Olight M20 XM-L Upgrade Module (U2, 1x18650/2xCR123A) Review: RUNTIMES, BEAMSHOTS+


May 27, 2006
Warning: pic heavy, as usual. :whistle:


Olight has recently upgraded its classic M20 and M21 lines to XM-L-based emitters. Conveniently, they have also made available upgrade modules for the M20 and M20S, so that you don't have to buy a whole new light. :)

In this review, I will be looking at the M20 XM-L U2-bin upgrade module. Please refer back to my original M20 XR-E R2 review for info on the build of the light.

Manufacturer's Specifications:
  • LED: Cree XM-L cool white U2
  • Reflector: Orange peel
  • Output Mode and Lumens:
  • Low- 11 lumens
  • Medium- 107 lumens
  • High- 364 lumens
  • Strobe: 364 lumens, 10HZ
  • Beam diameter: 0.8m (3M distance, measured to 50% intensity)
  • Launch Angle: 15 degree
  • Glow Diameter: 2.9m
  • Launch Angle: 52 degrees
  • Dimensions: D- 27.6mm x L-42.0mm
  • Weight: 32g
  • Please Note: This module is only for Olight M20 Models. Can work in your Olight M20 Q5, R2, R5, S2 LED flashlights. Not made for the Olight M20S models.
  • MSRP: ~$40

The module comes in re-sealable plastic bag. There is a clear plastic cover over the opening at the top of the reflector. Both of these are convenient for storing your old module after you are done the upgrade.



First order of business is to open the head of the light, exposing the reflector of the old module.


Next, unscrew the reflector.


You can now see the retaining ring holding the brass pill in place. Unscrew this ring with a pair of snap-ring pliers, or fine needle-nose pliers, or a sturdy set of tweezers.

Once you have it unscrewed, be careful – the emitter/pill will just fall out of the head of the light. Hang on to the retaining ring – you are going to need it again.

Now disassemble the new pill, so that you have the reflector unscrewed from the brass heatsink/pill.


Drop the pill in place, re-apply the retaining ring from the earlier step, and screw tightly in place. If you don't have the module fully secured by the ring, the interface won't work properly.

Next screw the new reflector back in place. You can then close up the head.


And you are done. :) Olight also provides a good set of easy-to-follow instructions for changing the pill.

So what does it look like with the new module installed?



The upgrade module uses a Cree XM-L emitter (T6 or U2-bin, well centered on my sample). Reflector is a light orange peel (textured reflector). Given that the reflector is fairly deep, I would expect throw to be pretty good for this size XM-L-based light.

User Interface

UI is unchanged from the original M20 I reviewed. Basic operation is straightforward – lightly press the forward clicky for momentary on, click for lock-on.

Light moves between brightness/mode states by a simple switch of the head - loose/tighten the bezel to move to the next state. Sequence is: Lo - Med - Hi - Strobe, repeated in an endless loop.



The M20 XM-L module retains the tactical 10 Hz strobe.

There is no sign of PWM that I can see, at any output level. I believe the replacement module is current-controlled, as the original M20 was. :)


And now the white-wall beamshots. ;) All lights are on max output, on 1x18650. Lights are about ~0.75 meter from a white wall (with the camera ~1.25 meters back from the wall). Automatic white balance on the camera, to minimize tint differences.









Beam profile of the M20 XM-L upgrade is good – similar to other recent general purpose lights (e.g. Sunwayman V20C, Klarus XT-10). An overall balanced beam for a XM-L light. Note that overall output is not quite as high as most of the other recent XM-L based lights (scroll down to my Summary Tables for more info).

Testing Method:

All my output numbers are relative for my home-made light box setup, a la Quickbeam's flashlightreviews.com method. You can directly compare all my relative output values from different reviews - i.e. an output value of "10" in one graph is the same as "10" in another. All runtimes are done under a cooling fan, except for any extended run Lo/Min modes (i.e. >12 hours) which are done without cooling.

I have recently devised a method for converting my lightbox relative output values (ROV) to estimated Lumens. See my How to convert Selfbuilt's Lighbox values to Lumens thread for more info.

Throw/Output Summary Chart:

Effective November 2010, I have revised my summary tables to match with the current ANSI FL-1 standard for flashlight testing. Please see http://www.sliderule.ca/FL1.htm for a description of the terms used in these tables.




Olight's lumen estimate seem reasonably good, although the low level on mine is definitely more than 11 lumens.

Max output is less than most XM-L based lights, but that's likely sensible given the drop-in pill design. Note that the M21-X (which has a larger head) is driven to a higher level (Olight reports 600 lumens).

Throw is reasonable for the size reflector and max output level.

Output/Runtime Comparison:






The M20 XM-L upgrade has admirably flat regulation at all output levels. :thumbsup:

Overall efficiency and output on Med/Lo seems similarly to the Klarus XT-10 (except for the full regulation on the M20 XM-L).

Potential Issues

Rated at 364 lumens, the M20 XM-L module is not as high output as other recent XM-L based lights (which are typically in the 450-600 lumen range).

M20 XM-L lack a true low/moonlight mode.

Preliminary Observations

The M20 XM-L upgrade module lives up to its billing – it provides a nice upgrade path for those looking to breathe a little more output into their old M20.

Do you lose anything in this upgrade? The minimum output level is higher on my XM-L U2-bin sample (both compared to specs, and my original M20 XR-E). And depending on the version, you may lose some max throw (i.e. my original XR-E R2-bin threw further). But it also had a ringy beam and one of the worse green tints in my collection. :green: In my case, the XM-L upgrade module is going remaining permanently installed. ;)

Lights with drop-ins provide an obvious upgrade path – but only if the manufacturer continues to support it. I am glad to see Olight made this option available, as well as releasing new M20S-X and M21-X models. Of course, drop-ins are generally not driven as hard as fully-integrated lights, as you are relying almost solely on the pill heatsink to disperse heat. As such, the max output of the M20 XM-L emitter is lower than most lights in this 1x18650, 2xCR123A/RCR class.

That said, you could also pick up the new M21-X if you wanted more output with the same interface (note the M21-X is also a bit larger than the M20 – see my original M21 SST-50 review for a size comparison).

Performance of the XM-L upgrade module was certainly good – I am sure a lot will like the perfectly flat regulation on all batteries, at all levels (including 1x18650). :thumbsup: Overall efficiency could be higher, but is certainly reasonable for the class.

If you are happy with your existing M20 build but are looking for more output, this XM-L upgrade module may be a good choice for you.


The M20 XM-L upgrade module was provided by Battery Junction for review.


Jan 2, 2008
With the slightly lower output, does it have longer runtime? I have 2 M20's. One hand held and one with a pressure switch on my rifle. For the ~$80 to replace both it would be better than getting 2 new ~$100 lights each?


Newly Enlightened
Jul 6, 2011
I got the new M-21X and it is an improvement over the M-20S in beam quantity and throw, but if you have the original M20's the best thing you can do for them is just put in the smooth reflector. I use the M-20s with smooth reflectors on two of my SIG 556s.

Instead of upgrading your older M-20's with the Upgrade Modules (I did and went back to XPG and smooth reflectors), get the new M-21X.


May 27, 2006
With the slightly lower output, does it have longer runtime? I have 2 M20's. One hand held and one with a pressure switch on my rifle. For the ~$80 to replace both it would be better than getting 2 new ~$100 lights each?
Right, sorry I didn't include the original M20 R2 in the runtime graphs.

To compare, the original XR-E R2 module is direct-drive on 18650 on Hi, starting ~200 lumens and slowly dropping down to ~130 lumens after 2.5 hours, and which points it then drops down more quickly in output (time to 50% is a little under 3 hours). On Med, output is a regulated ~80 lumens for about 7.5 hours.

This new XM-L U2-bin is brighter on max (~330 lumens) and is well-regulated on 1x18650 - I get about 2 hours before the drop-off in output occurs. But there is no abrupt shut-down with the battery protection circuit, just a gradual drop-off at this point. On Med, output is a regulated ~100 lumens for about 6.5 hours.

As you can see from the numbers above, there is no real efficiency difference at the lower levels (I've noticed this before with XM-L). The main advantage is really the higher output and better regulation on Hi of the XM-L upgrade module (i.e. regulated 330 lumens for 2 hours, instead of direct-drive starting at 200 lumens for 2.5 hours).

If you want even greater Hi output, I would consider the M21-X.
Last edited:


Newly Enlightened
Dec 15, 2011
I have an Olight m20s with an s2 340 lumen. Would this upgrade be worth the money in my case? Would I get any more throw, better beam, etc.


May 27, 2006
I have an Olight m20s with an s2 340 lumen. Would this upgrade be worth the money in my case? Would I get any more throw, better beam, etc.
You would get less throw, but more overall output on max. Beam profile would be smoother.

Sent from my handheld device

Sparky's Magic

Apr 8, 2010
Queensland, Australia
OLIGHT M20 Warrior Upgrade module XM-L U2 easily installed, about 370Lu.at turn on; with 18650 Trustfire True 2400mAh. (Red and Black).

Cell fresh off charger (Cold) 4.19V - 87min. to 3.7V run terminated and output about 200Lu. Very little drop until the 1hr. mark and then a gradual taper.

Large intense hotspot which I suspect will throw as far as the R2 it replaces but with much more peripheral light: What it doesn't have is the horrible donut the R2 had; it bothered me from day 1, it will bother me no more.

The Tint is very good on high with a very white hotspot and a warmish spill. The lower modes lean towards a slight greenish halo, still acceptable but the lowest mode may worry some. In practical use it is not an issue (for me). :thumbsup:
Last edited: