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Thread: Thrunite TN42 (XHP35 HI, 4x18650) Review: BEAMSHOTS and more!

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  1. #1
    *Flashaholic* selfbuilt's Avatar
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    May 2006

    Ooo Thrunite TN42 (XHP35 HI, 4x18650) Review: BEAMSHOTS and more!

    Reviewer's Note: I am very backlogged with lights, so expect somewhat less detail than typical in my upcoming reviews.

    Following on my review of the TN40, here is the latest member in the high-output TN line of flashlights from Thrunite, the TN42 - featuring a single XHP35 HI emitter for maximum throw. Let's see how it compares to other lights in this high output class …

    Manufacturer/Dealer Reported Specifications:
    (note: as always, these are simply what the dealer/manufacturer provides – scroll down to see my actual testing results).

    • LED: 1xCREE XHP35 HI LED
    • Runs on: 4 x 18650
    • Working voltage: 5.5V-8.4V.
    • Output & Runtime (Tested with four pieces ThruNite Li-ion 18650 batteries (3.6V/3400mAh) and for CW. NW parameters is 10% off): Strobe(680 lumens /10.8hrs), Turbo(2000 lumens/1.5hrs), High(780 lumens /5.3hrs), Medium(256 lumens /17.8hrs), Low(38 lumens /4.3days), Firefly (0.8 lumens /58days).
    • Peak beam intensity: 600750cd.
    • Max beam distance: 1550m.
    • Waterproof to IPX-8 Standard (2 meters).
    • Impact resistant: 1.0 meter.
    • Working Temperature: -40℃-40℃.
    • Dimensions: 206mm (length) x 100mm x 52mm.
    • Weight: 666g (including battery carrier).
    • Accessories: Shoulder strap*1, Strap ring*1, A, Spare O-ring*2, Side switch Cap*1, Battery Carrier x1 (inside the flashlight).
    • MSRP: ~$200

    I don't have the retail packaging, but I would expect it is similar to the TN40 I recently reviewed.

    All dimensions directly measured, and given with no batteries installed (unless indicated):

    Thrunite TN42: Weight: 661.6g, Length: 206mm, Width (bezel): 100.0mm
    Thrunite TN40: Weight (with battery pack): 780.0g, Length: 171mm, Width (bezel): 100.1mm
    Thrunite TN36: Weight: 390.4g, Length: 125.4mm, Width (bezel): 64.0mm
    Thrunite TN35 (MT-G2): Weight: 571.4g (723g with 3x18650), Length: 201mm, Width (bezel): 78.9mm

    Acebeam K70: Weight: 584.6g, Length: 204mm, Width (bezel): 88.1mm
    Eagletac SX25L3 3x18650: Weight: 315.9g, Length: 150.2mm, Weight (bezel): 47.0mm
    Fenix TK75: Weight: 516.0g (700g with 4x18650), Length: 184mm, Width (bezel): 87.5mm
    Nitecore TM11: Weight: 342.6g (476g with 8xCR123A), Length 135.3mm, Width (bezel): 59.5mm
    Niwalker MM15: Weight: 333.7g (without handle), 355.9g (with handle), (539g with 4x18650 and handle), Length: 114.6mm, Weight (bezel): 63.7mm
    Niwalker MM18: Weight: 510.g (without handle), 534.1g (with handle), Length: 135.3mm, Width (bezel): 73.9mm

    The TN42 is a substantial light, with a massive head/reflector for throw. Anodizing is a flat black, and is in good shape on my sample. Body labels are very minimal, and clear. Knurling on the body handle is aggressive, which definitely helps with grip. There are a number of attachment points for a shoulder strap or wrist lanyard. The light can tailstand stably.

    Screw threads are square-cut. Threads are anodized, but it is the tension on the battery carrier connection to the head that determines if the light can activate. The light can be easily locked out by a simple twist of the head.

    The TN42 uses a single side-mounted electronic switch to control on/off and mode switching. Switch feel is about typical, and there is a definite "click" when making full contact. Scroll down for a discussion of the user interface.

    The battery carrier works with flat-top 18650 cells, thanks to the raised contacts. This also means that you will find it a tight fit for most button top cells.

    The TN42 has a massive smooth reflector, coupled with the small profile XHP35 HI emitter. This design is clearly optimized to produce very good throw. Scroll down for details.

    User Interface

    Click the switch to turn the light on/off.

    When the light is on, press-and-hold the side switch to cycle through Low > Medium > High, in a repeating loop. The light has mode memory and remembers your choice.

    To access Turbo, from any mode, double-click the switch. To access Strobe, double-click again from Turbo.

    To access Firefly, from Off, press-and-hold the switch. Note that Turbo, Strobe and Firefly are not on the main sequence.

    From Off, the light will turn on is the last memorized mode with a single click (except for Firefly, Turbo, and Strobe).


    For more information on the overall build and user interface, please see my new video overview:

    As with all my videos, I recommend you have annotations turned on. I commonly update the commentary with additional information or clarifications before publicly releasing the video.


    There is no sign of PWM that I can see, at any output level – the TN42 is fully current-controlled.


    Strobe was a typical fast tactical strobe of ~13Hz.

    Standby Drain

    A standby current drain is inevitable on the TN40, due to the electronic switch in the head. Similar to the TN40, I get a ~40uA current. Given the 2s2p arrangement in the carrier, that would mean that 3400mAh cells would be fully drained in around 20 years (theoretically). Since this is below the self-discharge rate of Li-ion, it is not at all a concern.

    Note that you can easily break this current by unscrewing the head slightly, thanks to the tension on connection to the battery carrier. I recommend you do for this for lowering the risk of accidental activation – it certainly is not necessary from a current drain perspective.


    All lights are on protected 18650 ICR chemistry batteries, except for the TN40 which is on its custom cells. Lights are about ~0.75 meter from a white wall (with the camera ~1.25 meters back from the wall).

    It is always hard to compare high output lights at this ridiculously close distance. But the TN42 is clearly an incredible thrower, with a very smooth spillbeam (i.e., none of the artifacts of the TN40 multi-well setup).

    I haven't a chance to do outdoor beamshots yet, so you will have to rely on the actual beam measures below for now.

    Testing Method:

    All my output numbers are relative for my home-made light box setup, as described on my website. 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 devised a method for converting my lightbox relative output values (ROV) to estimated Lumens. See my How to convert Selfbuilt's Lightbox 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 discussion, and a description of all the terms used in these tables. Effective July 2012, I have updated all my Peak Intensity/Beam Distance measures with a NIST-certified Extech EA31 lightmeter (orange highlights).

    As predicted by the beamshots, the TN42 is an incredible thrower. It even outperforms my first-generation Vinh Nguyen-modified TK61vn. This makes the TN42 the current distance champ in my collection.

    That's pretty good concurrence to published specs.

    Output/Runtime Graphs:

    As always, my standard runtimes are done under a cooling fan.

    The light is very flat-stabilized at all levels. You can see a few minor step-downs on Turbo over time. Runtime was consistent with Thrunite specs. Overall efficiency is very good, but the TN40 and some other XHP35 HI lights seem to exceed it.

    Potential Issues:

    The light is a substantial size, and I'm not sure what carry options it comes with (my review sample was an engineering sample without standard packaging)

    Due to the electronic switch in the head, the light has a stand-by current when the battery pack is connected. But this is completely negligible, and not a concern. To prevent accidental activation though, I recommend you lock the light out by a simple twist of the head.

    The battery carrier is bit tight for longer cells. I recommend you use flat-top 18650s in the carrier.

    Overall output/runtime efficiency is very good, but a bit less than the TN40 or some competing XHP35 HI lights.

    Preliminary Observations

    The TN42 is an outstanding thrower – in fact, it is the new distance throwing champ in my collection.

    The single emitter design means you don't have any of the artifacts from the multi-well TN40. The head/reflector design gives you incredibly focused throw, and broad (but dimmer) spillbeam. I suspect many throw-fans would find this beam pattern right up their alley.

    The interface is the same as the TN40, with Turbo and Firefly off the main sequence (available as a double-click and press-hold-from-off, respectively). I find it fairly easy to remember and easy to use.

    There is a lot of competition in the extreme throw camp, and the TN42 adds yet another option. It's interesting to compare this one to the TN40 – which produces a number of beam artifacts, but provides more overall output (while still producing outstanding throw). Certainly a lot to consider – hopefully the detailed testing results of the various lights presented here will help you come to a decision if you are in the market for such a light.


    TN42 was supplied by Thrunite for review.
    Full list of all my reviews: Latest hobby: New: Selfbuilt's MID-RANGE MYSTERY BOX Sale
    Gratefully accepting donations to my battery fund.

  2. #2
    Flashaholic* MikeB.'s Avatar
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    Aug 2015

    Default Re: Thrunite TN42 (XHP35 HI, 4x18650) Review: BEAMSHOTS and more!

    Excellent review. Thanks.

  3. #3
    Flashaholic* maukka's Avatar
    Join Date
    Dec 2015

    Default Re: Thrunite TN42 (XHP35 HI, 4x18650) Review: BEAMSHOTS and more!

    Thanks for the review and confirming the lack of PWM. This is one amazing light albeit for only very specific purposes. Never seizes to amaze me though.

  4. #4

    Default Re: Thrunite TN42 (XHP35 HI, 4x18650) Review: BEAMSHOTS and more!

    Was this the 5000k or 6000k selfbuilt?

  5. #5
    *Flashaholic* selfbuilt's Avatar
    Join Date
    May 2006

    Default Re: Thrunite TN42 (XHP35 HI, 4x18650) Review: BEAMSHOTS and more!

    Quote Originally Posted by lund1660 View Post
    Was this the 5000k or 6000k selfbuilt?
    Thrunite didn't specify, but the beam definitely looks Cool White to my eye. The Neutral White version should be ~10% lower on output and beam specs.
    Full list of all my reviews: Latest hobby: New: Selfbuilt's MID-RANGE MYSTERY BOX Sale
    Gratefully accepting donations to my battery fund.

  6. #6
    Join Date
    Jan 2008
    Boden, Sweden

    Default Re: Thrunite TN42 (XHP35 HI, 4x18650) Review: BEAMSHOTS and more!

    Thanks Selfbuilt for another great review with very valuable runtime graphs!

    Though I very much like regulated output I have changed my mind a bit. I don't find it at a problem if the output isn't absolutely stable, because I have learned according to personal experience that a slight difference isn't perceptible for the eyes. And in this case I would say turbomode, while it's a like you say: few minor step-downs on Turbo, the output will be perceived as stable for the eyes.
    I understand TN42 is a great light. With a probably not really necessary performance, but for sure it's a fun light! I really think it will noticeably illuminate some lower located clouds!

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