Vf @ 4A for the FC40 is more like 12.4V. So power input power at 4A and 90% driver efficiency is about 55W. 55W input with a max of 7A allowed means it should regulate until 7.87V. This is 3.93V per cell.
The numbers work out but suggest the driver won’t hold max output very long. Luckily, Simon has chose to use good looking springs and with a low resistance cell specified output could be reached at least for a few minutes with a fully charged cell.
I worked at a place where I was charged with defining specs of POS equipment. “Point-of-sale”, but also the other kind, after I saw the innards.
Anyhoo, I asked for the test-spex. Min/max RH, max altitude, temp tests, etc. “Make ’em up.” Huh?? “Here’s what our competitors have for their equipment. Copy those spex.”
So pretty much everything was 10%/90% RH (non-condensing), –40°F to 120°F, 25,000ft ASL, etc.
Doubt the competitors did any tests on their equipment, either.
So… most lights have O-ring in the usual spots, rubber-boot switches, so they should be good for soaking rain and even dunking in a bucket or pool, but without actually paying $$$ to a test-lab to put actual light samples through actual tests, it ain’t happening. And O-rings wear, so those spex would only be good with new O-rings, not worn ones. The O-rings in my E03 pretty much turned to goo, and that’s with factory lube, nothing that I added. I don’t intend on dunking ’em anytime soon, but dropping one in a pool or into a toilet should be survivable (if yicky), even with the goo-ring.
A diving light, etc., with 2-3 O-rings should be that much more waterproof, but I doubt any are tested except informally.