Any of the small AAA Olights for me. I have the Olight i3s eos (and the i3e) and find them brilliantly simple and reliable. The i3s on my neck lanyard inside my shirt has been there three years now without a single problem. And I use it a lot out here in the countryside.
I spend waaay to much time at Parametrek.
Here are 50 flashlights, 50 lumens or more, weighing less than 25 grams.
If I were giving a keychain light, it would probably be AAA or AA based with NiMH or Enerloops.
Missing are the Rovyvon line if that’s interesting to you, as well as the Klarus Mini One which is very similar to many other 10180 lights. Also several DQG lights, such as Hobi, Hobi+, Fairy, etc. A banggood search for “DQG” is always fun
What do you mean?
Quite clearly, the FOB style keychain lights are popular… but I specifically excluded them in my question. Their size and dimensions give them advantages in brightness, battery size/runtime, and maybe even durability, but I am trying to see if reliable options exist in the tiniest form factor.
As for AA/AAA lights, yes there are appealing options in that category, but do people actually put those on their keychains? 
The smallest AAA (i3E, EDC01) are maybe at the limit. I want something that is as imperceptible as possible, since I expect I would rarely use it anyway.
Rovyvon looks interesting, but I find it quite expensive and a bit on the larger side of the smallest lights. Klarus… well the comments in that thread make it less appealing. DQG also seems quite expensive, though the Hobi Plus with USB charging looks appealing.
In general, I find it difficult to pay more for a keychain light than a far more practical one like the SP40. To my mind, there would have to be a very special justification. And unfortunately I’m not getting the strongest impression on the reliability of these tiny lights.
Excellent points. To me, the more expensive keychain lights don’t make sense unless they are, and you’re also interested in, exotic metals.
I also don’t recommend my Klarus Mini One, or Klarus at all, but kind of meant to point out another notable copycat. The one thing it does right is having the head captive still when charging the light.
You’re also right on the reliability front. To my knowledge, all the small 10180 lights use the same “twist more to push the button” approach to give two modes, and that does not lend itself to reliability. Some execute it better than others, but there are none that I would really trust. It’s a shame because I rather like the form factor as well as the built in charging. Maybe I’ll think of a way to fix it.
I will say, the cheaper Rovyvons have served me well as gifts for muggles. Their keychain lights generally suddenly become brighter than any light they’ve ever held, unless I’ve handed them my other lights before.
The only reason I’d be interested in exotic metals is to avoid anodized aluminum from getting a scratched appearance. However, I am careful and take care of my stuff. Generally I’d prefer aluminum for price and its physical properties.
I think one or two others had captive heads too but can’t remember which. I’m surprised they don’t advertise it, since it’s a very relevant feature.
Many 10180 lights have the “twist for on, and keep twisting for high”, but some have the “twist on and off multiple times to change modes”. Not sure which is preferable. I’ve lost track of which lights have which design.
Interestingly, many AAA lights are cheaper than 10180 lights. I’m in no hurry, so I’ll keep looking for reviews and deals. If nothing satisfying comes up, I might try a small AAA light and see how I feel about the size/weight and lack of USB charging, but at the moment I haven’t given up just yet on the tiniest ones.
BLF-348 doesn’t have onboard charging, but otherwise fits the bill. (It’s even high CRI.)
https://www.gearbest.com/led-flashlights/pp_227505.html
Nice light, nice price, but there’s no way an 89mm long object is going on my keychain.
I don’t know why I keep having to repeat this, but I’m looking for the SMALLEST tubular lights around 40mm long. ~60mm would be a stretch, and considered only if nothing in the smallest category is suitable in reliability and price.
Of course it’s your choice, but I hope you realize that those dimensions either means low lumens or ridiculously short runtimes.
Yes, and neither of those points really matter for the keychain use-case.
The typical (100/10 lumens, 0.5/6 hours, High/Low) specs are quite sufficient for something imperceptibly small and light on a keychain that is present at a rare moment where light is needed briefly.
I do, too.
I have one with the possibility of lockout.
the Olight i3E now lives on my keys. it’s great. really small and light and so far perfectly reliable. barely feel it in a suit jacket or pants pocket with the keys. last week i tried switching it out for a nitecore tube which is just slightly lighter and rechargeable but it didn’t last a day. I’m typically using it to look for something under a table in a bar or in a staircase that doesn’t have lights or power yet and the one mode beam is great for that.
the tube is omni directional, not good for looking at things, and I think will live on a backpack or something as a backup camping or location light.
I concur. Although my TIP CRI is the 2018 version without lockout, I cover the buttons with the clip to avoid accidental activation. It has never turned on in my pocket.
Mine was from the first batch.
I believe the second batch didn't have lockout.
I don't know what happened after that, but I wouldn't get one without lockout.
Jetbeam Mini-1 has served me well for years.
My solution was a no compromise carry of a 10440 light and a similar sized knife hanging separately on a corner of my pocket.
My key-chain only has keys on it.
The list prices from DQG are high but there are serious deals sometimes. I’ve had a Fairy for $10. Twice. I think I’ve seen Spy for like $12. Hobi? I wasn’t interested.
I never saw the utility of a light that’s closely tethered to a noisy clump of metal. For me, “keychain light” is one of these
https://www.amazon.com/dp/B000LNWVY4
to literally light up the hole the key is supposta go into.
Even my Glarees (about as lightweight of an AAA twisty as you’re gonna get) I keep separate, and not attached to a pile of keys.
nydude The Olight i3E is appealing as an AAA light since it’s among the smallest in that class. I do wish it had a low mode though. I agree, some directionality is useful for this type of light.
BOO5TED The Jetbeam Mini-1 is quite nice, if only they cut the price in half…
chinooker That’s a reasonable solution if it works for you. I like having just one cluster to bring with me, plus I prefer not having the knife visible since it seems to make people uncomfortable. How long is your knife? Mine is 65mm and although it’s the bulkiest and heaviest item on my keychain, it’s been so useful to have it with me all the time.
Agro Those prices are more like it! Though the lack of USB charging on several of them is still disappointing. At least the Hobi Plus has that. When/where were the deals?
Lightbringer Don’t worry, photons aren’t bothered by noise. 
I think that argument would be more relevant for a knife on a keychain, and yet it’s been very useful for me. To each their own! Gotta say, for an AAA light at 70mm, the Glaree E03 seems pretty nice: moonlight/low/high and weighing 12g. Price isn’t terrible, but it’s still double the Sofirn C01S which lacks moonlight, but has high CRI…
After reading some more, the RovyVon Aurora A3 upgrade seems interesting. At 57mm long and 19.5g it’s 1.5X as long and 2X as heavy as the smallest options, but it compensates with a 260mAh battery, 2lm moonlight mode, and crazy (short duration 450-650lm) brightness. Plus there’s no head to unscrew/lose and build quality looks good. So it might be something to rationalize, but the 30+ USD price plus shipping is hard to swallow.
I won a RovyVon Aurora A3.
I love it.
It's amazingly small and bright (for its size.)
It is pricey, though.