Water Cooled LED Flashlight : 10 Steps (with Pictures)

Be sure to check out the above video for amazing beam shots and instructions. In this instructable see how I got over 7,000 lumens from a single Cree XHP70 LED. If you want to take your building and modding to the absolute extreme, to squeeze out every last drop you possibly can. There's one thing that you always need to remember........ THERMAL PATH IS KING!!!

Step 1: Basic Parts

The first thing we need is a piece of 3/4" brass tubing. We also need a DC water pump so I got a 12V one for a fish tank. The water lines will be made from vacuum tube. A copper 12V 20mm mcpcb and Cree XHP70 LED are also needed. A mason jar is what will be used for the water container.

Step 2: Assembly

I reflow soldered the LED and MCPCB to the end of the brass tube to make sure no water could leak from the end.

If you need help doing this here is my instructable on reflow soldering:

https://www.instructables.com/id/How-to-Reflow-Sol...

Step 3: The Reflector

Next I made a collar for the reflector to sit on. 2 holes were drilled for the wires to pass through.

Step 4: Water Lines

I the water "in" line to just below where the mcpcb is and ran the water "out" line in just a few inches so that the coldest water would be hitting the LED. Using a mason jar I created a reservoir. This allows the pump to sit directly in the water so no priming is needed.

Step 5: Battery Power

Since the voltage of the pump and LED are very different I hooked up two sets of batteries and also ran separate switches for the LED and pump. The pump is powered on 3x 18650s in a battery adapter, and the LED is powered by a stack of 26650s housed in a maglite body. Once assembly was complete I put the whole apparatus in a back pack for easy carry.

Step 6: The Proof

To see just how much power we gained with our water cooled LED flashlight I set the light in my lumen tube and powered it on. The Cree XHP70 is rated at 3773 lumens at 2400ma on a 12V mcpcb, but our water cooled LED flashlight is able to drive the emitter to a much higher current and net us over 7,200 lumens. Even after minutes of run time the output is stable. There is very little drop.

Here is how to build and operate a lumen measuring device.

https://www.instructables.com/id/DIY-Lumen-Measuri...

Step 7: The Beam

The beam of our water-cooled LED flashlight is pretty much what you'd think. It's all of the power of a multi emitter set up concentrated into one tight hot spot the beam from this LUM 590 reflector is incredible with the XHP there's not rough edge on it, and man does it throw!