Lumintop S40 (2x18650, XM-L, dual-switch) Review: BEAMSHOTS, VIDEO, RUNTIMES and more


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



The S40 is part of the new "star" series from Lumintop. This 2x18650/4xCR123A light has a distinctive dual switch tailcap. Let's see how it compares to other lights in its class … :whistle:

Common Manufacturer Specifications:
  • 4 Modes – 720 lumens (2 hrs), 200 lumens (7 hrs), 20 lumens (65 hrs) and Strobe
  • Operational voltage 2.8v - 18v
  • Powered by 4x CR123A / 2x 18650 (not included)
  • Tactical tailcap switch - Click for constant-on, press for momentary-on
  • Tailcap side button switch – Click for Lo – Med – Hi, Press and hold for Strobe
  • Precision reflector creates smooth, optimized beam
  • Peak Beam Intensity: 30,822cd
  • Beam Distance: 320m
  • Coated tempered window resists impact, 99% Transmission of light, protect the reflector and LED
  • High-strength aerospace aluminum body, Mil-Spec hard-anodized for extreme durability
  • Weatherproof O-Ring sealed that keep moisture, dust and dirt outside of your flashlight
  • Wear resistant square thread, IPX-8 standard (2.0m)
  • Size: L 220.5mm (8.7 in), D (Bezel) 45.6mm (1.80 in), D (Body) 26.4mm (1.04 in)
  • Weight 243g (8.6 oz)
  • Package Includes box storage case, Lumintop Flashlight, Belt Pouch, Spare O-Rings, Lanyard Strap
  • MSRP: ~$140



Packaging is a presentation-style plastic display case with cut-out foam (similar to some Olight models). Inside, you will find the light, spare o-rings, good quality wrist strap lanyard and belt holster. The manual/spec chart is printed on the back of the case.



From left to right: Redilast 18650, Lumintop S40, Crelant 7G5, JetBeam BC40, Thrunite Catapult V3, Niwalker 750.

All dimensions are given with no batteries installed:
Lumintop S40: Weight: 247.2g, Length: 219mm, Width (bezel): 45.6mm
Lumintop TD15X (with two extenders): Weight 180.8g, Length: 216.1mm, Width (bezel): 37.8mm
JetBeam BC40: Weight: 226.3g, Length: 224mm, Width (bezel): 48.5mm
Sunwayman T40CS: Weight: 296.7g, Length 227, Width (bezel): 63.5mm
Thrunite Catapult V3: Weight: 434.8g, Length: 254mm, Width (bezel) 58.0mm, Width (tailcap) 35.1mm.

The overall size and weight of the S40 is similar to the JetBeam BC40 (i.e. fairly compact for the class). It is still a bit larger than the Lumintop TD15X, which is built on a smaller 2xCR123A frame (and needs two extenders to run 2x18650/4xCR123A).




Build feels fairly solid, with above average body and head wall thickness.

The S40 has a glossy black anodizing, with no chips or damage on my sample. Knurling is present on the tailcap, mid-section and head of the light, but is not very aggressive. Overall grip is reasonable, thanks to the additional ridge elements. Lettering is minimal, and bright white against the black background.

Tailcap screw threads are traditionally cut, and are not anodized (so no lock-out is possible). :shrug: Light can tailstand, although it is wobbly if the switch is clicked off.

The secondary side-switch has a smooth silver finish, and would be hard to locate by feel with gloves on (although the color makes it visually distinctive, if there is enough ambient light to see it). The tailcap interior shows a secondary metal sleeve, that makes contact with a matching region of the battery tube.

There is a scalloped aluminum bezel ring on the head.

There is a small spring on the positive contact plate in the head, so flat-top batteries should work fine (my Redilast cells 2900mAh all worked fine). :thumbsup:

Note that the light can roll fairly easily.

User Interface

The S40 has a dual-control interface. Turn the light On/Off by the tailcap forward clicky switch - press for momentary on, click and release for constant on.

Mode switching is controlled by the electronic tailcap side switch. Press and release to change modes. Mode sequence is Lo > Med > Hi, in repeating order. Light has mode memory, and returns to this setting after turning Off/On.

To activate strobe, press and hold the side switch for more than 3 secs. To exit strobe, press-release or press-hold the side switch to return to the last memorized level.

For a more detailed examination of the build and user interface, please see my video overview: :wave:

Video was recorded in 720p, but YouTube defaults to 360p. Once the video is running, you can click on the 360p icon in the lower right-hand corner, and select the higher 480p to 720p options, or even run full-screen.


Unlike some other lights that use a tailcap side switch (e.g. Olight M30), there is no sign of PWM that I can see, at any output level. I presume the light is current-controlled. :)


There was some faint high frequency noise detected on my oscilloscope at the Med level, but this not visually noticeable.


Strobe was measured at a fast 9.7 Hz.




The S40 has a smooth reflector, with a well centered Cool White XM-L emitter on my sample. The overall reflector dimensions look intermediate to my Lumintop TD15X and JetBeam BC40/RRT-15, so I would expect intermediate levels of throw here. The head seems rather thick-walled.

And now the white-wall beamshots. ;) All lights are on 2x AW protected 18650. 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 is as you would expect, with reasonable throw. Spillbeam width is a bit narrower than some other lights (more in keeping with typical "thrower" lights, like the Thrunite Catapult)

And now for the outdoor shots. :grin2: These beamshots were done in the style of my earlier 100-yard round-up review. Please see that thread for a discussion of the topography (i.e. the road dips in the distance, to better show you the corona in the mid-ground). We are also in early winter here now, so I was lucky to get these in without snow on the ground. :whistle:


As expected, the S40 doesn't throw as far as the Lumintop PK30 (which has a much larger reflector focused for throw).


The S40 is a closer match in overall size to the JetBeam BC40, but the smaller reflector on the S40 reduces the throw somewhat. Sorry, I was little off-center for the S40 pic. :sssh:

Testing Method:

All my output numbers are relative for my home-made light box setup, a la Quickbeam's 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:

My summary tables are reported in a manner consistent with the ANSI FL-1 standard for flashlight testing. Please see for a description of the terms used in these tables.


Max output of the S40 is lower than the rated spec of 720 lumens (i.e. closer to ~600 estimated lumens in my testing). Note also that output drops after 3 mins of runtime, to a regulated ~460 estimated lumens. See my runtime graphs below for more information.

Throw is reasonable for the size reflector – intermediate to the Lumintop TD15X and JetBeam BC40, as expected. But again, the rated ANSI FL-1 specs (30,822cd and 320m beam distance) seem overstated for my sample (actually measured at 16,500cd and 257m).

Output/Runtime Comparison:




Although max overall output is lower than most other lights in this class, runtime is very good at all levels tested. Performance is generally quite similar to the Lumintop TD15X.

Although Med/Hi mode lumen output levels seem lower than published specs, runtimes are higher than reported (and consistent with a good quality current-controlled light).

Note the drop-off in max output after the first three minutes of runtime. Recent TD15X lights have a similar circuit feature.

Potential Issues

Side mode-changing switch is smooth, and may be hard to locate by feel alone.

Light cannot be physically locked-out.

Light rolls easily.

Max output and throw are toward the lower end of the 2x18650, XM-L class of lights.

Preliminary Observations

The S40 is an well-balanced 2x18650/4xCR123A light. Not too heavy (or too light), too throwy (or too floody), the S40 strikes the middle ground on most build features. Even the spacing of modes is well balanced, with a true Lo, Med and Hi. :)

What actually distinguishes the light from most others in this class is the interface – specifically, the tailcap side-switch for controlling output modes. I have seen this design before on smaller lights, although most of the time the placement of the secondary switch is different – either near the head (as on the Fenix TK15/21), or right next to the On/Off switch (e.g. Klarus XT-series lights, or the 4xAA lights like the Fenix LD40 and JetBeam PA40). The Olight M20S/M30 series lights are probably the closest comparable for this particular switch placement.

Like many of the above lights, the switch cover is smooth and may be hard to access through tactile feel alone (something I noted in both my Olight M30 and Fenix TK15 reviews).

I am happy to see that Lumintop has kept their standard current-controlled circuitry for this model (i.e. output/runtime circuit performance is very similar the TD15X, on comparable batteries). :thumbsup: They have also kept the relative level spacing of the TD15X, which includes reasonable Lo, Med, and Hi levels - although Hi seems a little lower on the S40. The S40 is not a particularly thowy light for the class, but it does throw a little farther than the TD15X.

I like that they have kept Strobe off the main sequence (i.e. need to press-hold to activate it).

All in all, performance is what you would expect for a current-controlled light at these levels. But note that the reported ANSI FL-1 specs seem to overstate lumen output and throw, and understate runtimes. If you like this sort of tailcap side-switch interface, this would be another light to consider in the 2x18650/4xCR123A class of XM-L lights.


S40 supplied by Lumintop for review.

candle lamp

Flashlight Enthusiast
Jun 16, 2010
South Korea
Thanks for your excellent review & your time as always. Selfbuilt! :thumbsup:

Is the XM-L "U2" or "T6" ?