This one only runs the current through two contacts isolated in the head Review: Acebeam D45 (XHP70 3x18650) | Candle Power Flashlight Forum Acebeam D45vn Diving & All Weather | Candle Power Flashlight Forum The slightly older D400 is still available and viable. Both heavy enough for land and water use on the D400 I’d put a rubber washer on the bottom side to insulate any current. They may be pricey, but add salt water and everything changes.
Yeh, goggle “sacrificial anode”. Even in car coolant systems, just dangle a hunk o’ Mg on a chain and it’ll get et before more critical goodies.
The critter should be insulated (anodised, ie, passivated), so ideally that should protect the body. And there should at least be some potential common to both metals, the protected one and the sacrificial one. The light itself should be a closed loop.
Maybe if the light has a bunch of starter scratches and dings, that’s where it’ll start to corrode first (like paint bubbling on a car where water gets under pinholes in the paint job).
Anyway, I ain’t gonna be using it for diving, as I don’t dive. I just got it because it looks purty, has the “infinitely adjustable” mag-switch, and is nominally at least more waterproof than the usual bunch of lights.
For actual diving, I’d imagine something sealed in plastic or rubber would be best. Also grippier when wet.
Why do you need to get “certified” to dive? Can’t just plop on all the accoutrements and fall into the water?
Or is this as a dive instructor or something?
In fresh water mostly. In salt water the heaviest anodizing won’t stop the corrosion especially when you place a current through the body. As a fancy toy light she looks good. She’ll also have much better waterproofing than most others. What I like about landlocked dive lights is that a bit more went into making them. They tend to have thicker host and heads. This is a modders dream for heat sinking.
Yep, this is a nice solid donk.
Ordered a set of 4 LK 26550s from GB to go with (and my L2, maybe, as these LKs are flattops).
This would be a nice critter to keep in the car (barring weather/temperature extremes) for those Just In Case scenarios. 5AH beats 3.4AH or even 3.6AH, and you won’t mind it rolling around in the mud as you’re changing a tire. 
Well, I wouldn’t keep it in the car, at least not all the time. Got a small Craftsman toolbag (almost always “on sale”, and well worth it) that I switch from car to car. Phone charger, flashlight, spare bulbs/fuses, other crap I would keep in each car but got tired of “maintaining” different versions, so now it’s in one bag that I bring into whichever car I’m taking.
Gotta say again, the color’s fantastic, more of a deep indigo than generic blue as listed. Just like the XTAR WK50 which looked like a pale Barbie Pink in the ads, yet is a nicer satiny “hot pink” in person. Same with this. More than anything, I think that’s why I ordered a 2nd one.
Good review Lightbringer, thanks for the heads up on this one. :+1:
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.