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Thread: Auxiliary Lights.....Hot Hot Hot

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    143439 bobr9's Avatar
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    Auxiliary Lights.....Hot Hot Hot

    Recently installed a set of Martin Fabrication aux lights on my RT. Bought the optional LED bulbs and went with those first. Noticed the left side light out the other day. Take apart and positive lead separated from bulb. Replaced with a halogen bulb. After three hour ride yesterday got off bike and noticed left side light angled down so reached down and grabbed light to angle back up and almost burned my hand it was so hot. Is this normal temp for halogen (45 w) bulb?

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    No. They must have cooled off a bit because they are normally hot enough to burn your hand instantly. You got lucky, punk.

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    yeah 45W doesn't sound like much but with a small enclosure it will build up

    I don't have these but from the google search they appear to be well made and designed for the bulb.
    The aluminum body should dissipate enough heat to keep it from being a problem.

    Just let it cool down a bit before adjusting.

    I wouldn't bother with LED "bulbs" - the entire light really needs to be designed around the way LEDs throw out light.
    Which is to say in a narrow beam.

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    143439 bobr9's Avatar
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    Quote Originally Posted by scott.lambert View Post

    I wouldn't bother with LED "bulbs" - the entire light really needs to be designed around the way LEDs throw out light.
    Which is to say in a narrow beam.
    Are you saying that the LED bulbs will not work as well as the halogens because the casing was not specifically designed for the LED's?

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    Quote Originally Posted by bobr9 View Post
    Are you saying that the LED bulbs will not work as well as the halogens because the casing was not specifically designed for the LED's?
    I guess so, yes. I would stress "as well" and for the specific application of a driving light.

    The main reason they won't work as well is they're just not putting out as much light - in any direction.
    If the LED "bulb" were putting out the same amount of light as the halogen bulb it would dissipate 45W too, getting just as hot.

    Now, LEDs are pretty amazing and they can put out a bunch of light these days.
    I'm just saying that LEDs generally put out light in a certain direction. Typically a 15 degree cone of light.
    You have to design around that.

    The halogen driving light reflector and lens are designed around the light coming from a point source (the filament) and going out in a spherical pattern. An LED array is not going to be focused correctly, further dimming the apparent brightness.

    For conspicuity it would be better to have the LEDs all facing the same direction, arranged in a flat panel. This would be an excellent application for LEDs.

    For a driving light you're really interested in how much light is reflecting back off of things down the road, so you want to bring as much power to bear as possible.

    I have the same opinion for signal lamps - brake and turn signals - they are designed for a light bulb, on the assumption that light is going to leave the bulb going in all directions. And if you could cram enough LEDs into the same space as the light bulb making the same amount of light, it would draw the same amount of power and it would get just as hot.

    {edit: this is a bit arm-wavey - LEDs are more efficient, just not miraculous.}
    Last edited by scott.lambert; 06-20-2013 at 03:23 PM. Reason: caveat

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    143439 bobr9's Avatar
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    OK, I understand. Thanks for the post...

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