LED headlight experiment, part 2... and a discussion on headlight optics

argleargle

Enlightened
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Jan 7, 2013
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321
The subject of lens durability came up, and I remarked that it seemed odd for them to have chosen a particular lens material for their LED headlamp, because it's a material known to cloud up and degrade with time -- not a huge deal if it's a lens on an inexpensive halogen headlamp, but a different matter on an expensive LED headlamp with "to infinity and beyond" light source lifespan. Shouldn't the lens durability come closer to matching the light source durability? The engineer's answer sort of came out of left field for me. He said they'd discussed using hardened glass or a more durable polycarbonate, but decided against it because despite the practically infinite rated lifespan of the LEDs they were using, there would certainly be some failures before the end of time. They decided that if an LED failed, it would give their company (and LED headlamps in general) a "black eye". But if the lens clouded up and became useless in seven years or so, well, all headlamps do that; it's just how things work, sigh, guess it's time to replace it

I'm 100% agreeing with you.

Planned bean-counter replacement schedules. Just like Gillette, only better! We'll make a scad of cash selling the cutting edge light solution, but you're going to have to buy our razor bla... I mean LED headlight lenses. Since the LED isn't burning out anymore... I'm reminded of Thomas Edison and the light bulbs that wouldn't burn out fiasco. A few are still burning today in America... even STILL! IIRC, one is still going in a firestation in the American northeast. Sometimes, I think we need fewer Thomas Edisons and more Nicola Teslas. Just a personal opinion, there. Sort of like how horse buggy whip makers lobbied congress to stop the horseless carriage...

This is my view on obsolete-by-plan and planned-failure-replacement. There will be no such thing as an industry standard LED headlight solution due to the real-world equivalent of the PHB from Dilbert. I hate so much to be so cynical.
 
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DIWdiver

Flashlight Enthusiast
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Jan 27, 2010
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So why don't headlight makers (surruptitiously, of course) promote headlamp testing stations, annual safety checks, etc that would force people with cloudy lenses to replace them? Hey, come to think of it, we could nail all those idiots with crappy conversions too!

I remember that decades ago New York State annual vehicle inspections included checking the aiming of the headlights.
 

argleargle

Enlightened
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Jan 7, 2013
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I think you nailed the question, DIW. Annual safety checks, headlamp testing stations. You'd THINK this would be called a vehicle inspection sticker. You'd hope.

Awesome comment. It made me smile with bitter irony. "Why do we need more laws? How about we enforce the ones we have and get rid of the junk instead of passing more?"

Oh goodness. It's that whole "legal thing." Great post, thanks.
 

-Virgil-

Flashaholic
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Mar 26, 2004
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7,802
So why don't headlight makers (surruptitiously, of course) promote headlamp testing stations, annual safety checks, etc

Because Americans don't care about car lighting, and meaningful periodic vehicle inspections are suspiciously regarded as some sort of infringement of liberty. Even those very few states that still go through the motions don't check headlamp aim, at least not to any meaningful degree of precision. It just takes too long when people are writing angry letters to their lawmakers about having to wait for twenty minutes for their car to be inspected.

In Germany, there's nothing surreptitious about any aspect of any of this; they have a whole big loud "car lighting safety month" sponsored by Hella and other makers, where drivers can get their lights' condition checked and adjusted (aim, dead bulbs, etc.) free of charge.
 

SemiMan

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Jan 13, 2005
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On the issue of LED degradation in car headlights is that the total operational time of the typical car at night over its whole life is relatively short. The very very outside is 10,000 hours with < half of that more typical. DRLs will run full time, but the amount of light required for a DRL is minimal with todays LEDs.

PMMA (Acrylic) is more typical for LED optics due to the lack of yellowing, but anti-yellowing polycarb is in use for cover plates. I would expect the polycarbs in use for automotive and their need to deal with UV in sunlight would make them suitable for LED. It is often the UV in sunlight for outdoor fixtures that can be the bigger concern, not the actually blue pump LED. That said, an issue for automotive LED given the hard driving and high temps is plastics that are optically stable at design temps.

Germany just takes driving a whole lot more seriously than in many other areas. People get it that it is a privaledge, not a right.

Semiman
 
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