Beam Shots are up - Modifying a 109 LED flashlight to an 18 XP-G2 FETlight

I bought one of these 109 LED 3xAA flashlights for $8 USD. I am going to mod it into something that will end up costing about $100 USD when all is said and done.

I have already gutted the light and saved the parts I will reuse.

I ordered a 3" diameter piece of Aluminum rod stock that is 22mm thick. That will sit in the bottom of the head and be a press fit. It will hold the six triple XP-G2 mcpcbs (18 leds). That's enough of a heat sink to work fine, since the battery will not last long at all when they are all wired parallel and run with a Mtn Electronics FET driver.

I am waiting for the components to come in next week, but you all know I just can't resist holding off till it's all done.

I will cut a glass lens in place of the plastic one. I only had one 3-up lying around, but you can get the idea.

I will use a Shockli 26650 and I hope to at least pull one amp per led. Maybe even more if the cell will take it, but it will be a 30 second wonder most likely, as the voltage will plummet quickly.

I am going to use a center screw for each 3-up, but only to tighten them down while the AA adhesive sets. After they are glued down, I will take the screws out, due to clearance problems with the screw heads. Each 3-up will have 22ga wires on them and they will all run down below the heat sink, where they will be joined to 16ga wires for the main positive and negative.

The switch will be momentary, so I don't have to deal with all that amperage going through a switch. I will also heat sink the FET, since I believe it will be getting very hot.

It won't be a monster, but it should at least put out a few lumens on high.

More when I get more---------------------------------------------------------------------------------------------

04/14/16 Parts came in.

All the parts came in and the light is assembled.

18 leds

Wiring, driver and momentary switch.

I did not get a lens for it. I tried to cut one, but I gave up after ruining a dozen of them. I just used the old plastic lens and made it so it surrounds the optics. Maybe sometime I can get a glass lens. I tried, but they never answer me. I guess they are afraid I will complain about their lenses, since I complain about everything else.

Anyhow, it wasn't worth all the money. I am seeing only 15.28 amps on turn on and then it drops like a rock, due to the single cell. I would guess that on turn on, it's about 3,000 lumens and by 30 seconds, it's probably all the way down to 2,500 lumens or less, so it was a loss and not a smart mod. Just one to say it was done.

I might do beam shots tonight. I don't know yet for sure.

Beam shots in post #2

beam shots

Woah. This is gonna be awesome. Can’t wait!

reserved a seat…


Thanks for the idea for what to do with the other srk and the 3” x 3” round aluminum bar that was delivered today.

I sense another Old Lumens masterpiece in the works!!! :crown:

Is it ready yet ? :slight_smile:

In for GB if using Nichia. LOL

So if you put 109 xpg2 in the old led spots what would happen?

Do 19*3 LEDs fit in there?
Or how many are you aiming at?

They wouldn't all fit.

18 leds is what is going in. six of the triple mcpcbs.

The FET won't get hot, that only happens in other driver types where it is switched constantly in the MHz range to regulate the current and so spends a significant amount of time inbetween fully on and fully off. In these DD drivers the FET has plenty of time to rest between PWM pulses. On high/100% it's basically just a resistor about equal to a short piece of fat copper wire. No heatsinking required.

Looking forward to seeing this!


Awesome man! So only one 26650 cell for the engine?

Who’s got the popcorn?
I believe we may need a fire extinguisher when the switch is turned on for this light.

Ah I was eyeballing it (with that figure 109 in my head…. shave a bit here, shave a bit there…no…HOW DOES HE PLAN ON DOING THAT??
6 I get, but why not 7, that should fit right?

This is going to be cool. Looking forward to it!

Smaller circles in larger circle

Useful for determining how many stars will fit in the head.

I’ll just pull me up a chair. Good stuff right here.

that calculator broke firefox, i calculated 200 and 0.1!
I could hear the CPU struggling!

Someone else try it and let me know what happens