DIY diving light

I am building a diving light to my friend.
We are using a Underwater Kinetics C8 for host

It has to be a 1-mode spotlight, no flood.
Dont know about batteries yet, maybe 4x18650?
What do you suggest for LEDs? I was thinking about 3x XM-L2 U2, or maybe a single xhp50?
What reflector do you recommend to get maximum throw (the lense/glass diameter is 60mm)?
And what about the driver? We want to drive the LEDs to max. So I was searching for a 6-9A drivers with only on/off modes, but no luck.

Throw won’t really work underwater will it?
For the driver, what about the LD-2?

I think XHP50 is to big to give you good spot.
XM-L2 or something similar size (maybe XP-L HI or bigger XHP35 HI) will be better.

This is regular incandescent version, it is all plastic, right?
I don’t think you will be able to run LED in it at 20W+ power.

Note that eLED version of this light has heat sink going from LED thru lens to water.
I may be wrong but I would check with one how hard you can push a led in this host before going to far with project.

I agree, drive a led hard in that and it may overheat inside.

Btw, welcome to BLF!

Many years ago I tried to mod a Princetontec mini wave II diving light with 4x 26650 and a single cree MC-E, with a couple of laptop heatsink style copper pipes going through the head as heatsink. Failed miserably because I couldn’t secure the LED on the pipes. Copper mcpcb didn’t exist at that time so there wasn’t a way to secure it by solder.

If I were to do the same mod today I would use an XHP-50, 2S2P batteries config, and a heatsink like this that goes through the head. Copper pipes can be cut and re-soldered.

These aren’t mere copper pipes, they’re heatpipes
Cutting them open will release the working fluid, usually water. The inside of the heatpipe is at low pressure, once you open it the water will immediately boil/vaporize.
Why didn’t you try thermal glue or just screwing the MCE down?

for drivers

how about these?

since you only need one mode so a regulator would do.
plus you can adjust voltage on this

some even allow you to adjust amps so a small cpu heatsink would work if you have it balanced.

just search for dc-dc converter