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Should LED bulbs overheat and disintegrate?
Posted by
edy
on 11 Nov, 2018 15:35
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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?
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#1 Reply
Posted by
NiHaoMike
on 11 Nov, 2018 15:36
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Were they exposed to sunlight? Some plastics degrade in UV light.
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#2 Reply
Posted by
edy
on 11 Nov, 2018 15:45
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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!
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#3 Reply
Posted by
Whales
on 11 Nov, 2018 16:09
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In practice: LEDs can be run just as inefficiency (or worse) than CCFLs. It depends on:
- Quality of the leds
- How hard they are being pushed (efficiency drops as you increase power)
- How well they are cooled (efficiency drops as temp rises)
Why is the bulb so different and why is it not designed to be cool?
Can you provide a photo of the bulb + what wattage it claims to consume? Some quick estimations on the explanation can be made from there.
In this case it was bulb up, socket down, so heat should have radiated up and away from the socket and electrical components.
I'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.
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#4 Reply
Posted by
coppice
on 11 Nov, 2018 16:18
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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.
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#5 Reply
Posted by
edy
on 11 Nov, 2018 20:26
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In practice: LEDs can be run just as inefficiency (or worse) than CCFLs. It depends on:
- Quality of the leds
- How hard they are being pushed (efficiency drops as you increase power)
- How well they are cooled (efficiency drops as temp rises)
Why is the bulb so different and why is it not designed to be cool?
Can you provide a photo of the bulb + what wattage it claims to consume? Some quick estimations on the explanation can be made from there.
In this case it was bulb up, socket down, so heat should have radiated up and away from the socket and electrical components.
I'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.
Yes, 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:
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#6 Reply
Posted by
Zero999
on 11 Nov, 2018 20:32
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What a stupid design. If you need to adjust the light output, then use a dimmable LED, rather than shuttering which wastes power!
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#7 Reply
Posted by
rdl
on 11 Nov, 2018 20:35
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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.
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#8 Reply
Posted by
edy
on 11 Nov, 2018 20:39
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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.
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#9 Reply
Posted by
Twoflower
on 11 Nov, 2018 20:45
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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.
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#10 Reply
Posted by
edy
on 11 Nov, 2018 20:52
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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.
Well 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).
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#11 Reply
Posted by
rdl
on 11 Nov, 2018 21:12
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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.
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#12 Reply
Posted by
edy
on 11 Nov, 2018 21:19
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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?
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#13 Reply
Posted by
edy
on 11 Nov, 2018 21:28
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#14 Reply
Posted by
GeoffreyF
on 11 Nov, 2018 22:01
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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.
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#15 Reply
Posted by
abraxa
on 11 Nov, 2018 23:20
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I assume it is just a heat sink and not electrically connected to the innards, but what gives? I thought these things ran cooler [..].
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?
Those 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.html and
https://www.powerelectronictips.com/whats-stuff-capacitive-power-supplies-leds/
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#16 Reply
Posted by
cdev
on 11 Nov, 2018 23:28
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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?
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#17 Reply
Posted by
james_s
on 12 Nov, 2018 04:43
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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.
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#18 Reply
Posted by
james_s
on 12 Nov, 2018 04:44
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What a stupid design. If you need to adjust the light output, then use a dimmable LED, rather than shuttering which wastes power!
It 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.
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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.
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#20 Reply
Posted by
cdev
on 13 Nov, 2018 18:46
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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?
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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.
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#22 Reply
Posted by
james_s
on 13 Nov, 2018 22:11
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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).
The 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.
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#23 Reply
Posted by
NiHaoMike
on 14 Nov, 2018 00:42
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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?
Big 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.
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.
The warm white LEDs are labeled as such.
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#24 Reply
Posted by
james_s
on 14 Nov, 2018 04:58
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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.
