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Thread: Overheating and smoking resistor! Help!

  1. #1

    Default Overheating and smoking resistor! Help!

    This is my 10th build, 4th Nano biscotti and this the first time this has happened.

    I have a tri-Cree RB,RB,W, Nano biscotti, and 18650 battery

    Wiring is per usual: positive battery to charge port, board and + of LED
    L1 on board to .5 ohm 3W then on to the - pad of both RB of the tri-cree
    L2 on board to a 1 ohm 2W then to the - pad of the W

    Board boots, activate and in 3 seconds the .5 ohm resistor is blazing hot and smoking.

    Any thoughts? I am at a complete loss as to what’s going on.

  2. #2

    Default

    It’s one resistor per LED. You’ll have to obviously replace the resistor.
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  3. #3

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    Quote Originally Posted by Forgetful Jedi Knight View Post
    It’s one resistor per LED. You’ll have to obviously replace the resistor.
    Thanks for the info. I am curious in regards to the NB since there is only one LED driver pad driving 2 of the 3 tri cree’s, why would I need 2 resistors on one wire? When I wire up the prizm it makes sense because it each LED has its own driver.

  4. #4

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    I am far from an expert, but a question I would ask is if L1 can even handle the current required for two LEDs (I do not know this answer). Assuming L1 can handle the current for two LEDs, your resistor may be undersized as that resistor would be appropriate for one LED.

    The tri-cree installs I have seen have one LED per channel, with a PEX (power extender) to utilize L3, and separate resistors for each LED.
    Last edited by kazibole; 07-20-2019 at 01:04 PM.

  5. #5

    Default

    Quote Originally Posted by kazibole View Post
    I am far from an expert, but a question I would ask is if L1 can even handle the current required for two LEDs (I do not know this answer). Assuming L1 can handle the current for two LEDs, your resistor may be undersized as that resistor would be appropriate for one LED.

    The tri-cree installs I have seen have one LED per channel, with a PEX (power extender) to utilize L3, and separate resistors for each LED.
    I have already done this type of install with BBW tri Cree, this is the first time doing RB RB W. That is the only difference.

  6. #6

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    The resistor should be able to handle that current load. It sounds like something else is going on, it could be that your + and - are bridged on your LED and your LED is seeing full current from the battery. In any case, my bet is you are shorting out somewhere.

    It is always ideal to limit each LED separately, and in this case the resistor should only really need to be 1/2W each. That 3W job isn't necessary, and actually 2 1/2W resistors would take up less space, even two 1W resistors would be more manageable.

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