Homemade 100W LED Flashlight

This is a simple DC circuit for a 100 Watt LED chip. You can use it e.g. in a flashlight. The maximum brightness will be in the range of 9000-10000 Lumen! You will get all the stuff you need for this build online, e.g. from chinese online shops like banggood.

  • 100W LED chip
  • DC-DC 10-32V To 12-35V adjustable Boost Module
  • 44mm Lens+Reflector Collimator+Fixed Bracket For 20W-100W LED
  • CPU Heatsink with cooling fan
  • 3s Lipo battery
  • On/off switch (not necessary, you can power it on/off by connecting/removing the power source)
  • Voltmeter (not necessary, you can use it to display the remaining power of the lipo battery or the output to the LED)

and of course soldering iron, solder, screw driver, wires and thermal compound.

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Step 1: Install LED

  • solder wires on the + and - pole of the LED
  • put thermal compound on the heatsink
  • put the LED on the heatsink

Step 2: Install Reflector and Lens

  • put the reflector on the LED
  • put the lens on the reflector
  • mount the lens and reflector on the heatsink, I have used cable ties

Step 3: Connect Boost Module

The boost module has + and - inputs and + and - outputs. The power source has to be connected to the input, the LED to the output. The fan of the heatsink has to be connected to the input as the voltage of a 3s lipo is close to 12 Volt. Watch for the correct polarization, connect + to + and - to -! If you use a voltmeter, you can either connect it to the input to monitor the power of the battery or to the output to monitor the voltage to the LED (which helps to find the correct voltage for the LED ). I have connected the voltmeter to the output to tune the voltage to the LED. However, my voltmeter was limited to 30 Volt, so it didn't work out as the LED needs 32-34 Volt.

  • connect the power source (3s Lipo or 12V DC) to the input of the boost module. I have integrated an on/off switch to easily turn the LED on/off.
  • connect the fan of the heatsink to the input
  • connect the LED to the output
  • connect a voltmeter to the input to monitor the battery or to the output to monitor the voltage to the LED

Step 4: Power Up!

  • By connecting to the power source you can turn the LED on. I have used a 3S Lipo but you can use other 12V DC power sources too.
  • To increase or decrease the brightness of the LED, change the output voltage of the boost module. By turning the screw clockwise, the LED should get brighter.
  • The LED chip I have used needs 32-34 Volt to reach is maximum brightness of 9000-10000 lumen. If you use this setup as a flashlight you will light up the night!

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    5 Discussions


    17 days ago

    how hot does this heatsink get?


    3 years ago

    How long will this monstrosity burn? How much heat does the heat sink generate? I fail to see the utility in these 100 watt, blinding devices for real world use. Requiring a heat sink of that size to manage wasted power seems the height of inefficiency. I was under the impression that an Led was valued as an energy saver for lighting not as a small space heater.

    1 reply

    Reply 2 years ago




    3 years ago

    Good installation. The only concern is about using a not current regulated boost unit.

    These led chips working voltage is between 26V to 36V having its optimal working state from 34V to 36V. They reach 100W at 34V at thermal equilibrium if they are right cooled, but as their current rise with temperature you could overpower the chip and burn it easily without an enough power dissipation installation. At 36V they reach up to 120W watts at thermal equilibrium in a same perfect right cooled installation, but you need in these case always a current regulated boost to fix the maximum amps at 3.5A, as they are very sensitive to current overload at this voltage. In any case is always recommended a current regulated boost for a consistent power output


    3 years ago

    Hi! I want to replace a 40w florescent tube light in my kitchen with more or same amount of light as the tube rod from 220v AC. kindly enlighten my way.