# Which LED's and drivers should I use to convert this headlight?



## BennyLava (Dec 2, 2009)

I am looking to convert my 1987 Chevy Silverado's headlights to LED. I know this is a challenge to say the least, but from what I have seen some of you guys do on here with the flashlights, it should not be too hard. Seeing as how they don't need to be anywhere near as bright as some of the flashlights I have seen yall post up lol. Anyway, here are the lights. Pretty basic shape.

http://cgi.ebay.com/ebaymotors/HEAD...ptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

They are 6"X8" rectangular. So what do yall think? Perhaps a cluster of 8 or 10 of these? (300 Lumens output)

http://www.cree.com/products/xlamp_xpg.asp

Or maybe a cluster of 6 of the more powerful P7's? (900 lumens potential output)

http://www.dealextreme.com/details.dx/sku.12721

I don't think it would be all that hard to wire up. Just the proper driver/resistor in place to slim that 12v way down and get the proper juice fed to the LEDs. The only real problem I can think of, would be blinding oncoming traffic. But I think I can rig up a projector lens out of an Acura headlight (that I get out of the junkyard or something) to focus the beam downwards a little. I know there is some bias/nay saying against LED's as vehicle headlights, but the new cadillacs and audi's seem to be doing fine with them. And if they can do it, I can do it. Thoughts, opinions?


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## fyrstormer (Dec 3, 2009)

Modifying your headlights is illegal. Just so you know.


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## TorchBoy (Dec 3, 2009)

*Re: Which LEDs and drivers should I use to convert this headlight?*



BennyLava said:


> The only real problem I can think of, would be blinding oncoming traffic.





fyrstormer said:


> Modifying your headlights is illegal. Just so you know.


You know, these two issues might just be related. 



BennyLava said:


> ... the new cadillacs and audi's seem to be doing fine with them. And if they can do it, I can do it. Thoughts, opinions?


I think they have probably spent tens of thousands of dollars in getting regulatory approval for their LED headlights. But if they can do it, you can do it.

And dude! "Y'all" has an apostrophe!


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## BennyLava (Dec 4, 2009)

Yeah, I'm actually just lazy. Thats why I said "yall" instead of "you all." But uh, if it's illegal, how come it's legal to sell HID kits? (That they sell for pretty much any vehicle headlight that you can name.) That would also be "modifying" your headlights. And tons of people do _that_. Also I wouldn't be blinding oncoming traffic if I focused the beam downward where it needed to be, correct? Just like HID's. Feel free to correct me if I am wrong on any of this, it's just how it occurs to me. Come on, guys. Let's here some positive ideas, and not just a bunch of nay saying.


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## John_Galt (Dec 7, 2009)

Well, modifying your headlights with HID kits is illegal, but apparently it's not illegal to sell these kits.

Two problems you are going to run into: 1) focusing. I would suggest getting a set of HID projector headlight from a wrecked BMW/Mercedes/whatever. These should have the appropriate cut-off beam pattern. But they'll probably only focus right if you use one LED, so using multiple LED's isn't really doable. 2) Heatsinking. LED's need the heat they produce to be removed from them very quickly, to keep the junction temperature from damaging the LED. To have adequate output (1500 + lumens) you are going to look at a high output, and not necessarily very efficient LED. Take a look at the SST 50 and 90 LED's. 

To heatsink these, you are going to need two things: 1) thermal mass (think a big heavy chunk of aluminum, copper, brass, but not steel that weighs several pounds. This heavy mass will be able to absorb heat the light produces, for situations where the other form of cooling isn't working very efficiently, such as sitting at a stop sign, in traffic, etc.) and 2) fins. Remember, you need to remove the heat from the heatsink, not just absorb it, so surface area is crucial. Fins will be needed to capture the rush of moving air and dissipate the heat. Unfortunately, you are not going to have a lot of air movement by your headlamps, so you will need some way to transfer the heat from the thermal mass to the fins in another area of the front. If the car has any opening in the bumper for factory foglights, etc, these would be a good location. This will probably be most easily done by using heat-pipes (google it).

As for the driver, you are going to need a single mode driver with an input range of 12-15/16 volts, and thermal protection for the LED (basically a small sensor placed on the LED which tells the driver to reduce current to the LED to keep it from getting too hot.

Hope this helps.


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