LED's In Exterior Car Lights

Satanofall

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LED\'s In Exterior Car Lights

<font color="red">I'm working on a project of replacing each of my front directionals with 5 LEDs. I'm not sure which rating of resistor I should use though. Does anyone know or have a way I can figure it out? <font color="red"> </font>
 

James S

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Re: LED\'s In Exterior Car Lights

have you decided that 5 LED's are enough? There are regulations about how bright those things have to be I think and 5 little 5mm LED's dont' sound to me like they will be bright enough. However 2 amber luxeon LED's might do it. I've read accounts of other people using those.

to calculate resisters, there are plenty of resister calculators on the web. My personal favorite is at

http://linear1.org/ckts/led.php

There are problems with just using a resister in a car though. When your battery is charging the voltage may be as high as 14v and it may sink quite a bit under 12v when running a lot of accessories. Just having a resister can't compensate for that and your flashers might be too dim sometimes and in danger of overheating others. So a current regulated powersupply would be a very good idea. especially if you go with the larger Luxeon or other big LED's.

Finally, the last problem is that your blinker probably won't blink with just the load of the LEd's on it. even in new high tech cars these are still often heat strip switches and won't work with such a small load. So you may have to replace your blinker thing under the dash with a no load version

So there is lots of research to do around here to get it right /ubbthreads/images/graemlins/smile.gif I really would not recommend that you just wire some LED's up with a resister and expect it to just work...
 

BobVA

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Re: LED\'s In Exterior Car Lights

...and car wiring can be EXTREMELY odd. They will do all sorts of stuff to save a ten cent piece of wire.

For example, the wiring may presume that the bulb can conduct current both directions (my motorcycle was wired like this). If one side of the bulb is grounded, you're probably ok in this regard, but there's always something. (Another example is the "bulb out" sensing systems that expect some particular characteristics....)
 

Blackbeagle

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Re: LED\'s In Exterior Car Lights

Federal law regulates exterior lighting according to the DOT regulations. Take a look at the reflectors on your car, the bulbs you buy at the store and they'll usually have some small print saying DOT certified. If you swap out lights and get into an accident, the other driver can say that the change in your lights contributed to the accident - even if it was totally his fault. You'd lack a legal leg to stand on. That and when it comes time to safety check, again, you could get nailed. This is one project I'd definitely vote against. Adding on interior lights is one thing, exterior... way spooky.
 

Hallis

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Re: LED\'s In Exterior Car Lights

[ QUOTE ]
Blackbeagle said:
Federal law regulates exterior lighting according to the DOT regulations. Take a look at the reflectors on your car, the bulbs you buy at the store and they'll usually have some small print saying DOT certified. If you swap out lights and get into an accident, the other driver can say that the change in your lights contributed to the accident - even if it was totally his fault. You'd lack a legal leg to stand on. That and when it comes time to safety check, again, you could get nailed. This is one project I'd definitely vote against. Adding on interior lights is one thing, exterior... way spooky.

[/ QUOTE ]

I wouldnt worry too much about that, but, you could always take the LED package out of the 3'rd brake light on a lot of the newer cars and use that. Those must be DOT certified /ubbthreads/images/graemlins/wink.gif

Shane
 

rwolff

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Re: LED\'s In Exterior Car Lights

[ QUOTE ]

you could always take the LED package out of the 3'rd brake light on a lot of the newer cars and use that. Those must be DOT certified


[/ QUOTE ]

NO!. The certification is for the complete assembly (light "engine", reflector, lens), so if you use the light "engine" in a different environment it's no longer certified.

The bigger problem is he wanted to do the front turn signals. I don't know about other jurisdictions, but in Canada the 3rd brake light is red (and would therefore use red LEDs), while it's forbidden for non-emergency vehicles to have red lights showing toward the front of the vehicle. By going the route you suggested, he wouldn't just have a "doesn't do what it's supposed to" issue - he'd have a "does what it's not supposed to" issue.

For anyone serious about doing LED turn signals despite the legal issues, the best source would probably be LED clearance lights (as used on trucks) - they're available in amber (typical colour for front signals), so all that would be needed is to rip out the "guts". I wouldn't settle for a 5-diode unit - go "whole hog" for a 12 diode unit. "Hot wire" clearance lights generally use a type 194 (small wedge-base) bulb, so if your turn signals use a different bulb I'd advise checking the current drain of a 194 and of your bulb, and using the "guts" of 1 clearance light for each 194 worth of drain that your turn signal bulbs use (round up to the nearest whole bulb). This is the source I'm planning on using for a (back-burner) homebrew turn signal and tail light setup - but it's for a bicycle, where there are no standards that have to be met.
 

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