If you’ve gone down the lighting isle of a store recently, you’ve no doubt noticed we are firmly in the age of the LED light bulb. Incandescent bulbs are kept in small stock for those who still have the odd-ball use case, there’s usually a handful of CFL bulbs for those who don’t mind filling their house with explosive vials of hot mercury, but mostly its all LED now. Which is as it should be: LED lighting is clearly the superior choice in terms of energy efficiency, lifetime, and environmental impact.
Unfortunately, a lot of the LED bulbs you’ll see on the rack are of pretty poor quality. In an effort to drive cost down corners get cut, and bulbs which should run for decades end up blowing after a couple of months. After yet another one failed on him, [Kerry Wong] decided to do a teardown to examine the failure in detail.
He notes that most of the LEDs seem to fail in the same way, flickering after they are switched on until they just stop lighting up entirely. This hints at an overheating issue, and [Kerry] opines that aesthetic and cost considerations have pushed heat dissipation to the back burner in terms of design. It also doesn’t help that many of these bulbs are sitting in insulated recessed fixtures in the ceiling, making it even harder to keep them cool.
Once he separates the actual LEDs from the driver circuitry, he is able to determine that the emitters themselves still work fine. Rather than toss the whole thing in the trash, it’s possible to reuse the LEDs with a new power source, which is quickly demonstrated by showing off a shop light he built from “dead” LED light bulbs.
[Kerry Wong] isn’t the only one to put his LED bulbs under the knife. We’ve covered a number of teardowns which explore the cutting edge of home lighting; for better or for worse.
29 thoughts on “Resurrecting Dead LED Lightbulbs”
That’s interesting to note he found the drivers to have failed. In the few I have disected it has been the LEDs them selves that have expired.
The difference I suspect is that his appear to be mains powered units while mine have been 12v replacements for halogen globes.
In most places the 12v units have very little regulation between the LED and the Power, there maybe a resistor but not much else, so if there is a spike in the power it will kill the LED. you are completely dependent on the halogen original power supply and Halogens have a much higher resistance to a power spike. Also it seem most of the LEDs in bulbs are slightly under driven. I believe it part heat reduction and part using the cheapest drivers you can. Most of my dead LED bulbs have the cheap 105*C capacitor dying on them.
I suspect newer bulbs like the LED “filament” models have better heat management and as such will last far longer. I’d love to experiment with the latest COB LED tech but so far I’ve only used COB for flashlights. Those produce huge amounts of light but they tend to chew up alkaline batteries fast. More on COB LEDs – https://www.digikey.com/en/articles/techzone/2016/aug/the-basics-of-chip-on-board-cob-leds
If you’re interested in the engineering details of LED lighting check out this PDF from Osram – http://www.osram-os.com/Graphics/XPic6/00102625_0.pdf.
I have one of the Walmart brand which failed (only one so far) when I tried to make it work in a double arm lamp whose socket was damaged by years of burners. Instead of on or off it suddenly flickered in a pattern suggesting not random. So I pulled it and replaced the socket.
It’s waiting to have a pass thru the bandsaw to-nite.
One of the first I got succumbed to the knife (x-acto) by slowly engraving the slot at the bottom of the globe and then prying and it will come off neatly. I hung a work light reflector over it with it’s naked chips that are hot to ground. It’s been about a year and it runs full time outdoors under the gable 20 feet up for the whole walkway and yard (jungle) without any light spill or milky globe. I forgot how many chips maybe a dozen with screws holding the heatsink?
“CFL bulbs for those who don’t mind filling their house with explosive vials of hot mercury”
I think it was meant as light humor!
Surprised you didnt link back to this post .. https://hackaday.com/2017/04/04/how-to-trick-your-electrical-meter-by-saving-power/ cause people should be aware of the issue that these great LEDs that are the ” superior choice in terms of energy efficiency, lifetime, and environmental impact” may be costing them more then they realize.
SHsshhhh! It works the other way half the time! Don’t want it getting around too much.
Never thought about the failed LED bulbs. Interesting that those failed LED bulbs I’ve tossed, makes sense it’s not the LEDs! New Toys!
There’s been millions of LEDs used as indicators for 50 years or so. Basically, none of them have failed. There probably is a failure rate but I doubt anyone knows what it is.
That’s because those LEDs have been run at a low current and cool temperature. If you give LEDs that, they’ll never fail.
Heatsinks are just lumps of dumb metal, but I suppose even that costs money. It’s a shame though. Then again you don’t make profit by making your bulbs last twice as long, so only selling half as many. Unless you charge more, of course, and beat the competition.
Maybe a bit of improvement in the casing to increase convective airflow would be good. Might be there’s some optimum way, that all manufacturers will start copying. That said, it surely can’t be hard to discover with FEM and whatever else being commonplace. So maybe there’s other reasons. There’s plenty of mains-powered products with external metal heatsinks. There’s lots could be done, if profit and a race to the bottom on price weren’t ruling the market.
“filling their house with explosive vials of hot mercury”
I have some serious problems with this “below the belt” piece of text. CFL has served us all many many years with great specifications regarding energy consumption and light output not only intensity but also the quality of the light itself.
It deserves much more respect then displayed in this article.
Yah.. when they first came out it was a huge bill if you botched and believed the bogus hype and called for help… meant hazmat cleanup during that first year in this city. Used for tens and ten of years as straight and circline with no problem but make ’em squiggly-curly to replace a normal incandescent and suddenly they’re deadly poison. Not a bit of sense was displayed, but cleanup bills were levied for it, while lead painted homes are still grandfathered today without a thought.
I’m honestly really surprised that so many people took offense to Tom’s joke about CFLs.
I thought it was so obviously overstated that folks would get a chuckle — that’s certainly the sense in which it was intended.
I also had a LED lamp (from Aliexpress or Dealextreme) which started to flicker after some days. There it were clearly the LEDs. When I changed the defective LED I noticed, that all installed LEDs had the polarity mark on the + side! That must have been the crappiest batch of LEDs I ever encountered. Every time I changed a defective LED it took another day until the next failed. Now I have changed all 5 of them and the lamp works. It would have been more economical to throw the damn thing out. But it has a nice base with good heat dissipation and it can be opened easily. The front lens is held on by a threaded ring with extremely fine threads on the cooling fins
It’s not that they’re cutting corners to save cost, but they’re cutting corners to sell more bulbs. The manufacturers are knowingly selling you a lemon, because they know people will try the cheap option first.
Half the LED bulbs out there are utter crap. The other half too expensive for the quality and quantity of light they put out, but what can you do when the better alternatives are outlawed?
LED strips seem to be fairly cheap for their quality and generally don’t have cooling problems as they also have a low thermal density.
The problem is that the bare diodes rarely have very high CRI.
People seem to be happy installing weirdyl colored lights in their homes though, especially now when the comparison is with only slightly better CFL tubes.
what better alternatives are outlawed?
I see it similar. I am sure the old fluorescent tubes (T8, T12) also contain mercury, probably more of it. The long warm up time is what disturbs me.
I had a CFL (6000K) in the kitchen, which was used several hrs/day for 4-5 years. Then not the tube but the electrolytic was gone. It started a strange green/white flicker and was quite dark. This came from the fact, that the “cool-white” phosphors have some quite long phosphorescent afterglow.
I even have 12V halogen lamps in the bathroom and toilet – in use for >15years. Only 1 of the 9 had to be replaced in this time. Obviously the electronic transformers I used there have a very good soft start, so this bulbs.
The bulbs in the living room which use a conventional 50Hz transformer have been replaced many times in this time and are nearly all LED now.
Can’t believe there’s literally CFL apologists in the comments today. There are MANY reports of CFLs failing catastrophically, why do you think everyone has switched to LED so quickly?
If you had to trust the Chinese to either make either an LED driver or a high voltage transformer inside the base of a light bulb, which would you pick?
I am happy, that we have now LEDs instead of CFLs. But only because of the inconvenient warm up time. Of course CFLs also failed, but in my experience never “catastrophically”.
I also did not yet encounter a HV transformer in a CFL. Normally you have a combined gate-drive/current-sense transformer and a resonant output circuit for start.
Back plate of a magnetron :,D
CFLs can explode? Which chemical reaction makes them do that?
If you expose your CFLs to too much hyperbole, they will explode.
i have had a few LEDs fail as described in this article. i’ve had quite a few DOA. and a repeat failure mode that has caught my attention is mechanical. they are so crappy that a physical connection is loose — it simply doesn’t turn on at all unless I wiggle it. i’ve got a CFL with the same problem. so i love that they’re so cheap that i can throw them away and get the next one, because — get this — i’ve had the same failure rate with the $8 bulbs (and the $20 bulbs before then) as i’ve had with the $2 ones. all things considered, about 80% of them have behaved flawlessly for me for about 2 years. now that i’ve replaced the obvious faulty ones, the only bulbs i ever change are the few CFLs scattered around. so overall it’s a win. definitely a detectable bonus on the electric bill!
it’s been a long time since i’ve seen a CFL that didn’t have burn marks on its white plastic casing. i hate CFLs.
CFL Bob’s do not explode with a chemical reaction. However they do make a pop sound when they break. The popping is because of the tubes imploding. They are made by creating a vacuum and then filling the vacuum with mercury vapor. As a result the overall pressure is somewhat below atmospheric pressure, this causes an implosion if the light is broken.
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We had a house built in 2014; I insisted that everything be LED lights — about half BR40 bulbs, half A19. I bought and tested a lot of bulbs before buying everything we needed, and I didn’t go cheap. Over the past 3.5 years, of the 65 or so bulbs, I’ve had about 10 fail, a mixture of the BR40 and A19 bulbs. The first few that died I tore apart and every single time it was the voltage conversion board that was at fault.
And before you yowl that 10 is a lot of failures, the 20 year lifetime rating is based on being on 3 hours a day, and many of our lights are on far more than that.
I have had cfl’s from the $1 store in places in my house for over 10 years now. I really like the color balance of these lamps. I would gues they are on for 8 hours a day most of the year.
I recently bought some of the 60W incandescent equivalent lamps at the dollar tree. They are not bad looking and I have replaced a few CFLS with them, mostly in places where we only occasionally turn the lights on and don’t keep them on for long.
So far I am happy with the LED’s but I can not speak about their longevity. Ask me again in 10 years.
One thing that really sucks about the LED’s that I got is they flare out too quickly to fit into my trouble lights. That is one place I really did want to use them as they should be able to take a lot more physical abuse than anything else out there..
So, cheap LED lamps fail for the same reason cheap CFLs do: crappy power supplies. Great…
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