3 Watt LED in Puddle lamps!!!!

[Bill Kemp]

Shortstack, I see you used a heat sinc. What is it for / what does it do?
I remember that some guys have come close to melting their lenses with the larger (912?) regular bulbs. Is heat something to worry about?
I assume you could leave them on all night in -40 degrees but what about your week of summer?

 

[shortstack]

the led and the regulator have to have heat sink or they will burn up, then you cant use them any more. i can step the mA down a little, cause that part does get pretty warm, it was -15 and mine gets hot to the touch, so it cracked the lens portion of the puddle lamp (still intact big a little crack), but the actual light that comes out of the led doesn't put out any heat. not a big deal just puts out a little less light, but still way brighter then the 10mm led version, i could try bigger heatsink but i dont think much more will fit in there.

 

[jad2411]

Will those heat sinks from older PC processors work? I have a couple in my junk box, if so I can go to Radio Shack and buy the rest of the parts right? I'd only do 2 so buying in bulk at ebay wouldn't work for me...

 

[shortstack]

they dont sell those resistors at radio shack though, yes cpu heat sink would work.

note" it was mostly the regulator that producing the heat, not so much the led

 

[jad2411]

oh ok, are these the same thing?
http://cgi.ebay.com/3W-LED-Driver-f...5|66:1|65:12|39:1|240:1318|301:1|293:1|294:25

 

[shortstack]

yes that will work

 

[thunderhorse]

Hummm
How about a remote heat sink? Like in the door or under the hood?

 

[shortstack]

not all metal transfers heat the same, aluminum is one of the better ones. not sure if i understand your question either

 

[shortstack]

just made some with the Cree p4's, i ran these ones at 350mA where as the others were 700mA to help with the heat problem. the cree is actually 2X as efficient as the pro light (ones used before) although the cree puts out about 20 lumens less with half the watts it puts out more light.
NOTE: i wouldn't run this for more then 10 min in fear it might melt the housing.

 

[ExplorerXLT95]

just made some with the Cree p4's, i ran these ones at 350mA where as the others were 700mA to help with the heat problem. the cree is actually 2X as efficient as the pro light (ones used before) although the cree puts out about 20 lumens less with half the watts it puts out more light.
NOTE: i wouldn't run this for more then 10 min in fear it might melt the housing.

Any pics of the new Cree p4s installed in the stock puddle light locations?

 

[PedroDaGr8]

So i got some 3 watt leds (110 lumens @ 700mA) so i got a LM317 and a 1.8 ohm 1W resistor. now the resistor will change depending on how many leds you want to hook up and what mA you want to give them

Two things about this design:

First off, the idea I underlined above, be careful how you hook up said LEDs. Do NOT under any circumstances hook them up in parallel. Using a constant current driver for more than one LED in parallel is a REALLY bad idea. A constant current driver circuit works to keep the current constant not the voltage (who would have thought right ). Due to the nature of LED's one LED will have slightly less resistance than the other. This means that you can end up in a situation where one LED pulls more of the current than the other. As it heats up due to the increased current load, the resistance drops. You enter what is known as thermal runaway. Eventually the led dies, which then overloads the other led, now both are dead.

Two, I don't see a decoupling capacitor on there. You really should ahve one, especially in an automotive environment. Decoupling capacitors help smooth out voltage spikes and more importantly help prevent situations that can cause the regulator to oscillate (where the voltage or current will cycle above and below your target voltage). It sounds very technical, all it is usually is a 20V 1 to 10uF capacitor with the positive leg of the capacitor connected to your line in and the negative leg of the capacitor connected to ground.

Third, remember when you are wiring stuff in series you need 3V of overhead. So you couldn't say make the output 12V, because at most your cars voltage is at 14.5 which means the highest you can EVER get the voltage output is 11.5, though typically much lower since most cars run at 12.5-12.8ish. There ARE what are called low drop out regulators but they tend to be Constant Voltage. They only require 0.5V of overhead, which means you COULD plan for a 12V output. This is important because difference in voltage between input and output is let off as heat.

 

[Jtorsey91]

do you think that you could post a video of you doing this and installing it into the side mirrors? thanks

 

[WhiteLimited]

do you think that you could post a video of you doing this and installing it into the side mirrors? thanks

Its really not hard to put them in your mirrors at all. Shorty does not know that Explorer anymore he sold it. But its only two screws I think to take the lights out.

 

[energie]

wouldnt you need a 3w resistor for a 3w led instead of a 1w resistor.

 

[PedroDaGr8]

Nope that is a pulldown resistor for the sense wire. It shouldn't take anywhere near the full 3W of current.

THat being said, it appears he either has a derivant LM317 or hooked it up backwards

Pin 1: Adj aka Sense or SW
Pin 2: Vout
Pin 3: Vin

 

[techieman33]

I wouldn't take to much info from this thread, the 2 he sold me blew up in pretty short order, and then he never responded to my PM's about it.

 

[WhiteLimited]

I wouldn't take to much info from this thread, the 2 he sold me blew up in pretty short order, and then he never responded to my PM's about it.

Wow, I am sorry to hear about that. He made me LEDs for my puddle lights over a year ago and there working great. I know he is never on this forum anymore because he sold his truck to his mother in-law. Next time I call Randy or see him I will ask him about that.

 

[Jtorsey91]

Wow, I am sorry to hear about that. He made me LEDs for my puddle lights over a year ago and there working great. I know he is never on this forum anymore because he sold his truck to his mother in-law. Next time I call Randy or see him I will ask him about that.

could you ask him if he would still make them for people because i would love for him to make me a set. thanks

 

[damagexinc]

Atleast now if you drop something when getting into the car you'll be able to find it. Atleast we'd hope so

 

[damagexinc]

If your gonna use a cpu heatsink couldn't you also attach a cpu fan to it?