Selective Yellow LED Headlights

Hi All,

I stumbled upon this bit of news that made me feel good. It looks like BMW showed off one of their concept cars, and that car has what appears to be selective yellow LED headlamps.

https://www.automobilemag.com/news/bmw-m8-gran-coupe-concept-unveiled-geneva/
"This car stands for a new type of performance-oriented luxury," explains the designer. "The warm yellow headlamps are an emotive antithesis to the cold white LEDs with their piercing blue ultra-intensity."

Click to expand...

I would love to have the option for selective yellow/low blue LED headlamps, the selective yellow especially. I would pay extra to get something other then the terrible 6500K blue-rich junk. Daniel Stern on selective yellow.

Daniel Stern Lighting
Blue also is a very difficult colour of light to look at; it stimulates the reaction we call glare. Within the range of allowable white light, bluer headlamps have been shown to be 46% more glaring than yellower ones for a given intensity of light.."

Click to expand...

cetary35 said:

I would love to have the option for selective yellow/low blue LED headlamps, the selective yellow especially.

Click to expand...

Only were you to be in France could you select that option. France permits selective yellow headlamps, everyone else requires white.

However, the real takeaway is that selective yellow LED fog lamps are certainly possible. Sadly, the marketers have overpowered the engineers and real lighting experts and 5000K or 6000K CCT LEDs are everywhere, even in fog lamps.

Alaric Darconville said:

Only were you to be in France could you select that option. France permits selective yellow headlamps, everyone else requires white.

Click to expand...

Old info. There were two edges to the European sword that sliced away a bunch of country-specific lighting requirements in the early 1990s (French yellow headlamps, Swedish headlamp wipers, German "one side at a time" parking lights, British dim-dip lights): France could no longer prohibit white headlamps, but the rest of Europe could no longer prohibit yellow ones. And the Principality of Monaco still legally requires yellow headlamps, or at least it did the last time I looked at the primary source (official legislative text). I've never been to Monaco and guess I probably never will, but I also guess this law is not enforced.

However, the real takeaway is that selective yellow LED fog lamps are certainly possible.

Click to expand...

That is true, and it doesn't have to be with a yellow filter over white LEDs. Selective yellow LEDs not only are possible, but they actually exist.

Sadly, the marketers have overpowered the engineers and real lighting experts and 5000K or 6000K CCT LEDs are everywhere, even in fog lamps.

Click to expand...

:-(

@-Virgil- do you have a source for selective yellow led's? I have used kapton tape over a few LED lamps with mixed results. Most recently over my cibie super oscars (LED, which appears to be a cree xml or xm-l2, 6500k), which resulted in a poor green-ish blue light color. A second layer of kapton tape resulted in more yellow appearance, but at significant loss of light. The 6500k output is way too cool for my taste, and I plan to crack them open and swap in some 4000k binned xm-ls. A selective yellow emitter, however, with the same output pattern and similar die size would be fantastic.

-Virgil- said:

France could no longer prohibit white headlamps, but the rest of Europe could no longer prohibit yellow ones.

Click to expand...

I did not know that!

Selective yellow LEDs not only are possible, but they actually exist.

Click to expand...

That's what I was getting at, if not directly.

One day, someone will start marketing warm white LED headlamps as having that "retro look harkening to the old days of motorsports" or something like that and BOOM, everyone will want 3200K CCT headlamps.

John_Galt said:

I have used kapton tape over a few LED lamps with mixed results. Most recently over my cibie super oscars (LED, which appears to be a cree xml or xm-l2, 6500k), which resulted in a poor green-ish blue light color. A second layer of kapton tape resulted in more yellow appearance, but at significant loss of light.

Click to expand...

Because, of course, the filtration removes non-yellow light, and doesn't replace it with yellow light. You will need emitters that have more red & green in their output.

I plan to crack them open and swap in some 4000k binned xm-ls.

Click to expand...

And ruin them in the process, even if you get it all back together and it is sealed (yet vented!) properly.

John_Galt said:

@-Virgil- do you have a source for selective yellow led's?

Click to expand...

No.

I plan to crack them open and swap in some 4000k binned xm-ls.

Click to expand...

Unless you have access to a shop very well equipped with specialty equipment, this is a bad idea that will almost certainly end in tears (and lost money and time). The degree of precision required in placement of the LEDs is much tighter than can be achieved by hand/eye, and the lamps are not designed or built to be opened after they've been assembled. Once you take them apart it will be "very difficult" (polite way to say "not possible") to put them back together satisfactorily. But if you can afford to lose the money spent on the lamps, and just want to play with them and see what you can achieve, well, go ahead!

Virgil, the issue with cracking and resealing oem assemblies is well known. I'm not ignoring that. What I am trying to do is get rid of the pale blue light. The cibies are a wonderful lamp, they have an excellent beam pattern, very low current draw, etc. But cibie went with a very cold white LED (likely due to market demands), and there is no reason they had to. I'm glad not every OEM is going this way, jw speaker, for instance seems to stick to sub-5500k, which makes a dramatic difference. The color temperature is the only shortcoming of these lamps. I imagine that using a less aggressive filter tape over the lens (you've linked others to theater lighting lens filters before) would work, however, tinted lenses are illegal in P, and easy to spot by law enforcement for a citation. An emitter swap is my solution at this point.A

John_Galt said:

Virgil, the issue with cracking and resealing oem assemblies is well known.

Click to expand...

But, you don't acknowledge the issues with trying to R&R the emitters. That's a project-killer.

The two LEDs appear to be mounted to a small mcpcb, secured with a small phillips head screw, with a positive and negative wire (approx 20/22ga wire) coming to the mcpcb. It's not integrated into the driver pcb. Desoldering two leads, and reflow soldering a replacement LED of the same type is not a hard task. The led is an XM-L or xm-l2, either of which are commonly available as bare emitters. Reflow soldering to the original mcpcb will put the led bsck in its original mounting location.

Its not a project killer. I'm not trying to justify shoehorning a chinese led bulb in a headlamp housing. I'm talking about an emitter swap with a change from one color temperature (legally white) to another color temperature (also legally white) with no effective change in luminance, focus, beam pattern or output/level of intensity.

As it stands, a source for legitimate selective yellow LEDs would be of interest for a lightbar project I have in mind for my offroad only baja bug. A source would be awesome

John_Galt said:

Reflow soldering to the original mcpcb will put the led bsck in its original mounting location... with no effective change in luminance, focus, beam pattern or output/level of intensity.

Click to expand...

You say that, and in doing so you demonstrate a misapprehension of the extreme precision required to do this correctly. It requires absolute perfection, else you change the focus--and when you change the focus you ruin the lamp.

The emitter swap is essentially impossible if you lack the correct equipment to measure and place everything absolutely correctly.

John_Galt said:

Reflow soldering to the original mcpcb will put the led bsck in its original mounting location.

Click to expand...

No, sorry, it will not. Not to the required degree of precision.

I'm not trying to justify shoehorning a chinese led bulb in a headlamp housing.

Click to expand...

No, you're trying to justify the equivalent of cutting open a bulb, removing the filament, and replacing the filament with a different one, all by hand, and then going "See? It's right in the same place as the original".

How low of a white light CCT could we go and still be considered within industry/legal guidelines to be compliant with chromaticity/CIE 1931 points for headlights?

@ -virgil-, Alaric Darconville,

Reflow soldering is not the uber complex thing you make it out to be. Easy, no, impossible to replicate a mass produced lamps LED placement (especially of such a large footprint emitter like an xm-l) is not impractically difficult.

This is not replacing the fragile halogen lamps filament and attempting to capture and reuse the original halogen gas mixture. It is not a 100% sealed housing filled with pressurized dry nitrogen (how nice would that be? 100% factory sealed and no chance of moisture buildup at any point in the units life?), which even then would mean resealing in a pressurized, dry nitrogen environment, also not an impossible task.

It's swapping a pair of XM-L chips for two other XM-L chips. The footprint is massive, it's not an array of luxeon chips on a custom mcpcb. Even if the original mcpcb is not reusable for some reason, the die height is known from cree's publications. The original mcpcb is measurable.

It's not attempting to crack open a headlamp like a JW Speaker and replsce the osram oslon chips with a completely incompatible emitter , chopping the pcb up to attempt to fit some sort of flashlight oriented mcpcb on top of the heatsink. It's as close to oem as it can get, resulting in the same performance, just a change in color temperature.

We are straying far from the point of this thread, and likely to get it locked. This is my last post discussing this.

---

Back on topic, selective yellow LEDs and headlamps that could use them.

IMHO, every headlamp would be fantastic with selective yellow output. My personal experience with SY headlamps has made me appreciate its qualities. OEM manufacturers of vehicle lighting are filling the roads with ultra blue lamps that seem to cause more glare than useful illumination, and unfortunately, lots of people are trying to upgraydd" their lamps with the latest and greatest, just as they were with PnP HIDs. Between lax standards, nearly non-existent enforcement, and the market being able to be flooded with non-conforming junk due to self certification (and again a nesr conpkete lack of enforcement), we are going to dealnwith excessive glare and high CCT lamps for the forseeable (hehe) future.

John_Galt said:

Reflow soldering is not the uber complex thing you make it out to be.

Click to expand...

Nobody's doubting your ability to solder. That's not the issue. This deflection attempt fails, as does the one about capturing halogen gas.

But clearly you're very determined to believe in your belief, facts be damned. Not a thing we can do about it. You've been given the right advice; it's a free country so you get to ignore it and insist you're right as much as you want.

We are straying far from the point of this thread

Click to expand...

We're straying from the narrative you prefer.

market being able to be flooded with non-conforming junk due to self certification

Click to expand...

Type-approval isn't better. The loopholes are different, but equally present.

We are actually straying from the point of this thread. You have stated a source of SY led emitters. I have asked for a source, or other additional, pertinent information, which has yet to be provided.

John_Galt said:

You have stated a source of SY led emitters.

Click to expand...

You sure about that?

John_Galt said:

@-Virgil- do you have a source for selective yellow led's?

-Virgil- said:

No.

Click to expand...

Click to expand...

cetary35 said:

How low of a white light CCT could we go and still be considered within industry/legal guidelines to be compliant with chromaticity/CIE 1931 points for headlights?

Click to expand...

The CCT (Coördinated Color Temperature) of the light is immaterial.

White is defined in SAE J578 (and in ECE R48; the two are in agreement) according to the CIE 1931 Color Space as:
x = 0.310 (blue boundary)
x = 0.500 (yellow boundary)
y = 0.150 + 0.640x (green boundary)
y = 0.050 + 0.750x (purple boundary)
y = 0.440 (green boundary)
y = 0.382 (red boundary)