Astrolux FT03 Luminus SST40 Flashlight Review

Astrolux FT03 Luminus SST40 Flashlight Review

Here’s the Astrolux FT03 Luminus SST40 flashlight!  It has USB-C charging and can use a few different cell types.  It’s a nice light; read on!

Official Specs and Features

Here’s a link to the official product page.


There’s really only one version of this light, but it’s available with neutral white or cool white emitter.  Both are SST40, though.

Price and Coupon

This light retails for $45.95, but I have a coupon!  (And the coupon is quite good!)

Coupon Code: WFT03
Price after coupon: $31.99
Expires: 2019-04-30

Click here to buy the light at!  That’s an affiliate link.  Click it just for the heck of it, even if you aren’t a buyer!

Short Review

Great size, great throw.  USB-C charging, multiple cell size support… and $32!?  This is a fantastic deal of a light.

Long Review

The Big Table

Astrolux FT03 Luminus SST40 Flashlight
Emitter: Luminus SST-40W (CW)
Price in USD at publication time: $45.95
Cell: 1×26650
Turbo Runtime High Runtime
LVP? Yes
Switch Type: E-Switch
Quiescent Current (A): 0.00533 (with Indicator on)
On-Board Charging? Yes
Power off Charge Port with no Cell? Yes – all modes but lower
Claimed Lumens (lm) 2400
Measured Lumens (at 30s) 2313 (96.4% of claim)^
Claimed Throw (m) 875
Candela (Calculated) in cd (at 30s) 5950lux @ 6.191m = 228054cd
Throw (Calculated) (m) 955.1 (109.2% of claim)^
All my Astrolux reviews!

^ Measurement disclaimer:  Testing flashlights is my hobby. I use hobbyist-level equipment for testing, including some I made myself. Try not to get buried in the details of manufacturer specifications versus measurements recorded here; A certain amount of difference (say, 10 or 15%) is perfectly reasonable.

What’s Included

  • Astrolux FT03 Luminus SST40 flashlight
  • Spare o-rings (2)
  • Lanyard
  • Cell size adapter (26650 to 18650)

Package and Manual

The FT03 ships in a nice Astrolux box, with the light illustration embossed.  A sticker on the end describes the emitter tint, and on the bottom is an SKU sticker.

The manual is pretty and descriptive.  It’s a manual that’s generally been used in other lights since the firmware is one Astrolux uses a lot.  That’s fine… makes for nicely fleshed-out manuals.

Build Quality and Disassembly

No build quality complaints.

The anodizing feels nice.  Slick, smooth.  Not overdone with knurling, not overdone with fins in the head.

It’s impossible to get “clean” shots around here lately.  All this yellow stuff gets on anything black.

The head has very minimal fins for cooling.

The diamond pattern knurling has deep grooves.  So even though there’s minimal knurling, the body is still plenty grippy.

Here’s the light apart.  The cell tube comes completely off the head and tail.

Both the head and the tail have massive double wound springs.

The cell tube is not reversible, because one end (the head end) has unanodized square-cut threads, and the tail end has very lubed trapezoidal threads.

The included cell tube adapter is plastic and only fits around the body of the cell.

Size and Comps

Weight: Approximately 295g without cells
Dimensions: 170mm * 69.5mm * 34.5 (length * head diameter * body diameter)

It’s not really a small light.

Here’s the test light with the venerable Convoy S2+.  Mine’s a custom “baked” edition Nichia 219b triple.  A very nice 18650 light.

And here’s the light beside my custom engraved TorchLAB BOSS 35, an 18350 light.  I reviewed the aluminum version of that light in both 35 and 70 formats.

Retention and Carry

The included lanyard attaches to the tailcap, through two holes.  There’s a relief, which allows flawless tailstanding – a nice touch.

There is no pocket clip or anything else included for carry.

Power and Runtime

The FT03 has a few options for power.  Primarily, this is a 26650 light.  Or at least, at the maximum, it’s a 26mm in diameter light.  The cell capacity also allows for longer cells, like the 21700 variety.  I opted to use a 21700 cell, and really I’d recommend that for you too.  The reason is that 21700 cells are more easily available in higher drain abilities, and with this being a FET light on Turbo, you’ll benefit from a higher current cell.  I tested this exclusively with a high drain 21700 cell.  The included adapter also allows 18650 use.  Even that might be a better choice than 26650 because most 26650’s I know aren’t really high drain.  But if you need the larger capacity, by all means…

Below is a 21700 – the Vapcell INR21700.  As you can see the cell sort of swims in this big cell tube, but the springs do hold it in place well, and contact is good.  I’d really rather the cell adapter have worked for 21700 cells instead of 18650…

I didn’t really set out to “reset to turbo” multiple times, but the temp-based throttle kicks in so hard that I kept resetting the light for that reason.

The light never really shut off in either test, but did switch to such a low output, to render the light obviously in need of a charge.


The light also has onboard charging.  It’s unusual in that it’s USB-C.  This is a nice addition to lights, and I hope we see much more of it.

One interesting thing about the charging in this light is that if the cell inside is over 4V, the charge circuit can’t initiate charging.  If the cell has been charging since below 4V, then it’ll charge to full, no problems.

Pulse Width Modulation

Here are the PWM charts for the five discrete modes.  PWM disappears on the middle mode and Turbo.  I don’t consider it “bad” PWM though – I can’t notice it on any mode.

For reference, here’s a baseline shot, with all the room lights off and almost nothing hitting the sensor.  And here’s the worst PWM light I have ever owned.  Also one of the very first lights I ordered directly from China!

User Interface and Operation

There’s a single indicating side e-switch on the FT03.  It’s a responsive and clicky button.  The FT03 has NarsilM which is a ramping UI.  Ramping is all the rage, and I do like ramping just fine.  The Narsil version of ramping is good, too.  (Narsil also has a stepped option, which is what I generally opt for, at least for testing purposes).  The PWM tests above, for example, are of the stepped modes.

Just like another light with NarsilM I reviewed, the Astrolux S43, I won’t put NarsilM in a table.  I’ll link this awesome flow chart type table, and leave it at that.

There are two groups.  One group has ramping, one group has discrete modes.  It’s possible to switch between ramping and discrete easily.  The default is ramping, and to switch to modes, first turn on the light, then hold the switch for 3.2s.  It’ll blink twice, pause, and blink once.  At that point, click once.  This disables ramping.  Once this is done, put the light down so you don’t change other settings (which is very easy to do.)  There are other things you could do to expedite termination of programming, but just skip it, and wait.

NarsilM is wonderful firmware.  It’s extremely versatile, and possible to change many (most? all?) of the settings about the light.  I still don’t think it’s suited for a table, so I’ll leave the UI at the flow chart above, for now.

Again, here are the two manuals.  They’re worth reading since there are some differences from “normal” Narsil.  (These links are for the S43, but are .pdfs, unlike the .docx on the FT03 page.  I prefer the .pdf files.)

Click Here To Get: User Manual 1
Click Here To Get: User Manual 2 (Detailed Explanation Of The Manual)

Interestingly the FT03, like the S43, seems to always have a Moon mode activated.  So selecting a discrete mode group set can be confusing, since, when picking the default stepped group, which is 4 modes, you get 5 (since moon is always added).  It’s a little confusing.

The switch does have some indicating functions, too.

Modes and Currents

Mode Mode Claimed Output (lm) Claimed Runtime Measured Lumens Tailcap Amps
Turbo 100 2313 [FET]
High 38 950 1.10
Medium 7 174 0.36
Low 0.7 10 0.03
Moonlight ~ 0.01

LED and Beam

In this light is a Luminus SST40-w.  The reflector is very smooth and quite flawless, and the emitter has a white centering ring.

The light is available in both CW and NW options.  I have the CW, which should be fairly obvious from the photos below.  (Again, this is the default discrete mode option).

These beamshots are always with the following settings:  f8, ISO100, 0.3s shutter, and manual 5000K exposure.

Tint vs BLF-348 ( 219b version) (affiliate link)

I compare everything to the Killzone 219b BLF-348 because it’s inexpensive and has the best tint!


What I like

  • Multiple cell size options – particularly 21700 cells
  • USB-C on-board charging
  • Great throw and output
  • NarsilM UI
  • NW and CW both available

What I don’t like

  • The temp based throttle on Turbo is a little annoying.


  • This light was provided by BangGood for review. I was not paid to write this review.
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25 thoughts on “Astrolux FT03 Luminus SST40 Flashlight Review”

  1. There are settings to alter how the throttle operates. Temperature is the default, but you can extend the time to 7 minutes: or disable throttling entirely.

  2. Nice review, as usual, so thanks!

    I don’t think users should favor 18650’s in this light, as good 26650’s are available and can provide more current over a longer period than almost any 18650. The best 18650’s may start out at a higher output, but may fall below that of a decent 26650 within just 5-10 minutes. A high-drain 21700 is optimal, *BUT* buyers should be aware that this emitter was tested a couple years ago and found to burn out at around 9.5A (bond wire failure).

    Some FT03’s are consuming 9.5A with high-drain cells already, so I recommend using a decent 26650 as it may keep your current below 9A. Anything over 8.5A is likely reducing the lifespan of the emitter, but we haven’t seen reports of over-current failures so it’s unclear if perhaps today’s SST40’s are somehow more rugged than those previously tested. This light offers a lot of value and I really like mine, but the factory version is already pushing the emitter very hard; I don’t recommend using ultra-low-resistance cells or doing any mod that will increase the output even further.

    Astrolux does label the emitter as “SST40(2)” in the marketing and instruction manual, so it’s possible that this is an improved version somehow, but no one seems to take this idea seriously and most believe that the “(2)” has no real meaning. The Luminous website and datasheet certainly mention nothing about a new version, though they also don’t admit the existence of the Neutral White tint, so their literature is likely out of date.

    1. Thanks for the comment Rob! I don’t disagree with anything you said really. The 26650 cells are great (though I think finding a “high current” version is not quite as easy as it sounds), and for sure have higher capacity.

    2. The emitter that burned at 9.5A was an older design. The newer ones are much tougher. No one has burned an emitter in this light yet, even at 10A. This seems to not be an issue at all.

  3. As the author of the NarsilM firmware, your detailed review is much appreciated! I didn’t participate in the design, or driver design of this light, but really love the way it came out. It’s a little bit a large carry, but has great throw, specially if you swap to a more throwy emitter.
    Can’t agree more that it is a great deal at the discounted price – the performance and quality you get is unheard of.

    1. Hi TomE! Thanks for the comment, and welcome!

      Also thanks for NarsilM. Such a great firmware!

  4. I noticed that your runtime tests are cooled. How or what are you cooking the fan with?

    1. Not sure what you mean exactly, but I cool with just a small fan, always blowing on the light.

      1. Sorry for the typo as I meant ‘cooling’ and not cooking.

        I’ve been debating between this and the Catapult V6 because of its spill.
        Which one would you recommend?

        1. I’d probably buy the cheaper of the two.

          That also gets better throw, a ramping UI, and an arguably better tint.

          So I’d go with the FT03.

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  6. Nice review! I’m not sure what to make of the tailcap current measurements, though. It’s impossible for them to be that low. Maybe I’m interpreting them wrong? Are they in amps, from a single-cell battery? If so, 1.1 amps can’t produce 952 lumens. You’d need double that current, at least.

  7. Hello Zeroair,
    thank you for this nice Review of the Astrolux ft03 !
    But I must admit, that now I am a bit confused about the right (high drain ???) battery.
    I have ordered one Molicel INR-21700 P42A 4200mAh for the Astrolux ft03 – but not sure if I should use it.

    Would like to hear from you or others and their experiences with 21700 high drain batteries.

    1. That Molicel P42A should be fine. The light is made for 26650 cells, so the 21700 will have a bit of extra room, but it’ll work fine.

      1. Thank you Zeroair !
        Than you dont think what RobAllen said would be an issue (“… A high-drain 21700 is optimal, *BUT* buyers should be aware that this emitter was tested a couple years ago and found to burn out at around 9.5A (bond wire failure).
        Some FT03’s are consuming 9.5A with high-drain cells already, so I recommend using a decent 26650 as it may keep your current below 9A. Anything over 8.5A is likely reducing the lifespan of the emitter …”) ?
        Because the Molicel P42A could be discharged with up to 45 A.

        1. Right, I understood what you were asking, and no I don’t believe this is something that would concern me for use with this light.

          1. Thank you again, Zeroair !
            Also I discovered at the Shockli IMR 26650 5500mAh (Black) 2017 – this seems to be the best 26650
            Battery for high load.
            Compared with the Molicel INR-21700 P42A 4200mAh – both under 10A discharging , the current-graph of the Shockli 2017 is roughly 0.1 V under the Molicels current-graph at the first 0.75 Ah, the the two graphs approach slowly until they cross at 2.10 Ah.

  8. Comparing your graphs, the Catapult can maintain its High output close to its rated lumens at a longer time. With a consistent lumen, only then the throw distance can be maintained, correct?
    Whereas on this FT03, its high output mode lumens is falling off over time and hence its throw distance can not be maintained as well as the Catapult right?
    In terms of throw distance “endurance” numbers, would you still recommend FT03 over the Catapult?

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