Heat sink size for xm-l2

I'm working on a headlamp and wondering how big of a pill do I really need ? It will be aluminum and mounted inside a copper pipe housing.

The copper pipe is 3" long and I cut and fit a short piece to make basically a "T". I used the copper pipe instead of just a 3/4" "T" because the carlco optics I have fir perfect inside on the lip. standard "T" was too big and they just fell inside.

I want to drive an XM-L2 T5 5B1 to around 2100ma on high. with a 105c driver

probably no optics just mule or a carlco 60' floody thing

since it will sink to the copper pipe. can it be smaller ?

I plan to run the thing with 4xAA probably eneloops. I have a headlamp that has a 18650 but still just not that comfortable with that on my head.

I plan on making the pill almost press fit and then screw it to the housing with a small screw.




sorry my photos are acting weird...or i am....

once i figure out the stack height i can cut down the "T" to length.

it gets a tail cap from a Hugsby P31 that was a DOA donor my dad gave me. A little sanding and it will be a very tight press fit. and on the other side looking for a nice small wire strain relief. 4aa case is from a princeton tec apex

Cool project!

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at 2.1 amps you should be fine with what you’ve got as long as the star has a good thermal path to all of that copper. There is plenty of surface area there although it will get warm/hot to the touch with extended use.

I have two factory XM-L headlamps driven at right around 2 amps that get really hot (not an instant burn but uncomfortable to hold) after extended use but seem to handle the heat just fine; they have less surface area than your setup so yours should be fine.

Nice recycling project.
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If the heatsinking is good, it will get hot like always.
I have a cheapoheadlamp one of my first modding victims I put a XML and a KD nanjg and serious wire resistance in it, so it will give 1.5-2A.
It has a aluminium pill surrounded from plastic, gets hot and even smells a bit grilled if driven with a good cell, but it works like a champ. But I guess the led won’t reach maximum lifespan but as I have only used it <100h so no long term experience.

This whole reflector/pill is aluminium, there is a aluminium disc screwed in from the underside to fasten the led and this is also leading the heat into the reflector through the threads.
Lens is plastic too…look at the tiny wires…