Review: UV light shootout, seven lights tested

My KD drop in just arrived today so I've been checking it out and comparing it to my Inova X5 UV


general impressions of the KD: sloppy soldering, gets hot fast on 2 cells, output seems to drop erratically (possible host issue but possibly heat), really makes stuff glow in the hot spot but not so much on the spill.


I couldnt find anything that would only glow using one of these lights and not the other.


Neither of these lights make any part of Canada's new plastic bills glow but aparently thats how it should be.


All in all I think I prefer the floody light of the Inova most of the time. The price of the single mode Inova has come down decently too.

FYI a company called YellowJacket sells a rebranded Inova X5 UV that costs more and is not as good. They replaced 2 of the UV LEDs with white LEDs so my coworkers Yellowjacket wasnt able to pick out the UV dye traces my Inova could.

FWIW, I’m waiting on a KD drop-in. I ordered it plus a SF L2m host on the same day. The L2m showed up today, but the KD drop-in apparently hasn’t even been sent yet (it just recently changed state to “order pending-packing”).

After it arrives, I’m planning to drop by the bank for a set of fresh US currency, to test how it responds to my two UV lights.

That KD drop-in just showed up. So far, I can say it’s quite a bit brighter on 2x16340 than it is on 1x18650. Both visually, and by measurement.

The current seems to increase with voltage. I measured a few different batteries, and got:

  • 0.1A at 3.6V = 0.36W
  • 0.2A at 3.8V = 0.76W
  • 0.36A at 4.16V = 1.49W
  • 0.6A at 7.9V = 4.74W

At 4+ watts, I don’t even need to go into a dark room, or get close to the objects I’m trying to light up. And this is with the lens on; I haven’t even tried it with the bare emitter. However, I’m a little concerned about heat, because the drop-in doesn’t fit this SF L2m very well. Neither the pill nor the reflector make much if any contact with the body, and it seems that the heat is only transferred via the spring (which fits so tight that it shaved off a bit of metal while screwing the body together).

However, even at just ~0.36W, it still fluoresces things better than my cheapo 3xAAA ~375nm light. Before using this light, I never even noticed there was a big red/green-checkered “20” printed on a UK 20 pound bill. Also, things light up in color now instead of everything being bright green.

Hopefully I can get some beam shots up soon, but I’m kinda sick and trying to rest.

You might want to wrap the drop-in with aluminium foil or copper tape.

It takes a couple of tries as every one seems to be a different size but you get the idea.

Hello all. I’ve been following this thread for a little while, and I was thinking about taking the plunge. I’m thinking of going the 365 nm route for a wide-range of things, from checking bills (more curiosity than anything else) to looking for bodily fluids (to gross me out when I stay in motels) to geocaching.

One route I see here involves buying the Ultrafire 1000 LM WF-502B and the Kaidomain dropin —did I get that right as far as the pairing? Another involves buying something like this, which I know nothing about other than Amazon reviews.

Since this purchase isn’t going to be for something I’ll use regularly (as compared to my “standard” flashlight collection) I’m not looking to go towards the higher end (certainly under $50). So… any thoughts? Am I wrong to stick to 365nm lights?

Welcome to BLF, ScottR!

You might want to consider 385nm. It seems many 385nm leds are more efficient / produce more light then 365nm leds do & with regards to geocaching its uncommon for UV pigments to need 365 exclusively.
Its not wrong to go 365, you just might not need it & sometimes a 385 light will be brighter.

Do you already have li-ion 18650, 16340 batteries?

Thanks for the reply, Helios. I was thinking that geocaching would be a lesser use, since so many places you can do it close at dusk. Ironically, I’d come across that post on the subject while doing regular caching, and was moved to check the cheapo so-called UV lights I had, and realized they were more or less useless—for example, this Complete joke.

So, you’re saying that the 385 lights are generally “brighter” (acknowledging that the output itself is invisible) than the 365s, so it’s more useful at a distance? If so, what distances are we talking about?

I’m not sure what wavelengths my UV lights actually put out, but I have a cheapo from amazon which claims to be 375nm, and a reasonably nice P60 drop-in which claims to be 365nm. I can believe the latter, given that it puts out almost no visible light. My “375nm” one emits a lot of visible light though, which requires yellow glasses to block.

The 365nm drop-in fluoresces things much better, and fluoresces them in a much wider variety of colors.

It’s too bad I don’t have a Nitecore CU6 to compare against. It most likely has a pretty nice UV emitter, and would work well with one cell instead of requiring two.

Oh, hey, I just realized that my “transition” lenses (which darken in sunlight) are actually pretty perfect for use around UV lights. And I can darken them before going out if I wave a UV light over them a few times. :slight_smile:

Thanks for your review. Would like to own them.

Sort of, you can just get the WF-502B shell. You don’t have to get it with the “1000 Lumen” dropin, unless you really want to. Cheap enough I guess and you can have a spare to play with.

hey great review, and great thread! i was never interested in a uv light, but after browsing through the first page, i kinda want one.

the one that looks good to me is the tank tk 566, but it sells for close to $50.
am i not looking at the right one, or is that how much these uv lights sell for?

It was closer to $35 when Manafont had them. Manafont now seems to redirect to DX now, which has them for about $40.

The 502B is also sold as a host, so you don't have to buy the complete flashlight if you don't need/want it. The KD 365nm drop-in works just fine with the 502B and is actually the setup I went with for infrequent use. IMHO, if you plan on using it with any regularity, you'll want to spend a little more on a better quality host--the 502B works but feels really cheap. FWIW, the KD drop-in works well for detecting bodily fluids.

Heh, I just did, and managed to get the drop-in stuck on the first try.
The hardest part on this particular item is that the outer spring doesn’t quite fit between the outside of the pill and the inside of the body, so I end up having to either leave out that spring or twist it in really hard. I’ve already dented the aluminum inside the body and caused a little bit to shear off. But now that I’ve got foil packed in as tight as it can go, I think I’ll just leave it.

It’s hard to measure objectively, but it does seem to heat up the body faster now. Could be my imagination.

ToyKeeper wrote:

ImA4Wheelr wrote:

Speaking of which, I got these glasses for my laser, but they really make UV light pleasant on the eye and you really see fluorescing objects so much better. I have several pair of yellow glasses, for some reason these work better. Haven’t really compared side by side though. So caveat emptor.


I picked up a pair of those. They really, really cut out the blue and purple light. Probably some green, too. It cuts out so much, actually, that I have a harder time seeing UV fluorescence with them than I do with cheap yellow dollar-store glasses. Even under a UV light, everything looks orange. So, that was a bit disappointing. However, they might also be rather useful for a test I’ve been meaning to run for a few years… getting myself to be sleepy earlier by wearing blue-blocking glasses at night.

ToyKeeper,

Thank you for reporting that and I'm very sorry for that. I'll find my post above and update it. I just learned yesterday in that 5mW laser thread that there have been issues with the newer batches of those glasses. I don't know if it is that or if I just am bad judge of colors and such.

They definitely cut UV and blue significantly (I used them for an almost 2watt 445nm laser). They are not effective for a green 532nm laser, but that doesn't mean they don't cut green wavelengths to some extent. I still really like them. For some reason UV light bothers me and I find these make using UV much less irritating.

I did warn that I could be wrong, but if you are in CONUS, I'd be more than happy to purchase them from you for your cost plus shipping.

I personally would go with a Solarforce host rather than the 502B host. They fit most p60 sized drop ins.

No, no need for that. Not every purchase is a win. :slight_smile:

I just wanted to let people know the glasses might be a bit stronger than necessary. They also fluoresce under UV, so they tend to make everything a bit hazy. They’ll be awesome if I ever get that purple laser I’ve been wanting though.

I have the 365 nm KD drop in and a 385 nm dropin that came in a Sky Ray S-R5 host. The 385 nm seems brighter but that is likely due to the fact that in puts out more visible violet light.

365 nm seems to work much better on US bank notes but they are about equal in fluorescing pet stains. Many plastic items, mostly red, orange or yellow, fluoresce brightly but some better at 365 and others more at 385.

So, do what I did, buy both.

Edit: The KD 365 nm does need a higher voltage to get good output. I have it in a Solar Force L2P with an extension tube running two 18650s.

Am I the only one who's KD drop in gets extremely hot on two cells?

Hot to the point where I half expect something to pop.