# LEDs for Headlights **URL:** \ **Category:** Factual Questions\ **Created:** [November 7, 2002, 4:17am UTC](https://boards.straightdope.com/t/leds-for-headlights/135655 "2002-11-07T04:17:05Z")\ **Posts on this page:** 16\ **Page:** 1
**Author:** ![bcullman](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bcullman/32/8207_2.png) [@bcullman](https://boards.straightdope.com/u/bcullman)\ **Post date:** [November 7, 2002, 4:17am UTC](https://boards.straightdope.com/t/leds-for-headlights/135655/1 "2002-11-07T04:17:05Z")
I’ve noticed that in the last few years, LEDs have become more common in application such as rear brake lights and turn signals in cars, and traffic lights. LED computer monitors put out a range of colors using RGB subpixels to mix colors to simulate the entire spectrum of visable colors per pixel, including white light. Using this idea, is it possible that eventually we will see LED car headlamps? ---
**Author:** ![Enola\_Straight](https://avatars.discourse-cdn.com/v4/letter/e/dec6dc/32.png) [@Enola\_Straight](https://boards.straightdope.com/u/Enola_Straight)\ **Post date:** [November 7, 2002, 4:42am UTC](https://boards.straightdope.com/t/leds-for-headlights/135655/2 "2002-11-07T04:42:50Z")
I’ve already seen a flashlight with white LEDs. Is a cluster of LEDs…using a parabolic reflector or some kind of lens…strong enough to project a beam so-many hundred feet ahead of a car? This is yet to be seen. ---
**Author:** ![scotth](https://avatars.discourse-cdn.com/v4/letter/s/b9e5f3/32.png) [@scotth](https://boards.straightdope.com/u/scotth)\ **Post date:** [November 7, 2002, 4:59am UTC](https://boards.straightdope.com/t/leds-for-headlights/135655/3 "2002-11-07T04:59:14Z")
Every year affordable LED’s are becoming available in higher powers. As Enola Staight already pointed out, LEDs are available in white today with some of them pretty bright. It wouldn’t surprise me if they get bright enough for a reasonable cost and we see some used in car head light before long. (say, less than 10 years, and 5 wouldn’t be to unreasonable.) There would be some great advantages. 1. The would use quite a bit less power for a given brightness. 2. The could probably last on average of a million miles in a car. (Few people would have to replace them in the normal life of a car). ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [November 7, 2002, 5:06am UTC](https://boards.straightdope.com/t/leds-for-headlights/135655/4 "2002-11-07T05:06:18Z")
White LEDs aren’t as efficient as manufacturers lead you to believe. The efficiency is actually close to that of high quality halogen bulbs. Also, it’s difficult to make a large bright LED. The Nichia LEDs found in flashlights are less than 0.2W. The brightest LED currently available is the [Luxeon Star](http://www.luxeon.com/products/star_index.html), but it’s still only 5 watts so you need several of those to make an effective automotive headlight. But if you use an array of LEDs, you need a reflector and lens on each LED. Worse still, LEDs are very sensitive to heat so you need a heat sink connected to each LED. LEDs do have advantages such as long life, whiter light and faster response, but currently not enough to overcome the disadvantages. But there is another alternative - high intensity discharge (HID) lamps. These are several times more efficient than halogen bulbs or LEDs and produce a pure white light. They are complex and expensive, but they are already common in luxury cars. LED headlights _are_ already available for bicycles. The [CatEye EL-300](http://www.cateye.com/detail_mod02.php?cat=hlt&&products_id=91) uses 5 LEDs, each with its own focusing lens. Still, I find it’s not a big improvement over halogen lights. The manufacturer claims long battery life but that’s because of the low power (1 watt total), not high efficiency. Incidentally, HID bicycle lighs are also available, like the [NiteRider Blowtorch](http://www.niterider.com/products/bike_blowtorch.html). They cost over $300 and intended only for competitive off-road riding. ---
**Author:** ![Mirage](https://avatars.discourse-cdn.com/v4/letter/m/eb9ed0/32.png) [@Mirage](https://boards.straightdope.com/u/Mirage)\ **Post date:** [November 7, 2002, 5:12am UTC](https://boards.straightdope.com/t/leds-for-headlights/135655/5 "2002-11-07T05:12:46Z")
Most car owners replace their headlights maybe once or twice during their time with their vehicles, and at $15 bucks a pop it’s no big deal. A white headlight LED array would cost close to $1,000 and the benefits are intangible (a few cents worth of gas each 100 miles lost due to increased alternator load). You might save $2,000 in gas over 100,000 miles but who’s gonna go for that $1,000 of potential profit when it comes with a $1,000 increase in dealer price? ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [November 7, 2002, 8:37am UTC](https://boards.straightdope.com/t/leds-for-headlights/135655/6 "2002-11-07T08:37:28Z")
White LEDs are not exactly what they seem; apparently the actual diode emits coloured light internally, which is converted to white light by a phosphor. I was looking yesterday and RS components have packages with R G and B in a single unit; I think I’ve seen these used in arrays as stage lighting. ---
**Author:** ![Urban\_Ranger](https://avatars.discourse-cdn.com/v4/letter/u/e9c0ed/32.png) [@Urban\_Ranger](https://boards.straightdope.com/u/Urban_Ranger)\ **Post date:** [November 7, 2002, 12:12pm UTC](https://boards.straightdope.com/t/leds-for-headlights/135655/7 "2002-11-07T12:12:48Z")
Behold! It has been done - check out the Fioravanti Yak concept car. As it has been pointed out LEDs aren’t all that efficent - 10% for green, 20% for blue, and 40% for red. So there’s plenty of room for improvement. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [November 7, 2002, 12:35pm UTC](https://boards.straightdope.com/t/leds-for-headlights/135655/8 "2002-11-07T12:35:45Z")
Where does the remaining energy go? (I thought LEDs generated very little heat) ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [November 7, 2002, 12:47pm UTC](https://boards.straightdope.com/t/leds-for-headlights/135655/9 "2002-11-07T12:47:49Z")
The remaining energy turns into heat, as you’d expect. White high-power LEDs generate quite a bit of heat. I was playing around with a 1-watt Luxeon star LED yesterday and even with a heat sink it got too hot to touch. Color LEDs generate very little heat compared to colored incandescent bulbs. With a bulb you are generating a white light and then absorbing most of it with a color coating or filter. Color LEDs produce monochromatic light to begin with, so there is no need for a filter. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [November 7, 2002, 12:56pm UTC](https://boards.straightdope.com/t/leds-for-headlights/135655/10 "2002-11-07T12:56:20Z")
I want to get some of those Luxeon LEDs, but it looks as if I’d have to buy 200 of them. ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [November 7, 2002, 1:01pm UTC](https://boards.straightdope.com/t/leds-for-headlights/135655/11 "2002-11-07T13:01:51Z")
\> it looks as if I’d have to buy 200 of them Are you trying to buy direct from the manufacturer? There are many on-line shops that sell those. I got a pre-packaged 1-watt bulb from [LEDCorp](http://www.ledcorp.com/) but I think you can find bare LEDs for much less elsewhere. Just do a net search. I’m not sure about the availability of 5-watt versions, those are very new. (LEDCorp doesn’t say what LEDs they use, but I’m pretty sure their “Pro Series” bulbs use Luxeon Stars. The cheaper ones are plain old Nichia LEDs.) ---
**Author:** ![kanicbird](https://avatars.discourse-cdn.com/v4/letter/k/5f8ce5/32.png) [@kanicbird](https://boards.straightdope.com/u/kanicbird)\ **Post date:** [November 7, 2002, 1:48pm UTC](https://boards.straightdope.com/t/leds-for-headlights/135655/12 "2002-11-07T13:48:52Z")
Please give a cite where LED’s are close to halogen bulbs - I just can’t beleive it. I have a Photon fusion 6 white LED light and on max brightness I get about 5-6 hrs of light on 3 AA’s and about the same amount of light as a 2 D cell flashlight that may last about an hr or 2. aLSO on max brightness the light is not even warm. Perhaps upscalling LED produce heat? ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [November 7, 2002, 2:28pm UTC](https://boards.straightdope.com/t/leds-for-headlights/135655/13 "2002-11-07T14:28:22Z")
[This FAQ](http://www.pioneernet.net/optoeng/LED_FAQ.html), for example, states that LEDs are slightly less efficient than halogen bulbs. I tried to look for actual data sheets but Nichia doesn’t seem to state the brightness in lumens. (Candlepower is power output in a particular direction, so a high candlepower just means the beam is well focused.) ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [November 7, 2002, 2:56pm UTC](https://boards.straightdope.com/t/leds-for-headlights/135655/14 "2002-11-07T14:56:29Z")
… that being the case then, is it that all these LED torches are only able to boast superior battery life because of a reduction in light output? ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [November 7, 2002, 6:33pm UTC](https://boards.straightdope.com/t/leds-for-headlights/135655/15 "2002-11-07T18:33:11Z")
Basically, yes. The color is also different - LEDs are more white or bluish, so they appear brighter. ---
**Author:** ![\_etalhea](https://avatars.discourse-cdn.com/v4/letter/_/779978/32.png) [@\_etalhea](https://boards.straightdope.com/u/_etalhea)\ **Post date:** [November 7, 2002, 9:43pm UTC](https://boards.straightdope.com/t/leds-for-headlights/135655/16 "2002-11-07T21:43:10Z")
**BCULLMAN** > [@](#): > > \*Originally posted by bcullman \* > \*\*LED computer monitors put out a range of colors using RGB subpixels to mix colors to simulate the entire spectrum of visable colors per pixel, including white light. > \*\* Are you sure you’re not confusing LED with _LCD_ in this statement? I realize that some large screens, like Jumbotrons and stuff, use LED’s but most everything I’ve seen that qualifies as a “monitor” was LCD.