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#4586500 - 11/27/17 11:29 AM Engineering a LED Headlamp
SubLGT Offline


Registered: 01/31/06
Posts: 2646
Loc: Idaho
Here is an interesting article that gives some insight as to the engineering (at Renault) required to design and manufacture a LED headlamp at reduced cost. Hint: they are not just dropping a LED source into an existing halogen headlamp.

http://www.ledsmagazine.com/articles/pri...-with-leds.html

an excerpt:

Quote:
...Looking deeper at our general CFD-based thermal analysis approach that typically is used to optimize headlamp designs, we would normally be interested in predicting lighting performance at 23°C outside the headlamp in ambient air and up to a maximum of 70°C for the outside temperature for the outer boundary of LED reliability. To validate our simulations, we performed some experiments where we fixed the ambient temperature outside the headlamp at 23°C and installed eight thermocouples outside the assembly for a car with its engine on and off...

...We concluded that it was not possible to design an LED system if we were to take into account all the use cases. The OEM must therefore define the best compromise. For example, at 23°C after one hour of engine idling, lighting performance was shown to be at 100%, but if the ambient temperature rose to 50°C for the same situation, the lighting performance would go down to 80%. To respect this specification, we concluded that a thermal sensor had to be added to the PCB (printed circuit board) so the current could be reduced if the temperature at the LED was greater than a threshold we would define. We could then do a thermal derating and a flux derating of the full LED headlamp...

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#4586504 - 11/27/17 11:35 AM Re: Engineering a LED Headlamp [Re: SubLGT]
Quattro Pete Offline


Registered: 10/30/02
Posts: 35850
Loc: Great Lakes
With all the hoopla around LED headlights, it seems like they are performing poorly in real life, based on IIHS headlight test scores. Either the IIHS has set some unrealistic expectations, or the manufacturers still have a lot of work to do in the headlight department.
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#4586512 - 11/27/17 11:41 AM Re: Engineering a LED Headlamp [Re: Quattro Pete]
SubLGT Offline


Registered: 01/31/06
Posts: 2646
Loc: Idaho
Originally Posted By: Quattro Pete
... the manufacturers still have a lot of work to do in the headlight department.


Ford comes to mind as having some poor LED headlights on the F150 (excessive glare combined with inadequate illumination). But there are also good OEM LED headlight out there, according to IIHS. IIHS testing protocol will usually lower the test score on headlights if they come from the factory misaimed.

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#4586523 - 11/27/17 11:57 AM Re: Engineering a LED Headlamp [Re: SubLGT]
bdcardinal Online   content


Registered: 06/03/05
Posts: 10985
Loc: Santa Barbara, CA
My issue with LED headlamps and taillamps, at least in the brands I do parts for which is Ford and Mazda is there are no serviceable bulbs. If you have a light go out, you have to replace the entire assembly. The F-150 LED housings are around $928 which does not include the ballast.
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#4586536 - 11/27/17 12:05 PM Re: Engineering a LED Headlamp [Re: bdcardinal]
Ethan1 Offline


Registered: 12/29/14
Posts: 1632
Loc: 'murica
Have you sold a lot of the LED ones for failed bulbs? They're *supposed* to last a long time.

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#4586543 - 11/27/17 12:09 PM Re: Engineering a LED Headlamp [Re: bdcardinal]
bmwjohn Offline


Registered: 01/04/08
Posts: 728
Loc: indianapolis in
having purchased a good many Chinese lights for various vehicles, ALL of which have been good, I strongly suspect a popular vehicle like F150 will quickly acquire several clone headlights at very good prices. The only aftermarket lights I have had problems with were for older Volvo's 3rd party lights made in Estonia. $928 is a price point many Chinese would love to beat and still make a profit.

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#4586547 - 11/27/17 12:20 PM Re: Engineering a LED Headlamp [Re: Ethan1]
bdcardinal Online   content


Registered: 06/03/05
Posts: 10985
Loc: Santa Barbara, CA
Originally Posted By: Ethan1
Have you sold a lot of the LED ones for failed bulbs? They're *supposed* to last a long time.


Just to body shops who have a meltdown at the price difference because insurance usually only authorizes money to cover halogen assemblies.

There is a service campaign for Mercury Milans that have LED taillamps that offers extended coverage. Have sold a fair amount of those under the campaign.
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#4586787 - 11/27/17 04:20 PM Re: Engineering a LED Headlamp [Re: SubLGT]
Rand Offline


Registered: 08/20/03
Posts: 12639
Loc: NE,Ohio
All I notice lately is they are like lasers..

super bright and blinding but you cant see off to the sides for DEER etc.

Oh and just wait a few years until cars with "high beam assist" start getting older and its not working good.
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#4586822 - 11/27/17 05:24 PM Re: Engineering a LED Headlamp [Re: Rand]
Reddy45 Offline


Registered: 08/15/08
Posts: 2967
Loc: USA
Originally Posted By: Rand
All I notice lately is they are like lasers..

super bright and blinding but you cant see off to the sides for DEER etc.

Oh and just wait a few years until cars with "high beam assist" start getting older and its not working good.



Augh.

I'm blinded enough by totally oblivious drivers in Hyundais and then brotrucks with a 12in lift.

It has me thinking I should just run around with my highbeams on all the time if we're all just racing to the bottom.

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#4586923 - 11/27/17 07:08 PM Re: Engineering a LED Headlamp [Re: Quattro Pete]
Carmudgeon Offline


Registered: 04/26/05
Posts: 534
Loc: Under the hood
Originally Posted By: Quattro Pete
... the manufacturers still have a lot of work to do in the headlight department.


That has always been true, regardless of the technology.

Juggling the balance between the demands of regulations, stylists, and accountants in order to produce soemthing that performs well, looks good, and is cheap to make doesn't always end in good results.

The are good and bad examples of every type and application.


Consumers are the ones who pay the price when the actual lifetimes don't meet the ones expected, or when other circumstances require replacement, such as when insurance coverage is only sufficient for aftermarket or other "LKQ" junk that isn't of the same quality or performance.

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#4587552 - 11/28/17 12:20 PM Re: Engineering a LED Headlamp [Re: SubLGT]
Quattro Pete Offline


Registered: 10/30/02
Posts: 35850
Loc: Great Lakes
Originally Posted By: SubLGT
But there are also good OEM LED headlight out there, according to IIHS.

In 2016, they only gave one "good" rating...
http://www.iihs.org/iihs/news/desktopnew...eed-improvement

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#4588598 - 11/29/17 10:09 AM Re: Engineering a LED Headlamp [Re: Quattro Pete]
SubLGT Offline


Registered: 01/31/06
Posts: 2646
Loc: Idaho
Originally Posted By: Quattro Pete
Originally Posted By: SubLGT
But there are also good OEM LED headlight out there, according to IIHS.

In 2016, they only gave one "good" rating...
http://www.iihs.org/iihs/news/desktopnew...ed-improvement.


If IIHS aimed the headlights before testing, more of them would get a "good" rating.

Quote:
Using the data and protocols provided by the IIHS, Dr. John Bullough, Director of Transportation and Safety Lighting Programs at Rensselaer Polytechnic Institute’s Lighting Research Center, performed some post-hoc analyses of the data. He shows in his editorial that demerit scores tended to be better when headlights were aimed properly and worse when the headlights were aimed either too high or too low. Though not all of the variation in headlight performance can be attributed to aiming, it was a meaningful factor. The number of systems rated as acceptable or good would have doubled if they had been correctly aimed.


http://newsroom.taylorandfrancisgroup.co...ty#.V6LCV-mmReV

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#4588739 - 11/29/17 11:50 AM Re: Engineering a LED Headlamp [Re: SubLGT]
Quattro Pete Offline


Registered: 10/30/02
Posts: 35850
Loc: Great Lakes
Thanks. This makes it sound like we have some widespread epidemic of incorrectly aimed headlights straight from the factory. If that is indeed true, that is appalling to me that manufacturers can't get this right.
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#4590996 - 12/01/17 12:42 PM Re: Engineering a LED Headlamp [Re: Quattro Pete]
circuitsmith Offline


Registered: 12/17/09
Posts: 620
Loc: Wash, DC
Originally Posted By: Quattro Pete
This makes it sound like we have some widespread epidemic of incorrectly aimed headlights straight from the factory.


This is covered in Nader's "Unsafe At Any Speed", believe it or not.
It wasn't just bout the Corvair.
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