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  • Stephen Knight

Flashlight Reviews: Convoy T4, S21D, and M3-C

Updated: Feb 10, 2023

Convoy is one of the best budget flashlight/torch manufacturers around, and this article contains mini reviews of three Convoy flashlights:

  • Convoy T4 - 2xAA/14500 battery, 1000 lumens max (with 14500), SST-20 6500k emitter.

  • Convoy S21D - 21700 battery, 2000 lumens max, 4xNichia 519A 4500k emitters.

  • Convoy M3-C - 26650 battery, 4300 lumens max, Cree XHP70.2 5000k emitter, USB-C charging.

These reviews are written from the perspective of a flashlight enthusiast, light painting, and night photographer.

Convoy T4, S21D, and M3-C
Convoy T4, S21D, and M3-C

Convoy T4

Review updated 17/07/22 - 13 mode user interface, and 519A options.

Whilst flashlights with Li-ion batteries are all the rage now, most peoples first flashlights used AA or AAA batteries. However, the quality of these lights generally varies from cheap'n'nasty to overpriced'n'nasty. I'm sure a few gems exist, I just haven't found them yet! Convoy's 1xAA T2 and 1xAA/14500 T3 lights have proved popular, and now Convoy have released the 2xAA/14500 T4 for more lumens and/or longer runtime. I have only reviewed the T4 with rechargeable NiMH AA batteries and not with Li-ion 14500s (as if I wanted to use Li-ion batteries, I would purchase a Convoy S2+ instead). There appears to be no reverse polarity detection, so make you insert the batteries the correct way (+ve end at head). Some reviewers have found that non-rechargeable Lithium batteries (such as Energizer Lithium Ultimate) do not work in the T4.

The T4 has a long 21mm diameter tube to fit 2xAA/14500 batteries. The head size is larger than many lights in this class at 27mm. For light painting photographers, this means that it fits Light Painting Brushes (Universal Connector), Light Painting Paradise, and T8 Tubes systems with ease. There is however no side clip for the latter, though a side clip is expected to be released soon. The light is available in grey or orange, though more colours may be available in the future. The Convoy S21A/B diffuser will fit the T4.

When released, the T4 was advertised to have the basic 4 group user interface, however it was subsequently found to use the 13 group user interface. By default, the light uses group 1 with 1%, 10%, 30%, 100% and last mode memory for all modes. A full click is on/off, half click to advance mode. I would advise sticking with this mode group for most use cases. However, by following the instructions on Convoy's product page, and probably quite a few attempts, it is possible to change the settings to one of 13 mode groups, or toggle mode memory on. Some of these mode groups contain bike flash, (which creates a cool pulsing effect useful for light painting), and strobe. Unfortunately the strobe is alternating frequency - please Convoy change your strobes to constant frequency (e.g. 10Hz) as it will increase sales to light painters.

As is usually the case with Convoy, there is an excellent range of emitters including Luminus SST-20 (4 CCT options), Samsung LH351D (5 CCT options), Nichia 519A (7 CCT options!), Nichia 219C 4000k, and Nichia 219B (3 CCT options). All are at least 90CRI, expect for SST-20 at 5000k and 6500k. The Convoy T4 is one of very few AA/AAA flashlights which offer warm white and high-CRI options. I tested the <70CRI SST-20 6500k emitter to get maximum output from the available emitter options, for use with light painting tools. This does the job, but does have a slight green tint, increasingly so at lower brightness levels. Optics are similar to the Convoy S2+.

With 2x14500 batteries, the max current is 3A. With 2xAA batteries, the max current is 1.5A.

Testing was performed in 27C heat, indoors, no cooling, and 2x Ikea Ladda 2450mAh NiMH AA batteries. Measured brightness of each mode at 30 seconds was <1lm, 65lm, 190lm, and 420lm. On the highest mode, the light sustained >390lm for the first 15 minutes, which is very impressive for a 2xAA flashlight. The brightness remained above 250lm for 90 minutes, and then declined in brightness until it reached "moonlight mode" at 120mins. The light ceased producing light at 150mins and 0.91V per battery. With 14500 batteries, I would expect almost double the maximum brightness. Pulse Width Modulation (PWM) was not detected on any mode.

When used for light painting photography with a 2mm diameter Plexiglass Rod tool, I was surprised that the Convoy T4 required the same photographic exposure as some 1,200 lumen Li-ion 18650 based flashlights. This impressive performance may be due to an optimal "intense" hotspot with the SST-20 emitter.

Convoy T4 and 2 NiMH AA batteries
Convoy T4 and 2 NiMH AA batteries

The Convoy T4 has similar optics to the S2+
The Convoy T4 has similar optics to the S2+

The Convoy T4 has the same optics as the S2+
Convoy T4 beam profile with SST-20 6500k

The Convoy T4 can compete with Li-ion flashlights for Light Painting
The Convoy T4 can compete with Li-ion flashlights for Light Painting

Things I liked:

  • Good value for money (US$21).

  • Excellent output for a 2xAA light - 420lm.

  • Good sustained brightness.

  • Excellent range of emitter options, including 95CRI and range of CCT options.

  • Default mode group is easy to use - 4 brightness levels with last mode memory.

  • No detectable PWM.

  • Compatible with some light painting systems.

Things I didn't like:

  • Alternating frequency strobe (not in default mode group).

  • No side clip (though it is coming soon).

Other than for specialist use cases (such as the Ledlenser P7QC), the Convoy T4 is by far the best AA/AAA flashlight I have tested. It is priced competitively with hardware store grade flashlights, yet has a much better user interface with last mode memory, high-CRI and warm or neutral white options that you will rarely see in AA/AAA flashlights. Whilst I personally prefer to use more powerful Li-ion lights, this is a fantastic flashlight for use by people who either shouldn't be using Li-ion based lights (such as children), or people who prefer to use AA batteries instead of Li-ion. Sadly the alternating frequency strobe means that only the continuous modes (and bike flash) are useful for light painting.

For use with light painting tools, go with the SST-20 6500k option. For night photography illumination, go with high-CRI 519A options in your desired colour temperature/CCT.

If you want to know the best rechargeable AA NiMH batteries and chargers for use with this light, check out my Battery and Charger Buying Guide.

Convoy S21D

Review updated 17/07/22 - 519A CCT options, more drivers, and more lens options.

The Convoy S21D is an evolution of the slightly larger triple emitter S12, which has previously been my go to light for use with backlight scanners, and bright high-CRI illumination. This light, replaces the triple LED emitter/reflectors, with quad high CRI LED emitters and TIR lenses. The light uses a single 21700 battery and sits somewhere between what I would call a compact and medium sized light, with a 27.2mm body, and 32.1mm head. It is in the same size class as the more expensive Acebeam E70-AL (95 and 70CRI options), and Olight Seeker 3 Pro (<70CRI only). There is no internal USB charging for either the flashlight or battery, which is something increasingly expected in 2022. It is compatible with Kaidomain D37 diffusers, U-shaped tripod mounts, and is a good choice for use with backlight scanners. For some reason "S21C" was printed on the light instead of "S21D".

The S21D has a single tail switch, and uses Convoy's 12 mode user interface, which allows the user to select one of 12 different modes. I usually just use Mode 3 - 100%, 35%, 10%, 1%, 0.1%. A full click is on/off, and half click to advance modes. As always with Convoy lights, no instructions are included, but can be viewed on the product page at Convoy Flashlight Store. Mode memory can be turned on or off. There is a strobe, but unfortunately it is alternating frequency, however as the use case of this light isn't optimal for use with light painting tools this isn't a huge issue (The alternating frequency strobe needs to be replaced with a constant frequency strobe on the S2+ and S21A/B please Convoy!)

The light is available with Nichia 219B and 519A emitter options, 219B in 4500k only, and 519A in 7 CCT options from 2700k to 5700k. This test was with the "original" 95CRI Nichia 519A 4500k emitter, which is proving an instant hit with flashlight enthusiasts. This emitter results in a very neutral tint, very close to the black body line, which is generally better for photography than the "rosy" 219B. It also has a good efficiency for 95CRI, noting that high CRI lights will produce less lumens/watt than more common 70CRI flashlights. Possibly due to the TIR optics and low current to each LED, the CCT was more around 4200k than 4500k.

The TIR optics result in a very floody 60 degree beaded/diffused hotspot, and 170 degree "wall of light" spill beam. I really like this floody beam profile with no hard edge to the beam. There is still enough throw to illuminate more than 100m. If you require more throw, but with a wide spill beam, then consider the recently added options of 10 degree flat, 10 degree beaded, and 30 degree beaded. Convoy now sell a "party bag" of all lens options.

Testing was performed with the 8A CC driver option. Testing was inside, no cooling, 27C heat, and with a 4000mAh Samsung 40T 21700 battery. For each mode (group 3), I measured 2055lm, 850lm, 260lm, 20lm, <1lm. On 100% mode, the light managed >2,000lm until 105secs, and then slowly ramped down to 790lm at 10 minutes, where the brightness stabilised. Heat was a little too high for my liking. On 35% mode, the light sustained 850lm, and runtime was 100 minutes until low voltage warning started to flash at 3.05V. PWM was not detected on any mode. There is also a new 12A FET option that will produce higher turbo output, but faster step-down, and lower sustained brightness. I recommend the 8A version.

Convoy S21D with 21700 battery
Convoy S21D with 21700 battery

The Convoy S21D has quad TIR optics
The Convoy S21D has quad TIR optics

The Convoy S21D has a very floody beam profile
The Convoy S21D has a very floody beam profile

The Convoy S21D produces a wall of light
The Convoy S21D produces a wall of light

Things I liked:

  • Good value for money (US$36-$41).

  • Good high CRI max brightness/size.

  • Good high CRI sustained brightness/size.

  • Gradual brightness step-down.

  • Excellent range of colour temperatures/CCT.

  • Excellent range of beam profile options.

  • Diffuser, U-shaped tripod mount, and backlight scanner compatible.

Things I didn't like:

  • No USB charging.

  • Runs very hot on 100% mode.

The Convoy S21D is a fantastic, compact, (very) floody, and budget 95CRI flashlight. Sustained performance is pretty close to the excellent Acebeam E70-AL 95CRI at half the price. It is likely to replace my use of the S12 for use with backlight scanners.

The range of colour temperature/CCT, optic, and driver options means that there is a Convoy S21D model to meet most illumination requirements. USB-C charging or a 21700 battery with charging port would be a product improvement, and one may be in the design phase!

Convoy M3-C

Convoy offer a somewhat confusing range of medium sized, single battery flashlights with USB-C charging, side e-switch, and large format LEDs (XHP70.2 and GT-FC40). These are the M21D, M21E, M21F which use a 21700 battery, and M3-C which uses a 26650 battery. Despite each of these lights having similar performance, but different reflectors, Convoy don't really make it clear which ones are more suitable for floody or throwy use, and in fact, none are true flooders.

The M3-C uses a single 26650 battery (I would advise purchasing with the optional Keeppower 5500mAh battery instead of the Liitokala 5000mAh option), It has a 35.1mm tube, and 48.1mm head. The side switch is located 40mm from the head. which means that this light can be used with backlight scanners. This is an excellent flashlight for backlighting, but a tripod clamp (such as SmallRig Super Clamp) is required to mount this light on a tripod. Convoy make a dedicated diffuser for this light.

The USB-C input is located on the opposite side of the light to the switch, and charges at up to 2A. Charging terminated at 4.17V. Unfortunately I could only charge with a USB-A to USB-C cable, and was not able to successfully use the powerbank functionality to charge a phone with a USB-C to USB-C cable.

The M3-C uses Convoy's ramping user interface, which has a good compromised between functionality and ease of use. Instructions are provided on the product page. It is possible to use ramping brightness, or change to stepped brightness (1%, 10%, 40%, 100%) with last mode memory. Moonlight mode (0.2%) is available, as is 100% only Tactical mode, and Lockout. As night photography requires consistency, I prefer the stepped brightness mode. The ramping is a bit too fast at lower brightness levels in my opinion. There is no strobe, but as this light does not fit light painting connectors, that is not an issue. The clicking required to change settings, such as 6 clicks from ramping to stepped brightness needs to be done quite quickly - this took a few attempts to get right!

The M3-C has options for either the 70CRI XHP70.2 for maximum output (4 CCT options 3000k, 4000k, 5000k, and 6500k), or 95CRI GT-FC40 (4 CCT options 2000k, 3000k, 4500k, 5500k) for decent high-CRI output. This review is of the XHP70.2 5000k version.

I was hoping for a wide floody beam to match the large format LED emitter. Unfortunately, the spill beam angle of the orange peel reflector is only 70 degrees, The similar format Sofirn SP33S is 100 degrees. The XHP70.2 emitter produced as expected the Cree "fried egg" beam, with a warmer hotspot and cooler spill beam - this isn't really an issue in real world use. The GT-FC40 version will have less tint shift. No PWM was visible on all modes.

Testing was inside, with no cooling, 24C ambient, and Keeppower 5500mAh battery. Measured brightness on the stepped modes (at 10 seconds) was 25, 460, 1320, and 4430 lumens. On 100% turbo mode, the light managed to stay >3870 lumens for the first 90 secs, and then ramped down gradually to 1440 lumens at 8 minutes, where the brightness stabilised. The light stepped down to 1% mode at 100 minutes. On 40% high mode, the light sustained more than 1300lm for 150 minutes, before stepping down to 1% mode. 40% High mode seems to be under-performing for some reason, and my tests show it to be approx. 30% of max brightness.

Convoy M3-C and 26650 battery
Convoy M3-C and 26650 battery

The Convoy M3-C has USB-C charging and powerbank functionality
The Convoy M3-C has USB-C charging with limitations

Convoy M3-C has a 70 degree reflector
Convoy M3-C has a 70 degree reflector

Convoy M3-C beam profile with XHP70.2 5000k
Convoy M3-C beam profile with XHP70.2 5000k

Night photo using the Convoy M3-C
Night photo using the Convoy M3-C

Things I liked:

  • Good value for money (US$42-$53)

  • Good maximum brightness/size - 4430lm.

  • Good sustained brightness/size - 1440lm.

  • Gradual brightness step-down.

  • Good range of emitter options - high/low CRI, and 4 CCTs from warm to cool white.

  • Good user interface - choice of stepped or ramped brightness.

  • USB-A to USB-C charging, optional 26650 battery.

  • Diffuser, clamp tripod mount, and backlight scanner compatible.

Things I didn't like:

  • Spill beam could be wider.

  • 40% mode was under-performing (approx. 30% of max brightness).

  • I could not get charging or powerbank functionality to work with USB-C to USB-C cables.

I rate the Convoy M3-C as the best medium sized flashlight for illumination purposes for night/light painting photographers. This is due to the good user interface, output, choice of emitters and CCTs, diffuser and backlight scanner compatibility, and tripod mountable (with a clamp). It can perform almost as well as previous generation "Soda Can" flashlights such as the BLF/Sofirn Q8, but with just a single battery. However, some more compact 21700 flashlights such as the Acebeam E70-AL and Convoy S21D are hot on its heels, particularly for high-CRI.

I would like to see Convoy add a proper floody model to their USB-C rechargeable/side switch M range, with a 90 degree spill beam whilst maintaining excellent thermal performance. I would also like 40% mode to be 40% and not 30%.


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Mark Lisk
Mark Lisk
Apr 07, 2022

Hi, does the Convoy T4 only have 4 modes? or does it have the 13 group driver? I'm confused because Simon says it has the 13 group driver but the description on Aliexpress says 4 modes. I have seen in other reviews that it has strobe, bike flasher and battery check modes too. Also can mode memory be turned off?

Stephen Knight
May 31, 2022
Replying to

I would expect that for 95% of users would never move beyond the duplicated mode 1 anyway, and few people use lithium primaries, though it is a limitation. For those that use NiMH or Alkalines, the T4 leads it markets segment due to good output and range of LED options.

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