100w LED Flashlight





Introduction: 100w LED Flashlight

About: Maker from USA. Follow me to stay up to date on my projects and possible kickstarters! Business email: constructed@mail.com

It this tutorial Ill be teaching you how to build an extremely powerful flashlight!

Its very easy to make, and extremely cheap as well!

This flashlight has many uses, Pure white light means its great for filming. Or you could use it as a motion activated spotlight in your backyard! The possibilities are endless!

Step 1: Gather Supplies!

You will need

Metal box (used as a heatsink)

12v battery

100w LED

Thermal paste

12-35v step up transformer

Thats it!

You will also need assorted tools

Step 2: Connect Some Wires!

Add connections to the 12v battery and wire it directly into the transformer

This is not permanent because we will be adding a switch here later

Step 3: Step Up Voltage

Using a multimeter measure the voltage of the transformer.

Use a small screwdriver to slowly turn the voltage up to about 34 volts

Step 4: Add a Switch

Now cut one of the wires going into the transformer and add in a switch

You will also need to use a dremel to cut a square into the metal tool case and feed the switch through there.

Step 5: Scratch Away Paint

Using a dremel, scratch away the paint until you have a big square that can fit your LED

This is alot harder than it looks and took about an hour.

Step 6: Final Touches

Now add some thermal paste and mount the LED directly onto the metal parts, being sure that the positive and negative tabs dont touch.

Then solder on wires from the transformers output onto the correlating LED tabs (+ and +) (- and -)

Step 7: You're Done!

You're done! You now have an extremly bright flashlight!

Thanks for reading my instructable!



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    26 Discussions

    I can't watch the video

    nice, can you help me here



    2 years ago

    Have a look at < >. The presenter uses a variable power supply to show that many of the LEDs are actually defective!


    2 years ago

    I have a bit of a fetish for LEDs and LED lasers, especially since living next to China, in VietNam, where we buy LEDs by weight and not by the count - at least up to 3W units.

    My LEDs are from an importer which means my supplies are 'loose' - and one of the things I buy are circular alumin(i)um PCBs. The conductive tracks are insulated from the alumin(i)um by a carrier film.

    Where the LEDs are situated are naked circles of exposed alumin(i)um so that heat transfer, using heat conductive paste, is optimised.

    The LEDs are of the builders choice, the only constraint being the PCB, but I use 3W units connected in series / parallel which is the choice of the professional illumination companies. They never use a single high-power LED. The series / parallel configuration allows the LEDs to be driven at optimum levels from a 12V power source. And don't forget a breaker or fuse in the power feed.

    Power consumption is minimised by use of PWM based on a 555-timer chips and a handful of components. The frequency and waveform ratio can be preset or brought out as controls.

    In a couple of my larger 'flashlights' I have mounted a single LED laser - green is best for temporarily blinding people - under a separate control. I use stainless steel Grade 302 for my cases.

    I use LEDs on my motorcycles for daylight running lights, the headlight, etc. Bus drivers, who tend not to dip their headlights for motorcycles, get respect when I crank all the LEDs up to brightest.

    It would be less confusing to call the DC-DC converter by its correct name instead of calling it a transformer (which is an AC-only device).

    2 replies

    I don't mean to take away from your main point, because you are right, but you CAN use a transformer for some special-case DC work.

    Awesome! At first glance I thought it was a 20W in a flashlight body, but looking closer, it's much bigger than I thought!

    thanks, it is 2.5ft long. the tube helps the fan keep things cool.

    well i dont have super specifics... but its some pvc pipe. i think 3" with some 12v lead acid batteries inside, 4 i think, around 30amps total.

    a cpu cooler with the 100w led mounted to it, and a stepup circuit to feed the led.

    the cpu fan gets 12v, the led gets 36v.

    I would add a potentiometer(PWM) because 100watts can be really bright...

    I woud also be nice if you made It have 2 LED's that one was warm and one was cool so the spectum would have a more daylight color like this:


    (If is doesn't bring you exactly to the project you have to click on the first link)

    The last thing I'm not sure about is:
    You chose a 12v 7amp lead acid battery, 12X7= 84, the battery can only give 84 watts so the LED can't produce 100 watts of light when only 84 are supplied... Correct me if I'm wrong...

    1 reply

    His battery was a 7AH battery - that is, amp-hour. While it's not the best choice, it should put out 114 watts (12V @ 9.5A) to the voltage regulator, which gets converted to about 100W at 34V, plus heat.

    Idea itself is umm... not really original, however, I would made some upgrades. If it is really 100W LED than it need something more than thin metal wall of the box to radiate the heat. Also you wasted half syringe of thermal compound, you should make the contact surface mirror finish, next put small drop of thermal paste, and then make thin layer with credit card or something. In this case less is more. I reccomend you placing heatsink inside the box where the LED is. Keep up good work ;)

    2 replies

    Yeah, kondzio29 is spot-on. You used about 100x too much thermal grease. Watch a video on applying thermal grease- you want as thin a layer as possible, as it's not as conductive as the metal itself. A pea sized dollop smoothed out with a razor blade should be more than enough for a heat spreader that size.

    You also need a heatsink with enough mass to efficiently wick away all the heat your LED is producing or you'll "release the magic smoke". You can find a chunky one from a scrapped desktop computer. Look up the TDP of the processor you want to use the heatsink from before using it though, as you want a heatsink intended for a processor with a TDP of at least 95W.

    Why didn't you just mask off the surface and use some stripper on the tool box if you wanted to remove the paint? They make gel paint remover that would have taken 15 minutes tops, with no drips.

    Are you using a CC-CV step-up regulator? You have to control current and voltage to get the most out of the LED.

    How much does it output in Lumens ?

    My 7 LED FL spawns about 8100 while powered by 3 Li-Ion cells.

    What's the exact consumption of that LED and what series is it ?

    You have to use a current regulated switching power supply. They are specific for power LEDs

    You have to use a current regulated switching power supply. They are specific for power LEDs