10W LED Flashlight Retrofit!




About: I am a sound designer who's studied computer game development, run my own sound design business and like to build thing in my spare time.

Hi everyone! Today I'm building a 10W flashlight retrofitted into an old lantern style lamp.


Step 1: Parts

Parts I used:

10W LED. I used the 3x3 style one since it requires less voltage.

10W LED driver. I used one like this ( Ebay )

A VGA heatsink and fan ( Ebay )

Heatsink compound

3pcs 18650 batteries



Hot glue

Step 2: Assemble

This is one of the easier builds with great results I've done!

First, clean the heatsink and back of LED with rubbing alcohol. Add a small amount of heatsink compound and the led. I just used some hot glue but you really should screw the LED to the heatsink.

The driver has a full bridge rectifier on the input so it is reverse polarity protected. Now, since I also have a fan on the heatsink, I soldered its wires to the input of the driver. I soldered the driver output to the LED being careful it was the right polarity. Connect the three 18650 batteries in series and add a switch between the battery and the driver.

Connect the batteries to the driver input and the circuit is pretty much done!

I hot glued the heatsink with the LED in the old flashlight. I placed it tightly against the reflector so that the LED shines through the reflector hole with minimal light leakage. Then I attached the driver and batteries inside using double sided foam tape. Then, all that was left was the switch.

The flashlight had an old switch that was far to unreliable to reuse. So I removed it and in its place I put a new switch.

I kind of messed up the "on/off" plate on the front when I tightened the nut... But over all I'm happy with the results! The lens and reflector really helps focus the light :)

Step 3: Pics

Step 4: Done!

I hope you've enjoyed this Instructable! Please let me know if you decide to make your own!

If you liked this Instructable you should check out my other Instructables!



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    11 Discussions


    1 year ago

    Uber newbie question - where do I buy the LEDs?


    3 years ago

    I love this build. I'm working on something similar using an old camera. The problem I'm running into is the heat-sink. Due to the configuration I can't figure out how to get a big enough heat sink in proximity to the LED. Does anyone here know how I could route some of the heat to a heat-sink elsewhere in the enclosure or even into the body of the camera itself?


    3 years ago

    Awesome! It reminds me a bit of Rulof Makers "Extreme LED Torch Inside Old Camera"

    You might also want to enhance the size of that heat-sink, These LED's get extremely hot in no time!

    Also, What's the voltage output of your LED driver? Is it a step-down, Or step-up, Or none of those? It says that it has an output of 8-11V, The LED won't be at full brightness at 11V

    4 replies

    Reply 3 years ago

    Hi! Thanks for commenting :)

    The LED's have a If of 1050mA and the driver only supplies 900mA constant current. So the LED is not driven at its max. However it will not get as hot, which is nice.

    As your said, the driver inputs 9-24VDC and converts it to 8-11VDC (Just measured mine, it outputs 10.55V) so I think it's a step-down. Remember, the LED's are rated 12V max so I think driving them at a little less than that will extend it's life a bit :) .

    I'm hoping the fan+heatsink+not driving it at its max will keep the LED cool enough.


    Reply 3 years ago

    I've actually experimented quite a lot with these LED's while making SpectrumLED, And at 9V they don't heat up at all, And are almost at full brightness.

    I think it works like this:

    LED @9V: Room temp, Draws 200mah, 75% brightness = more efficient

    LED @12V (my experiment were more @11.5V): Extremely hot, Draws ~1.1A, 100% brightness


    Reply 3 years ago

    Oh, is that your? I read that :) turned out great!
    Yeah i think it's plenty bright as it is right now. I've ordered one of those adjustable constant current drivers. Planning on driving those leds to their max! So another instructable is on it's way soon ;)


    Reply 3 years ago

    Hi Simon I have an old railroad latern that uses the big six volt battery how could you incorporate what you have done into the lantern I have, this build really sounds interesting, thank you for this great idea.


    P.S. if you want a photo of the lantern I will send it to you ....thank you


    Reply 3 years ago

    Sounds like there is tons of room inside a railroad lantern. This should work just fint with it :) if you could send a picture that would be great!