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LED DRL Temperature Inside the Headlight

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  • LED DRL Temperature Inside the Headlight

    I have the clear acrylic rod inside the headlight with 1 LED on each end. What kind of temps can I expect to see or is there any recommended temp I should try to keep them at?

    LED: XHP35

    BOARD: 20mm Copper DTP Star

    HEAT SINK: Aluminum

    DRIVER: BuckPuck DC 700ma with dimming trim pot

    Each LED will have it own BuckPuck driver. The headlights will not be on the same time as the DRL's.

  • #2
    Typically speaking, LED light source in an automotive headlamp are designed to handle 60C of ambient temp

    What you need to worry about is heatsink thermal resistance. what kind of heatsink spec you have in mind?
    XHP35 has a thermal resistance of 1.8C/W Each heatsink has separate heatsink? Or 2 LEDs are layout close to each other onto one heatsink?

    BTW, if you use Flexblock 700mA, you can run 2 x XHP35 It has boost logic built-in, pretty efficient too.


    • #3
      Thanks for the reply. Each LED has it's own heat sink and will not be close to each other. The heat sinks are 20mm x 20mm round finned Aluminum mounted directly to the star board. I have the headlight open and on a power supply. With the LED mounted on the acrylic rod after 1 hour temps were around 50C.

      I only used a BuckPuck driver because that's what LEDsupply recommended. I will look into the Flexblock. If I run them at 350mA would that help reduce the temp's?


      • #4
        20mm x 20mm is very small for handling 700mA if you are planning to run for constant ON use. send me drawing and I can run a thermal simulation to see what kind of heatsink you will need.

        Where did you measure the temperature? Junction temperature is not something you can measure directly, but rounding area, you can estimate if LED is handling well or not.

        Do you have link of LED you got?

        350mA drive of course will reduce heat generation, but will that serves your application needs?