working out heat production

Discussion in 'General Electronics Chat' started by ktnch, Jan 25, 2011.

  1. ktnch

    Thread Starter New Member

    Jan 19, 2011
    Hi guys, How do i work out heat produced by an led so i can find a heatsink

    the leds 1700ma max @ 36v max


  2. someonesdad

    Senior Member

    Jul 7, 2009
    Voltage times current is power; thus, 1.7 A times 36 volts gives you the power in watts: 61 watts. That's a lot of power to remove from an LED -- are you sure you have your numbers right?
  3. ktnch

    Thread Starter New Member

    Jan 19, 2011
    Oh yes its a big bugga lol around 30mm square going to get 5 or 6 of them for a big reef tank

    Trying to find some big heatsinks
  4. kubeek

    AAC Fanatic!

    Sep 20, 2005
    CPU heatsiks are quite good if you can get them.
  5. Jaguarjoe

    Active Member

    Apr 7, 2010
    All Electronics has CPU heat sinks real cheap.
  6. marshallf3

    Well-Known Member

    Jul 26, 2010
    Even the old mom & pop PC stores may have a pile of small heat sinks with fans that they can't sell since they're now to small for the current processors, always worth a call. 3 fans in seres = 36V

    An alternate is to use those aluminum door thresholds from a home improvement stores but watch their temperature.
  7. tracecom

    AAC Fanatic!

    Apr 16, 2010
    It would be "cool" if you could use the water in the tank to cool the led's and the heat from the led's to heat the tank. If the led's were mounted to a piece of metal that dipped in the water...OK, I don't know anything about reef tanks; it just seemed like a green idea. :)
  8. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    I doubt that is the correct specs for the LED in this case.
    But you need the current level that you will be supplying to the LEDs x the forward voltage of the LED.
    Assuming natural convection..
    Example.. Cree XR-E with a forward voltage of 3V run at 700mA is .7 x 3V=2.31 Watts
    Then you need to calculate the thermal resistance from LED junction to air (must include all interfaces..ex..LED junction to circuit board to thermal compound to heat sink to air.

    And cooling/heating via the reef tank water has been done and is a decent idea ( I like it anyways).. However finding the proper materials that will not contaminate/leach into your tank killing the inhabitants nor corrode when exposed to salt water is a different story (well from a cost standpoint anyways). Titanium,etc.. ain't cheap
  9. timrobbins

    Active Member

    Aug 29, 2009
    Do you have tropical fish ;-)
  10. bertus


    Apr 5, 2008
  11. ktnch

    Thread Starter New Member

    Jan 19, 2011
    Was thinking of water cooling but all metal and alloy is out of the question as its a marine tank could use the flex pipe

    Its a marine tank 5ftx3ftx3ft see attached

    Was running 2 x 150w halide bulbs but the magnetic ballasts were 1.8amp each @ 240v so was pulling 864 watts for two 150w bulbs didnt beleive it so got a wattmeter and was just about spot on, So bought an elec halide ballast and that pulls 0.7 amp each 336 watts much better

    Going to order 6 of these heatsinks as i am getting 6 of the high power leds also putting 10 x 10w blue leds on the same heatsinks

    This is the led just for the none believers of the current and voltage

    50W 10000K High Power 4000LM LED Panel for Aquarium


    * Color Temperature: 10000K cool white
    * LED chips: Epileds EP-B3838B-A3 38*38mil
    * DC Forward Voltage (VF): 32-36V DC
    * DC Forward Current (IF): 1700mA Max
    * Viewing Angle: 120 Degree
    * Intensity Luminous (Iv): 4000LM
    * Life span 30000 hours guarantee

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    Last edited: Jan 27, 2011