[Review] Convoy S21A SFT40

Convoy S21A SFT40

At the end there will be a summary for those who like only particulars. In each topic I will bold the key sentences, so it will be easier to notice what's the most important. Enjoy!

This flashlight was provided by FlashlightBrand for the review. Check their store, I was genuinely impressed by the amount of flashlights they have: https://www.flashlightbrand.com

And here you can buy this flashlight: https://www.flashlightbrand.com/convoy-s21a-sst40-6500k5000k-kw-cslpm1tg-sft40-search-light-p4073429.html

Or other Convoy lights: https://www.flashlightbrand.com/Convoy-Flashlight-c134171/

Table of Contents:
- General parameters
- Package content
- Appearance, parameters
- UI, runtime and charging
- Waterproofness
- Light pattern, tint
- Usage and my experiences
- Gallery and Summary

General Parameters

Material: Aluminium alloy

LED: Luminus SFT40 6500K

LVP: Yes

Reverse polarity protection: Yes

Lens type: AR coated glass lens

Reflector: SMO (smooth, more throw)

Mode memory: Yes

Tailstand: Yes

Battery: 1x 21700 flat top unprotected (not included)

Modes: 4 modes 0.1% - 3% - 30% - 100%/12 groups (Biscotti), max current 6000mA, internal temperature protection (I changed mine to group 10: (1%, 10%, 35%, 100%))

Size (length x width): 123mm x 26.6mm

Weight: 88g

Package content

As usual, Convoy flashlights don't come with a bunch of stuff, this time it was the flashlight + lanyard.

Everything secured by bubble wrap, in small white package.

Appearance, parameters

S21A looks definitely like older and beefier brother of S2+

To be honest, it looks exactly like the S2+. It is just bigger, with slightly better heat dissipation than S2+. Still not good heat dissipation, but better, only because it is heavier.

S21A is a little bigger than S2+, but keep in mind it fits 21700 cell, so it is not that big. It is small, in fact. Look at this comparison:

And yes, my S2+ is doing great, no worries.

But a quick word about S21A:

Starting from the front, we have an AR coated glass lens

and an SFT40 LED, with max output of 1460 lumens. If you want something between thrower and flooder...ok maybe not between, let me start again: If you like throwers, but also want something with a bit of light spill, the SFT40 is for you. It has long distance with a bit of spill, so you won't end up with a laser-flashlight.

Greased square cut threads with o-rings on both sides. As we discover later, this is enough for very good waterproofness.

Tailcap with a mechanical reverse switch, good and universal option. The spring is good, not the thickest of all time, but enough for a small flashlight.

Sadly, it is hard to get to the diode, because there is no unscrewable bezel, so I was unable to check for thermal grease condition and if screws are tightened securely (if there are any screws).

UI, runtime, heat dissipation and charging


Biscotti-like UI with 12 groups, each with different modes set. Default group: (0.1%, 1%, 10%, 35%, 100%, strobe, bike flash, battery control). I don't find the last 3 modes that useful, so I switched to group 10, which is: (1%, 10%, 35%, 100%)


Pretty normal runtime, nothing special. I tested a 35% mode, about 648lm. It lasted ...

Here is the runtime graph of 35% brightness, 648lm:

It seems like Convoy moved a step forward from a flat brightness - runtime curve to rising curve :P

Heat dissipation

Heat dissipation is...is there. But I didn't expect anything great from that design. Don't give me wrong, it can dissipate heat, just look at the graph and my temperature readings:

Temperature after given time on turbo:

At 2min: 56°C

At 5min: 56°C

At 10min: 60°C

Brightness at 10 min: 600lm

It looks fine, but luckily I was curious if the flashlight would get hotter after my standard 10 min test. Unfortunately, it got. Oh boy, it indeed got.

After 10min (so total 20min after turning on) it reached 66°C and brightness decreased to 592lm.

After next 10min (so 30min total) it reached, and stabilized, at 70°C and 586lm. It was VERY hot, definitely way hot to carry, even the tailcap was at 57°C

It seems like the driver doesn't have a constant temperature checking + brightness decreasing, but checks temperature constantly and decreases it only once each time you power the flashlight on and it detects overheating. Maybe I'm wrong, but why it behaves like this then?

It was definitely not as bad as my tests with Mateminco S03, which reached 100°C and I brewed a tea using the flashlight

To this day I wonder why they don't want to send me flashlights for reviews anymore...


You have to manually remove a battery from the flashlight and put it in Li-Ion charger. You can remove it by unscrewing the tailcap. It's a lot of work, I know, but if it's not your day you can ask someone for help.


Did not observe any flickering on the lowest mode. Good


Convoy generally doesn't add an IP rating, but those flashlights are usually waterproof, and won't leak any water even when submerged. Is this the case here? Let's find out.

I submerged my S21A for 2 hours and it did not leak. Great.

Light pattern, tint

SFT40 LED, cool white, max output 1460lm (my measurements). SMO reflector in pair with a throwy LED gives...you guessed it, a good throw.

Light pattern is very nice, as mentioned, with a bit of spill. And also without a tint shift, definitely good.

Usage and my experiences

Convoy makes sturdy and durable flashlight. I think I will be actually using this one, instead of putting it on shelf...

Thermal regulation has been done not very carefully, as it triggers once. I don't know how the UI code looks like, but it seems that the thermal stepdown trigger is not looped. Or maybe I'm wrong.

I am now wondering if all Convoy flashlights have the same issue, and because S21A has poor thermal dissipation we can notice that here, and not in other flashlights.

In any case, it is not a deal breaker for me, as it is not dangerous - unless someone decides to glue the S21A to his hand and turn the turbo on... but in other cases it is not harmful.


Convoy S21A is a compact flashlight with minimalist design. Don't be fooled by its design, though. Equipped with 21700 cell, and thanks to SFT40 LED it can output up to 1460lm and work for many hours on lower modes like 35%. Waterproof rating (or lack of it) doesn't mean you can't use it in heavy rain. Convoy flashlights are generally waterproof, and this one is not an exception. Just remember to not glue it to your hand and turn max brightness...

+ Max brightness 1460lm

+ Small size

+ No tint shift

+ Waterproof

- Thermal regulation trigger is not looped, activates once every turn on

- Poor heat dissipation

Again, thank you FlashlightBrand for sending this flashlight.

FlashlightBrand official store: https://www.flashlightbrand.com

If you have any questions, put them below, thanks for sticking for a while :)

Nicely done mate. I picked up a couple of these exact lights to give to some buddies of mine. The first guy has about 4 people trying to steal it and is going to order 10 of his own to give as gifts. Muggles be muggling over this light. The second guy hasn’t gotten his yet(and might never get it) I like it too much. Lmfao

Edit: Did you mean S21A not M21A?

It is indeed a nice light, good as a gift. Simple and but bright. Good to carry in backpack.
:person_facepalming: It is S21A, thank you. For what ever reason, the M21a stuck to my head

Nice review, and thanks for the tea brewing idea! :+1:

Very informative. Your wall shot makes the beam profile appear excellent. Do you have any outdoor shots? Is the AR coating green or purple?

Thanks for the review, great as always. But the temperature control works indeed odd. Do you think it’s works this way with all Convoy biscotti drivers?

This review gave me a good solid belly chuckle!! The tea…brilliant.

What on earth happened to your S2+…?! I don’t think I’ve ever seen a light that was bent/crumpled like that!

I like the S21 hosts…prefer the B with the smoother surface but they’re just good platforms and a nice improvement over the venerable S2 for many people.

It could be. As mentioned, my other Convoy flashlights have better thermal management, so I didn’t notice.
I assume it is the same, why it wouldn’t be?

This review gave me a good solid belly chuckle!! The tea…brilliant.

What on earth happened to your S2+…?! I don’t think I’ve ever seen a light that was bent/crumpled like that!

I like the S21 hosts…prefer the B with the smoother surface but they’re just good platforms and a nice improvement over the venerable S2 for many people.[/quote
I was really angry one day and throw it really hard…
Just kidding, it was part of a project - testing flashlights durability.
Believe or not, the S2+ is still working!
I don’t think people in Mateminco think the same about the tea… :wink:

…so you’re the reason Mateminco doesn’t seem to want to sell us parts anymore? :slight_smile:

I don’t think so :innocent:

I am thinking about this overheating event not being looped in the UI. How it is possible it is not looped? It must be a simpler case: after detecting certain temperature, flashlight decreases brightness to a certain declared level. If the temperature rises again, flashlight still tries to decrease brightness to a certain level. But there is only one level programmed, and it already is on that brightness level. It seems quite easy to fix, the easiest way being to set a second brightness level in case of reaching higher temperature.
So for example if it reaches 55degC, decrease brightness to 60, if reaches 65 decrease to 40

Thanks for the review. I just ordered a pair of these for my adult daughter and her boyfriend. I wanted to get them something relatively compact, but with good battery life. I also wanted something that could be started at 100% from a tail switch, and have a relatively high candela.

Does anybody know the throw numbers for the S21A with the SFT40? I'm guessing it's something close to 430m given that the S21B culpm1 is good for 480m

Nice review… I haven’t landed on the host I want to try for this emitter yet… thinking a large side switch model like an M21*

It’s possible, the LED you mentioned has similar throw, just lower brightness and more pencil-like beam profile. SFT40 is as described in review, a bit more wide, good if you don’t like very narrow beams

Bump cuz these are currently about the same price as the s2+ w/ sft40. If you were going to get a color other than black or grey it’s actually cheaper than an s2+.

Trying to decide between getting a 3x21a w/ SFT40s or just duct taping 3 of these together.

A Reddit user measured around 350~380, but he used a 8A Kaidomain driver in a S21b. I’m pretty sure that the S21 a/b reflectors are the same, but I would love to know the numbers of the S21A with a Convoy driver…

Oh my bad its the 21b that i was looking at.

how much mAh battery do use on this test?