[REVIEW] Wurkkos TS21 (SST20 4000K, Anduril 1) - An Excellent Budget Enthusiast Light

This review is for the Anduril 1 version of the light, which has been superseded by a newer version offering Anduril 2 and powerbank functionality:

The lastest versions (late 2022 - 2023) of this light now feature flashing pads! The MCU is now the ATTINY1616 which has a different flashing process than the older model, some changes were also made to the button indicator behaviour

So you guys have all seen several (great) reviews of this light already, I’ll just share some thoughts and opinions in this written portion here.

First, test results (all done with the included 5,000mAh cell):

Wurkkos TS21 (SST20 4000K) Review - Test Results

High & Turbo Step-down:

High & Turbo: first 30 minutes

High & Turbo: First 30 minutes (zoomed y-axis)

High & Turbo Total Runtime

High & Turbo Total Runtime (zoomed y-axis)

Turbo Temp Regulation (% Relative Output) - 45C, 50C, 55C, 60C

Max Regulated Output (1 hour run)


  • Turbo Max Output (Startup): 2,237 Lumens
  • High (Default Ceiling): 1,096 Lumens
  • Max Regulated Level: 126 Lumens
  • 1/150: 0.24 Lumens

cd/lumen: 3.7 (8,277 max cd)

AUX LED current draw:

  • High: 3 mA
  • Low: 0.08 mA
  • Off: 0.03 mA

Moonlight (1/150) Current Draw: 2 mA

One of the most talked-about issues with this light is the thermal step-down. It is very aggressive, and I tested four different target temps (configurable in the UI): 45C, 50C, and 55C.

Note that in the graph, 50C actually performed a bit worse than 45C, which I suspect is due to ambient temperatures, as I don’t have a very well-controlled environment… as always, my measurements are not super accurate, so take them for what they’re worth.

I found that 60C made for a significant improvement, and while normally I would not set my lights this high, I don’t find it to be a problem here - it still steps down quickly enough that it doesn’t get too hot to hold.

This light uses the 4000K 95CRI SST20s, which I think are the perfect match for value, performance and color rendering. They’re not the most accurate, but I still find them very pleasant to use.

Even better, the TS21 uses a custom optic (as stated by Wurkkos) which provides a very clean and very nicely-shaped beam. This is my favorite part of the TS21, the actual light quality is very nice and highly functional.

  1. CHEAP
  1. Excellent beam quality
  1. Anduril!
  1. 21700!
  1. USB C charging port (with a great cover!)
  1. AUX light in the switch
  1. Small enough to carry with ease


  1. Sharp thermal stepdown
  1. No flashing pads :frowning:
  1. Mediocre efficiency

My thoughts:

The TS21 is a fantastic budget option for those looking to get into enthusiast lights, those interested in Anduril, and/or those wanting a very functional light with all the fun features. It also makes a great gift for flashlight nerds. It comes very highly recommended from me.

Note that Wurkkos did send this light (free of charge) for review, at my request. All test results and opinions are my own. Thanks for reading/watching!
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Thank you for the great review and charts! Nice to see some objective info to clarify what my experience has been. Great job of explaining the thermal management.

In another thread I said that the ATR worked great for me and it does as a toy. As a tool I think it is important to note that it can definitely be an issue as if the light is needed for more than a few minutes the ATR can drop the output to a level that affects its usefulness as a tool. You did a nice job of demonstrating that by upping the max the output sustained is much more useful as a tool. I think there is also an output level where the light will maintain higher lumen due to the ability of the ATR. Perhaps one or 2 steps down from top of ramp?

I noticed that my SC31 Pro with Andruil seems to have a much less aggressive ATR. Did not occur to me that this is just the manifestation of your con 3. The SST 20 4000k is my favorite emitter. Efficient it is not;-( Don’t much care for the 6500k SST 40 but it is much more efficient and you can certainly see it in the difference in the ATR.

Seems to me that there must be a point on any light that say you set the temp to 60c, for a given emitter, you should be able to maintain a certain amount of lumen. Sustained output? Thermal limit of the light? In other words if you put 3 Amps of heat into it the light can dissipate 3 Amps and maintain the 60c. Whatever that number is for a particular light and DTP, that would be a very useful thing to know. How many amps can a given light dissipate at a reference temp? Unfortunately, this is where the wonderful sst 20 would not fare too well. The rather ugly sst 40 would be able to sustain about 2x the lumen while dissipating the same amount of heat.

What is the max regulated level? Can one set it?

Glad you liked the review!

I’m not sure if this is true, my understanding is tha Turbo actually lasts longer relative to the amount of heat produced, since the heat is generated by the LEDs instead of the components (as a reuslt of direct drive), and the temp sensor takes longer to heat up as a result. Any lower than 150/150 and the components would take more of the current and will produce more heat.

Yes the efficiency definitely makes a difference. It is also worth noting that the SC31 Pro has just a single emitter, so efficiency aside, it’s not really capable of putting out as much heat as a triple like the TS21.

It definitely would be useful to have a standardized number like this, it’s a great idea. We have lumens and candela, it would be nice if we had a number that would tell us total heat dissapation at a current draw - there must be something like this already I feel, but I don’t recall seeing it in the flashlight world. This would of course change with the emitters/components as you say.

The maximum regulated level is limited to the highest amount of current regulation provided by the onboard 7135 chip, which is rated for 350 mA, so it can’t be adjusted. Anything above 350 mA (126 lumens on this light) will be more current than the 7135 is designed for, so the FET will be used to provide more current for higher outputs - which is much less efficient.

Thanks a lot for the review

The TS21 is a must have. Great review.

Waiting on new color releases.

Thanks for making such a great light, and for sending it along!

I would love to see the purple color from the FC12. The champagne on the updated version looks very nice too

In hindsight, I figured posting here instead of as a YouTube comment might make this information easier for others to find - I hope that was okay.

Context: I left a comment mentioning trying getting this flashlight for a non-enthusiast family member due to having Anduril 2 with Simple UI.

Finally got the flashlight in! Ordered Nov 3rd, arrived Nov 30th - partly processing, partly 15 days of traveling who-knows-where within the United States. Everything’s intact and looking great.

My Wurkkos TS21 is running a 2021-06-06 build for model 0612 (Sofirn BLF SP36…? I wonder if they customized the thermal configuration), defaulting to Simple UI, with AUX LEDs set to “low” when off and “blinking” for lockout, as per the Anduril configuration for BLF SP36 and BLF Q8 . This one has an orange AUX LED instead of green, which matches the champagne color.

It stopped charging at 4.16 volts according to my digital multimeter, which is nice - less wear on the battery. My meter also claimed 10.3 mA for high brightness AUX LED, which seems… inaccurate. The low brightness mirrored yours - 0.1 mA (likely rounding up as that’s the lowest the meter measures).

While I’d be happy giving that to someone as is, since I have the opportunity to pre-configure it, I did so:

  • Calibrated the temperature sensor (ambient: 19.4°C)
  • Raised the thermal limit to 52°C (53°C+ got kind of hot, 52°C only stayed hot if top of ramp is repeatedly pushed)
  • Enabled 10 minute hybrid memory to the highest regulated level (I really wish this was a build that had auto-lock available in Simple mode )
  • Lowered Simple UI ramp minimum to 1

As you noted, flashing pads would’ve been nice so the community could tinker with improving the thermal behavior, update to include new Anduril 2 features, etc. I also could have baked in my custom configuration so factory resetting would restore everything. But still, it’s a nice, solid flashlight.

I’ve put together a simplified Simple UI text manual to print out alongside Wurkkos’ included manual, 1 page when printed at 116% zoom in Firefox:
Anduril manual - v2 - simple mode, Wurkkos TS21.txt

Fingers crossed this goes well when I have a chance to give it to the aforementioned family member. I’ll try to remember to follow up after they’ve had some time to use it.

You mention the "bug" of the blue switch LED lighting up on it's own - wondering if we can find a cause, possible fix, or it's just built-in into that USB-C controller chip.

How is your relative doing?

Who knows? Is there enough space under the optic for 3x xhp50 leds?:laughing:)

Newer models do have flashingpads

Can you add at the top, that the Andúril 2 got an hardware revision which added Pads?

Regarding the blue switch LED
I can get the old one get blue when I go to TURBO and ramp straight down.
The newer version stays orange! Sth. seems changed

I hope anybody with a TS21 from Feb 2023 and newer can confirm this.,

Parsitic drain with switch LED low
old: 0,16mA (every 20sec 0,4mA bursts)
new: 0,26mA

Parsitic drain with switch LED high
old: 13,8mA
new: 2,0mA

Despite drawing more the newer switch LED in low seems a bit darker, but high draws now 1/7

For me the only thing people can complain about the Wurkkos TS21 is they advertise 3500lm and the 4000K SST20 is around 2500lm.
But that’s because of warmer tint and higher CRI.
The rest seems fixed and you get flash pads.

And there is a short tube you can buy from Wurkkos but named 20350.
(inner diameter fits 21mm) 20350 Short Tube, for Wurkkos HD20, TS21,TS22, TS25, compatible with all flashlights with a 21700 battery.

2 Thanks

Pardon, I missed the notification email for this (and now BLF is on new forum software, neat).

Last I recall, this relative has been rather happy with their TS21, finding simple mode totally usable. They’ve not been getting around much (recovering from back surgery, etc), granted, so I don’t think they’ve needed to use it much.

Regarding your later remark on flashing pads and fixing the LED high current, that’s awesome! With that, alongside updating Andúril 2 I could bake in temperature calibration and other settings for someone at the firmware level.

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What changes were made to the button indicator behavior?

When the older TS21 is in FET-level high output/Turbo, the switch button LED immediately displays solid Orange, but then changes to solid Blue when the flashlight is shut off.

When Wurkkos updated the TS21 with the Attiny1616 MCU and it’s Andúril-2 firmware, that odd secondary behavior of the switch button’s LED going to Blue after the flashlight was shut off was eliminated. Solid Blue is now dedicated to battery voltage indication, blinking while charging, and turning solid Blue when complete.

As for the switch button LED’s Orange auxiliary indicator duties (aka: locator beacons), nothing has changed in terms of its HI/LO/Solid/Blinking behavior. (FWIW, I personally don’t notice any difference in the high or low level output between the TS21’s two versions.)

More importantly as mentioned in posts above, the parasitic draining issues attributed to the switch button’s LED, were improved with the new MCU.

In my opinion, the Wurkkos TS21 v2 with flashing pads is the best FET-driven, triple emitter flashlight ever produced in the budget category. Discontinuing this model is unfortunate as it could be easily improved with a better Andúril-based driver and ala Emisar-like optional emitter choices.

Personally, I would have loved for @Wurkkos to produce a single SFT-40 version with custom-tuned TIR optic!

Ok. Mine behaves like luxwads does in his video. Just orange instead of green as mine is the grey model. While running on the 7135 channel, it’s low orange. When it goes past the linear channel, it turns high orange. This is the same regardless what the aux brightness settings it has.

Agreed it’s a good light. I’m still having I guess a hard time getting used to the beam, as I’m not used to such a huge hotspot that it almost looks like there’s a hole in the beam. But it’s just because the bottom of the hotspot hits the ground many many feet closer than the middle so the middle looks dimmer

You last point. Wouldn’t this basically be the sofirn if22a?


OIC. You want the same form factor but a single emitter with a tir. That does sound excellent. I have a noctigon dm11 on the way to me so it’ll be my first tir designed light. Went with xhp50.3 hi for a more all around beam. And I don’t like the sft-40

I’m not upset with the beam pattern. I have plenty of more throw oriented type lights. I’m just not used to a triple yet. But thank you for the suggestion

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