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I discovered that due to a lucky co-incidence of voltage and internal resistance, a 100W LED can be connected directly across the terminals of two 18V Nickel Cadmium power tool batteries. And that means you can build a 100 Watt (7,500 Lumens) flashlight for less than $10 (not including batteries).
Note: Don't try this with other battery types - you'll almost certainly fry the LED!

By Julian

Youtuber, shed dweller, solar charge controller aficionado

13 thoughts on “Monster 7,500 lumens 100w led flashlight for under $10”
  1. Avataaar/Circle Created with python_avatars Nishit Er says:

    Julian i have one request, can you guide me diy fast blinking circuit for these high power 100W leds? I am not able to find anything on topic on google.

  2. Avataaar/Circle Created with python_avatars Nishit Er says:

    Back then after watching your video i made and got this led fitted on my car hood with remote switch…it was death warrant for other drivers 😂😂😂 i removed later lol

  3. Avataaar/Circle Created with python_avatars Clacktronics says:

    Its not so much to do with the voltage as the ESR of the CR2032, that's why you can also put a red or yellow LED with a 2V Vf and it still works.

  4. Avataaar/Circle Created with python_avatars Magma Boy says:

    cant you just use a 12v driver??

  5. Avataaar/Circle Created with python_avatars Roger Bühler says:

    Hi Julia, I just wonder what would be the cheapest way to power this LED from mains.
    Is there a cheap driver for such purpose?

  6. Avataaar/Circle Created with python_avatars Antonis Chatzianestiadis says:

    Simple means the best …

  7. Avataaar/Circle Created with python_avatars yuvan m says:

    Is that 100w
    Then it is not 7500
    Our humanitys latest tech is 640l/w
    Cheap retail led max is around 430l/w
    And that to possible by 3020 led strip not single cob

  8. Avataaar/Circle Created with python_avatars jbalazer says:

    Forty volts from your left hand to your right hand could be dangerous.

  9. Avataaar/Circle Created with python_avatars David C says:

    hook it up to the mains on a variac until it pops

  10. Avataaar/Circle Created with python_avatars ch2o2 says:

    this measly heat sink is far from dissipating the heat generated by a 100W LED, but it is ideally suited to help kill the LED within 20-30 seconds. Regardless of this, it doesn't make sense to me not to simply use a trivial power supply (with a boost-up module if you like) instead of these two lousy, misappropriated battery packs to power the LED. It would also be advisable to check the current consumption during operation .. in your case, however, the direct temperature measurement directly on the LED would be the best way to save the life of the LED in time 😉

  11. Avataaar/Circle Created with python_avatars vachanpal prabhakar says:

    This is waste cost of this led is a2
    h

  12. Avataaar/Circle Created with python_avatars Spaghetti God says:

    They sold light bulb made from that 100w led for 100 bucks

  13. Avataaar/Circle Created with python_avatars LinuxDebugger says:

    What's the green board in the background called?

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