LED to replace HID

jaymasta

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Mar 19, 2007
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Will we ever see LED technology replace HID lighting systems, at least on the small scale, like vehicle headlights, motion lights around residences etc...it seems that most HID lights are huge in size and draw a huge ammount of power and put out a huge ammount of light, if one were to make an LED that could give out the same ammount of light as a say 24w HID flashlight would it be practacle, and or make the smaller HID systems outdated?
 

jrv

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I believe Lexus has already announced that the next generation of their cars will use LED headlights.

LED tri-lights will be bright enough to replace 10w HIDs in about a year. The tradeoff is that the reflector will be a lot trickier and the power supply a lot simpler. LEDs will win in terms of increased durability and instant-on.

Remember that LEDs, as efficient as they are becoming, still produce a lot more heat than light (in terms of output) and since LEDs are sensitive to heat this is a problem competing with larger HIDs.
 

MikeSalt

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I hope Lexus are not going all-LED. LEDs cut through fog like a plastic knife through concrete! I will have to watch out in the fog for the odd Lexus in the ditch. I sure hope they will have incandescent backups for this scenario.
 

yellow

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apples and oranges again :rolleyes:

any light with much spill will blind and not work good in fog,
any light where spill is cut off will work good in fog,
any fog optimated light (think of these projection fog lights) wont be good in no fog - compared to a light with spill
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has nothing to do with leds, but with the construction of the light.


PS: a Led-Multiemitter running on the same power than an automotive HID light will kick *** the HIDs (thats ~ 20 emitters), or imagine one like normal Halogen (35-40 Leds!)
PPS: sure that low output single AA led light has no edge in the fog - ever tried this with an 1 AA incan (if You can find one)? ;)
 
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Ron Schroeder

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They are pretty close now. HID is from 30 Lm/W to 105 Lm/W and white LEDs are about the same. LEDs are improving faster than HID.

Masimum theoretical efficiency is 683 Lm/W for 555nm monochromatic green light with somewhat lower maximums for other colors or white.
 

MikeSalt

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Yes, the optics do contribute to fog-penetration, but the spectral resolution of an LED cannot yet match that of an incandescent. LEDs excite reflective modes within fog, causing glare. With smooth distribution, incandescents do not cause these glare-spikes.

Warm-white LEDs are pretty close, but of course, they have an efficiency disadvantage over cool-white.
 

2xTrinity

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Yes, the optics do contribute to fog-penetration, but the spectral resolution of an LED cannot yet match that of an incandescent. LEDs excite reflective modes within fog, causing glare. With smooth distribution, incandescents do not cause these glare-spikes.

Warm-white LEDs are pretty close, but of course, they have an efficiency disadvantage over cool-white.
I have found the optics have a lot more to do with fog penetration than wavelength, although that does matter (that is why a lot of fog lights have amber filters -- to cut down on blue light that tends to get scattered). While in general LEDs are terrible on fog, I've found TIR optic based lights with little spill do fairly well, as they have little spill. One common trend I have noticed with flashlights is that the ratio of spill to hotspot intensity is usually much much higher for LEDs.

I do strongly believe they should not permit LEDs with a color temperature higher than 4200K due to glare and light scattering concerns (that is the color temperature of legitimate OEM HID lights, also the same as cool white fluorescent). By using emitter arrays with separate optics, it should be possible to have a greater control over light distribution with LEDs than with a single HID point source, and provided color temp is the same, ability to penetrate fog with LEDs should actually be better due to the greater ability to direct the light with optics. Now the more common 6000K LEDs will not do as well though (much higher ratio of blue light emitted).
 

PayBack

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IIRC the water droplets in fog are far too small (or too big, I don't recall that bit) for amber light to have any advantage over white. I was looking into replacing my white fog lights with amber but once you got past the urban myths and fluff the amber had no true advantage.
 
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