Just ordered one of these Ultrafire DV-S9 dive lights, but who am I kidding, I don’t even swim! However, I do like the 26650 size lights, and Lightbringer makes it sound nice - I am sure it will find a use in my collection.
I can confirm that FastTech discounts 5% with the code BLF in case anyone else is shopping…
thanks, Lightbringer, for pointing this one out
And the “funny” (not really) thing is, I’m STILL waiting for those LKs I ordered!!
I’m still using that old DE-whatever 26650 I got from Rat Shack…
Enjoy, all y’all!
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Oh, another addendum is that I love the “waterproofness” of the light if you do keep it with your car (changing a tire in the rain, etc.), and just for the sheer yummy goodness of that ’S9, for ~15bux?!? Can’t beat that price.
As I mentioned in the other thread, this critter really surpassed all my expectations. I’d consider this my buy of 2016/2017.
Dang, that light needed one of these shaft zincs clamped around the battery tube……… 
Certification covers the knowledge you need dive safely. Breathing at depth causes nitrogen (70% of each breath) to dissolve into the blood and accumulate in soft tissues and repetitive diving increases accumulation. Coming to the surface too rapidly or getting on a plane too soon can literally make you fizz and die. Deep dives can cause nitrogen narcosis(a sort of drinker disorientation). Knowing how to monitor your nitrogen(or O2 if using Nitrox) along with hand signals covering different situations, proper use of boyancy control and breathing, what to do in an emergency, these all take some practice to become second nature and certification is a means of verifying you have it down pat. Not to mention you need to show proof to get tanks filled. Check your weight belt and turn on your air. Certification doesn’t expire but if you haven’t done it for awhile then a refresher is a good idea. New technology and changes in boat diving practices can take getting used to.
As long as current is past through the body it wouldn’t help. Current has to be isolated from all external parts. At 8.4 volts 3 amps you could probable see gas bubbles forming if done in still water like a fish tank. Simply having both contacts at the head and none of this would happen.
Kewl, tnx!
Looks similar to the Starry Light DXM.
Mike
Ha… twins!
I was wondering if there were any “relatives” of this light floating around out there. Now I know!
From Ultrafire’s website for this DV-S9 light:
Hmm…. something does not add up here. 
Anyway, do you have any beam shots?
Naw. One of the websites had nonsense descriptions, like “switch: clicky”, “modes: h/m/l/SOS”, etc.
Ah, here ya go! Right from the horse’s ass, umm, mouth:
Number of Modes: 3
Mode Arrangement: Hi,Low,Slow Strobe
Whaaaat??
Methinks lots of these “specs” are just c&p from other lights, and no one bothers to even look at them half the time.
I doubt that’s because of electrical current.
The shell is (usually) negative and there’s no positive outside, so there’s no current through the water surrounding the body.
Let me rephrase:
There is current through the battery tube from tail to head.
But since the battery tube has very very low electrical resistance, there’s hardly any voltage between tail and head, so i expect electrolyses is negligible or just not happening.
The picture shows problems on the edges.
Probably damaged anodization, and so the seawater just has a go with the aluminium.
The result is porous salts which absorb seawater so that the process continues on dry land.
Those pics are from a 2012 thread. The damage you see is from galvanic corrosion and electrolysis when this light is submerged in salt water. Basically it forms a cathode / anode and the salt water is the electrolytic solution. It only happens when this light is turned OFF (IIRC) though because the electrical circuit when turned on becomes the current path of least resistance. The condition is worsened for spots where the anodize is scratched off or etched off. Thread here… skip ahead to page 5-7. IIRC a couple different members were complaining about the same thing.
See post 178 and 191….
Good read, and answers some questions I had about all this.
Specifically, even with a decent tailcap switch, if it’s tightly connected to the body, the only breakpoint is between the internal switch and the (-) end of the cell. The whoooooole head+body+tailcap should be one long electrically-conductive piece, all at 0 potential. So like a shielded cable, the entire length would be one long 0.
And unless you turn your flashlight into an electron-gun, it’s only 1 electrode in a salt-bath, and no fizzing should occur.
That’s why, a design like this one, no switch in the tailcap, screwed on tightly, no reason to twist/untwist anything, and a magnetic slider, nothing should make a 2nd connection/electrode. (Think of way bigger version of an Astrolux A01 1-piece body, only no twist-head, but one solid piece, internals (incl. battery) accessible only through the front bezel and lens, and an internal magnetic switch.)
That’s why, in the shown pix, what’s fizzing off of what. If it’s a 2-electrode system bathed in saltwater, 1 set of bubbles should be H2 and the other set should be O2.
Lookit Electrolysis of water - Wikipedia . The (-) end should fizz H2, and the (+) end should fizz O2.
By figuring out which is which, you can narrow down where’s the break in continuity, and see what can be done to fix it.
Point being, in a good solid conductor, there should be no fizzing of any kind no matter how much current is going through it, not unless the voltage drop is more than 1.23V.
There’s also at least one more version that’s sold under various names that has the Starry Light DXM tailcap and simple spiral knurling. Here’s a (fake?) ultrafire-branded version:
https://www.fasttech.com/products/1601/10010861/4516600-ultrafire-cree-xm-l2-u2-1-mode-900lm-diving-led
It’s also around in black and green variants:
www.amazon.co.uk/d/s7v/Flashlight-Underwater-Waterproof-Torch-Submarine-Battery-Included/B01JYF4N04/
There’s also the Ultrafire UF-S11 which looks like it might be a slightly more distant relative as it has similar proportions and a magnetic switch. Although it seems to consistently claim 3 modes instead of being infinitely variable:
http://www.gearbest.com/led-flashlights/pp_576215.html
Back to the DV-S9. Does it take protected batteries and what is the beam spread like? Similar to the Starry Light DXM? How hot does it get if left along on maximum brightness?
Interesting clones, cousins, whatever.
Yeah, I got a protected 26650 that fits just fine. Big honkin’ springs on each end, so could probably take a ¼” spacer, too, and still fit.
Beam’s nice, pretty well-defined hotspot, decent spill, maybe the size of an XM-L in a C8. Wider than an XP-L HI C8, narrower than my (stock) VG10.
Bulb above my washing machine went out, had the DV-S9 tailstanding on full, using ceiling-bounce for light. Had it going about 10min straight, comfortably warm, nowhere near hot. It’s got a good amount of bulk to it.
Since the body of this DV-S9 is made to use both 18650/26650, when using 18650 there should be ample space left on the sides, right?
Maybe it is possible to disconnect the body contacts and make one's own wire connections going alongside the 18650 battery to the head?
Aha, it has a tailcap that acts as a twisty switch. I didn’t know that.
So, when it’s turned ‘OFF’ there’s the battery voltage between tailcap and body, and then electrolyses will happen.
I see i forgot to ask how the PWM is.
I assume they use PWM, and i know the big XHP70 diving lights with stepless slider is quite noisy (but not visible).
So how’s this one doing?
I like the concept.
The DV-S9?
Think I mentioned it early on. My phone’s camera can see it, but honest to B’Harni (pbuh!), I can’t see it.
Didn’t take it into the shower or in the rain, but even flicking the light back’n’forth across the room, I don’t notice anything.