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Question: heat from HID vs Halogen

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  • #16
    Originally posted by gearbox View Post
    most hid projector ive measured never gets above 180F at the bowl. most halogen bowl gets to at least 250F.
    When and how did you measure that? because my HID reflector bowl could withstand 180 C but id burned. So is must have been hotter. And as posted earlier, Osram tech dept. confirmed this.

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    • #17
      Originally posted by DJLeonardo View Post
      I've been thinking why this is the case now that we know HID bulbs run much hotter.
      I think it's because the halogen bulb radiates directly to the plastic headlamp cover, there is nothing in between. Whereas the HID bulb has a lens in front of it so there will be almost no radiating heat from the bulb itself, just form the lens that absorbs the part of the heat generated.

      However, I happen to drive a Volvo as a daily (leasing car) and that car has projector headlamps with halogen bulbs inside (!) they also do melt the ice off the unit I discoverd recently... there goes my theory
      That is because halogen/incandescent sources emit significantly more infrared light. This is the same reason why filament bulb taillights do not build snow on them as quickly as LED ones. (IR emitted vs no IR emitted)

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      • #18
        Yes that is a good point indeed, did not think of that...

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        • #19
          i have the temp data in a different thread im still trying to find. bowl temps i just measured with IR thermometer which ive found to be fairly accurate. the thing you have to realize is proximity plays a big role in how stuff burns. even if the filament puts out a certain amount of heat, very rarely will it be distributed and vented evenly. it can form "hotspots" on the bowl (areas that are much hotter than you would expect). while the overall temps of the hid projector can be 100-180F, some parts i have seen get to around 200F. this is all surface temp too. inside the projector can trap heat much better and raise temps further. there are also different types of chrome finishes and usually material ratings are not very accurate. some of the highest temps listed on paint for example signify "pulse" heat resistance and not continuous use. your chrome coating is likely the same. anything over 250F and you are getting into engine manifold temps which can easily burn most types of coatings. but i wonder, have any of you guys heard about jet-hot.com coatings for exhaust parts? i have some on my header and even several yrs later it still has most of its original luster and shine. there is slight bit of yellowing. but this could be an option to chrome projector bowls that need serious heat resistance.

          the data i got from old textbooks or white papers. its very hard to find stuff like this online where typing in hid bulb temp gives a million links to stupid hid kits. just wish i could find the data in that old thread.

          finally found the halogen info. if you think these numbers are too high, remember that the filament is just a piece of metal wire with electrical charge moving thru it. you have to heat it up considerably before it starts to emit light (think about those large burner rods in your toaster oven that turn dull red when you turn it to high heat, its the same thing but with much more current and much smaller filament).

          temp of the glowing filament = 5,480 F
          temp of the bulb glass = 1,340 F

          for hid bulbs, which basically use an arc discharge.

          temp of the plasma arc = 10,800 F

          ofcourse plasma will be hotter than a glowing metal wire. but the temp is not really important so long as proximity of the light source to the projector is great enough. if you put the hid arc too close to the edge, it will burn chrome in no time. if you put it at a safe distance, it will not really cause damage since there is not much infrared being produced. the spectra of halogen and hid is so different, you really cannot compare the two at all. they are completely different in every possible way aside from the fact that they both "produce light of some kind." but i guess to answer the question, hid core is 2x hotter than halogen. its really not important for any other reason except maybe impressing your friends lol. as far as whats important, heat radiation, halogen wins hands down due to the infrared. when you tell people what kind of headlights you have, isnt it better to have plasma instead of glowing wire?
          Last edited by gearbox; December 14th, 2010, 07:35 PM.

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