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Ridiculously-Bright Flashlight

Take one 100W, 7500-lumen LED and eight 18650 Li-Ion cells. Do not stare at flashlight with remaining eye.

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This project was created on 03/10/2014

After watching a youtube video about these cheap 100W LED elements, I decided to try one out for myself. I have a big cache of 18650 cells, and eight of those at a nominal 3.7V (really more like 4.1V at full charge) do a fantastic job of driving this thing.
This is a naive first-order approximation.
The LED element needs a heatsink, the cells need protection, I need to install a switch, and I am inclined to change out the cell holder wires for 14 or 12-ga stranded.
Cosmetics such as a case and a lens are also in the works.
Right now, this is really as simple as batteries, an element, and touching the wire to the terminal, held together with black gaffer's tape.

Ultimately, what i want to get to is a stupid-bright flashlight. I simply want to drive this element at peak output, with decent collimation in a handheld (and possibly weatherproof) form-factor.

Project logs
  • Second-Iteration Planning

    03/12/2014 at 17:32 0 comments

    I spent some time today ordering parts for the second iteration of the light:

    * DC-DC boost converter

    * Li-Ion charge/protection PCBs

    I've also got a few high quality heatsinks which I may compare to try and figure out which I ought to use, and a reflector and collimating lens.

    Ideally, I want to add a switch and a charging port, in addition to upgrading the cell-holder wiring to something that will more comfortably carry that much current. With those things in place, I may be able to start planning things like a case and how to manage heat-transfer if I make this thing weatherproof to any degree.

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Norman wrote 07/20/2014 at 19:01 point
I created an LED hand-holding flashlight with 100W LED.

i know the blue lithium battery pack from ebay.
it is big bullshit. inside of the batterypack are 9 mobilephone batteries.
dont usw it, cause there not made for such an discharge energie, the LED need to use.
Use LiPo, its the only way. But be careful and read information in using LiPo and its charging

I used:

100W LED Cold-white
150W Power converter
LiPo battery (

when someone whats to know more about is and much details, message me:

iam from germany

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Andrew wrote 03/11/2014 at 21:28 point
Also I think it's probably safer to under volt these LED's unless you have good cooling, ie, copper/allu heatsink with fan.

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stripeytype wrote 03/12/2014 at 14:35 point
That's definitely true. Right now, with 8x3.7V LiIon cells, I'm significantly under-driving this element. it's rated at 3A * 33.3V, but I'm only running it at 29.6V. The brightness is still really impressive, but until I've got a heatsink in place, I don't want to drive it at full.

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Andrew wrote 03/11/2014 at 21:27 point
Hi Yeah I have bought way too much stuff so far. This is what I'm going to use, it's a power converter 12v-34v

I also got this one which is apparently capable of twice as much amps:

I have seen a youtube video of a guy using the first converter I linked. Here it is:

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Andrew wrote 03/11/2014 at 04:58 point
This is cool I'm making one too but batteries are hard to sort out. I bought one of those blue Chinese 12v lithium batteries that claims to be 6800mah but actually it's only close to 2700mah.. so I bought a sealed lead acid 9ah 12v. It's heavy but not TOO big.. but it ruined my plans of using an existing 6v lantern torch as the body. So now I need to somehow make a body for it.. I have no idea how to. I might try to make one in autocad 123D and then get it printed somewhere..

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stripeytype wrote 03/11/2014 at 16:02 point
I anticipate that my first-attempt at a body will be 3D printed, simply because I've got a few printers.
Are you using a DC-DC converter to drive the voltage from your Lithium up to the 33-or-so volts that the LED wants? My eight Li-Ion's fall short when nominal, at around 29V. The element still comes up, but does not get to full brightness. (it's still scary-bright)

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