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Bloody LED number plate bulbs won't work - doing my nut!

Discussion in 'A3/S3/Sportback (8P Chassis)' started by heeman10, Feb 11, 2011.

  1. klik

    klik Member

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  3. koocuz

    koocuz New Member

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    So I bought a set off Ebay and I wanted to share my findings (bought the first auction listed in original post below):

    [​IMG]


    My findings were not good, and I would not dare put these in my car.

    Original Incandescent bulb: I measured out the current at .34A and using a laser thermometer the hottest part of the bulb measured 220F, keep in mind this is probably the filament, most of the other areas around the bulb were about 180F and after turning the light off I could handle the bulb without burning myself moments later.

    New Ebay LED Bulb: First off the color temperature was great and I had high hopes. It measured out at .2A so less than the original and im guessing it would still throw an error on newer cars. Now comes the scary part. I measured 240F on the heat-sink. The entire light was radiating heat and I could not touch the bulb after shutting it off because it was so hot, the festoon ends were very hot as well. I had it running for about 10 minutes.

    Keep in mind this was in an open garage so the test results would likely be different in a small enclosure. Its no wonder folks who have used these resistive LED's burned up their light enclosures.

    Honestly, this is very disappointing. I wish I could slap a cheap regular LED in the socket that consumes .03A and doesnt get hot at all. Even the factory incandescent's are starting to melt the housings.

    If anyone has any ideas on how to get the nice LED look without destroying your car let me know.

    I was thinking maybe a 3W or 5W "Hyper White" "Xenon" incandescent would work fine. Anyone know where I can find them? Brightness is not the goal for me, just nice white color temperature. Also less heat and energy use should be an added bonus.

    If a Admin wishes to grant me attachment privileges I would be happy to upload photos.

    Thanks



     
  4. koocuz

    koocuz New Member

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    I was also curious about the make up of this little Resistive LED.

    If you look at the photo (identical to mine) you will see two 910 (91 Ohm) resistors next to each other, they are series connected for a total draw of .857W assuming 12.5V and on the other side of the LED's, you will see a small unlabeled component (capacitor ???) and a 151 (150 Ohm) resistor for a total draw of 1.04W. I hope they used at least 1W resistors :)

    I am wondering what the little un-labeled component is. My guess is its a capacitor, I am just curious what purpose it might serve for this circuit? Anyone know?

    I was thinking about removing one side of the circuit, the "2x 910's" or the "Capacitor? and 151". It would seem like the 151 and Capacitor would be ideal to remove since the one resistor has to dissipate over 1W of heat VS. the two 910's sharing .875W dissipation. I just don't want to pull the capacitor side if its there for a reason. My hope is that this will reduce heat enough to use and not piss off the canbus system with the reduced current.

    Thanks
     
    #83 koocuz, Apr 8, 2012
    Last edited: Apr 8, 2012
  5. koocuz

    koocuz New Member

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    Alrighty, I went ahead and removed the 151 resistor and had good results. Brought the total current draw to .12A and the heat down to 145F. With only one license plate light (LED) installed, canbus shuts it off. With both of them installed they work perfect.

    I have a 2006 A3 (no dash screen). No warning lights, good to go! Nice clean LED look, and minimal heat and current draw.

     
  6. Batez10

    Batez10 New Member

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    I've install the number plate lights that have the resistors built in and they work sometimes and then sometimes they don't anyone else had this prob??
     
  7. Matty-m

    Matty-m New Member

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    I've got an 07 plate S3 I've put the genuine Audi a5 led number plate lights that stoke Audi sell and they work fine with no errors hope that helps
     
  8. Boon

    Boon Active Member
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    Even with the canbus cold lamp diagnosis turned off I cannot get any LEDs to work in mine '54 sportback'. Can get one LED and one normal to work but two LEDs throw the error. LEDs give off next to no heat so it must be coming from the resistors as these will produce heat as the effect of resistance..

    anyone thought of installing a regular bulb (or 2) inside the talegate to take the load, with LEDs in the bulb holders?!
     
  9. sliced

    sliced Drive safe, stay alive.

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  10. audiman123

    audiman123 New Member

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    Hi Mike,

    Any ideas on how i can solve my flashing num plate bulbs on my audi a3 2.0 tdi sportback?
    its driving me mad!!.
    Any suggestions more than welcome...

    Thanks...Robert
     

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