Should LED bulbs overheat and disintegrate? - Page 1
Forum section: electronics / general

author: edy
author_rank: Super Contributor
timestamp: November 11, 2018, 03:35:11 pm
content: I decided to replace some CFL bulbs with LED thinking it would use less Watts while providing same lumens and also produce less heat. I was surprised then to find the other day my LED bulb plastic disintegrating and dried up to the point it was flaking off the base of the bulb! See photos.... And the metal underneath was scorching hot! I assume it is just a heat sink and not electrically connected to the innards, but what gives? I thought these things ran cooler and why did the plastic flake away after barely using the bulb (it is still operational but is it safe)? For sure less than 1000 hours of use.I think about using a 5 volt wall-wart and hooking it up to an array of LEDs and they run cool and still very bright. The wall-wart stays cool too. Why is the bulb so different and why is it not designed to be cool? And is this a defect or safety problem or actually better now that the plastic insulation is gone, the metal heat sink can actually cool off?

author: NiHaoMike
author_rank: Super Contributor
timestamp: November 11, 2018, 03:36:49 pm
content: Were they exposed to sunlight? Some plastics degrade in UV light.

author: edy
author_rank: Super Contributor
timestamp: November 11, 2018, 03:45:21 pm
content: Nope, not exposed to sunlight at all. But I guess depending on whether the light fixture is enclosed or not it could make a difference? What about bulb being upside-down or not? In this case it was bulb up, socket down, so heat should have radiated up and away from the socket and electrical components. Very surprised after so short a time... Now I can't even identify the bulb and manufacturer and rating... All erased!

author: Whales
author_rank: Super Contributor
timestamp: November 11, 2018, 04:09:13 pm
content: In practice: LEDs can be run just as inefficiency (or worse) than CCFLs. It depends on:Quality of the ledsHow hard they are being pushed (efficiency drops as you increase power)How well they are cooled (efficiency drops as temp rises)QuoteCan you provide a photo of the bulb + what wattage it claims to consume? Some quick estimations on the explanation can be made from there.QuoteI'll be a little anal here: convected, not radiated. Radiation is not effected by gravity (at this scale). If the bulbs were in enclosures (glass covers, etc) then the convection would be contained and cooling hampered considerably.

author: coppice
author_rank: Super Contributor
timestamp: November 11, 2018, 04:18:16 pm
content: Some early LED bulbs from big makers, like Philips, ran at a ridiculously high temperature when operated with no restrictions around them. Most lamps are better now, but if you look at the recommendations for use they usually say they are not suitable for use in an enclosed luminaire. They get super hot if you do use them that way.You see the same issue with most CFLs. They are designed to be used in the open air. If you use them in an enclosed luminaire, which millions of them are, their lifetime is greatly reduced, and the plastics are brown and rather nasty looking by the point of failure.

author: edy
author_rank: Super Contributor
timestamp: November 11, 2018, 08:26:42 pm
content: Quote from: Whales on November 11, 2018, 04:09:13 pmYes, correction noted... It is CONVECTION. As such, I have included some photos of the hardware in question below and will explain the poor design which is why I think it is leading to overheating. I will also show you what I did to hopefully improve the situation, but I am not sure if it is necessarily going to make a huge difference or not.Here is the lamp, it is composed of a base and another long rotating tube that slides inside of it. The idea is, when it is rotated so that the opening in the rotating tube lines up with the white plastic at the front, it lets all the light out. You can rotate the "hexagon" on top which rotates the cylinder inside and provides various decrease of "shuttering" of the opening, with the result that if you turn it 180-degrees you stop all light from exiting the lamp. This way you can adjust the amount of light, but also accidentally leave it on without realising it as it would appear dark with a bulb burning inside of it 24/7:You can see the lamp here with the bulb, and then removed, some plastic pieces still stuck at the bottom that flaked off the bulb:Here is the information on the base of the lamp. I *DID* follow the specified ratings, I made sure of it, knowing that it was an enclosed area I specifically went for an LED when the CFL (that came with it) burned out also after a relatively short period of time, and the reason I got the LED was exactly because I thought it was going to last longer and not get as hot!!!!!! It would have been 9W max. Here is the info:

author: Zero999
author_rank: Super Contributor
timestamp: November 11, 2018, 08:32:13 pm
content: What a stupid design. If you need to adjust the light output, then use a dimmable LED, rather than shuttering which wastes power!

author: rdl
author_rank: Super Contributor
timestamp: November 11, 2018, 08:35:54 pm
content: I just checked and in my bathroom there is one of those horizontal 5 bulb fixtures that I put 60 watt equivalent LED bulbs in (even though they look funny) the base of those read about 90-95 F. I have a clamp on "architect" style lamp at my bench which has a spotlight style 75 watt equivalent LED bulb in it (which is basically upside down), that reads about 100-105 F. All the bulbs are Cree. I have many LED bulbs in use from six to two years and none have failed in any way.

author: edy
author_rank: Super Contributor
timestamp: November 11, 2018, 08:39:39 pm
content: SO I drilled a bunch of holes on the top and the bottom part of the lamp. There are 4 holes on the bottom and 4 holes on the top, towards the side facing away from the front white plastic window. These will always let light through, but most importantly, will also let air through so that convective air currents can (*I hope*) cool down the bulb a bit and reduce the temperature (below shows holes in the inner rotating sleeve):However, the holes in the outer lamp housing and the inner ROTATING portion will only line up when the hexagonal flats are lined up (that is, in one of the 6 positions of rotation, 60-degrees apart). That shouldn't be an issue because we will just have to remember to have it in one of those 6 positions. Truthfully the lamp really only has 4 possible positions, the other 2 (of the 6 possible rotations) are just a repeat. The 1st is fully open, the 2nd is 2/3rds open, 3th is 1/3rd open, the 4th is fully closed, then 5 and 6 are just (1/3rd and 2/3rds open again, repeated):This way also there is less of a danger of forgetting the lamp on. Even if you end up rotating it for whatever reason, you still have a trickle of light coming out of those air vent holes so you can see that it is working. If you really want it DARK you can just rotate it *slightly* so the holes don't line up, there is enough leeway there that you can do that without allowing any light through the front window still.... But that will close up the convection holes.

author: Twoflower
author_rank: Frequent Contributor
timestamp: November 11, 2018, 08:45:05 pm
content: I would have attached 2 or 3 LED stripes each 20cm length to the inner cylinder. They get cooled through the metal case and provide probably a more even light. And I would probably also use a dimmable PSU.

author: edy
author_rank: Super Contributor
timestamp: November 11, 2018, 08:52:27 pm
content: Quote from: rdl on November 11, 2018, 08:35:54 pmWell this bulb, at least that metal portion now exposed because the plastic dried up and flaked off... gets much hotter than 100 F! I can tell you that it burns the finger so it has got to be up there (I have not measured the temperature but I will get out a thermocouple and see if I can get a reading through the holes I made now).So the bulbs were probably something like these.... CHEAP AS DIRT, 60 W equivalent incandescent which consume about 9W (2 pack for under $3 Canadian):https://www.canadiantire.ca/en/pdp/noma-led-a19-60w-light-bulbs-soft-white-2-pk-0528077p.html(NOTE: I don't know if this is the brand of bulb I bought, but I remember whatever I did buy it was relatively cheap... not this cheap though)Notice the poor reviews... Seems like this is another unfortunate scam and much more wasteful in my opinion than incandescent bulbs.At least those don't have multiple electronic components in them which require much more time and energy and materials to manufacture. If the world is getting flooded with garbage LED bulb, this is just another ***BULB-CARTEL*** because they claim LED's last forever and save money but actually fail to live up to any of of these inflated expectations (not to mention governments around the world are banning regular bulbs left right and center yet doing nothing to enforce the reliability of what we are supposed to be replacing them with, which by the way cost WAY MORE, even the cheapest brands that don't last anywhere near an incandescent bulb).

author: rdl
author_rank: Super Contributor
timestamp: November 11, 2018, 09:12:34 pm
content: Okay, so I have to amend my test results. On the Cree bulbs I have, I just noticed there is what must be a sort of heat sink. It's between the bulb and the base, about 12mm wide and has fat stubby fins all around. Pictures of newer Cree bulbs at Home Depot and the Cree site don't have this. When I measured the temperature before I was aiming as far down the base as I could. When I rechecked at the heat sink band, it's actually very hot. I was able to get readings over 150 F.

author: edy
author_rank: Super Contributor
timestamp: November 11, 2018, 09:19:35 pm
content: WOW Folks! I can boil water with this bulb!!!I put a thermocouple on the actual PLASTIC bulb and measured 124F (51 C) which is not too bad.... See photos below. At this temperature I can still grab the bulb with my bare hands and unscrew it, which I did and then proceeded to quickly measure the exposed METAL part (where the plastic had flaked off) and to my astonishment got over BOILING!!!!!!! (214F, 100C).Measured on the bulb plastic:Position of probe on plastic seen here:Bulb unscrewed quickly and metallic part measured in F and then C:Somebody please tell me I'm not crazy here. Since when do LED bulbs operate this hot? Is it really my LAMP fixture or a bad design of the bulb being used? Somehow I am getting the feeling this bulb would get that hot even in a totally open fixture. I can test it out to confirm. Does anyone have stats on nominal temperatures for these devices to function at? What about the electronic circuit driving the LEDs? How long it is going to last in this environment?

author: edy
author_rank: Super Contributor
timestamp: November 11, 2018, 09:28:26 pm
content: Apparently I am crazy... This is expected:https://www.lifx.com/blogs/the-latest/19032975-how-hot-are-led-light-bulbsSeems to be a normal behaviour!!!! PHEW!

author: GeoffreyF
author_rank: Regular Contributor
timestamp: November 11, 2018, 10:01:02 pm
content: It's not the LED's but the power supplies on many of this type of product. No they shouldn't but sometimes they do. Contributing factors can be light dimmers not suitable to the particular device, device not suitable to any light dimmer, bulb is screw in but not intended for local voltage and finally surges of voltage that can occur.

author: abraxa
author_rank: Frequent Contributor
timestamp: November 11, 2018, 11:20:22 pm
content: Quote from: edy on November 11, 2018, 03:35:11 pmThose bulbs are designed to be cheap, as you noticed. Cheap LED bulbs use a capacitive voltage divider - meaning that a lot of energy is wasted as heat, as you noticed already. Examples:http://danyk.cz/ledzar_en.htmlandhttps://www.powerelectronictips.com/whats-stuff-capacitive-power-supplies-leds/

author: cdev
author_rank: Super Contributor
timestamp: November 11, 2018, 11:28:01 pm
content: I can't possibly tell you how many of these bulbs Ive had fail. Lots, a real lot. Sure, they last longer than a conventional bulb, but its increasingly hit or miss on quality because so many run so hot - especially when hanging downward or mounted so that they are sideways. They start to flicker and then they go in a drawer. We return them when they reach a critical mass but I have a bunch that are probably not returnable.I would like to extract the working LEDs to use in smaller (DC driven) lamp projects. How does one get the dome off, a heat gun, or does one have to break it?

author: james_s
author_rank: Super Contributor
timestamp: November 12, 2018, 04:43:12 am
content: It's been more than a decade since I've seen an LED bulb that used a capacitive dropper. The proper drive electronics are so cheap now that there's little reason to try to get away with just a capacitor.I've had good luck with Philips and Cree LED bulbs, as long as you get the ones rated for enclosed fixtures where needed they hold up well.

author: james_s
author_rank: Super Contributor
timestamp: November 12, 2018, 04:44:36 am
content: Quote from: Hero999 on November 11, 2018, 08:32:13 pmIt probably made a lot more sense when CFLs were the norm, while dimmable CFLs were available, they were rare and didn't work very well. A CFL at full brightness will still consume less power than a dimmed incandescent lamp. Now with LED lamps the shutter mechanism makes little sense.

author: fourtytwo42
author_rank: Super Contributor
timestamp: November 13, 2018, 06:14:18 pm
content: This is worrying, I have no experience of LED lamps at all being a CCFL user but they have been harder to get as stupid Halogens replaced them here in the UK duhhh. I had one store left where I was buying CCFL's, I was in there today and noticed there stock of CCFL's was almost gone and the space taken over by cheap LED's, so cheap in fact there cheaper then the CCFL's. Both being own brand I don't know what make they are but I bet they have the problems outlined here! Most of my lamps are traditional hanging ceiling fittings so cap up but open air, ohhh dear maybe. Anyway I didn't buy any as I still have a few spare CCFL's but I am thinking I should sweep up the remaining stock of CCFL's.

author: cdev
author_rank: Super Contributor
timestamp: November 13, 2018, 06:46:18 pm
content: Seems as if many of these bulbs would last much longer if there was a way to add more heat sinking to their driver enclosure, and/or make them a bit longer to put more distance between LEDs and driver.How do people get the domes off?Do I have to pry the bulbs apart/ break them?

author: SiliconWizard
author_rank: Super Contributor
timestamp: November 13, 2018, 06:48:22 pm
content: LED bulbs are marketed as the best thing since sliced bread, but they are riddled with specific issues. (They have a key advantage of being low power but unfortunately this seems to be an excuse for putting them everywhere even when not really needed. That's another story.)The most common issue especially on the cheaper ones is unproper heatsinking. Power LEDs *and* their power supply circuitry can generate a lot of heat and are often not heatsinked properly. The fact that the ones put in "bulbs" are confined makes matters worse.Another issue is the EMI noise they can generate.Yet another one is their light spectrum. Even though we can find LEDs that have a more "tamed" spectrum, again the mass of LED bulbs that are sold use LEDs which spectrum is atrocious (way too "cold") and bad for our eyesight.

author: james_s
author_rank: Super Contributor
timestamp: November 13, 2018, 10:11:59 pm
content: Quote from: edy on November 11, 2018, 08:52:27 pmThe cost of the bulb is virtually irrelevant, especially in the case of incandescent the cost of energy to run the bulb over its life is an order of magnitude greater than the cost of the bulb itself. Go figure if you buy the cheapest garbage you can find the results will be disappointing. I've been using mostly Philips and Cree LED bulbs in my house and since I started buying them in early 2011 I can count all the failures I've had on one hand. Every one of those was used in a fully enclosed fixture despite the bulbs saying not to so I consider it my fault that they failed. The bulbs in my porch lights were installed in November 2011 (I write the installation date on each lamp) and have been running dusk till dawn every night since then, still going strong. Even at the ~$30 each I paid at the time they have paid for themselves many times over.Buy quality lamps and use them as directed and they will last a long time and save you money. It's pretty hard to legislate quality, you have to vote with your wallet.

author: NiHaoMike
author_rank: Super Contributor
timestamp: November 14, 2018, 12:42:30 am
content: Quote from: cdev on November 13, 2018, 06:46:18 pmBig Clive has done teardowns on lots of LED lights. Given how cheap LED bulbs are nowadays, it can make sense to use multiple run at reduced power (with hacking or a dimmer) so that they run cooler. I would like to see LED bulbs that are dimmable with a knob on the case.Quote from: SiliconWizard on November 13, 2018, 06:48:22 pmThe warm white LEDs are labeled as such.

author: james_s
author_rank: Super Contributor
timestamp: November 14, 2018, 04:58:22 am
content: The vast majority of the LED bulbs on the market are 2700 or 3000k warm white. You have to go out of your way to find cooler colors, 5000k "daylight" is the next most common.

author: cdev
author_rank: Super Contributor
timestamp: November 14, 2018, 09:33:01 pm
content: After scanning his videos, I was surprised that none of the bulbs he seemed to review looked like the ones Ive bought here in the US. I probably didnt dig deep enough.I guess I'll just break out the heavy gloves and try to get the dome off with physical force or if all else fails, break the covers.I have no desire to use these LED bulbs with mains power any more, however the LEDs which I am pretty sure are for the most part are all still working, (because most of them are just intermittent, not completely nonfunctional) would be quite usable for task lighting if powered and heat sinked appropriately.Quote from: NiHaoMike on November 14, 2018, 12:42:30 am

author: Leiothrix
author_rank: Regular Contributor
timestamp: November 14, 2018, 09:52:49 pm
content: After reading the thread title I can state that I'm really glad that this is not about the struggle to design street lighting

author: cdev
author_rank: Super Contributor
timestamp: November 15, 2018, 12:57:46 am
content: From the manufacturers and vendors points of view, the observed 'problems' may be a feature and not a bug considering that they could easily last years, so long they would rarely need to be replaced,if they were designed properly.I can see them saying "where is the profit in that?"They likely think "there isn't practically any."Just like drug companies now want costly drugs to manage (newly) costly illnesses, they really don't ever want to cure people anymore. Not unless they can make it really expensive to buy.

author: james_s
author_rank: Super Contributor
timestamp: November 15, 2018, 02:19:35 am
content: The early LED bulbs were designed very well, but they also cost me $40 each. In order to get people to buy them, prices HAD to come down drastically, and naturally that means making some sacrifices, most low cost LED bulbs are rated 15,000 hours instead of 25,000 or more, and they tend to have more restrictions on the sort of fixture they can be used in for airflow reasons.It's no conspiracy, it's simple economics. How do you sell a bulb for $3 and still make a profit? A proper heatsink alone would consume more than 100% of the BOM budget.

author: amyk
author_rank: Super Contributor
timestamp: November 15, 2018, 02:53:10 am
content: Quote from: abraxa on November 11, 2018, 11:20:22 pmOn the contrary; a cap dropper doesnotdissipate any power (besides that caused by the ESR of the cap, which is insignificant) and its simplicity means it will outlast more fancy circuits (whichdodissipate power in normal operation); the only reason it's not used for higher power is because of the capacitor size required, as noted in your second link, and the horrible power factor.

author: cdev
author_rank: Super Contributor
timestamp: November 15, 2018, 08:33:13 pm
content: If they derated them a bit and added say a 10 cent better heatsink the driver would last 2 or 3 times longer and still deliver acceptable light output.

author: james_s
author_rank: Super Contributor
timestamp: November 15, 2018, 08:49:18 pm
content: That 10 cent better heatsink would add at least a dollar to the retail price, and de-rating would require more LEDs to match the lumen output of the incandescent lamps they are meant to replace. Engineers at the major lighting companies have thought of all this, they're not dumb.

author: cdev
author_rank: Super Contributor
timestamp: November 15, 2018, 09:28:27 pm
content: They should add a failure rate to the spec, so that people are aware that the lifetime they specify for the bulbs is wildly optimistic, not the real world condition.It really is a shame they cant be derated somehow, run at a slightly lower voltage perhaps, so they lasted longer. I have LED bulbs in fixtures where they get only very infrequent usage and they still often burn out in a year or less, often just a few months.

author: edy
author_rank: Super Contributor
timestamp: November 15, 2018, 09:58:01 pm
content: So are the LED bulbs burning out because of the electronics inside that need to convert the high voltage mains down to what the LED's need? Those electronics are getting cheaper, taking short-cuts and not designed as well, and getting too hot?Why not build the electronics into the light-switch (and eventually into the actual lighting runs in new houses) to be on a different voltage?For example, in my kitchen I have a 2-switch panel to control both lights. It is just taking the mains 120V in and then I have a run that goes to the ceiling. Would it not be possible to have the voltage converter in the wall, take 120V down to say 12V (or whatever) and therefore the voltage of the bulb sockets in the ceiling would be 12V and I could use LED bulbs that run on 12V... they would not have as much heat dissipating issues, they would have simpler electronics, they would last longer. Put a single voltage reducer in the actual switch-box and I'll wire up the house with new switches, then the bulbs will never heat up or burn out. The cost of the switches may be less than changing bulbs all the time.Quote from: cdev on November 15, 2018, 09:28:27 pmYes, the so-called "lifetime" is sounding like a marketing scam with a big asterisk and tiny print underneath. There is NO WAY my LED bulbs, none of them so far I tried, lasting anywhere close to the number of hours they claim. 10,000 hours? The bulb is $1.93 CANADIAN:https://www.canadiantire.ca/en/pdp/noma-led-a19-60w-light-bulbs-soft-white-2-pk-0528077p.htmlWhat exactly is 10,000 hours in real-world usage? If the bulb is kept on 24x7 that's 168 hours per week, so it should last slightly more than 1 year (about 13.5 months). But most people don't use bulbs continuously like that... So I would expect if you have the light on 5 or 6 hours a day, that's 1/4 of the time so it should go closer to 4-5 years! Every LED I've ever owned has "poofed" out well before that. It's a sham!

author: coppice
author_rank: Super Contributor
timestamp: November 15, 2018, 10:48:33 pm
content: Quote from: edy on November 15, 2018, 09:58:01 pmI think the opposite is the case. As the strengths and weaknesses of early LED solutions have been seen, newer solutions have been developed which allow both lower cost and lower heat. Most new LED lamps are not getting to the kind of blistering temperatures that even expensive lamps were getting to 5 years ago.Quote from: edy on November 15, 2018, 09:58:01 pmHow exactly would that work? Different lamps require different electronics, based on things like how many LEDs are in the chain. Are you proposing that a lamp replacement would require exchanging a piece in the switch AND a piece in the luminaire? Good luck with that.

author: james_s
author_rank: Super Contributor
timestamp: November 15, 2018, 11:56:40 pm
content: Quote from: cdev on November 15, 2018, 09:28:27 pmThey *can* be derated, but that means more parts and higher cost for the same light output. You can already get high quality long life LED bulbs but they cost more money. If yours are failing frequently you are either buying cheap/poorly designed bulbs or using them in ways they were not designed for. I've mentioned previously I changed my whole house over to LED between 2011-2014 and I've had only 4 or 5 failures in that time, all of which were in fully enclosed fixtures despite the bulbs warning against that. The LED bulbs in my outside lights have been running all night, every night since 2011 and they're still as bright as new, zero failures. Those are older Philips bulbs.

author: james_s
author_rank: Super Contributor
timestamp: November 16, 2018, 12:00:38 am
content: The future trend is away from bulbs entirely. In new houses they're building, the lights are integrated fixtures with the LEDs and driver built into an aluminum pcb permanently mounted in the fixture. When the unit fails, you replace the whole thing. Dispensing with the bulb means you can have much more effective cooling at lower cost. The bulbs will stick around a long time for retrofit purposes.

author: coppice
author_rank: Super Contributor
timestamp: November 16, 2018, 12:07:56 am
content: Quote from: james_s on November 16, 2018, 12:00:38 amHaving the entire luminaire for cooling really transforms the problem of achieving high reliability. However, economically it only works if these cooler running integrated luminairesgenuinelyoffer high reliability, because the replacement cost of a luminaire is far greater than the cost of a bulb. People need totrustin the reliability to go for integrated luminaires, and its not clear they have much trust right now. They've seen too many early LEDs dim badly or go pop.

author: cdev
author_rank: Super Contributor
timestamp: November 16, 2018, 12:17:55 am
content: Replacing an entire luminare because one LED in a row of 100 goes bad makes no sense either. What we need are replaceable or even repairable (if people want to do it) LED sub assemblies that have thermal connection to the larger light thats are user replaceable.. Users can smear some thermal grease on the thing. People are intelligent enough to understand this.Standardized DC driven LED assemblies.

author: coppice
author_rank: Super Contributor
timestamp: November 16, 2018, 12:26:32 am
content: Quote from: cdev on November 16, 2018, 12:17:55 amThat depends entirely on the reliability of the product. Typically as we make a product cheaper and more reliable it becomes less repairable. Expect the die by die packaging of the LEDs in most lamps with chains of LEDs to go away. It has already disappeared where it was a big physical liability, such as in the fake filament lamps. It will disappear from most other lamps over time.

author: james_s
author_rank: Super Contributor
timestamp: November 16, 2018, 12:51:48 am
content: No normal person wants to replace an LED or an assembly, everyone just throws it away and buys a new one. People like me will still repair things because we can but most folks will just go buy a new $40 light fixture when it fails 10 years down the road. By that time it will probably be cheaper and more efficient anyway.Seriously, I'm just not seeing the reliability issues you are. I've had very few LED bulb failures and I know people with integrated fixtures, never seen one fail. There would be no market for replacement modules.