Running a Convoy S2+ UV on 2 X CR123A (and other questions)

First of all, this is the product, right?: https://www.aliexpress.com/item/1005001427736745.html
Supposedly it has that Nichia 365nm LED everyone's raving about.

Then what is this?: https://www.aliexpress.com/item/4000903351583.html
In the specs it's also a 365nm light but there's a black filter at the front. If I had to make a guess, the emitter on this one is inferior to Nichia's 365nm LED, in terms of being a true UV-A source, so that is why they had to block a large portion of what wants to come out of there. Please correct any ignorance on my part.


I've seen a couple of videos on youtube and found out that even the 365nm Nichia LED seems to put out a decent amount of visible light. Now, I DO want to see the actual beam with my eyes but not a whole lot of it. Suppose I buy that Nichia 365nm version and find out that the beam is "too visible", is there a way to mod this flashlight to bring it closer (but not completely) towards 'black light'? What I had in mind was to install some sort of "black filter" in front of the emitter. I'm not sure I would even want to mod this light but I need to know my options, since I'm planning on buying 3 of them.

Now, to the most important part. I want to run these (3) flashlights on CR123A batteries, not the 18650's. I'd be using my Nitecore "2 x CR123A to 18650" sleeves/adapters, so, physically, there should not be any compatibility issues. What about the driver? Can it handle the 6+ volts? I've already been told that - yes, but has anyone actually tried it? I'm not expecting the same performance that I'd get with a 18650 cell (lower current and such), I just need to know that the product will work as designed and put out a usable amount of UV light.

Would really appreciate any input from people who have actual experience with this product!

The first link is correct, generally considered the standard bearer of mass-produced handheld UV torches. The second appears to showcase a previous gen LG in an S2 host. Tip: If purchasing a Convoy off Aliexpress, try to stay within the confines of the Convoy Store to ensure that what you are receiving is exactly what is specified. Inferior is relative: The LG is more powerful and more efficient than the Nichia at the expense of emitting more visible light. This is why the LG ships with a filter up front: To reduce the emittance of visible light. If you reside in the US, the current gen LG in an S2 host can be found on Banggood as Convoy does not ship filtered UV lights stateside. The S2/S2+ driver is not tailored for 2xCR123A, hence the reason you will not hear much of anything regarding an S2/S2+ running off 2xCR123A. You can at the risk of overheating the driver and/or the LED. Moreover, you may also end up taxing 2xCR123A cells by way of amp draw once you drop out of constant current into direct drive. It is why Convoy will direct you towards the C8 UV with its 1.5A buck driver to accomodate 2S (Li-ion) configurations.

adamlau said:

The S2/S2+ driver is not tailored for 2xCR123A,

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Yeah, I kinda figured that out already. I need to clarify something though, something I should have made clear from the beginning.

I'm not looking to match the performance of a 18650 cell with my two CR123A's. I know the flashlight is not designed for it and all that, but WILL IT:

• Turn on and stay on for 2 minutes, without starting to blink or doing something else crazy?

• For those 2 minutes, put out a decent and usable amount of UV light?

• Last me for at least a total 15 minutes of runtime (on a set of fresh CR123's)?

If, the answer to all of the above is YES, then it's a go.

My usage of the S2+ will be very unusual from anything 'typical'. I will only need to switch it on for 1 or 2 minutes at a time. And once I switch it back off I may not have to switch it on again for another 15 minutes, 2 hours, 2 months or 2 years. I'm serious, I will almost never use these flashlights, which is one of the reasons I'm opting for a primary lithium power source.


Well, I wanted to order 3 units in one go and be done with it but given everything, I will have to order just one S2+ and test it out, before I buy any more.

Thanks for the tip on the Convoy online store, will definitely order from them.

If the driver isn't rated for 6 volts you'll fry it more than likely. Sorry don't understand the rational on why this is a must?

For the amount of time you plan to use the UVA, I'd purchase a CR123 spacer and run just one primary

Also I viewed the ZWB2 filter on Convoy Store available sold separately, but not sure if needed with the Nichia 365nm

Chicken Drumstick said:

If the driver isn't rated for 6 volts you'll fry it more than likely. Sorry don't understand the rational on why this is a must?

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You're driving down a countryside road, on a moonless night. The engine starts rumbling and soon thereafter it shuts down. But you know you can fix it! You grab your flashlight out of the glove box, pop up the hood and get out. You click the tail switch but nothing happens… Oh, no! The battery must have gone dead! OK, OK… You know there's a gas station just a couple miles up ahead, in fact, you can make out the lights in the distance. You walk the 2 miles, get inside and approach a pizza-faced kid behind the counter: "Hey, where do you keep your 18650 batteries?". And the kid replies: "Say what now?"
Indeed, that is a stupid situation to be in. Of, course, you could have used the LED light on your cellphone, had you not left it at home. But now, 'to save the day', you're gonna have to shell out 12 bucks on the only thing that can pass for a flashlight in that store: a plastic, double-D, good-for-one-use, piece of s***, batteries not included.
If only your precious 'car' flashlight could take CR123 cells… Because those are EVERYWHERE!, including every pathetic gas station in every god-forsaken place, and, look, right there, hanging on a stand, right next to the counter!

I'm a 'semi-prepper'. I have flashlights stashed all over the place, on and off the site. I don't even know how many I have, but – 'many'. When I come back to a flashlight, after having not seen it for 10 years and press the clicker, I expect the light to come on (and it usually does). Now, tell me you can do that with 18650 cells…
As far as I know, every "18650" flashlight that I own can take a couple of CR123's and just do what it's supposed to. If it was up to me, I would make it illegal to sell 18650 flashlights that can't work off CR123 batteries. Same for 14500's that don't take AA's. *I do not expect the same type of performance, however, 'some' functionality must be mandatory with the lesser batteries.
I think that, given the popularity and customizability of Convoy's S2, not providing for any kind of basic, 'primary' power source is unforgivable, especially, when the model does not feature a charging port. You run out of juice in the middle of nowhere and then what are ya gonna do? If your flashlight isn't stupid then you can at least hike up to the nearest convenience store, or better still, break out a couple of primary lithiums that you threw into the glove box 8 years ago and totally forgot about but now remembered, cuz you're a freaking genius!

Anyway… getting off-topic here. Seeing how it is, the only thing left for me to do is to buy and test out the S2+ myself. I don't think that it'll fail on me, at least not right away but if it does, I will tell everyone not to buy it.

If nothing else, from this discussion I've learned that I must put the S2 through the wringer, even if, initially, everything seems to be fine.

knucklegary said:

For the amount of time you plan to use the UVA, I'd purchase a CR123 spacer and run just one primary

Also I viewed the ZWB2 filter on Convoy Store available sold separately, but not sure if needed with the Nichia 365nm

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That thought has actually crossed my mind. The cut-off voltage on that driver is what? 2.8V? The voltage of a single CR123A would be 3.2 -3.3? But I think that under the load it'll immediately drop to something very close to, if not below the 2.8V mark. Still, it might linger just above that cut-off, and yes, potentially, it could be enough for how little I need to use the light.
However, believe it or not, the primary function of my S2+ flashlight is going to be "storage" of 'backup' CR123A cells for my other (non-UV) 18650 flashlights. So, I better get two CR123 batteries into each of my S2's.

As for the filter, I wasn't smart enough to just search it up, so thanks, man! Imma order one with the Nichia S2+. It's cheap and it would be interesting to see what it does to the beam, regardless of whether I decide that I need it or not.

*Before I'll start "abusing" the S2 flashlight I want to run it off a 18650 first, to see what's what. It will be my first UV light ever, so I want to play around with it, before (potentially) destroying it due to "over-voltage" or running it too hot.

knucklegary said:

For the amount of time you plan to use the UVA, I'd purchase a CR123 spacer and run just one primary

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since he plans to use two CR123 in his Fenix, it would be a bad idea to create a mismatch by using only one battery for other purposes

cdm-dude said:

the primary function of my S2+ flashlight is going to be "storage" of 'backup' CR123A cells for my other (non-UV) 18650 flashlights. So, I better get two CR123 batteries into each of my S2's.

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you seem to be unaware of the risks of dual batteries

https://www.candlepowerforums.com/v...or-250-light&p=5431481&viewfull=1#post5431481

RCS1300 said:

Multi-battery management is a very serious safety issue. If this person is not using a voltmeter and not managing the labeling and use of each battery he may find himself starting his house on fire. Further, if he inhales the fumes from that fire he could permanently lose lung capacity. The issue is that in a multi-battery format each battery should drain at about the same rate. If there are mis-matched batteries one might drain fully before the others, heat up, start a fire, and possibly turn the flashlight tube into a grenade - think shrapnel wounds. I have only one two cell 18650 light and I manage those batteries extremely carefully. I hate that I have to do that and I do not let anyone else use that light. I have to lock it out when not in use.

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cdm-dude, I suggest you set your lights up in such a way that dual battery risks are not part of your setup.

jon_slider said:

since he plans to use two CR123 in his Fenix, it would be a bad idea to create a mismatch by using only one battery for other purposes



you seem to be unaware of the risks of dual batteries

https://www.candlepowerforums.com/v...or-250-light&p=5431481&viewfull=1#post5431481


cdm-dude, I suggest you set your lights up in such a way that dual battery risks are not part of your setup.

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Hmm... thanks, man.. I don't know what I'm supposed to be reading in that post though... I never suggested that I was going to "mismatch" any of my batteries. If, indeed, I decided to run my Convoy S2 off a single CR123A (which is extremely unlikely to even happen) I would use that cell only for that one purpose and nothing else. I would use it up and dispose of.

The thing about fires.... Man... did ya hafta? I just stopped having those nightmares!

Personally, I don't like li-ion batteries or any of the other "risky" chemistries, but what are you gonna do? You want lotsa light in a small package? You're gonna have to deal with those voltages and currents.

Although I have a couple of non-brand 18650's (that are just "spares"), I buy only the "high-end", protected stuff from Fenix and Olight.

I do have lots of flashlights that are stashed in all sorts of places, or just laying around but all of those have either primary lithiums or Eneloops inside them.

All of my li-ion flashlights, powerbank(s) and batteires, regardless of the make, including my cameras' batteries and others are stored inside an air-tight metal container. So, even if something catches fire it will be contained in that box and will likely go out very quickly due to lack of oxygen... I'll lose a ton of flashlights, batteries and tech, but hey, better just those things than the entire house! Am I right?

(all my primary cells are kept in the freezer and the spare NiMH Eneloops are always in the fridge)

My (2) cellphones is what concerns me the most but I can't keep those in a metal box, can I?

cdm-dude said:

I don't know what I'm supposed to be reading in that post though

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just pointing out that:
"Multi-battery management is a very serious safety issue..."

Mismatched CR123 Primary batteries (non LiIon), can overheat and vent with fire.
This safety issue is not only about LiIon, it is also about Primary CR123..

did you already know that?
if so, apology for preaching to the Choir

I respect your other safe storage strategies.
(except using a Convoy to store two CR123)

jon_slider said:

just pointing out that:
"Multi-battery management is a very serious safety issue..."

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And a pain in the neck. I have color-coded most of my AAA Eneloops with thin bands of different-color nail polish that go all the way around, so that each pair (or a different combo) always goes together into the same device/charger. From a very young age I've known that mixing different batteries was a no-no...

The thing about CR123's is that, yes, there's slightly more voltage involved but they do not have the capacity of pushing the kind of currents that li-ion chemistry does, so I do not consider them nearly as hazardous as 18650's or 16340's.

Many types of batteries have "heat vents". They are there for just that: venting out the heat. So, instead of exploding, they can fail more safely. I don't think that any actual flames would come out though. Some steam and other nasty stuff - yes. But, if for example, that type of cell happened to be hermetically sealed inside of a confined space, let's say a flashlight, I can see a potential pressure build-up. Although, I don't believe there could be a legit explosion, especially if the body is made from thin aluminum. The structure would fail long before any "dangerous" pressure could build up... With titanium or stainless steel housings?... Who knows? It is a potential hazard regardless

Electricity can be a nasty thing. One could rig up a stupid number of 1.5V batteries and shock a man (or self) to death with that, no need for fire or explosions. That's batteries for ya.


Anyway, I realize that I'm about to do something, which is at the very least is inadvisable (feeding that driver ~6.5 volts). Yes, it could fail, but would that push the CR123A cells over the edge? I mean, what currents are we talking here? I am skeptical that anything eventful will happen, though I promise to be extremely vigilant throughout the testing phase (not joking here). If something goes really wrong I am sure I'll be able to get away in time from any steamy batteries or shrapnel (Okay, here I am joking).

I am much more concerned by your remark regarding the "storage" of the CR123 cells inside the S2 body. Provided, they are fresh out of the box batteries, what kind of risk is there in simply placing them inside and aluminum tube? I mean they would not be a part of any (complete) circuit. Why do you think that "storing" them like that is problematic?

cdm-dude said:

regarding the "storage" of the CR123 cells inside the S2 body. ... Why do you think that "storing" them like that is problematic?

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1. I see a potential for frying the driver when turning on the light with overvoltage dual cells.

I would want to idiot proof the battery carrier function, so the light cannot be switched on by mistake.

2. I dont think overvoltage to the driver will cause the batteries to explode..
The risk of mismatched cells is a separate issue, that you seem to already understand very well.

given those two concerns, instead of carrying two CR123, I would carry a spare 18650.

jon_slider said:

I would want to idiot proof the battery carrier function, so the light cannot be switched on by mistake.

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Get out of my mind!

Great discussion, man. Thanks for all the pointers!

get the s2+ with nichia uv led. forget the lg one.

https://www.banggood.com/Convoy-S2+-Nichia-365nm-UV-LED-1Mode-OP-Reflector-Flashlight-p-1024097.html

i have this light. it's pretty nice and puts out a lot of uv-a.

even though it doesn't put out a lot of visible light, it still benefits from a uv-pass filter. WELL WORTH IT!
take out the old, clear lens and replace it with a black 20.5mm diameter 2mm thick ZWB2 lens:
https://www.ebay.com/sch/i.html?_sop=15&_nkw=2mm+ZWB2+20.5mm
for fun, i tried stacking it with the old lens, but the combined thickness is too much. remove the old lens.

what i actually want out of this s2+ nichia uv is a multi-mode driver. i find it too bright for a lot of everyday things actually. i would like the option of dimmer output and longer battery life.

as for CR123, idk. the only place i have for primaries is in emergency-only lights that will realistically never get used.
i've never used CR123 for anything real in my life except smoke detectors, alarm sensors, and similar niche applications. good idea to have a CR123 light in the trunk of my car or "bug out bag" or whatever i suppose, but like i said, it will almost certainly never get used. just "nice to have" for safety. i always have a real flashlight on me anyways, and if i'm going on a trip, i bring a charger and multiple charged 18650s and/or 21700s.

if my life comes down to not being able to use CR123 in a flashlight, someone please just kill me. **** CR123, i give up.

one more thing.

i strongly suggest wearing eye protection.

i keep this light stored with ANSI Z87+D3 lab-style goggles to reduce the amount of direct (and indirect/reflected) UV-A exposure.
i think these are UV-blocking polycarbonate.

you should test to verify that they block UV. shine the light at a white sheet of paper. most paper is dyed with UV-reactive optical brightening agent, so it should strongly fluoresce. then pass the goggles between the lamp and the paper. it should block the beam, and you won't see the paper fluoresce anymore.



i keep the lanyard looped around the glasses.

i also keep a note on the light in storage because people are idiots.
the note reads:

DANGER

• Powerful UV-A (365nm) radiation
• Always use UV eye protection
• Never shine in eyes
• Emitted light is mostly invisible

Clearly you have not read through the entire thread, which I cannot blame you for. My (hopefully, multiple) S2+ flashlights will be just that: (almost) never to be used. They'll be sitting in various "bags" for 1-2-5 years, until MAYBE someday I need to use one for a couple of minutes. That's where the CR123 cells really shine (pun intended). As a nice bonus, those couple CR123 batteries (per flashlight) can be used in my other (non-UV) 18650 flashlights, should I run out of juice in those...

The light output cannot possibly be too much for what I need, which is spotting scorpions at night, period. If I needed a UV light for anything other than that, I would be definitely looking for something with variable output.

Thanks for the safety tips and I have already ordered (just one, for now) S2+ and the filter from Aliexpress.

Also, I know it's obvious but to some it may not be so. Any flashlight can be made (much) dimmer in a pinch. All you need is your (white) T-shirt, a paper towel, a nylon shopping bag, or anything else to block some of the light. There are obvious drawbacks (and possibly, hazards) to this approach and I would be interested how (and whether) it would work with a UV emitter. A potential problem, right off the bat, is a bunch of UV light reflecting off the makeshift "diffuser" and searing your retinas.