Why/how do these LED lamps fail so fast? - Page 1
Forum section: electronics / repair

author: soldar
author_rank: Super Contributor
timestamp: September 20, 2023, 04:49:28 pm
content: We are told LED lights are eternal and will last more than 10,000 incandescent lamps but not in my experience.About a year BP (Before the Pandemic) I bought a bunch of round flat ceiling LED lights and I installed some of them in a second home where I do not spend that much time. Today the third one out of seven has failed. They all fail in the same way. The flicker but do not start up. The symptoms are that the PSU is failing but it is the string of LEDs that fails and the PSU is fine. If I exchange PSUs between lamps the problem stays with the lamp, not the PSU.I do not know how to interpret these symptoms except that the LEDs are demanding more current and the PSU is limited and shuts down. So I have three PSUs to play with. I am talking from memory but IIRC they provide a constant current of about 240 mA at about 60V. Not isolated from mains so care is recommended.I am assuming the LEDs fail because they are being driven too hard. But for the brief moment they are on I do not see any one of them not lighting.This time I might test the string of LEDs with a DC power supply (which I do not have and will have to rig).My experience with LED lamps is not being good. And what ticks me off is that these are complete ceiling fixtures where you can't just change the light-bulb like in the good old days.Any ideas or knowledge on this topic?I am thinking that, with a constant current PSU, I could divert some of the current through a resistor in parallel and this would lower the dissipation in the LEDs. Suppose it is putting 240 mA at 60 V. If I put in parallel a 2K4 resistor it will take away 25 mA from the LEDs (and dissipate 1.5W).

author: Grandchuck
author_rank: Super Contributor
timestamp: September 20, 2023, 05:06:12 pm
content: I don't know if it is relevent to your lights, but if an LED in a series string shorts out the others draw more current if the power supply is a CV type.

author: artag
author_rank: Super Contributor
timestamp: September 20, 2023, 07:19:44 pm
content: Big Clive often autopsies (biopsies ? some aren't broken when he starts) LED lamps and looks into the current control. Often, there is a resistor whose value sets the LED current.A while ago he investigated some Philips lamps only available in Dubai which were underrun for longer life. So he often explains how a given lamp can be modified to run at lower current.

author: soldar
author_rank: Super Contributor
timestamp: September 20, 2023, 08:02:58 pm
content: Quote from: Grandchuck on September 20, 2023, 05:06:12 pmI was thinking along those lines. If one LED fails open then none will light. If it fails shorted then the other will draw more current depending on the PSU. This one seems to be more like constant current, variable voltage. If one or more LEDs short out then the current should stay the same but the voltage should drop. It could be that if the voltage drops then the PSU shuts down as detecting a short.But, without looking too closely, I did not see any individual LEDs obviously not lighting.I think I need to do some more testing with both the LED string and with the PSU.

author: dobsonr741
author_rank: Frequent Contributor
timestamp: September 20, 2023, 08:07:04 pm
content: I saw electrolytics causing the trouble many times. Usually, the simple plastic encased bulbs. So my working theory is overheating, caps blowing up or getting leaky and cascading into semiconductor and LED failure.

author: soldar
author_rank: Super Contributor
timestamp: September 20, 2023, 08:07:47 pm
content: Quote from: artag on September 20, 2023, 07:19:44 pmI remember those videos.When a previous lamp failed I did a bit of reverse engineering with the PSU, maybe hoping I could find some use for it but I remember (1) it was not isolated from the mains and (2) it was constant current with about 240 mA so I thought it really was not very useful. I will investigate furter to see if it can be modified but, in any case, if it is constant current then I can just put a resistor in parallel with the LEDs and it will shunt some current away.

author: IanB
author_rank: Super Contributor
timestamp: September 20, 2023, 08:19:40 pm
content: You could:- buy more expensive lamps (no guarantee of course, but cheap lamps are more likely to cut corners)- buy lamps with more LED chips for a given light output (more chips means less power per chip)- modify the lamp for lower power consumption by changing the current sense resistor (not practical for more than the occasional lamp)- buy dimmable lamps and run them on a dimmer at lower powerI tend to use the last option, since for ambient light I do not need arc lamps. If I want bright task lighting, I just turn the dimmer up temporarily, or use a separate task lamp.

author: srb1954
author_rank: Super Contributor
timestamp: September 20, 2023, 08:31:25 pm
content: Quote from: dobsonr741 on September 20, 2023, 08:07:04 pmIn the many autopsies I have performed on failed LED lamps I find the electrolytics are never faulty and usually test as good as new.The failures I find are always an individual LED having small burn marks in the centre; what BigClive calls the "black spot of death".

author: Zero999
author_rank: Super Contributor
timestamp: September 20, 2023, 08:37:26 pm
content: Quote from: srb1954 on September 20, 2023, 08:31:25 pmI've seen both, but I sometimes it's the LED failing which caused the electrolytic capacitor to blow up. If the capacitor is across the LED, which is driven from a capacitive dropper and it's not rated to the full peak mains voltage, it'll blow, if the LED goes open circuit.

author: soldar
author_rank: Super Contributor
timestamp: September 20, 2023, 09:48:07 pm
content: Quote from: IanB on September 20, 2023, 08:19:40 pmI have not had good luck with dimmables. I bought a load of them at Ikea and they are complete crap. They sort of work (with a triac dimmer) in the brighter range but with more dimming they start to flicker. Utter crap.OTOH, I have discovered that the "non-dimmable" types can be dimmed very easilly and effectively by simply putting a resistor or potentiometer in series. This woks better than buying the dimmable type. I have several desktop lamps with this kind of dimmer and they work very well. But I cannot see how to do it for a ceiling fixture controlled by a wall switch.These ceiling fixtures that are failing I bought at a Big Box Depot. It's not like I bought them at the Dollar Store.

author: themadhippy
author_rank: Super Contributor
timestamp: September 20, 2023, 10:55:21 pm
content: Quoteon AC a capacitor is a better optionQuoteIf you can live with 1 or 2 fixed levels change the single gang switch for a 2 or 3 gang 2 way switch and wire the caps in the back of the switch.

author: IanB
author_rank: Super Contributor
timestamp: September 20, 2023, 11:42:02 pm
content: Quote from: soldar on September 20, 2023, 09:48:07 pmThis seems to depend on the brand. I am getting really good results with Philips bulbs and a Lutron trailing edge dimmer (the Philips bulbs being the most important part of the equation).

author: shakalnokturn
author_rank: Super Contributor
timestamp: September 21, 2023, 01:08:04 am
content: "The black spot of death" that could be caused by overcurrent (including overshoot at power up if PS is poor design), excessive heat or just inevitable thermal cycling.The odds are that the bonding wire breaks away from the die slightly, the PS being constant current, when supplying an open string will hit its voltage limit often high enough for the open LED to arc, causing the whole string to flicker.LED bulbs are definitely not what they're advertised to be, on average they're junk! (Once procuction, lifetime and recycling are taken into account I'd bet they're less ecological than your old tungsten filament...)Osram in my experience have been expensive crap. I have had decent results with Philips and Toshiba though.

author: alligatorblues
author_rank: Regular Contributor
timestamp: September 21, 2023, 01:21:47 am
content: If LEDs are run off constant current, the voltage remains steady. But if the current is not well controlled, the voltage will rise exponentially in comparison to the rise in current. It sounds like a poor design. The current creeps up. I doubt if it's worth trying to salvage.

author: dobsonr741
author_rank: Frequent Contributor
timestamp: September 21, 2023, 01:33:18 am
content: +1 for Philips. I’m only buying 458430.

author: IanB
author_rank: Super Contributor
timestamp: September 21, 2023, 01:37:17 am
content: Quote from: alligatorblues on September 21, 2023, 01:21:47 amActually, this is not entirely true. Constant current supplies like to kill loads connected to them, and they are more deadly when the current is controlled more tightly.Here's an experiment I did:I took a length of nichrome resistance wire and connected it to a variable power supply with voltage regulation ("constant voltage"). I was able to gradually turn up the voltage until the wire glowed red, orange, yellow, quite brightly. Everything behaved fine.Then I took the same length of wire and switched the power supply to current regulation ("constant current"). This time, when I gradually turned up the current the wire glowed red, started to be orange, and then quickly burned out and failed with a molten hotspot.I tried again, two more times, with a fresh piece of wire each time. Each time the wire rapidly melted and failed before getting much beyond a dull red heat.This is the problem with constant current supplies. They are really unforgiving and like to destroy the things they are powering.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 21, 2023, 02:44:32 am
content: Quote from: IanB on September 21, 2023, 01:37:17 amActually, this is not entirely true. Constant voltage supplies love to kill loads connected to them, and they are more deadly when the voltage is controlled more tightly.Here's an experiment I did:I took a string of LEDs and connected it to a variable power supply with current regulation ("constant current"). I was able to gradually turn up the current until the LEDs glowed painfully bright. They got warm and that was about it.Then I took the same string of LEDs and switched the power supply to voltage regulation ("constant voltage"). This time, when I gradually turned up the voltage, the LEDs glowed dimly at first, but as they started to heat up, they got brighter and brighter, until suddenly eclipsing the previous test and then nothing. I tested the LEDs and found one had failed open.I tried again, two more times, with parallel arrays of rectifier diodes this time, hoping that their robust ratings would do better. The LEDs were only rated a few hundred mA after all. Alas, each time, one of the diodes failed shorted, while the rest hardly even warmed up (WTF!).This is the problem with constant voltage supplies. They are really unforgiving and like to destroy the things they are powering.Tim

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 21, 2023, 03:08:05 am
content: Anyway, regarding LEDs: they are extremely long lived, in and of themselves, when ratings are respected.The phosphor is actually the higher wear element, as it tends to fade over time. The power density on it is quite impressive, for just a powdered mixture of ceramics that have this one magical property (fluorescence). The blue LED chip itself also declines, but slower.But that's just the LEDs themselves.What's powering them, is another matter.Lifetime can always be lower, and when it is economical to do so, it absolutely will be done. Electrolytic capacitors are the most obvious and worst offender, with 2khr 85°C parts being common picks. Put that in a stuffy lamp fixture and it might last mere months!To make a long life LED lamp, one must use:- Quality LEDs, derated modestly to reduce phosphor and LED chip wear- A robust controller/driver, to limit current, typically to smooth light output, and optionally to perform power factor correction- Long life or low-wear components (e.g. 5khr+ 105°C electrolytics, if any)- Adequate transient protection and filtering (suitably sized MOV, somewhat-thicker-metallized EMI caps)- VERY GOOD thermal management, spreading heat from the LEDs throughout the package, and allowing air to permeate it- This includes the fixture, which should preferably be an open vertical or horizontal design, or made with holes or louvers in the reflectors/diffusers to allow free air flow.For pretty much everything, heat is the killer. Phosphors, despite being mere ceramics, are indeed sensitive to temperature, and seriously degraded when ran hot. LED chips accumulate defects faster when hot, and when ran at high current density, as well. Electrolytics notoriously degrade quickly when hot. So do other capacitors, and other components generally. Resistors, film capacitors, and semiconductors (other than LEDs), generally are fine within ratings of course, and those listed above are the major wear elements. Filtering and transient protection are key to long life through environmental disturbances, especially surge which will progressively (or outright) damage passive / unfiltered / bare LED strings (and most likely filtered ones too, since the filter capacitor will only be 10s of uF, not enough -- nor nearly low enough ESR -- to swamp the pulse).LED derating also has the knock-on benefit of lowered resistive losses (higher efficiency). On top of this, for a variety of reasons, modern LEDs are closer to 3.0V drop at typical operating levels -- they're very efficient. Compare to the oldest (~first generation illumination) which were typically 3.6V or more, and dissipated more like 90% of power input (which was still an impressive showing, as illumination technology goes). The optical (quantum) efficiency is remarkable: modern LEDs produceso much lightthat the power dissipation is, not just palpably, but substantially, lower than the power input. Compare a first-generation 100lm LED (might be an 8mm dia. package rated 3W), running near ratings, to a modern one at the same intensity (which might be a 3x3mm DFN, rated for, actually about 3W still, PCB permitting), dissipating under 1W!Now, of a marketed product, obviously you can only establish so many of these things, even as an engineer willing to (potentially) destroy a few lamps in the process of evaluating them. As a consumer, you only have whatever claims the manufacturer makes, and 3rd-party testing. Some of the above points can still be evaluated, at least to a rough degree, as well as other points made in the posts above. As far as temperature, besides fixture selection (that's your own responsibility as decorator!), large size (more dissipating area) and more open structure (same!) for a given power rating is a potential indicator of performance.Also, regarding Philips specifically -- they made a remarkable early lamp, with I think still quite impressive lifetime today (though I think it's long since discontinued, I haven't checked?). The trick was making a large, replaceable phosphor module to place on top of the LED chips -- thus running cool, giving diffuse emission, and addressing one of the primary concerns at the time. Since then, phosphor lifetime has improved, as well as overall efficiency, and overall cost most dramatically -- this was back when LEDs were very new and rather pricey, IIRC, so the maintenance option had some promise. Whether that was an acceptable compromise for consumers, or just a good trick to convince them to buy the things, I don't know, but, I guess it's funny that it was a losing proposition in the long run -- in that, LEDs are now so pervasive and cheap that such steps are irrelevant, the whole bulb is easily disposable.(Which, let me see here. Here's a press release about them:https://www.ledsmagazine.com/company-newsfeed/article/16691970/philips-unveils-worlds-first-led-replacement-for-most-common-household-light-bulbTeardown:https://youtu.be/b4ZBfmLGRrkMSRP about $50:https://www.led-resource.com/2012/09/philips-l-prize-award-winning-led-bulb-review/I don't see an article about when they were discontinued, maybe it only lasted a few years even. Well made unit for what it is, just not very competitive!)You can also choose just completely different designs that literally never existed before. Well, sorta kinda. Fluorescent tubes are linear sources, obviously, and glow discharge systems have existed before, but tubes are rather rigid, and glow discharge requires custom glassware. LED strips can be placed anywhere, easily, and trimmed to length (with minor restrictions). They do need to be wired up correctly, but once installed, they are distributed sources, that run cool, while giving diffuse wide illumination. Combined with color customization options, whole new design/decoration spaces are possible.

author: soldar
author_rank: Super Contributor
timestamp: September 21, 2023, 11:54:53 am
content: Quote from: IanB on September 20, 2023, 11:42:02 pmThanks for that link. The video is very interesting and informative and I will keep that information in mind.The thing is that I am replacing ceiling fixtures, not lightbulbs. I will have to see if Philips makes similar fixtures.

author: themadhippy
author_rank: Super Contributor
timestamp: September 21, 2023, 12:56:44 pm
content: QuoteQuotewhy are you repeating your mistake, replace the fittings with something that has a standard lamp base

author: Zero999
author_rank: Super Contributor
timestamp: September 21, 2023, 01:49:50 pm
content: Quote from: IanB on September 21, 2023, 01:37:17 amQuote from: T3sl4co1l on September 21, 2023, 02:44:32 amBoth statements are correct, but it depends on the load. If it has a positive voltage vs temperature coefficient, like a piece of nichrome wire, then it will be more likely to be killed by a constant current supply, whist if it has a negative voltage corefficient, such as an LED, it will be more vulnerable to a constant voltage power supply. As the nichrome wire heats up, its resistance will increase, but the currrent is constant, so the supply will increase the voltage leading to progressively more power dissipation. As the LED heats up, its foward voltage will reduce, for the same current, but the power supply will maintain the same voltage, so the current will increase, leading to increasingly highr power dissipation. The nichrome wire heater should be powered from a CV power supply, whilst the LED off a CC power supply.

author: David Hess
author_rank: Super Contributor
timestamp: September 21, 2023, 01:56:01 pm
content: Quote from: T3sl4co1l on September 21, 2023, 03:08:05 amExactly, the "50,000 hour operating life" specification is a fantasy based on the operating life of the LEDs to reach 50% brightness and has nothing to do with operating life and reliability of the LEDs and ballast.When California passed their LED bulb mandate, they based the economics on that 50,000 hour operating life saying that LED bulbs would actually cost less over the long term. (1) After a few years, they admitted in a report that that operating life was grossly exaggerated (I knew that) and that the economics were so bad that incandescent bulbs were better; the extra cost of the LED bulbs was greater than the extra cost of the power for an incandescent bulb. (2) Unfortunately, but not surprisingly, California has since censored that report and removed access to it, because fuck you citizens.A reliable electronic ballast needs to not use operating life limited parts like aluminum electrolytic capacitors, be significantly derated, and include protection circuits which themselves will not fail. Because of operating temperature, it probably also needs to use hybrid construction.(1) I do not believe that politicians are stupid enough to fall for this. They did it deliberately for purposes of rent seeking, so fuck them.(2) I have had the same experience with government mandated electronically commuted motors which replace less efficient shaded pole motors. Their operating life is short and replacement cost is high so their total cost of ownership is higher despite the power saved.

author: soldar
author_rank: Super Contributor
timestamp: September 23, 2023, 09:47:23 pm
content: OK, I have had a closer look and the circular strip of leds is composed of 102 discrete units which may have more than one led per unit. I do not know how they are connected.Three contiguous leds are blackened and, sure enough, they remain dark when the others light.Anyone know how they might be connected? If I know this maybe I can try a repair by taking them out of circuit or by shorting them or by substituting a resistor....

author: coppice
author_rank: Super Contributor
timestamp: September 23, 2023, 09:57:35 pm
content: Quote from: T3sl4co1l on September 21, 2023, 03:08:05 amSome are. Some aren't. There used to be a huge number of LED lamps that gradually dimmed to a level of uselessness over a year or two. That problem seems to have improved a lot, but some still rapidly dim.

author: Zero999
author_rank: Super Contributor
timestamp: September 24, 2023, 09:19:34 am
content: Have you measured the voltage across the LEDs which do work?

author: soldar
author_rank: Super Contributor
timestamp: September 24, 2023, 12:02:20 pm
content: Quote from: Zero999 on September 24, 2023, 09:19:34 amI did some testing with the first few LEDs of the strip and, apparently they are grouped in groups of 4 LEDs in parallel. I put about 40 or 50mA through the first group , which would mean 10 or 12 mA through each LED and they light OK and measure about 2.8V.I then connected the two first groups and, sure enough, at the same current level I get about 5.6V. So those two groups are in series.If all the groups of 4 LEDs were all connected in series we would have about 25 groups adding up to about 70V.The PSU says 240mA and 40 to 76V which would mean a max of 18 W which is less than the 20W listed on the fixture.240mA which would mean 60mA through each LED. Hmmmm.... But 60mA x 2.8V x 100 LEDs= 16.8W which is less than the 20 W nominal for the fixture.In any case it does seem like the LEDs are being driven with too much power.If the group of failed LEDs were shorted the others would just light normally. If they were open circuit the others could not light at all.I measured the failed LEDs and they are opened, not shorted. I then soldered a 68 ohm resistor across in the hope that it may repair the problem but it does the same thing, it blinks on for just a moment.Quite baffling to me.ETA: I shorted the bad LEDs and the others now work correctly. I might shunt some current away. I will keep experimenting.

author: soldar
author_rank: Super Contributor
timestamp: September 24, 2023, 01:07:03 pm
content: I measured the current the PSU puts out and it is about 275mA which is in excess of the nominal 240mA.That is about 69mA per LED.If I put a 1K resistor in parallel it shunts about 70 mA away from the LEDs ... wasting about 5W but making life easier for the LEDs.I might do that on all the other similar LED fixtures I have. That should prolong their life.It would be better to adjust the PSU to output less current but I have no idea how to do it. I am attaching a photo.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 24, 2023, 01:32:29 pm
content: Probably there is a shunt resistor towards the output that could be increased, but if you can't identify the circuit and ICs, probably better not to screw with it.You might also just have poor quality LEDs.Tim

author: hobbylad
author_rank: Newbie
timestamp: November 23, 2024, 03:38:21 pm
content: I was equally puzzled seeing so many of my LED lamps fail. I could not resist doing an autopsy. Posted the results in my blog below:https://hobbylad.wordpress.com/2024/11/17/the-curse-of-the-failing-led-lamps/

author: tunk
author_rank: Super Contributor
timestamp: November 23, 2024, 04:09:19 pm
content: If you double the resistor value, the current willbe halved, reducing the temperature. This shouldincrease the bulb life.

author: cosmicray
author_rank: Frequent Contributor
timestamp: November 23, 2024, 06:27:53 pm
content: From the wordpress document ...QuoteThat is a sign that the LEDs are being run out towards the datasheet limits. Normal practice is that 50% of the power is being dissapated as heat, but a Cree Thermal Management document says to plan for as much as 70% heat. The heat is what destroys the LEDs. Get rid of that heat, and they will last a very long time.

author: jmelson
author_rank: Super Contributor
timestamp: November 24, 2024, 12:19:19 am
content: Quote from: cosmicray on November 23, 2024, 06:27:53 pmYup, I built my own fluorescent tube retrofits with a commercial constant current supply, see :http://pico-systems.com/Lighting.htmlI did this about 11 years ago. I made a very conservative thermal design, with PC board as the thermal sink, and they have lasted quite well. Possibly there is a tiny bit of brightness loss over this time, but I am REALLY happy with the results and longevity. I am running 20 1W LEDs in series, at just about the 1 W level each, total power draw from the mains is a measured 21 W.Jon

author: Pid
author_rank: Newbie
timestamp: November 24, 2024, 08:48:03 am
content: Quote from: David Hess on September 21, 2023, 01:56:01 pmMy understanding is that LEDs are rated by average rated life the same metric used for incandescent lamps.

author: cosmicray
author_rank: Frequent Contributor
timestamp: November 24, 2024, 11:27:04 am
content: Quote from: Pid on November 24, 2024, 08:48:03 amThe finished consumer device (a light bulb) may well be rated like that, some of this discussion is about the component parts (i.e. the LED chip). Those tend to have a much longer life span, when not pushed to the electrical maximum ratings.

author: David Hess
author_rank: Super Contributor
timestamp: November 24, 2024, 05:57:58 pm
content: Quote from: Pid on November 24, 2024, 08:48:03 amNo, the operating life of the LED bulbs was rated to be the operating life of the LEDs which is based on how long it takes for the LEDs to reach 50% brightness, so 50,000 hours or whatever. This is irrelevant because LED bulbs fail in other ways, long before that number is reached. Incandescent bulbs are rated by mean time to failure and designed so they say for a 1000 hour life.

author: coppice
author_rank: Super Contributor
timestamp: November 24, 2024, 06:07:12 pm
content: Has anyone seen screw in or bayonet LED bulbs that are rated for use in an enclosed or semi-enclosed luminaire? For both CFL and LED bulbs the life has a lot to do with their running temperature, which can be changed a lot by the air flow. CFLs go downhill several times as quickly with the restricted air flow in an enclosed luminaire, but look so ugly out in the open. LEDs seem to be similar. I wonder how the average life of luminaires with integrated LEDs, that have some space to breath, compare with bulbs that can get pretty hot, even without restricting their air flow.

author: floobydust
author_rank: Super Contributor
timestamp: November 24, 2024, 06:48:26 pm
content: I haven't and doubt they exist for the reason below. There's screw-in but no bayonet bulbs aside from old automotive this side of the Atlantic.I say the main reason LED bulbs are crap is because of the sea of patents particularly on heatsink design.So getting convective cooling in an enclosed fixture, it can't be done, legally. Cree has the patents for heatsink fins, along with related litigation with Feit etc.Meanwhile, households get smooth body bulbs that can't expel the required heat.I just replaced a bunch of Ecosmart bulbs (enclosed fixtures), Home Depot/Walmart pretty low quality and they run very hot. Maybe 12-18 months life.Autopsy showed the plastic body had cracked in two, 130°C rated 15uF Aishi cap seems worn at 10uF plastic wrap cooked and linear IC seems to have issues. They just sit there very dim. LED's look OK.10 years ago Ecosmart were smoking and burning, a few fires so those wererecalled 554,000 bulbs.Interestingly, they had fins and design house "Lighting Science Group" did EcoSmart, Sylvania, Westinghouse and Definity.So you see the problem with one design being flawed and many brands get affected. Or the skirting the patent issue, there is massive litigation still going on.

author: IanB
author_rank: Super Contributor
timestamp: November 24, 2024, 07:44:56 pm
content: Quote from: coppice on November 24, 2024, 06:07:12 pmTry looking at filament design LED bulbs like, for example, the Philips Ultra Definition kind. In these bulbs most of the heat is dissipated by the filaments, and less by the electronics in the base. The bulb itself does get warm over time, but it never gets hot to the touch. If you run them on a dimmer they get even less warm.

author: floobydust
author_rank: Super Contributor
timestamp: November 24, 2024, 08:47:14 pm
content: Isn't that the worst possible configuration for getting rid of heat?The filament in free space, enclosed in the bulb. Dissipate 5-12W? With tungsten, yeah but I'm not an optimist.It might be as you say that these filament bulbs have no LED driver, just the series string so a bit less heat."...average life of 15,000 hours/13.7 years... 3 year warranty" (Feit)Mainly radiation and a little conduction heat transfer on the one end."Feit Electric announced that it owns a set of patents directed to covering the yellow material used on LED filaments."against GEandagainst Ledvance LLCetc.It must be some high temp materialFeit Electric Announces First Patent Enforcement Action Against Infringing White LED FilamentsThen Seoul Semiconductor (sold under Philips name) and Seoul Viosys are suing Feit again.All this litigation just costs us, it gets added onto the bulb price and circumventing a patent usually means compromise ala hot running short life for other manufacturer's offerings.

author: cosmicray
author_rank: Frequent Contributor
timestamp: November 24, 2024, 09:11:26 pm
content: Quote from: floobydust on November 24, 2024, 08:47:14 pmFor incandescent bulbs, base down is best for heat convection (because the filament is where the heat is). For LED bulbs (with the one side PCB backed with aluminum), base up is better (because otherwise you are using the heat to slowly cook the LEDs/electronics). Sealing everything in a constricted air space is probably bad for both types.

author: coppice
author_rank: Super Contributor
timestamp: November 24, 2024, 09:13:16 pm
content: The filament style LEDs keep the heat away from the base. So, the driver, and especially the capacitors in the driver, are not being roasted. The driver itself is only a small part of the dissipation of the lamp in any sanely designed LED lamp. The interesting thing is at first sight those filaments look like their cooling will be really poor, but they actually seem to get the heat into the surround gas quite effectively. An IR camera doesn't show them as major hot spots. This is great for a reasonably cool running exposed lamp. However, if you put one in an enclosed luminaire, do they slowly cook if the lamp runs for hours?A general problem with luminaire design is their designers still seem to be living in the era of incandescent lamps, and haven't even caught up with CFLs. Their idea of adequate cooling is based on an incandescent lamp which is more efficient with poor cooling, and heat issues are all about not catching fire, or setting fire to the surroundings. I mean, its pretty common for luminaires to keep falling off the ceiling if you use incandescent bulbs and fix them with plastic screw hole plugs. The designs assume they won't be able to set the ceiling material on fire, but don't allow for softening a plastic hole plug enough for the screw to gradually pull out.

author: IanB
author_rank: Super Contributor
timestamp: November 24, 2024, 10:13:05 pm
content: Pictured below is the packaging for a Feit Electric bulb. It shows an enclosed outside lantern fixture as a possible use.Also pictured is the packaging for a Philips bulb. It says "Suitable for use in enclosed fixtures."The packaging for some GE candle bulbs (not pictured) says "Use in totally enclosed fixtures may result in lower lamp life."

author: coppice
author_rank: Super Contributor
timestamp: November 24, 2024, 10:27:24 pm
content: Quote from: IanB on November 24, 2024, 10:13:05 pmThose Philips Ultra Definition bulbs seem to hit all the right points. Dimmable, suitable for enclosed luminaires, low flicker, high CRI, and cheap. They don't appear to offer anything similar in Europe, and the less capable products they do offer are more expensive.

author: David Hess
author_rank: Super Contributor
timestamp: November 24, 2024, 10:42:19 pm
content: After testing various LED bulb brands from Home Depot and Lowes to quick destruction, I starting buy just Cree bulbs online and I started experimenting with their smart bulbs not long after Cree was sold and everything broke when their bulb designs were silently changed. I have been using Wiz bulbs since, but 100 watts equivalents (14.5 watts) are not bright enough for me.I thought tunable bulbs would help me with seasonal affective disorder but I cannot tell any difference.

author: coppice
author_rank: Super Contributor
timestamp: November 25, 2024, 02:56:10 pm
content: I was just looking at the Philips LED offerings in the UK. They have this pagehttps://www.lighting.philips.co.uk/consumer/led-lights/quality-of-light-led-lightingon the importance of high CRI. That page links to their actual high CRI lights, where it says "We can't find any products that match your selection".