1 Horsepower 80,000 Lumen LED Flashlight

This project started a while ago when I found out 100w LEDs are as cheap as $2 each on eBay. I finally finished the project up this summer when I got sent back home from college due to coronavirus. The flashlight consists of 8 100w LEDs and reused batteries from the electric hydrofoil project

I learned a lot about high power LEDs in this project, such as why current limiting resistors are required and what color temperature actually means. Overall it was a great project, though the flashlight itself turned out to be a bit heavy and impractical. 

LEDs, reflectors, lenses, resistors, a DC-DC converter, heat sinks, and cooling fans area all purchased. I chose to use a DC-DC converter to maintain a stable voltage across the LEDs in order to get consistent brightness as the batteries drain. The 8 LEDs are split into 4p2s with a 25w current limiting resistor on each branch. Everything is turned on by an old light switch which I found in my dad's garage. 

After a few days of Fusion 360 modeling, I 3D printed the flashlight structure. Since most of the structure was 3D printed, I was able to add wiring guides right into the parts. I also added 3D printed threads which I chased with a tap to hold all the LEDs in. I chose PETG filament because it's more heat resistant than PLA and much easier to print than ABS.

Fusion 360 Model. Files available here

After testing the flashlight for the first time I added some 3D printed guards near the LEDs to reflect some of the light that was shining backward; even though the lens cone angle was supposed to be 60° there was still quite a bit of light shining back at the user. 

Overall the project was a success, I learned a lot and have a (somewhat) useful flashlight. In the future, I might add an Arduino and a MOSFET so I can use PWM to make the light dimmer. 

Update: I played with the voltage a bit and burnt out some LEDs, but now the flashlight is bigger, brighter, and water-cooled. The greatly increased heat transfer area of the waterblock and radiators should prevent the overheating problems and make sure the LEDs don't burn out.