# Disappointing trend in LED manufacturing



## PhotonWrangler (Aug 6, 2022)

The other day I was looking at some LED nightlight bulbs from Feit. They had red, green and blue ones. The clear bulb reveals a wafer with the LEDs mounted on them. The blue LED had just the bare wafer-mounted LEDs, while the red and green ones had the wafer and a blob of phosphor on top of them. The phosphor blobs were glowing dimly under the store's lighting.

So all three colors are using the same blue LED chips, and the phosphor converts blue to either red or green. What bugs me about this is that it would be more efficient (and probably a little brighter) to use native red or green LEDs instead of the phosphor-downconverted blue ones.

I get it that this method reduces the number of components they need to stock at the manufacturer, but it adds one step to the manufacturing process - adding that dollop of phosphor to the non-blue bulbs - but it also introduces another point of failure in addition to the efficiency loss.

I've seen the same thing in a line of larger colored LED filament bulbs from the same manufacturer. Does this bug anyone else or am I just being pedantic?


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## ampdude (Aug 6, 2022)

Why would you do things correctly when you can do them cheaper in some way? Save a penny. It's a psycho world these days.

Who cares about the end product if only you or I and a few others notice the difference. The only saving grace is the interweb.. but nobody uses that anymore, everyone is on their phones watching TikToks. :/


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## idleprocess (Aug 7, 2022)

PhotonWrangler said:


> So all three colors are using the same blue LED chips, and the phosphor converts blue to either red or green. What bugs me about this is that it would be more efficient (and probably a little brighter) to use native red or green LEDs instead of the phosphor-downconverted blue ones.


I recall that Philips invented blue-pumped green precisely _because_ blue die were so much more efficient than green that it was still a significant efficiency boost despite the phosphor losses. Not sure about red, however.



PhotonWrangler said:


> I get it that this method reduces the number of components they need to stock at the manufacturer, but it adds one step to the manufacturing process - adding that dollop of phosphor to the non-blue bulbs - but it also introduces another point of failure in addition to the efficiency loss.


The common LED Vf / driver design for all three channels probably makes for less overall complexity.


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## LEDphile (Aug 7, 2022)

The biggest downside to the phosphor-converted color LEDs is that the color is a bit less saturated than you'd get with a direct-emission color LED. The big reason for using them in a design (assuming you aren't choosing them for their spectral content) is the thermal performance and Vf range are basically the same as for white and blue LEDs. Given that green LEDs are typically higher Vf and red LEDs are typically much lower Vf than blue, this can be significant. 

Looking at Osram LEDs (the Duris S5 is available in both direct and phosphor-converted green and red), the PC green is ~188 lm/W vs. 135 lm/W for the direct green (almost 40% more output). The story is a bit different with PC red, as the direct red is approximately 3x as efficient at 25C. But because of the much better thermal droop characteristics of the blue LED die, at 85C (a more typical operating point), the PC red is still outputting 90% of the amount it was at 25C, while the direct red is down to about 50% of its initial output. If you assume a linear driver topology (starting at a constant voltage and using a transistor to regulate current, with the voltage drop difference between the LEDs and power supply being dissipated in that transistor), the wallplug efficiency of the phosphor red is probably about the same as for the direct red due to the Vf differences.

So for comparable or increased performance, why wouldn't you want to go with the option that has greater commonality across variants (and thus a simpler supply chain), especially when the LED manufacturer is the one taking the extra complexity for building the phosphor-converted LED?

(side note - the LED manufacturer may also be seeing some supply chain and/or manufacturing benefits from the PC LEDs vs. the direct colors, but how much this matters depends on the LED manufacturer)


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## KITROBASKIN (Aug 7, 2022)

Very interesting thread. Wife just ordered a multi color, ambience, corded desk light. I will check it out but likely different than this issue. 

The observation that supply chain shortcomings could factor in this design decision; interesting, but thinking simplicity of components is probably why?


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## PhotonWrangler (Aug 7, 2022)

This is fascinating. I didn't know that PC green was more efficient than direct green, nor did I know about the thermal droop issue with direct red vs PC red. This makes much more sense now. And I can see how a manufacturer's engineering and procurement teams would want to keep the parts count at a minimum with the supply chain issues still going on.

Thanks everyone. I always come away from this place a little smarter than I was when I logged on.


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## PhotonWrangler (Aug 7, 2022)

It occurred to me that there's one disadvantage of PC red for night lights. The blue content could defeat the purpose of using red in terms of not upsetting one's circadian rithym. The bulbs that I bought were intended for just such a use, so I will need to conduct a check for fluorescence from them, or maybe use a prism to check for any blue energy escaping thru the phosphor.


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## LEDphile (Aug 7, 2022)

PhotonWrangler said:


> It occurred to me that there's one disadvantage of PC red for night lights. The blue content could defeat the purpose of using red in terms of not upsetting one's circadian rithym. The bulbs that I bought were intended for just such a use, so I will need to conduct a check for fluorescence from them, or maybe use a prism to check for any blue energy escaping thru the phosphor.


The better PC red LEDs have basically no leakage of the blue pump through the phosphor (of the spectra I've looked at, some have no leakage at all, and the worst I've seen have the pump leaking through at around 2% of the spectral peak). Based on the published nominal spectral sensitivity of the circadian system ( https://www.lrc.rpi.edu/programs/lightHealth/pdf/spectralSensitivity.pdf ), that small blue pump has slightly less effect than the broad red peak. But the other important consideration is that the light level matters, and the amount of output you get from a nightlight bulb is unlikely to have any effect unless you've got it inches from your eyeballs.


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## PhotonWrangler (Aug 7, 2022)

Thanks LEDphile. A pump wavelength leakage of 2% worst case doesn't sound bad. This light will be a good distance away, and depending on brightness I might add some semi-opaque tape over the lens to further reduce it.

I currently have an alarm clock with an adjustable RGB backlight on the LCD display. I've found that the red LEDs don't bother me at all and I can fall asleep while facing them only a couple of feet away. The other colors are a different story.


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## Lynx_Arc (Aug 8, 2022)

I'm of the mind that manufacturers are less interested in efficiency of these very low output bulbs and more interested in profit. I've seen stats that have 40watt EQ LED bulbs more efficient than 7watt EQ ones. I am still using night light LED bulbs (7 watt incan replacement) I bought long ago for really cheap about $1/bulb that have 3x5mm LEDs in them. Newer bulbs have smd type chip LEDs either a single flat mounted one or several on a sort of tower sticking out the middle of the bulb. I run 3 of these lights in other parts of the house so I can see late at night and they cost less than $1 a year to operate. I know when I get home if the power is out at night. 

And no, I don't have my main alarm clock close to me, it is by my TV across the room so when it goes off I have to get out of bed to turn it off. I do have a radio by my bed and a small LCD battery clock in case power goes off while I sleep.


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## JustAnOldFashionedLEDGuy (Aug 12, 2022)

The output consistency of the PC products over temperature and even manufacturing makes for much more consistent products especially if you are doing color mixing. As well, the electronics are easier.


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## PhotonWrangler (Aug 13, 2022)

I've just fired up one of those phosphor red nightlight bulbs and I could not see any visible blue leaking out. I also held another one of the phosphor red bulbs next to it and the light from the lit bulb did not produce any fluorescence in the adjacent bulb whatsoever, so I'm satisfied that these will be ok for night light use.


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## ampdude (Sep 10, 2022)

Till it degrades or the phosphor gets jolted off. Seems like another bean counter solution to a problem that didn't really exist, except for making more money for someone.


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## kaichu dento (Sep 10, 2022)

ampdude said:


> Why would you do things correctly when you can do them cheaper in some way? Save a penny. It's a psycho world these days.


The thread just started when you posted this one, so I could understand the cynicism, but then...


ampdude said:


> Seems like another beaner counter solution to a problem that didn't really exist, except for making more money for someone.


Lots of posts trying to explain, but your cynicism in the 2nd post wasn't a precursor to finding more out; it appears to be your permanent mindset. Too bad that negativity is all you can add, because there was a lot of interesting stuff here.


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## ampdude (Sep 10, 2022)

No, I did some more research and looked it up before I made my second post. The factory counters want to squeeze every tenth of a penny out of every metric ton. Have you ever worked in a factory? You'll see different parts and sub-parts EVERYDAY from anything they can source the cheapest. One day you'll have nickle sockets, the next day you'll have copper socket, the next day you'll have aluminum sockets, the next day you'll have stainless sockets. Some people are just all about efficiency and cost over reliability and quality, and that's where I differ in my opinions. I think that LED's are designed well for reliability, but when you start putting gunk on them so that you can mimic an effect by cheapening things out, I'm not going to agree with it.


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## jtr1962 (Sep 10, 2022)

This data sheet for Cree's new line of 2835 color LEDs is a good source to compare relative efficiencies of direct versus PC LEDs. PC green and amber are far more efficient than direct green/amber. PC red-orange is about equal. They aren't making PC red, but I imagine it would less efficient. LED wall-plug efficiency is highest on both sides of the visible spectrum (blue and red). It drops in between.

Since someone mentioned thermal droop, while PC red would have better thermal droop characteristics than direct red, I noted from the data sheet that photo red (660 nm) still has 88% output at 85C (compared to ~62% for regular red). So you don't necessarily have to use PC red if thermal droop is your only reason for considering PC red. Photo red also has higher WPE. It's not going to get as warm for any given drive current.


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## jtr1962 (Sep 10, 2022)

ampdude said:


> The factory counters want to squeeze every tenth of a penny out of every metric ton. Have you ever worked in a factory? You'll see different parts and sub-parts EVERYDAY from anything they can source the cheapest. One day you'll have nickle sockets, the next day you'll have copper socket, the next day you'll have aluminum sockets, the next day you'll have stainless sockets. Some people are just all about efficiency and cost over reliability and quality, and that's where I differ in my opinions. I think that LED's are designed well for reliability, but when you start putting gunk on them so that you can mimic an effect by cheapening things out, I'm not going to agree with it.


And this drives me crazy because I often end up fixing things where they cut corners to save tenths of a cent. Ask anyone who buys something if they would be willing to pay a few cents more for something much more reliable. The answer I'm sure would be yes. If the factory has to pay a nickel more for decent parts, so what? Charge the end customer $10.04 instead of $9.99 for the product. You make the same amount of profit on it.

The worst part about all this is the fact you don't even know what's good any more. Buying name brands, or paying a lot more, doesn't always guarantee better quality. More often than not the name brand of something is the exact same as the generic version, but it has a fancy sticker slapped on it. It used to be that more costly things were actually better made.

Too bad we don't have the same philosophy as manufacturers did a century ago. Design it to last a lifetime. And design it to be easily fixed if it does break. Now we intentionally design things to fail after x years or number of uses.


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## fulee9999 (Sep 10, 2022)

jtr1962 said:


> The worst part about all this is the fact you don't even know what's good any more. Buying name brands, or paying a lot more, doesn't always guarantee better quality. More often than not the name brand of something is the exact same as the generic version, but it has a fancy sticker slapped on it. It used to be that more costly things were actually better made.


for me this is the most infuriating part about today's manufacturing... I have to do extensive research sometimes to figure out if the $16 part is the same or worse than the $99 one. And sadly a lot of the times it's the same on the inside, just have a fancier package.


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## PhotonWrangler (Sep 10, 2022)

The trend in general is a "race to the bottom" as others have referred to it. The early name brand household LEDs were pretty over engineered with lots of potting compound in the base for heatsinking as well as decent component choices like higher-temp electrolytic capacitors. This was when they were touting 50,000 to 100,000 hours of lifetime for the bulb. Look at the lifetime claims on the current crop of inexpensive bulbs and they're much shorter. The goal is to get the cost of the bulbs down to the point that they were cost competitive with incandescents. It makes sense from the standpoint of getting your product to move off the shelves, but ultimately the customer pays by having to replace them more often.

That nightlight bulb appears to be an exception in terms of output vs cost and I have to admit that I was pleasantly surprised when I learned of the efficiency gains of PC LEDs vs native-wavelength LEDs. I always come away from this forum better educated than when I came, and I am humbled by the breadh and depth of knowledge and experience (and even healthy skepticism) shown by the membership here.


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## Lynx_Arc (Sep 10, 2022)

PhotonWrangler said:


> The trend in general is a "race to the bottom" as others have referred to it. The early name brand household LEDs were pretty over engineered with lots of potting compound in the base for heatsinking as well as decent component choices like higher-temp electrolytic capacitors. This was when they were touting 50,000 to 100,000 hours of lifetime for the bulb. Look at the lifetime claims on the current crop of inexpensive bulbs and they're much shorter. The goal is to get the cost of the bulbs down to the point that they were cost competitive with incandescents. It makes sense from the standpoint of getting your product to move off the shelves, but ultimately the customer pays by having to replace them more often.
> 
> That nightlight bulb appears to be an exception in terms of output vs cost and I have to admit that I was pleasantly surprised when I learned of the efficiency gains of PC LEDs vs native-wavelength LEDs. I always come away from this forum better educated than when I came, and I am humbled by the breadh and depth of knowledge and experience (and even healthy skepticism) shown by the membership here.


Now that they have pretty much turned their backs on incan and CFL bulbs they have to keep the cost down and the longevity claims were preposterous as the electronics in bulbs often give out long before the LEDs. I still have 20 and 60 watt CFLs I paid about 25 cents each for that I will use. I don't run these for hours at a time mostly the total amount of all is about 1-2 hours a day which would take a long time to pay for the difference in cost/efficiency of an LED bulb. 

As for efficiency of colored vs doped blue/white LEDs I've seen that for a long time. For me red LEDs vs firefly/candle mode white LEDs is a no brainer. I don't need to use red and the efficiency of RED LEDs as the same current/output is worse which makes them less attractive than ever. The two things I like about LED vs CFL is start up time and temperature in use. LEDs are better for garages


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## kaichu dento (Sep 10, 2022)

Lynx_Arc said:


> LEDs are better for garages


Absolutely superior for any unheated building. I changed out some tubes in the old fluorescent fixtures in a shed in the interior and the difference in winter was that it was too bright, especially coming in from and going back out into the dark. Flipping the tubes upside down helped a lot, but 8 tubes for what was probably a 20' x 30' shed was at least twice as much as was needed.

No more waiting for fluorescent tubes to warm up to a dim glow at -20 to -50 was fantastic; instant light.


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## fulee9999 (Sep 10, 2022)

CFL feels like a dead branch of the light evolution, I for one am glad it's basically almost completely gone. I remember the first "economic" CFLs that took literal minutes to come to an acceptable brightness, on power on it was just a dim glow. I hated it. Also the color rendering on those is just horrid, I only have two CFL bulbs now for spectroscope calibration.


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## Lynx_Arc (Sep 10, 2022)

kaichu dento said:


> Absolutely superior for any unheated building. I changed out some tubes in the old fluorescent fixtures in a shed in the interior and the difference in winter was that it was too bright, especially coming in from and going back out into the dark. Flipping the tubes upside down helped a lot, but 8 tubes for what was probably a 20' x 30' shed was at least twice as much as was needed.
> 
> No more waiting for fluorescent tubes to warm up to a dim glow at -20 to -50 was fantastic; instant light.


What amazed me is the same lumen output light of a 4 foot LED light vs 4 foot F40T12 the LED light looked 50% brighter to me. I keep wanting my fluoros to run out of tubes so I have an excuse to retube with LED drop in. I have about 4 fluorescent shop lights only 1 however is in service the others I never installed. I was also looking at LED tubes to swap out in a 18 inch fixture but they are as expensive as a LED light itself.


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## PhotonWrangler (Sep 10, 2022)

Lynx_Arc said:


> As for efficiency of colored vs doped blue/white LEDs I've seen that for a long time. For me red LEDs vs firefly/candle mode white LEDs is a no brainer. I don't need to use red and the efficiency of RED LEDs as the same current/output is worse which makes them less attractive than ever. The two things I like about LED vs CFL is start up time and temperature in use. LEDs are better for garages


I believe the CFLs with the long start-up time are based on a mercury amalgam rather than just straight mercury. We had one of those in the basement and the warm-up curve was annoying. I also prefer LEDs for this reason.


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## Lynx_Arc (Sep 10, 2022)

PhotonWrangler said:


> I believe the CFLs with the long start-up time are based on a mercury amalgam rather than just straight mercury. We had one of those in the basement and the warm-up curve was annoying. I also prefer LEDs for this reason.


I agree the startup time is slower especially in colder temps. As I'm more used to lower light levels having 40-60 watt CFLs only running half as bright to startup is not a huge issue it is only in my garage that it becomes a problem where it is most problematic is in the garage when it drops below 40 the lights there located in the ceiling so being 1/3 to half normal brightness till warmed up makes it not very bright in the garage to see stuff. Now that I have a 4 foot LED fixture the 100 watt EQ CFL I typically don't see it. I have an old screw in light socket that I've put a power adapter inline to hook up the LED light fixture so it comes on with the light switch.


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## kaichu dento (Sep 11, 2022)

Lynx_Arc said:


> I keep wanting my fluoros to run out of tubes so I have an excuse to retube with LED drop in. I have about 4 fluorescent shop lights only 1 however is in service the others I never installed. I was also looking at LED tubes to swap out in a 18 inch fixture but they are as expensive as a LED light itself.


I got rid of any remaining fluorescent fixtures I had a few years ago, replacing 4' fixtures in a couple places with short LED fixtures that I got from Home Depot for about $16-18 each. I liked them so much that I've probably bought a couple dozen in the last few years. 

At two of my friends stores I brought them boxes of LED replacement tubes and helped swap out all the remaining glass tubes and both places benefited hugely from the additional light and neither minded the tradeoff in getting rid of tubes that were still serviceable.

I'll be over next week to start on your place.


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## kaichu dento (Sep 11, 2022)

Lynx_Arc said:


> I agree the startup time is slower especially in colder temps. As I'm more used to lower light levels having 40-60 watt CFLs only running half as bright to startup is not a huge issue it is only in my garage that it becomes a problem where it is most problematic is in the garage when it drops below 40 the lights there located in the ceiling so being 1/3 to half normal brightness till warmed up makes it not very bright in the garage to see stuff.


You ought to see how dim those 100 watt equivalent CFL's are at -50 and -60 below; they look like anemic little night light bulbs, especially with the ice fog. Pretty pathetic as a light source.


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## jtr1962 (Sep 11, 2022)

kaichu dento said:


> You ought to see how dim those 100 watt equivalent CFL's are at -50 and -60 below; they look like anemic little night light bulbs, especially with the ice fog. Pretty pathetic as a light source.


I'm surprised they even start at those kinds of temperatures. I have 4 40 watt T12s in the garage. On days when it's below freezing they stay pretty dim. The two CFLs sharing the lone socket in the garage were even worse. Two years ago I bought one of these to put in the socket. Almost instant on, crazy bright. I looks even brighter in cold weather, which kind of makes sense. LEDs love cold. BTW, my review of it is still rated the most helpful.


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## bykfixer (Sep 11, 2022)

My home is loaded with curly fry bulbs. As they konk out they get replaced, sure but for now they get the job done.

When I bought my first LED light it said 100,000 hour lifespan. Soon after 50,000. Then 30,000. But that's still over 3 years of constant running. 

Some say conspiracy to purposly shorten lifespan, some say profit margin to make them cheaper, some say it's capitalism and keeps people employed. Since I don't build lighting stuff for a living it doesn't really affect me all that much if at all. I turn on a light, it works year after year... good enough. It don't work, I replace it. First world problem.


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## PhotonWrangler (Sep 11, 2022)

kaichu dento said:


> I got rid of any remaining fluorescent fixtures I had a few years ago, replacing 4' fixtures in a couple places with short LED fixtures that I got from Home Depot for about $16-18 each. I liked them so much that I've probably bought a couple dozen in the last few years.
> 
> At two of my friends stores I brought them boxes of LED replacement tubes and helped swap out all the remaining glass tubes and both places benefited hugely from the additional light and neither minded the tradeoff in getting rid of tubes that were still serviceable.
> 
> I'll be over next week to start on your place.


I have one of those desk magnifier lamps with a circular fluorescent tube surrounding the magnifying glass. I replaced the fluorescent tube with an LED equivalent recently even though the flourescent bulb still worked. Now I have more light with no UV, better CRI and no strobing, making it much less fatiguing to use. I can imagine what a difference it must have made in an entire store.


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## kaichu dento (Sep 11, 2022)

jtr1962 said:


> I'm surprised they even start at those kinds of temperatures. I have 4 40 watt T12s in the garage. On days when it's below freezing they stay pretty dim. The two CFLs sharing the lone socket in the garage were even worse.


When it's really, really cold most of them just limp along and many will be on all day since the daylight hours are so short and to have the CFL's produce any semi-useful light, they're just better off being left on. Many of them refuse to do anything in the time span you need, so carrying a flashlight becomes all the more important.
Really pathetic they made us change to the worthless things, only a few years later to finally start replacing all of them with LED bulbs and tubes.


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## desert.snake (Sep 11, 2022)

PhotonWrangler said:


> I have one of those desk magnifier lamps with a circular fluorescent tube surrounding the magnifying glass. I replaced the fluorescent tube with an LED equivalent recently even though the flourescent bulb still worked. Now I have more light with no UV, better CRI and no strobing, making it much less fatiguing to use. I can imagine what a difference it must have made in an entire store.


What about flicker, do you notice it? I mean PWM

LED lamps are quite economical, but so far those lamps that have a shelf life of 10 years, and those that have a shelf life of 3 years equally quickly fail after 1.5-2 years. I come to the store, and this store no longer exists to use the guarantee))


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## PhotonWrangler (Sep 11, 2022)

desert.snake said:


> What about flicker, do you notice it? I mean PWM
> 
> LED lamps are quite economical, but so far those lamps that have a shelf life of 10 years, and those that have a shelf life of 3 years equally quickly fail after 1.5-2 years. I come to the store, and this store no longer exists to use the guarantee))


I don't notice flicker directly from fluorescent lamps but I see it in terms of strobing if I wave something quickly underneath the light. I don't notice anything at all from the LED replacement tube.


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## Lynx_Arc (Sep 11, 2022)

kaichu dento said:


> You ought to see how dim those 100 watt equivalent CFL's are at -50 and -60 below; they look like anemic little night light bulbs, especially with the ice fog. Pretty pathetic as a light source.


We rarely even see 0 degrees here where I'm at so that isn't a problem at all.


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## Lynx_Arc (Sep 11, 2022)

desert.snake said:


> What about flicker, do you notice it? I mean PWM
> 
> LED lamps are quite economical, but so far those lamps that have a shelf life of 10 years, and those that have a shelf life of 3 years equally quickly fail after 1.5-2 years. I come to the store, and this store no longer exists to use the guarantee))


Long term guarantees from small corporations are almost worthless. All they do is differentiate between products with no guarantee. You see all these lifetime guarantees of products on TV but you don't see those products in stores 1-2 years later and products that last 5 years like you said the company that sold them changes their name and moves to a now rented warehouse with a new phone number or they charge twice the shipping it takes to send it back enough to pay for a chinese product on ebay and shipping usually. 
LED lamps aren't economical when the larger output ones like 100 watt EQ ones cost $5 each and CFLs were to be had costing $1 each before they were no longer available in most stores. You have to replace one 4 times to match the price and the savings of a 100W LED vs CFL back in the day was pretty small only a few watts difference in energy use taking 4 months to save maybe 15 cents in power if used 8 hours a day. I haven't shopped for LED bulbs but the efficiency of higher output bulbs and cost have not changed enough. You would think we would see 150W LED bulbs for $3 or so each by now but nope. I have a 150W CFL bulb that I bought about 20 years ago that I use about 2 hours a year that I'll likely never replace with LED. As much as I think LEDs are superior I don't see tossing out my flouros till I need to instead of spending $50 on LED bulbs and having to wait 10 years to get it all back in power usage 

I'm still wanting a 3 way lamp that has 200 watts on high mode but the way the 3 way sockets work the other two modes will have to equal 200 watts leaving them too close together


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## desert.snake (Sep 11, 2022)

I didn't have fluorescent or arc bulbs, or very powerful incandescent lamps, my main incandescent bulbs were 40-60 watts for a long time, but in the last 5 years the power quality has deteriorated. Frequent power outages or power surges killed incandescent lamps + the stock of high-quality lamps of the 70-80s is over, and modern incandescent lamps serve in my conditions for about 2-3 months and burn out, their price is $ 1.3. The cost of LED lamps which i buy is $ 4.5 dollars. it turns out that they pay off in about 1.2 years, the LED lamp itself dies after 1,5-2 years, but it eats less energy - 7-10W.

As for the companies, you are right, it is a big problem to find their official representative and he does not answer calls


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## Lynx_Arc (Sep 11, 2022)

desert.snake said:


> I didn't have fluorescent or arc bulbs, or very powerful incandescent lamps, my main incandescent bulbs were 40-60 watts for a long time, but in the last 5 years the power quality has deteriorated. Frequent power outages or power surges killed incandescent lamps + the stock of high-quality lamps of the 70-80s is over, and modern incandescent lamps serve in my conditions for about 2-3 months and burn out, their price is $ 1.3. The cost of LED lamps which i buy is $ 4.5 dollars. it turns out that they pay off in about 1.2 years, the LED lamp itself dies after 1,5-2 years, but it eats less energy - 7-10W.
> 
> As for the companies, you are right, it is a big problem to find their official representative and he does not answer calls


Even if you the company is honoring the warranty they can want you to pay one way shipping of the item which can eat up the cost of the bulb especially if you have to drive somewhere to mail it etc. It isn't worth a half hour of time and $3.50 postage to get another $5 bulb as you could spend $2 worth of gas and stand for 20 minutes in line at the post office and then have to wait 3 weeks for one back. Meanwhile you have already bought another bulb to replace the bad one. If they really want to warranty bulbs they should offer a swap in store for a good one.


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## LEDphile (Sep 11, 2022)

Looks like this thread was revived with a topic swerve - perhaps it makes sense for a moderator to split the recent general LED lamp discussions from the original discussion around phosphor-converted red LEDs...

That said, retrofit LED bulbs seem to have gone through at least three distinct technological maturity levels over the time they have been on the market. 

The first was the "can this be done" level of the first couple generations of the bulbs. At this point, the focus was on getting a viable product into the market. Costs were generally high, performance was typically at about the same level as CFL or perhaps slightly above. Products were typically positioned as a step up from CFLs with longer life, and especially in the case of directional lamps, much better performance. 

Once it was established that acceptable performance was possible, the market shifted to focus on cost-down. Corners were cut, limits of acceptable performance were tested, but it was possible to purchase an 800 lumen LED retrofit bulb for $1 on sale. 

Once it was established that LED retrofit bulbs could compete on both performance (first level of maturity) and cost (second level of maturity), manufacturers shifted to finding a good balance between performance and cost. Costs crept back up, but fewer corners were cut, and performance generally increased from the rock-bottom price offerings.

At this point, LED retrofit bulbs are commodity items, with little variation between vendors and a couple different levels of price/performance tradeoff available. Within a tier (premium, economy), performance, lifetime, and price are essentially the same across vendors. 

If you want something that's decent quality (at least in the US), I suggest looking for bulbs that meet the requirements of Energy Star. In addition to the efficacy, color quality, and light distribution requirements, Energy Star also requires at least a 35khr rated life, and performs testing to validate a manufacturer's claims. I'm guessing you'll pay more for that quality vs. the cheapest options on the market, though.


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## PhotonWrangler (Sep 11, 2022)

LEDphile said:


> Once it was established that LED retrofit bulbs could compete on both performance (first level of maturity) and cost (second level of maturity), manufacturers shifted to finding a good balance between performance and cost. Costs crept back up, but fewer corners were cut, and performance generally increased from the rock-bottom price offerings.


One of those steps of maturity was the development of LED filament bulbs. This breakthrough meant that it was finally possible to maker an LED bulb with essentially the same radiation pattern as an incandescent filament, as opposed to previous "ice cream cone" bulbs where only the top half lights up. 

The latest trend is towards tunable white bulbs as well as bulbs with a bland of cooler white and warmer white filaments. And it seems that everyone is putting wi-fi radios in their bulbs now where they no longer need a hub to control them. This trend actually bugs me a little bit because of the steady increase in unnecessary RF noise being produced by these bulbs in the 2.4ghz band. It's also wasteful - if the LEDs or driver burns out, you're throwing out a wi-fi transceiver as well as a bulb.


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## desert.snake (Sep 12, 2022)

Lynx_Arc said:


> Even if you the company is honoring the warranty they can want you to pay one way shipping of the item which can eat up the cost of the bulb especially if you have to drive somewhere to mail it etc. It isn't worth a half hour of time and $3.50 postage to get another $5 bulb as you could spend $2 worth of gas and stand for 20 minutes in line at the post office and then have to wait 3 weeks for one back. Meanwhile you have already bought another bulb to replace the bad one. If they really want to warranty bulbs they should offer a swap in store for a good one.


Everything is simpler here)) There is always a supply of replacement lamps, if the store still exists, they offer to replace it with another lamp of the same price. I do not pay for gasoline, I walk about 3 hours to the store, this can be considered as a workout. I am too fat and exercise is not a waste of time and loss possible income, but an improvement in the body.

But other than that you're right, the warranty sometimes sucks, I paid $30 to ship a faulty flashlight to China, waited 5 months for it to come back and it was in the middle of the year when they didn't have a new year otherwise it would have taken Seven months. Only because the store changed its name, otherwise they would have simply changed it on the spot to a serviceable one.

These diode bulbs get warm, I think because of this they mostly fail, I mean the E27 bases. But they still heat up less than incandescent lamps, and now my carbolite cartridge does not need to be changed every 1.5-2 years, because of the temperature it starts to crumble. Old lamp ~1950


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## JoakimFlorence (Oct 5, 2022)

PhotonWrangler said:


> So all three colors are using the same blue LED chips, and the phosphor converts blue to either red or green. What bugs me about this is that it would be more efficient (and probably a little brighter) to use native red or green LEDs instead of the phosphor-downconverted blue ones.


Theoretically, yes.
But the thing is, due to mass production, blue chips are simply cheaper than red or green chips, and also more efficient. Not that higher efficiency red or green chips do not exist, but I mean more efficient for the same price. For the same price as a blue chip, you are going to get a red or green chip that is half as efficient. What this ends up meaning is that a blue chip coated with phosphor is going to end up having about the same efficiency as red or green LED. Unless the manufacturer wants to shell out lots of money and get the most efficient red and green chips, which are probably going to be several times more expensive due to a lower volume of production than blue chips. Blue chips are used to make white LEDs, which are ubiquitous.


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## HarryN (Oct 17, 2022)

Part of the reason for this transition is that the gases used to produce red / orange and amber direct emitting LEDs are extremely toxic. The companies are under a lot of pressure to remove this from their production sites.

Some companies only have GaN production capability in house. For them to build a high end, red / amber / orange emitter would be very difficult and time consuming vs just using what they are good at making (for example Cree) vs a place like Lumileds.

The PC LEDs share the same general electrical and thermal characteristics as the B / G which makes assembly easier.

Less obvious is that the people who are really good at making these R / O / A direct emitters got their PhDs quite a while back. Many are retired or nearly so. Very few western Universities have the equipment or gas handling capability to train people to produce these materials anymore. 

In order to get a PhD in the US or EU, you have to do original work on a subject and it needs to be interesting enough to a government agency to fund it. Since these topics have been studied and documented so heavily in the past, it is difficult to find something novel. 

This isn't a problem in the far east as they are perfectly happy to hand out a PhD for "replicating" the work of others, but in the US this is at best Masters level work.


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## PhotonWrangler (Oct 17, 2022)

HarryN said:


> Part of the reason for this transition is that the gases used to produce red / orange and amber direct emitting LEDs are extremely toxic. The companies are under a lot of pressure to remove this from their production sites.


Harry, that's an angle that I hadn't considered before; thanks. It makes sense to move away from manufacturing techniques that involve toxic materials. What I didn't know was that the manufacturing of blue LEDs was less toxic.


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## HarryN (Oct 18, 2022)

PhotonWrangler said:


> Harry, that's an angle that I hadn't considered before; thanks. It makes sense to move away from manufacturing techniques that involve toxic materials. What I didn't know was that the manufacturing of blue LEDs was less toxic.



It is a relative thing as far as toxicity. The ones used to make direct emitting R / O / A are extremely toxic even when you can't smell them and the ones to make B and G give you a chance to escape. 

B / G use a lot of high purity NH3 / ammonia - similar to what is used in some farm applications.

I used to sell the equipment that used these gases to make LEDs. (all types).

The industry has had remarkably few incidents in spite of the very large number of users world wide. I credit HP (now Lumileds) and some related industry pioneers for setting such good examples for how it should be done in a safe manner.


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## JoakimFlorence (Oct 21, 2022)

It's true production of red LEDs involve a more hazardous production process, but I suspect that may not really be the main reason for more red LEDs not being used. (Blue LEDs are based on GaN, whereas red is based on GaAsP)
Rather I suspect there has been much less recent investment-research-development in LED wavelengths other than blue. Everyone wants to focus on better blue LEDs because those are going to make better white LEDs, and there are a lot more white LEDs (and higher power ones) being produced than color LEDs. So again it comes back to scale of production. It probably would be possible to develop cleaner technology to produce red LEDs, but the equivalent resources and motivation to make that happen are just not there.

If it was simply only an issue of environmental concern or hazardous conditions, it would not be much of an issue to simply offsource production to China. Although it is also true that LED production is a very high technology thing and the efficiency of LED chips produced by Chinese companies are much lower than American, German, and Japanese companies (Cree, Osram, Nichia being the big three). (And if I were a Western company, I would not want to hand the specifics of my production process over to a Chinese company because they would steal it - something that has been a huge problem)

There may be other smaller issues as well. I'm really not sure about this but I think red LEDs might be a little more vulnerable to degradation from UV in sunlight, which could be an issue for cars.
I'm sure this is not actually a real factor taken into consideration but also colors produced via phosphor could be perceived as a little more "pleasant" than bare emitters, or a little more desirable in color. Completely monochromatic light can come across as a little "unnatural".
It can also simplify the electronics for wiring the lighting in cars when there are not two different voltages, which I am sure could be another big factor.


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## JustAnOldFashionedLEDGuy (Oct 21, 2022)

Purely a matter of performance AND cost, and the two are tied together.

Phosphor pumped Green LEDs are right now more efficient in all cases. Phosphor pumped RED LEDs are more efficient are operating temperatures if not more efficient near room temperature. That is one aspect of performance.

Second aspect is thermal stability. Phosphor pumped LEDs are very stable w.r.t. output over temperature, both amount and wavelength. Direct RED LEDs are not very stable in output or wavelength.

If you want to make a multi-color bulb or fixture with consistent output without temperature feedback and the best efficiency in all cases (which defines your thermal envelope), then phosphor pumped is much better. Your product will be cheaper and perform better.

As well, some width to the emission can improve color gamut, another plus on the performance side.


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## jtr1962 (Oct 21, 2022)

JoakimFlorence said:


> It can also simplify the electronics for wiring the lighting in cars when there are not two different voltages, which I am sure could be another big factor.


That's irrelevant because properly designed LED lighting uses a constant current driver, not constant voltage. The only concession to voltage might be that an LED setup for a car using red LEDs will use 6 in series and a constant current driver, versus 4 blue LEDs in series. The idea is to get the total native voltage of the LEDs close to the supply voltage, in order to get maximum efficiency from the driver. The driver simply ensures the LEDs in the string get the same current whether the car battery is low or fully charged.


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## Monocrom (Oct 21, 2022)

Companies will do anything to save a buck. Especially when it comes to making cheap products.


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## kaichu dento (Oct 24, 2022)

Still trendy to ignore a whole slew of information based posts and call out the 'evil companies' because it's easier than discussing things one doesn't understand.


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## JoakimFlorence (Oct 24, 2022)

Monocrom said:


> Companies will do anything to save a buck. Especially when it comes to making cheap products.


I think this is mainly what's going on.

But I think the fault is mainly the consumer (in this case local governments and city councils). In many of these situations they will just go with the cheapest option, which puts a lot of pressure on companies to have to cut costs as much as possible. 
The main hurdle to conversion to LED street lighting was initial cost.
And of course (even more in the U.S. than in Europe) most of these LED streetlights are assembled by companies in China and are not "real" mainstream brands. (China is notorious for cutting corners and making products that will fall apart a short time after purchase)


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## JustAnOldFashionedLEDGuy (Oct 26, 2022)

jtr1962 said:


> That's irrelevant because properly designed LED lighting uses a constant current driver, not constant voltage. The only concession to voltage might be that an LED setup for a car using red LEDs will use 6 in series and a constant current driver, versus 4 blue LEDs in series. The idea is to get the total native voltage of the LEDs close to the supply voltage, in order to get maximum efficiency from the driver. The driver simply ensures the LEDs in the string get the same current whether the car battery is low or fully charged.



Resistors is a perfectly appropriate method for the application. A change in brightness for most lights in a car w.r.t. battery voltage is totally acceptable. The change is likely less than with an incandescent bulb.


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## JustAnOldFashionedLEDGuy (Oct 26, 2022)

JoakimFlorence said:


> I think this is mainly what's going on.
> 
> But I think the fault is mainly the consumer (in this case local governments and city councils). In many of these situations they will just go with the cheapest option, which puts a lot of pressure on companies to have to cut costs as much as possible.
> The main hurdle to conversion to LED street lighting was initial cost.
> And of course (even more in the U.S. than in Europe) most of these LED streetlights are assembled by companies in China and are not "real" mainstream brands. (China is notorious for cutting corners and making products that will fall apart a short time after purchase)



NO! Most of the street lights in the US are assembled in North America. Street lights are one area where the penetration of Chinese products is relatively low in lighting due to the high cost of failures. Most installed street lights ARE mainstream brands. 

Why do people feel the need to post as facts something they know very little about? 

Europe has every bit as much Chinese lighting product as the U.S., including a lot more poorly engineered power supplies.


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## JustAnOldFashionedLEDGuy (Oct 26, 2022)

kaichu dento said:


> Still trendy to ignore a whole slew of information based posts and call out the 'evil companies' because it's easier than discussing things one doesn't understand.



I always assume it is a show off / ego thing.


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## JoakimFlorence (Oct 28, 2022)

JustAnOldFashionedLEDGuy said:


> Resistors is a perfectly appropriate method for the application.


This was discussed in another thread. The short answer is that resistors are not really a satisfactory or practical method for limiting current in LED lighting. The problem is that either the efficiency losses are too high, or that small variations in input voltage can lead to large and intolerable variations in the amount of current going through the LED. You will only find resistors in very small indicator lights where the power level is so small efficiency losses do not matter.

Think of it this way. There is a certain amount of voltage. Wired into a string there is a series of resistors and LEDs. Each LED or resistor "sucks up" a certain amount of voltage. Although of course the LEDs each have resistance, they cannot be relied upon to provide that resistance, because their resistance value suddenly drops with any voltage a tiny bit above their voltage rating. Although a certain voltage might be fed to the LEDs, transient voltage spikes are normal and common from any power supply.
The more of that voltage is being sucked up by the LEDs, the more the circuit is going to behave like just an LED, rather than a normal resistor.
*If only 10% of the power was being sucked up by the resistor, that would mean that if there was a transient voltage spike 50% above normal, almost 15 times more current would be allowed through the circuit than normal.*
This is intolerable for two reasons. First high power LED emitters are expensive and it might not be very economical to be able to increase current rating of the emitters by a factor of 15. But second of all, if you run an LED on only a small fraction of the current it is rated for, there will typically be a wavelength shift, and in a white LED this could alter the tint of the light, giving a noticeable slight greenish tint, although this could be adjusted for with manufacturing specifications. Even this would not be pragmatic because it would be likely there might be occasional voltage surges in the electric grid. Even though they might only last a fraction of a second, it would result in a burn out of all the LED lamps in the city. For example, static electricity or from a lightning strike. It takes very little energy to cause a burn out of LEDs. You can burn out an LED with a thousand times less energy than it normally uses per second, if enough energy gets concentrated into a very short instant of time. Remember, wattage is energy per second of time. If you were to concentrate the energy of one watt over one second into only a hundredth of a second, that would be 100 Watts, enough to burn out a 10 Watt LED. One millionth of a Watt imparted through the circuit through a static discharge is easily enough to burn out an LED. (Remember again, a Watt is not an actual unit of energy. One Watt over one entire second equals one Joule of energy. A Watt is just the rate of energy flow)


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## Dave_H (Oct 28, 2022)

I agree in general, for high-power LED lighting resistive current limiting is usually not practical. It is generally done with switching constant-current output drivers. Linear constant-current regulators will work albeit not for street lighting. To cope with line variations they would need to be over-engineered and result in poor efficiency.

One case of linear regulation is (typical) 9W LED A19 bulb. If sufficient LEDs are stacked to get vf= 130-140v total (for 120vac line) the full-wave rectified line applied through a 60mA high-voltage regulator will do a reasonable job. One 100W equivalent bulb I opened uses two such chips (CYT1000A) in parallel.

Dave


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## JustAnOldFashionedLEDGuy (Oct 31, 2022)

JoakimFlorence said:


> This was discussed in another thread. The short answer is that resistors are not really a satisfactory or practical method for limiting current in LED lighting. The problem is that either the efficiency losses are too high, or that small variations in input voltage can lead to large and intolerable variations in the amount of current going through the LED. You will only find resistors in very small indicator lights where the power level is so small efficiency losses do not matter.



And you have designed how many professional LED products that have gone into mass production and for automotive? I know the answer to that question is 0.

Let me state again. RESISTORS are a PERFECTLY ACCEPTABLE method of setting current in many applications and automotive is definitely one of those applications since we have a reasonably narrow range of voltages and Vf is relatively well controlled on the LED side now. For many applications, highly accurate LED output is not needed, only meeting some minimum under some conditions. With the exception of forward lighting, resistors are quite common in automotive including for tail lights because they are cheap, reliable, and they do the job.

There are actually automotive lighting and general lighting experts in these threads. You are not one of them. Your high school lessons were not relevant 10 years ago, and they still are not for the majority of people here. This forum is not for you to try to look smart.


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## JustAnOldFashionedLEDGuy (Oct 31, 2022)

Dave_H, linear regulators for interior lighting had a go there for a few years, and even for exterior single voltage applications. The issue was not efficiency, but line rate flicker. Line rate flicker (and flicker in general) has become more of an issue the last 3-5 years. It is not acceptable for commercial lighting, and even large retailer put restrictions on their branded products. You can add capacitance to linear regulation solutions and still hit power factor and THD requirements, but your cost and size is now at the level of a switching supply. With residential, you already needed some added circuitry to keep dimmers happy, so cost savings of the linear quickly disappear. Low cost off-shore lighting is still seen with linear regulation solutions and high flicker.


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## KITROBASKIN (Oct 31, 2022)

Is this quote from Joakim accurate?

Remember, wattage is energy per second of time. If you were to concentrate the energy of one watt over one second into only a hundredth of a second, that would be 100 Watts, enough to burn out a 10 Watt LED. One millionth of a Watt imparted through the circuit through a static discharge is easily enough to burn out an LED. (Remember again, a Watt is not an actual unit of energy. One Watt over one entire second equals one Joule of energy. A Watt is just the rate of energy flow)


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## radellaf (Oct 31, 2022)

I wish the automotive LED engineers would quit using very low frequency PWM for tail lights. Personally would love to have had that outlawed from the beginning. Very distracting to me. I guess not to others.

As for the PC red and green (and yellow and orange), I've seen that on fairy light strings and... am not a huge fan. It's OK. The colors fade (yellow to white mainly) too fast. But as those are made absolutely as cheap as possible, I ain't gonna complain.

Otherwise I mostly see the RGB chip LEDs with all 3 in one package, whether 4-pin analog, or 5V with serial digital control. Ever seen a PC version of those?


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## PhotonWrangler (Oct 31, 2022)

radellaf said:


> I wish the automotive LED engineers would quit using very low frequency PWM for tail lights. Personally would love to have had that outlawed from the beginning. Very distracting to me. I guess not to others.


It's very distracting to me also. If I'm sitting behind someone with low frequency PWM brake lights at a stop light, any lateral motion of my eyes creates lots of flicker. This practice needs to stop.


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## Monocrom (Oct 31, 2022)

PhotonWrangler said:


> It's very distracting to me also. If I'm sitting behind someone with low frequency PWM brake lights at a stop light, any lateral motion of my eyes creates lots of flicker. This practice needs to stop.


Watching car review videos is frustrating too.
_Just ignore the constant flickering of the headlights. That only happens on camera. _


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## Dave_H (Nov 1, 2022)

JustAnOldFashionedLEDGuy said:


> Let me state again. RESISTORS are a PERFECTLY ACCEPTABLE method of setting current in many applications and automotive is definitely one of those applications since we have a reasonably narrow range of voltages and Vf is relatively well controlled on the LED side now. For many applications, highly accurate LED output is not needed, only meeting some minimum under some conditions. With the exception of forward lighting, resistors are quite common in automotive including for tail lights because they are cheap, reliable, and they do the job.


 Agreed; I have acquired a variety of automotive LED lamps for purpose of operating from 12vdc, not for automotive use as I suspect most would not meet required standards; that is topic of other discussions on this board. Smaller lights including marker, running/brake/signal, and small interior lights commonly use resistor dropping. 

Clearly, efficiency is not great on some. Groups of three amber LEDs in series only requires about 6v, so the rest is loss; similar with red. I have run some at reduced brightness from a 9v battery. Some have one diode in series, others have two or even full-wave bridge so does not care about polarity. This adds 1-2 diode drops, further lowering efficiency.

One little light actually used an LM317L linear regulator wired for constant-current. I could make out the resistor colour code through the amber plastic, and calculated 25mA, which was close to measured and spec. Anything which can run from 12/24vdc can't do well with resistors or any other linear regulation (but one strange exception I can add).

Larger "auxiliary" LED lights would not do well with linear regulation; use a variety of switching drivers and series/parallel arrangements.

Dave


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## JustAnOldFashionedLEDGuy (Nov 9, 2022)

KITROBASKIN said:


> Is this quote from Joakim accurate?
> 
> Remember, wattage is energy per second of time. If you were to concentrate the energy of one watt over one second into only a hundredth of a second, that would be 100 Watts, enough to burn out a 10 Watt LED. One millionth of a Watt imparted through the circuit through a static discharge is easily enough to burn out an LED. (Remember again, a Watt is not an actual unit of energy. One Watt over one entire second equals one Joule of energy. A Watt is just the rate of energy flow)



Some yes, practical standpoint no. A true 10W led will take 10x its rating for 0.01 seconds if it is of any quality. Remember they are just diodes and diodes usually can take fairly high pulse energy, 30-100x for short periods. Of course in automotive, there will always be something to protect against load dump s you don't see high voltages. For AC, you will similarly have a MOV to limit maximum excursion. Most larger LEDs have ESD protection as well. Reverse bias ESD hits are worse than forward.


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## JoakimFlorence (Nov 17, 2022)

radellaf said:


> I wish the automotive LED engineers would quit using very low frequency PWM for tail lights. Personally would love to have had that outlawed from the beginning. Very distracting to me.





PhotonWrangler said:


> It's very distracting to me also. If I'm sitting behind someone with low frequency PWM brake lights at a stop light, any lateral motion of my eyes creates lots of flicker. This practice needs to stop.


I think it can be assumed that any PWM (that involves flicker) for automotive LED lights (when the light is some color other than white) indicates that the LED is being fed by some sort of voltage converting power supply, not directly from the battery through a resistor.

For a lead acid (standard automotive) battery, between full charge and 50% charge, the voltage drop is only less than 0.5%. Even when the battery gets down to only 20% charge, the voltage drop is still less than 4%.




JustAnOldFashionedLEDGuy said:


> Let me state again. RESISTORS are a PERFECTLY ACCEPTABLE method of setting current in many applications and automotive is definitely one of those applications since we have a reasonably narrow range of voltages and Vf is relatively well controlled on the LED side now. For many applications, highly accurate LED output is not needed, only meeting some minimum under some conditions. With the exception of forward lighting, resistors are quite common in automotive including for tail lights because they are cheap, reliable, and they do the job.


I don't know if what you are saying is true, but here is something else to consider just from a basic electronics theoretical perspective: If the LED lights were being fed directly from the battery (through a small resistor), then can we assume that the circuit connecting to the LED lights would have to be isolated from the alternator which continually charges the battery? The alternator is a generator (that uses a coil of wire) and it is common for the alternator to have voltage spikes. (In fact a cheap and malfunctioning alternator can cause damage to the battery over time if the voltage spikes are too big, I have been told)

This makes me very skeptical about what you say.


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## JoakimFlorence (Nov 17, 2022)

KITROBASKIN said:


> Is this quote from Joakim accurate?
> 
> Remember, wattage is energy per second of time. If you were to concentrate the energy of one watt over one second into only a hundredth of a second, that would be 100 Watts, enough to burn out a 10 Watt LED. One millionth of a Watt imparted through the circuit through a static discharge is easily enough to burn out an LED. (Remember again, a Watt is not an actual unit of energy. One Watt over one entire second equals one Joule of energy. A Watt is just the rate of energy flow)


Perhaps not literally but I was just illustrating an example to try to prove a point.

The point was that only a surprisingly small amount of energy is enough to be able to burn out an LED, such as from a relatively small static electricity shock. It is actually NOT the voltage that burns out an LED but the wattage (the amount of energy imparted to the LED within a very short interval of time, a fraction of a second). Theoretically, you could supply an LED with a million volts and that LED would run just fine as long as the current (mA) level did not at any time exceed the LED's specifications.
(wattage imparted to the LED would be equal to the portion of voltage actually absorbed by the LED, multiplied by the current)

If you want to actually closely look at the numbers, a "typical" static shock is on the order of several milliJoules of energy. (a millijoule being 0.001 Joule, the equivalent amount of energy of 0.001 Watts over one second) Yet this is still enough to blow out an LED rated for, say, 3 Watts of power.

This may seem counterintuitive to many people, because you might think if a component should be able to normally handle power over one second it should be able to handle a small fraction of that same power over a fraction of a second. But basic physics works a little differently on small scales than it does on large scales. The components inside an LED are tiny, on a very small scale. It would be like the equivalent of observing that a 50 Watt light bulb uses 30,000 Joules of energy over 10 minutes, then asking why it can't candle 2,000 Watts over one second (only 2000 Joules) if not turned on for the rest of that 10 minute time period. The simple fact is that the filament cannot dissipate that much heat fast enough. With microscopic electronic components, they can reach excessive temperatures very fast from very small amounts of energy. On a small scale, a second is a long period of time.

I should clarify in my statement, when I said "One millionth of a Watt imparted through the circuit through a static discharge is easily enough to burn out an LED", that what I actually meant was the equivalent energy of one millionth of a Watt over one second, which could mathematically work out to many Watts in the time interval of a tiny fraction of a second.
I thought that should have been obvious from the context of the rest of my statement, so I did not feel it was worth the effort of correcting the error.

This is probably unnecessary but lastly I want to clarify something, for anyone who thinks my claim about an LED being able to survive a million volts is outrageous. It is technically true, but I am not aware of any high voltage (>20kV let's say) power supply that could meet the very tight current specifications. Even an extremely low powered high voltage power supply would be sure to blow out the LED. The high voltage power supply might have a low average current, but when high voltages like that are involved there will usually be current spikes. To explain this in a different way, the calculated average wattage output of the power supply might be only 0.1 watts, but within that there are going to be short intervals of hundreds of watts. It's just the nature of high voltage, it has a tendency of moving around very quickly in short little bursts.


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## LEDphile (Nov 17, 2022)

JoakimFlorence said:


> I think it can be assumed that any PWM (that involves flicker) for automotive LED lights (when the light is some color other than white) indicates that the LED is being fed by some sort of voltage converting power supply, not directly from the battery through a resistor.
> 
> For a lead acid (standard automotive) battery, between full charge and 50% charge, the voltage drop is only less than 0.5%. Even when the battery gets down to only 20% charge, the voltage drop is still less than 4%.
> 
> ...


Your "basic electronics theoretical perspective" appears to have missed "parallel circuits" - a circuit that is fed from an automotive battery is also fed by the alternator (which is in parallel with the battery).

Now, as to the use of a resistor for an automotive rear lighting application, if we consider a string of 5 mid-power red LEDs (e.g. Lumileds Signalsure 75), being driven by an automotive electrical system through a 47 ohm resistor, we get the following set of drive currents (linear models were used for simplicity - in reality, the current spread will be a bit smaller)

VoltageCurrent16V (max design voltage)87mA14.5V (nominal alternator voltage)68mA12V (nominal battery voltage)35mA10V (dead battery voltage)9mA

This gives about a 2:1 change in output (output is approximately linear with drive current) between the "engine on" and "engine off" states, keeps the LEDs within their maximum ratings at the max design voltage, and still has some output with a dead battery. At this point, it is worth noting that an incandescent lamp will be about 1.9x as bright at 14.5V as at 12V, so a comparable change in output.

Could a constant-current regulator make things more consistent? Absolutely. Will a regulator increase cost, size, and points of failure? Also yes. Is a resistor good enough? Probably.


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## JoakimFlorence (Nov 17, 2022)

LEDphile said:


> Your "basic electronics theoretical perspective" appears to have missed "parallel circuits" - a circuit that is fed from an automotive battery is also fed by the alternator (which is in parallel with the battery).


I have a feeling you don't understand what I was saying.

You understand that the battery cannot be connected to the alternator at the same time that the LEDs are connected to the battery?


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## JustAnOldFashionedLEDGuy (Nov 23, 2022)

JoakimFlorence said:


> I think it can be assumed that any PWM (that involves flicker) for automotive LED lights (when the light is some color other than white) indicates that the LED is being fed by some sort of voltage converting power supply, not directly from the battery through a resistor.
> 
> For a lead acid (standard automotive) battery, between full charge and 50% charge, the voltage drop is only less than 0.5%. Even when the battery gets down to only 20% charge, the voltage drop is still less than 4%.
> 
> ...



You are skeptical because you don't have the first idea of what you are talking about or even a hint of practical or professional experience and I apologize to the moderators if that is harsh, but it is quite obviously true.

YES they are doing PWM right from the battery with a resistor. NO they are not isolating from the output of the alternator and hence larger voltage swing. What the heck do you think happened when we used incandescent bulbs!!??


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## JustAnOldFashionedLEDGuy (Nov 23, 2022)

JoakimFlorence said:


> Perhaps not literally but I was just illustrating an example to try to prove a point.
> .... blah blah



Again you are talking about things you really have no clue about. Static electricity does not damage LEDs from over-current it damages from over-voltage. It literally punches through diffusions without the LED ever conducting as it is often a reverse bias situation. LEDs are quite robust w.r.t. forward biased static discharges as the effective source resistance of a static discharge is quite low. It is not usual for high powered leds to be in parallel with an esd diode conducting in the opposite direction.

LEDS are fairly large die devices because they have to be, thermal issues and all from high forward voltages and can take over current quite large (as can most diodes really).


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## JustAnOldFashionedLEDGuy (Nov 23, 2022)

JoakimFlorence said:


> I have a feeling you don't understand what I was saying.
> 
> You understand that the battery cannot be connected to the alternator at the same time that the LEDs are connected to the battery?



He understood what you are saying. What you are saying is wrong.


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## JustAnOldFashionedLEDGuy (Nov 23, 2022)

JoakimFlorence said:


> For a lead acid (standard automotive) battery, between full charge and 50% charge, the voltage drop is only less than 0.5%. Even when the battery gets down to only 20% charge, the voltage drop is still less than 4%.



And again, you have no clue what you are talking about. Just stop already. Anyone can find an online SOC versus voltage charge and see that basic calculations are eluding you. Just stop already.


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## Dave_H (Dec 13, 2022)

JoakimFlorence said:


> For a lead acid (standard automotive) battery, between full charge and 50% charge, the voltage drop is only less than 0.5%. Even when the battery gets down to only 20% charge, the voltage drop is still less than 4%.


 Your numbers are off, not sure where you're getting this. I regularly charge 12v gel-cells up to about 12.8v (approx. 100%) and discharged only down to 12.0v (about 50%); which is about 6-7% drop. Gel-cell is not exactly like flooded lead-acid but the numbers are representative.

Dave


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## desert.snake (Dec 13, 2022)

A friend broke the headlight in the car, there are LED bulbs from the factory. We looked and were horrified. The heat dissipation is very poor. It seems that this is done on purpose so that they overheat and degrade


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## JustAnOldFashionedLEDGuy (Dec 18, 2022)

desert.snake said:


> A friend broke the headlight in the car, there are LED bulbs from the factory. We looked and were horrified. The heat dissipation is very poor. It seems that this is done on purpose so that they overheat and degrade



No. Just no. They are adequately heat sunk for real world operation far beyond the life of a typical car. What are the odds the two of you have even 1/10th the knowledge/experience/tools of the people who designed the product?


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## desert.snake (Dec 19, 2022)

JustAnOldFashionedLEDGuy said:


> No. Just no. They are adequately heat sunk for real world operation far beyond the life of a typical car. What are the odds the two of you have even 1/10th the knowledge/experience/tools of the people who designed the product?


What's the chance that this headlight for design was given to a couple of students from another country who have no idea how to design headlights? Auto manufacturers have screwed up for the last 100 years in almost every car they make.

This Toyota Camry. The headlight is sealed, the radiator from the LEDs is located inside the headlight and gives off heat only to the air pocket, which is surrounded by sealed plastic.

My friend and I have a lot of experience.


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## LEDphile (Dec 19, 2022)

desert.snake said:


> The headlight is sealed, the radiator from the LEDs is located inside the headlight and gives off heat only to the air pocket, which is surrounded by sealed plastic.


Without knowing the Ts of the LED package in the application, and how it compares to the LED manufacturer's lifetime data, any claims about lifetime are pure speculation. And there is much more to the lifetime of the headlight module than just the lumen depreciation of the LED. There's also all the other failure modes, like water intrusion, corrosion, materials degradation, etc. 

There's a nonzero chance that when the design engineers performed their DFMEA (Toyota is a heavily process-driven company), they determined that extending a metallic heatsink through the plastic housing to improve the thermal performance introduced a greater risk of failure over the design lifetime than sealing the heatsink in. Additional sealing points, especially between materials with different CTEs, are potential points of failure and water ingress.


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## desert.snake (Dec 19, 2022)

LEDphile said:


> Without knowing the Ts of the LED package in the application, and how it compares to the LED manufacturer's lifetime data, any claims about lifetime are pure speculation. And there is much more to the lifetime of the headlight module than just the lumen depreciation of the LED. There's also all the other failure modes, like water intrusion, corrosion, materials degradation, etc.
> 
> There's a nonzero chance that when the design engineers performed their DFMEA (Toyota is a heavily process-driven company), they determined that extending a metallic heatsink through the plastic housing to improve the thermal performance introduced a greater risk of failure over the design lifetime than sealing the heatsink in. Additional sealing points, especially between materials with different CTEs, are potential points of failure and water ingress.


Perhaps, but this is the second headlight that my friend burned out in 3 years on this car. Something Toyota does very well, but something bad, like everyone else. In this case, headlights and a body that quickly rots.


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## JustAnOldFashionedLEDGuy (Dec 19, 2022)

desert.snake said:


> What's the chance that this headlight for design was given to a couple of students from another country who have no idea how to design headlights? Auto manufacturers have screwed up for the last 100 years in almost every car they make.
> 
> This Toyota Camry. The headlight is sealed, the radiator from the LEDs is located inside the headlight and gives off heat only to the air pocket, which is surrounded by sealed plastic.
> 
> My friend and I have a lot of experience.



Virtually none. The headlight would have a large interdisciplinary team of optics engineers, mechanical engineers, and EEs, as well as manufacturing specialists. Every aspect of it will have been simulated before a tool was every cut. After tooling and extensive design validation testing, extensive testing for abnormal conditions and extensive accelerated life testing would occur. Then, and only then will it get to the consumer. Things slips by in design, as no test has 100% coverage, but your post is pure fantasy. Your friend and you obviously have absolutely no experience with automotive design, and I expect you have little experience with lifetime prediction of LED assemblies for automotive.


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## KITROBASKIN (Dec 19, 2022)

Defects can result from a manufacturing error?


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## JustAnOldFashionedLEDGuy (Dec 19, 2022)

desert.snake said:


> Perhaps, but this is the second headlight that my friend burned out in 3 years on this car. Something Toyota does very well, but something bad, like everyone else. In this case, headlights and a body that quickly rots.



The first OEM headlight on a Camry was a 2015 model year. Are you telling me your friends 2015 is already rotting? Seems suspect. The Corolla used a reflector. The Camry a projector. There is active cooling.


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## desert.snake (Dec 19, 2022)

JustAnOldFashionedLEDGuy said:


> Virtually none. The headlight would have a large interdisciplinary team of optics engineers, mechanical engineers, and EEs, as well as manufacturing specialists. Every aspect of it will have been simulated before a tool was every cut. After tooling and extensive design validation testing, extensive testing for abnormal conditions and extensive accelerated life testing would occur. Then, and only then will it get to the consumer. Things slips by in design, as no test has 100% coverage, but your post is pure fantasy. Your friend and you obviously have absolutely no experience with automotive design, and I expect you have little experience with lifetime prediction of LED assemblies for automotive.


I've been working on some things for a while, where testing and development is much more rigorous and extensive than some small, middle-class car. Theory, tests and practice are two different things. . Despite what you have listed, cars still break down, their headlights burn out ahead of time, and their bodies crumble to dust due to rust. And mind you, I didn't talk about other aspect of headlight design other than terrible bad heat dissipation.

Yes, the body really rots very quickly. The salt on the roads and the climate are taking their toll. 2-4 years and through rust may appear in the body


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## JustAnOldFashionedLEDGuy (Dec 19, 2022)

desert.snake said:


> I've been working on some things for a while, where testing and development is much more rigorous and extensive than some small, middle-class car. Theory, tests and practice are two different things. . Despite what you have listed, cars still break down, their headlights burn out ahead of time, and their bodies crumble to dust due to rust. And mind you, I didn't talk about other aspect of headlight design other than terrible bad heat dissipation.
> 
> Yes, the body really rots very quickly. The salt on the roads and the climate are taking their toll. 2-4 years and through rust may appear in the body



Unless you are doing military or space, or infrastructure telecom, your design and testing is likely not nearly at the level of a small middle class car that has much more extensive and complete design and test that a low volume ultra high end car. The costs of high failure rates for cars is astronomical and hence avoided. You are showing you don't understand the process at all. Cars do breakdown, but less and less every year and I checked and no reports of unusual failure rates for Camry headlights. 

I have not seen any car rust through in 2-4 years in 3+ decades and I practically drive in a salt spray 4+ months of the year where it is cold enough that salt is used all the time, but warm enough to have liquid/corrosion at near optimal rates. I put 30,000+ miles/year on cars for decades and never had perforation in < 7 years. With the galvanation processes, and multi-step painting processes, even on cheap cars, it just does not happen any more, hence 5+ year unlimited mileage perforation warranties. You may get the odd process failure but exceedingly rare. You see a car with perforation on the road today, almost guarantee it is at least 7-8 years old and probably more.

There is nothing wrong with the heat dissipation in the Camry headlight. Frankly, as noted, you are purely guessing and have no idea the Tc of the die is, and even if high, the failure rate from high die temp would be light degradation, not outright failure. That is almost always mechanical in nature.


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## desert.snake (Dec 20, 2022)

JustAnOldFashionedLEDGuy said:


> Unless you are doing military or space, or infrastructure telecom, your design and testing is likely not nearly at the level of a small middle class car that has much more extensive and complete design and test that a low volume ultra high end car. The costs of high failure rates for cars is astronomical and hence avoided. You are showing you don't understand the process at all. Cars do breakdown, but less and less every year and I checked and no reports of unusual failure rates for Camry headlights.
> 
> I have not seen any car rust through in 2-4 years in 3+ decades and I practically drive in a salt spray 4+ months of the year where it is cold enough that salt is used all the time, but warm enough to have liquid/corrosion at near optimal rates. I put 30,000+ miles/year on cars for decades and never had perforation in < 7 years. With the galvanation processes, and multi-step painting processes, even on cheap cars, it just does not happen any more, hence 5+ year unlimited mileage perforation warranties. You may get the odd process failure but exceedingly rare. You see a car with perforation on the road today, almost guarantee it is at least 7-8 years old and probably more.
> 
> There is nothing wrong with the heat dissipation in the Camry headlight. Frankly, as noted, you are purely guessing and have no idea the Tc of the die is, and even if high, the failure rate from high die temp would be light degradation, not outright failure. That is almost always mechanical in nature.


Space.

If you have not seen such machines, then you are lucky. My friend in the car service sees 3-4 year old Japanese cars that are rusted through. The best in terms of corrosion protection are normal Germans. BMW, Mercedes, Audi - 30-40 years cars inside look like they came from the factory).

I already wrote, 2 headlight failures on a Camry from my friend. The LED is burned out.


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## JustAnOldFashionedLEDGuy (Dec 20, 2022)

desert.snake said:


> Space.
> 
> If you have not seen such machines, then you are lucky. My friend in the car service sees 3-4 year old Japanese cars that are rusted through. The best in terms of corrosion protection are normal Germans. BMW, Mercedes, Audi - 30-40 years cars inside look like they came from the factory).
> 
> I already wrote, 2 headlight failures on a Camry from my friend. The LED is burned out.



So a completely sealed, sonic welded assembly but you know the LED is burned out .... okay. Call me skeptical. 

I think your friend has bias and/or is lying to you. I have had Nissan, Mazda, Honda, VW, BMW, Ford, Chevy, Toyota, and Lexus in the family over the last 30 years in a high salt environment, often 30,000+/year, most cars kept 6-9 years. The earliest rust issue was the Ford, followed by the BMW, and larger surface rust, no rust through. We did get perforation at 9 years with the Mazda, but it had 200K miles. 3-4 year is frankly, a load of crap. Hyundais and Dodge failed like that 30 years ago. No cars do that made in the last 2.5+ decades. 40 year old Audi's and BMW would rarely be on the road any more (terrible reliability) and if they were, they body was long gone if they were near salt. Now they are the best out there. Can't say I place a lot of faith in anything you claim.


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