Acebeam M20 Flashlight Review

Today I have a small Acebeam M20 Flashlight review. It’s a twisty with good knurling and easy operation. Read on for testing!

Official Specs and Features

The Acebeam M20 flashlight seems wiped from the internet now and I can’t find an official link!

Versions

There’s just one version, but there are two body colors: black (seen here), and tan.

Price

The Acebeam M20 flashlight seems wiped from the internet now and I can’t find an official link! I recommend that you shop at killzoneflashlights.com for the newest and updated version of this light!

Short Review

I like the knurling on this little guy, and the user interface is simple and intuitive enough. I don’t care for the 6500K and XP-G3 is fairly renowned as not a favorite emitter. But at $20, this isn’t a bad gift or keychain light.

Long Review

The Big Table

Acebeam M20
Emitter:	Cree XP-G3 (6500K)
Price in USD at publication time:	$19.90
Cell:	1xAAA
Turbo Runtime	High Runtime
LVP?	No
Switch Type:	Twisty
On-Board Charging?	No
Claimed Lumens (lm)	150
Measured Lumens (at 30s)	151 (100.7% of claim)^
Claimed Throw (m)	50
Candela (Calculated) in cd (at 30s)	37lux @ 3.895m = 561cd
Throw (Calculated) (m)	47.4 (94.8% of claim)^
All my Acebeam 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

Acebeam M20 Flashlight
Spare o-rings (2)
Springy keychain connector
Split ring (attached to light)
Manual

Package and Manual

A packaged ACEBEAM keychain LED flashlight, model M20, is shown. The box lists specs: 150 lumens, 23 hours max runtime, 56m throw distance, waterproof, and uses 1 AAA battery.

The back of an Acebeam M20 flashlight package, listing features such as 150 lumens output, 3 brightness modes, and CREE XP-G3 LED. A price sticker shows $22.90. The package rests on a wooden surface.

Build Quality and Disassembly

There are a couple of things that stand out about this little AAA twisty right off the bat. First, the knurling. It’s diamond cut (my favorite) and is over enough of the body that there’s plenty of grip for twisting with one hand.

A small black Acebeam flashlight stands upright on a weathered wooden surface, showing its textured grip, pocket clip, and a keyring attachment on top. The background is blurred.

A small black flashlight stands upright on a weathered wooden surface, with a blurred background. The flashlight has a textured grip and visible labeling in white text on its body.

A small black flashlight with a textured grip and a pocket clip stands upright on a weathered wooden surface, with a blurred background.

A small black flashlight with a textured grip stands upright on a weathered wooden surface. The background is blurred with neutral tones.

Next thing you’ll notice is that the bezel has crenelations, so when headstanding, the light will shine out. Not a big deal but something I like to see.

The two-part body has reasonably long threads, and they’re anodized and triangle cut. Of course, when the head is just a tiny bit off the body, the light is mechanically locked out, so no standby drain on the cells.

The tail end has a spring, and the head has a button. There are two holes in the driver so unscrewing the head should be straightforward for an emitter swap.

The included, attached split ring is nothing to write home about. Just a wire…. good candidate for replacement.

Size and Comps

Officially 68mm x 14mm (head) x 12mm (body), and 10g (without cell).

A black Acebeam flashlight is placed on top of a two-dollar U.S. bill, which is lying on a wooden surface. The bill features a portrait of Thomas Jefferson.

A black flashlight is placed on the left edge of a two-dollar bill featuring Thomas Jefferson, both lying on a weathered wooden surface.

A small flashlight stands vertically on top of a two-dollar bill, placed on a wooden surface. The image is focused on the flashlight with the background slightly blurred.

A person holding a small black flashlight between their thumb and fingers, with the hand partially closed. The background is unfocused and brownish, and the person is wearing a dark jacket with a blue cuff.

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

Two flashlights, one small and black with a keyring and one larger and reddish-brown, stand upright on a weathered wooden surface with a blurred background.

Close-up view of two flashlight heads lying on a wooden surface, with the smaller flashlight on the left showing a single LED and the larger flashlight on the right showing four LEDs arranged in a square.

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, attached pocket clip is a fairly good one. The mouth makes for easy attachment to pockets, and it carries deeply enough that the light won’t fall out of a pocket. It’s a friction fit clip and has a couple of places to attach a lanyard if you’d like (though I’d attach a lanyard elsewhere).

A small black Acebeam flashlight with a textured grip, pocket clip, and keyring, standing upright on a wooden surface with a blurred background.

A small black flashlight with a textured grip and a pocket clip is standing upright on a wooden surface, photographed in soft, natural light. The background is blurred.

Also included and also already attached from the factory is this split ring. It’s nothing special. It is attached through a hole in the tail end of the light, which adds a good bit of length to the light overall. I’d rather this be removed altogether (just like on the Surefire Titan Plus).

A small black Acebeam M20 flashlight with a textured grip and pocket clip is lying on a weathered wooden surface. The flashlight is shown in a close-up, side view.

A small black flashlight labeled ACEBEAM #28 with a textured grip and metal clip, lying horizontally on a weathered wooden surface.

The pocket clip can be reversed. It’ll fit on the middle thinnest ring, just left of the Acebeam logo above. And in this configuration, the M20 may be used on the brim of a hat effectively.

Power and Runtime

Power is provided to the M20 by means of a single AAA-sized cell. Only primary 1.5V max cells are supported – no lithium-ion cells (10440). In my testing exclusively used NiMH cells.

Output goes about as you’d expect. It’s not very regulated and just tracks downward as the cell voltage drops. There is no LVP, but that’s not so bad with NiMH cells. Output is negligible when cell voltage gets low anyway. Plus, the emitter flashes in a strobe fashion when the voltage is low. In the graph below, sorry but my thermo probe broke off the light, and temperature wasn’t tracked past around 5.5 minutes. The light is notably hot, though, which is quite interesting. A temp of 47 degrees in a light this small is something you’d notice.

Output on Medium is remarkably flat and well-regulated. Still, no LVP but again the output drops off so fast and dramatically to nearly nothing that you’d notice it. Also, the emitter flashes to alert the user.

Modes and Currents

Mode	Mode Claimed Output (lm)	Claimed Runtime	Measured Lumens	Tailcap Amps
High	150	0.8h	151	1.77
Medium	30	4h	25	0.14
Low	2	25h	–	0.01

Pulse Width Modulation

No PWM in any mode.

Oscilloscope screen displaying a mostly flat yellow waveform near the center, indicating low signal variation; settings shown include 2V, 50 microseconds, DC coupling, and a reading of -0.24V.

Oscilloscope screen showing a mostly flat yellow waveform centered near 0 volts, with horizontal and vertical gridlines. Display indicators include “HOLD,” “Waiting,” “50us,” “AUTO,” “DC,” and a voltage reading of -0.24V.

Oscilloscope screen displaying a mostly flat yellow waveform near zero, with grid lines, measurement settings at the bottom, and status indicators HOLD and Waiting at the top.

Here you can see a “baseline” – a chart with almost no light hitting the sensor.

Then there’s the Ultrafire WF-602C flashlight, which has some of the worst PWM I’ve seen. It’s so bad that I used a post about it to explain PWM! Here are multiple timescales (10ms, 5ms, 2ms, 1ms, 0.5ms, 0.2ms) to make comparing this “worst” PWM light to the test light easier. That post also explains why I didn’t test the WF-602C at the usual 50us scale.

User Interface and Operation

The M20 is twisty, so you’ll twist the head to switch modes. It’s not a progressive twisty – so twist it on, then off and on again to advance modes. But mode advance is not the normal direction. Medium is first, then low then High. The output resets to “Medium is next” after a few seconds. As a result, High can be completely avoided if desired.

LED and Beam

The emitter in the M20 is a Cree XP-G3 at 6500K temperature. The reflector is shallow (of course) and has a very light texture. Not enough to make any flood out of the beam, but just enough to break up any artifacts from the XP-G3.

These beamshots always have the following settings: f8, ISO100, 0.3s shutter, and manual 5000K exposure. These photos are taken at floor level, and the beam hits the ceiling around 9 feet away.

A dim, circular beam of light is visible at the center of a mostly black background. The text ZEROAIR.ORG appears vertically along the left edge.

A completely black image with the text “ZEROAIR.ORG” in light gray, vertically aligned along the left side. No other visible details or objects are present.

A circular beam of white light shines on a dark background, gradually fading towards the edges. The text ZEROAIR.ORG is vertically aligned on the left side of the image.

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

Test light on the left.

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

Random Comparisons and Competitive Options

Here’s a link to a relevantly filtered page on parametrek.com. I use that site a lot! There are indeed a few other XP-G3 AAA lights, but the list is surprisingly short. This Acebeam makes a good entry in the group.

Conclusion

What I like

Knurling and smooth threads make for easy operation
Small size
Can be used as hatlight
No strobes
Highest output can be completely avoided

What I don’t like

Cree XP-G3, especially 6500K
Lack of LVP

Notes

This light was provided by Going Gear for review. I was not paid to write this review.
This content originally appeared at zeroair.org. Please visit there for the best experience!
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