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SVOboy 01-05-2009 03:50 PM

DIY LED Headlights
 
A few weeks ago, forum user captainslug posted great DIY instructions for LED headlights on his motorcycle. LED headlights will soon be catching on in the auto world because of their longevity and low power requirements, but they’re not quite there yet, probably because of the cost and the relatively low amount of lumens that [...]Related posts:
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captainslug 01-05-2009 04:51 PM

A few products I didn't know about until after making my first one

OSRAM OSTAR - 200 to 450 lumen 38deg output, being used in in the headlights for the premium edition of the 2009 Cadillac Escalade

Lamina Atlas - Slightly cheaper than the Endor Rebel and it doesn't require a lens.

An array of ten 200-400 lumen LEDs might be suitable for a full size vehicle, but that would get kind of expensive considering they're roughly $20 each.
My lighting requirements were fairly minimal since I was installing the headlight on a moped that already had a fairly weak headlight.
Even the addition of LEDs to a traditional halogen headlight would be beneficial since the color of the LED light makes reading street signs noticeably easier.

Current hurdles of power density will eventually be overcome by the manufactures. Expect newer individual models capable of reaching 600 to 700 lumens within the next year or two.
A few manufacturers already offer PCB array units capable of 800+ lumens @ 23 watts.

Christ 01-05-2009 06:50 PM

I was thinking about using LED's with projector lenses for my low-beams... if I could get like 200-300 feet of blue-ish/white light (below 6000k, probably closer to 5200k, easier to make out shadows at distance) that would be sufficient for a headlight for me.

I think the biggest obstacle would be proper aiming of the beam that would be created by a projector housing vs an open beam housing, and whether to use an actual projector crystal or just make a piece that is concave on the light side and convex on the emission side.

The problem with this is that projector lights don't seem to have very good side views, due to the beam density created by the lens. Maybe a different idea is in order, for that reason alone.

jamesqf 01-06-2009 12:40 AM

Quote:

Originally Posted by captainslug (Post 81687)
Even the addition of LEDs to a traditional halogen headlight would be beneficial since the color of the LED light makes reading street signs noticeably easier.

Humm... I'd noticed this with the LED headlamp (I mean the light's on a headband) I use when biking. Anything reflective - street signs, road striping, cateye reflectors, etc - looks incredibly bright. I'd put it down to the fact that the light source was so close to my eye that I was getting near 100% of the light reflected directly back to me. But if you get the same when the LEDs are in a normal headlight, maybe it does have something to do with the color of the light. I think I remember reading that the actual LED is blue or even UV, and that excites various phospors to give a white spectrum. So maybe excess UV is exciting the reflectors?

almightybmw 01-06-2009 03:59 AM

One thing that I've seen skipped (not saying cptnslug did) is the reflector housing. Getting the light is easy, anyone can make an array of 20 LEDs outputting the 9007 spec of ~1500 lumens at 55 watts (low beam). Setting the pattern properly so its not creating glare for others or yourself... A friend and I created an eight LED array, but we had problems with adequate beam overlap/coverage and range. We didn't want hotspots in our beam pattern. It might have been the LEDs we were using just had poor light angles (can't remember specs). So far I haven't seen DIY setup that can match any of the 900x series light specs for pattern and light output without consuming pretty much the same amount of power.

I'm no light expert, I just spent the last hour reading about candle, ft-lum, lux, and certainly learned a bit. Given what my car/truck outputs with the 9007 bulbs, the area it covers on the ground ignoring reflectivity, I haven't seen a LED that can match the ft-lumens needed for driving. Not even sure what the 9007 spec is measuring or how.

I think I've brutally confuzed myself. hmm. I still want to create a LED headlight using (thinking outloud now) something in the 30W array with a culminator and projector lens. It's okay if I sound silly, I never took optical physics. Maybe I should.

Random: the Audi R8 is 100% LED now. not much detail about the headlights currently, expecting better news in the following month.

captainslug 01-06-2009 05:08 AM

Quote:

Originally Posted by almightybmw (Post 81805)
Random: the Audi R8 is 100% LED now. not much detail about the headlights currently, expecting better news in the following month.

Details on that here: Audi Pioneers All LED headlamp with R8 model - worldcarfans

The low-beam is a set of 3 high-power LEDs angled into a projector lens. The high-beam is a set of 8 high-power LEDs in two reflectors.

order99 01-06-2009 04:06 PM

Several LED projects i've seen end up creating a 'diffuser lens' by the simple expedient of running an ultra-fine sandpaper across the lens and making it slightly opaque. I've also seen similar done with a layer of 'frosted' lens tape.

What I don't know is how well that would work for headlights-would they still illuminate the road properly?

I love those LED lights in the Link-but are they legal in the US yet?

Christ 01-06-2009 04:17 PM

We also know that typical 3-5mm LEDs have the rounded head on them that creates a light focal point. This isn't very conducive to making a single beam of light when using multiple LEDs.

The fix to this is simple - make the top of the LED flat. This will project the light outward and forward, which will allow it to blend more easily with the output from the other LEDs.

Something to consider when making a prototype light, for anyone who will do it.

metroschultz 01-07-2009 12:03 PM

How about focusing the LEDs backward into a parabolic reflector.
Line them on the rim facing the center of the reflector and then use a focusing lens to put the light where you want it.?

Christ 01-07-2009 12:18 PM

I was thinking something like that initially, only using a complete sphere, with reflective coating inside, and only a HID-type lens for the light to come out of at the front, which would fit into a socket, and could easily be aimed/adjusted.

So, it would basically look like an eyeball - only reflective inside, and the HID lens would be the cornea. LOL. Dunno how that would work out though, and I'm not THAT concerned about it to try.


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