bulb just above the join between the light diffuser and the solid base. The holes aren't visible when it's inside the holder and the bulb runs alotcooler than before. The holder used to be too hot to touch but now it's maybe 40 degrees C. It's amassivedifference.So far, so good...

author: onlooker
author_rank: Frequent Contributor
timestamp: September 13, 2016, 11:29:48 am
content: Interesting idea. Could you share some pictures?

author: Fungus
author_rank: Super Contributor
timestamp: September 13, 2016, 01:12:39 pm
content: Here's one of my modified bulbs. I did it with an electric screwdriver with a drill bit inserted. I remember it was a lot quicker and easier than I expected to drill the plastic. That's why there's so many holes ("Hey, that's easy!").The bulbs are in something like this but with the bulb part sticking out. This means they're sort of horizontally oriented in use. I figure the air goes in the bottom and out the top. YMMV. All I know is that they run alotcooler like that - I can pull one out and just about hold it in my hand where they used to be far too hot to touch.

author: Kjelt
author_rank: Super Contributor
timestamp: September 13, 2016, 03:32:08 pm
content: What also happens often is that the plastick diffuser changes color , browns and obscures the light.

author: jitter
author_rank: Frequent Contributor
timestamp: September 13, 2016, 04:55:28 pm
content: Quote from: zlymex on September 13, 2016, 05:56:59 amBased on teardowns I found on the web I believe there is an aluminium insert inside the base and the plastic covering it can conduct heat better than normal plastic.My test setup is reasonably controlled in that I setup everything as identical as possible. The readings may not be very precise in an absolute sense, but I believe them to be repeatable enough to make comparative measurements. I assign the light intensity of a thoroughly warmed up new bulb a value of 100% and then calculate from that the % drop in subsequent measurements (also after plenty of warm up time).Quote from: amyk on September 13, 2016, 10:58:42 amI recently replaced two LED bulbs of which I knew the install date. They had done 25,200 hours give or take a few, and were still operational at a somewhat reduced light output. These were small E14 based 3 W types that didn't nearly run as hot as this 13 W Ledare, though.I have no doubts about planned obsolescence, however when a bulb does more than just yellow the plastic a little, like this cracking, I'm guessing the planning when wrong a bit...Also, similarly built and powerful LED-bulbs by (e.g.) Philips and Osram only state 15,000 hours and a EOL lumen maintenance of 70%. If Ikea had specced this bulb the same, then I would have found those specs credible. Now 25,000 hours at 70% seems overly optimistic.

author: jitter
author_rank: Frequent Contributor
timestamp: September 13, 2016, 05:01:54 pm
content: Quote from: Fungus on September 13, 2016, 11:03:38 amThat's an interesting mod. I might consider this for my own bulbs. For this test I will keep the Ledare as it left the factory.I really wonder how the cracks in the base will progress over the next year...Quote from: AcHmed99 on September 13, 2016, 01:48:35 pmI know, and this bulb is in a reasonably well ventilated (semi-enclosed at most) luminaire.Quote from: Kjelt on September 13, 2016, 03:32:08 pmThat is not the case yet except for the vague little yellowish brown spot that a closer look at the first photo will reveal. I guess this is where the bulb sits close to the base of the luminaire (in it, it's horizontally placed).

author: Fungus
author_rank: Super Contributor
timestamp: September 14, 2016, 05:00:54 am
content: Quote from: jitter on September 13, 2016, 04:55:28 pmI think that's the plan, the plastic at the base is heat-conducting and will somehow act as a heat sink.It doesn't seem like a good design though. Most light fixtures are deliberately designed to hide/enclose that part of the bulb.I'm sure they could put a lot of little holes in the sides of the diffuser without any visible effect. People never really look at the bulbs directly so they won't see them. The only problem would be if it was projecting little dots of light on the walls but the light coming from the LEDs is very directional so that shouldn't be a real problem.

author: Srbel
author_rank: Frequent Contributor
timestamp: September 14, 2016, 05:46:39 am
content: It looks something like this on the inside:Plastic is just an electric insulator.

author: jitter
author_rank: Frequent Contributor
timestamp: September 14, 2016, 05:54:33 am
content: Quote from: Fungus on September 14, 2016, 05:00:54 amIt seems that at least Cree has had a go at ventilating a bulb using the chimney effect:I guess this was mainly done as there's no heatsinking surface on the outside of the bulb and the LED-PCBs are basically only cooled by convection.But I wonder about two things: dust accumulation inside the bulb and what if it's placed horizontally?I have a few somewhat older Yankon Y60G1 LED-bulbs (~2013) that I found quite clever: it also uses the chimney effect, but with the LEDs sealed from dust and with an aluminium heatsink:But in just a couple of years time the LED bulbs with large aluminium heatsinks have as good as disappeared from the market. They're all like the Ledare now with no exposed aluminium heatsinks, I guess the improvement in LED effeciency has negated the need for those.The main advantage of that is that the driver can do without galvanic separation from the mains, which will no doubt be cheaper to construct.But in the case of the 13 W Ledare, I agree, they just went a bit too far economising the design. The symptoms I see now seem to point to slight overheating with an expected result of a rapid deterioration of the light output, and the unexpected result of the cracking base.I'm planning on running this bulb for another year in its current application, and will come back to this thread.In the meantime I'm switching to integrated LED-luminaires. These have many advantages over retrofits:- light is radiated in the right direction in the first place. I can get the same light intensity from a 600-700 lm integrated LED luminare (7.5-8.5 W) as from a 11-13 W ~1000 lm retrofit;- LED mdoule has a large surface and runs moderately warm, not hot;- LED-driver is separate and can therefore be modded/replaced;- despite common belief: you can replace LED-modules and -drivers when they die (for industrial luminaires, there's already standardization in progess, e.g.Zhaga).

author: jitter
author_rank: Frequent Contributor
timestamp: September 14, 2016, 06:00:30 am
content: Quote from: Srbel on September 14, 2016, 05:46:39 amThanks, looks interesting.Here's a teardown of the North American version of the 13 W Ledare. Strangely, the blogger mentions it's a "metal base", so I'm not 100% sure they're actually the same (i.e. apart from the driver made for lower mains voltages, they are not universal).

author: Srbel
author_rank: Frequent Contributor
timestamp: September 14, 2016, 09:32:46 am
content: Just to mention, it is not my picture. I found it on the web, but that is how most of bulbs of that design look like.BTW, I use these:http://www.xled.rs/xled/?product=led-sijalicae27-5w220vtoplo-bela2700k-470lmhttp://www.xled.rs/xled/?product=led-sijalicae27-10w220vtoplo-bela2700k-810lmThey are Serbian brand (designed in Serbia but manufactured in China). They claim to have power factor of >0,7, but I have measured 0,55. The power draw is as they claim (5,2 W for a 5W one).

author: jitter
author_rank: Frequent Contributor
timestamp: September 14, 2016, 05:05:49 pm
content: Quote from: Srbel on September 14, 2016, 09:32:46 amNo worries, mine were borrowed as well (except for those in the first post).QuoteThey also claim to be replacements for 50 W and 75 W incandescent. Because of EU-regulations, over here the manufacturer would only be allowed to sell them as equivalent to 40 W (470 lm) and 60 W (806 lm). A 75 W bulb would need to have 1,055 lm, even more than the 13 W Ledare (which Ikea originally promoted as being a 100 W replacement, until the regulations changed to prevent this kind of overly optimistic specifying by manufacturers).The 13 W Ledare under test here has a PF of 0.93, Ikea specifies >0.7.For some reason the 13 W Ledare can carry different identifiers, namely LED1309G15, LED1465G13 or LED1480G13. Mine is the first, but the latter two may be successors with (slightly) different specs, maybe they have a PF closer to 0.7?I was going to say that all LED-bulbs are manufactured in China, but that wouldn't be completely true.I know that Osram assembles some models in Germany and I have one that says "Made in Italy". And I recently noticed this on an Ikea Ryet LED-bulb:You may have noticed that I wrote "assembled" and not "manufactured". I believe those LED-bulbs to be assembled over here from parts manufactured in China, probably on a highly automated and robotized process. But that allows them to legally put "Made in Germany" on it.

author: Srbel
author_rank: Frequent Contributor
timestamp: September 15, 2016, 08:40:07 am
content: Quote from: jitter on September 14, 2016, 05:05:49 pmI use three 5W ones and one 10W for my room (4 in total in one chandelier). It is a bit brighter than a 100W incandescent one. It is perfect for my room.