Modding a friends dive light, input on driver needed.

I’m going to rebuild a dive light for a friend of mine.
He is using a 12V/4,5Ah NiMH batterypack that has to stay because he is also running other stuff off it.

The case of the light is machined from aluminium and I have no chance do to change anything regarding design.
It’s nearly a straight tube with an ID of 35mm.

I’m going to put an XP-L Hi 1A on an Noctigon XP32 into it and would like to use this reflector sanded down a mm:
http://www.kaidomain.com/product/details.S021791
Any comments on that one?

That stuff will sit on a pressfitted or glued aluminium/copper shelf I have to get in there somehow.

But my main problem is the driver.
It has to be one mode, and he would like to have ~2h runtime from his batterypack.
Any ideas on that one?

Thanks in advance!
Julian

I’m not very good with specifying drivers (and may never be), but from what I see, a LFlex driver from TaskLED might do the trick.

TaskLED web link

RMM’s new MTN-MAX buck driver, 1-6A 5-15V. You can fully customize the UI and current. 22mm MTN-MAX 1A-6A Buck Driver - 5V-18V

Taskled buck drivers can also work but they are way too overkill for a single LED and the UI needs some programming (not really an easy thing to do).

Isn’t there a cheaper solution?
I thought about some MR16 drivers, but none I’ve found were above “3W”.

Well there are cheaper drivers, but im not sure you would want to use it in a sealed diving light, I believe it is best to use a reliable driver since an ordinary flashlight can’t be used as backup in case of failure.

MR16 drivers are rated for low power 1-3W or SMD leds, to power an XP-L and make it produce a decent amount of light for underwater use you’ll need at least 10W.