OK, if I saw two cheap lights apart, and stick this huge heatsink between head and battery tube ....

Off-topic Chatter
1

I’ve been musing for a while on ways to get really big heat sinks into/onto/around flashlights.
Seeing more bike light discussions recently to support a family member who’s started bike commuting in the dark keeps me worrying about this.

So I came across this relatively huge but not terribly sharp-edged/spiky/dangerous/shredder-type heat sink

(because I’ve seen bike riders get hurt worse by what they had on their handlebars than by everything else, in an accident — sharp edges are horrible in accidents)

This one:

Height: 40 mm
Diameter: 80 mm

I’m assuming it’s hollow, figuring that it could be fiddled with to hold an emitter on one side — with threads cobbled on to hold the light head
and fiddled to hold a driver on the other side — with threads cobbled on to hold the driver.

So it’d take sawing up two cheap lights, I guess, to make one Frankenstein’s Monster — with this in between battery pack and head.

I think it’d be good at losing heat, anyhow.

The heat sink at Mouser is $17 — but compared to bike lights generally that’s not awful.

Any thoughts, giggles, or good advice welcome here.

2

That looks like a Pentium III heatsink. Not worth it at $17 when a computer repair shop might have something cheaper.

3

Whatever the specific - good suggestion to look around - I’m after a way to take heat dumped into the flashlight and lose it to the outside rather than transfer it to the battery case and thus to the battery.

That’s for the times I want to hang a flashlight up (when I’m not cooling it by absorbing heat into my palm )
and have it lighting a workspace for a while.

Basically precautionary. I’ve read that heat-cycling lithium-ions degrades them or ages them and it’s a good idea not to let them pick up any extra heat.
So it’s got to go somewhere. “Away” would be nice.

There are lots of heat sinks — very few with rounded edges offering some protection — to reduce carving up if you slide over one during a bike accident.