Thrunite TN31 Review (1xXM-L, 3x18650): RUNTIMES, VIDEO, THROW, BEAMSHOTS and more!

selfbuilt

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Warning: even more pic heavy than usual! :sweat:

TN31036.jpg

TN31035.jpg


The TN31 is a new high-output "thrower" flashlight from Thrunite that runs on 3x18650 cells. Let's see how it compares to other recent lights in this class, including the new TN30 (a high-output 3x emitter light based on the same battery handle). :whistle:

Manufacturer's Specifications for the TN31:
  • LED: Cree XM-L U2 LED
  • Max 1147 lumen output using 3 * 18650 batteries: Level 1: 0.5 lm. 2000 hours; Level 2: 21 lm. 140 hours; Level 3: 146 lm. 22 hours; Level 4: 366 lm. 9 hours; Level 5: 620 lm. 5 hours; Level 6: 1147 lm. 2 hours; Standby: 65 uA; Strobe: 1147 lm. 4 hours.
  • Working voltage: 4V to 13V.
  • Max runtime: 2000 hours.
  • Max beam distance: 700 meters.
  • Peak beam intensity: 75000cd.
  • Impact resistant: 1.2 meters.
  • Waterproof to IPX-8 standard, 2M.
  • Dimensions: 201.70mm length, 79.00mm bezel diameter.
  • Weight: 452.80g without battery.
  • Aircraft grade aluminum body structure.
  • Premium type III hard anodized anti-abrasive finish.
  • Ultra-clear tempered glass lens with anti-reflective coating.
  • Momentary forward click tactical switch.
  • Strobe mode for tactical and emergency use.
  • Smooth reflector for max light output.
  • Highly focused beam for maximum distance.
  • Tactical knurling for firm grip.
  • Streamlined body design.
  • Mechanical reversed polarity protection design for battery carrier.
  • Intelligent highly efficient circuit board design for max performance and long run time.
  • Specially designed for Military, Law Enforcement, Self-defense, Hunting, Search & Rescue and Outdoor activities.
  • Intelligent temperature controlled light output for user safety.
  • MSRP: ~$220
TN31003.jpg


The TN31 production version sent to me came in the full presentation case, with metal hinges and closing flaps. Inside were the light, belt pouch, wrist lanyard, manual, warranty card, and extra o-rings and spare boot cover. Note the case is larger than the TN30 that I have recently reviewed.

Also, the cut-out foam had a noticeable acrid smell when the case was first opened, likely due to some sort of outgassing that had built-up inside the sealed case. It took several days of leaving it wide open before it dropped to undetectable levels. My TN30 sample case was affected by this too, but to a much lesser extent. :shrug:

TN31049.jpg

TN31064.jpg

TN30021.jpg

From left to right: AW Protected 18650; Thrunite TN30, TN31, Catapult V3; Xtar S1; 4Sevens S18 Maelstrom; Nitecore TM11.

All basic dimensions are given with no batteries installed:

Thrunite TN30: Weight: 468.2g, Length: 179mm, Width (bezel): 64.3mm, Width (tailcap): 49.0mm
Thrunite TN31: Weight: 572.1g, Length: 203mm, Width (bezel): 79.0mm, Width (tailcap): 49.0mm
Thrunite Catapult V3: Weight: 434.8g, Length: 254mm, Width (bezel) 58.0mm, Width (tailcap) 35.1mm.
Crelant 7G5-V2: Weight: 282.6g, Length: 251mm, Width (bezel): 61.4mm
Olight SR51: Weight: 405g, Length: 190mm, Width (bezel) 62.0mm
Sunwayman T40CS: Weight: 296.7g, Length 227mm, Width (bezel): 63.5mm

The TN31 is a substantial light, closer to many Search & Rescue style lights than typical 2x18650 "thrower" lights.

Let's start with the case:

TN31008.jpg

TN31011.jpg

TN31015.jpg


And now the light itself:

TN31037.jpg

TN31040.jpg

TN31041.jpg


Anodizing is a glossy black, and seems to be good quality – no chips or damage on my sample. Labels were sharp and bright white against the black background. Knurling is fairly aggressive on the handle, helping with grip. Scroll down for a discussion of the control ring feel and use.

Screw threads are anodized for head lock-out. Threads are standard triangular cut, but seem of good quality.

Light has a scalloped stainless steel aluminum bezel ring. For more details on the reflector, scroll down to the beamshot section of the review.

Here are some close-up shots of the control ring:

TN30055.jpg

TN30054.jpg


There are slight indents on the control ring to help with feel. There is a label mark on the control ring that lines up with the labels on the head. The six constant output modes are not individually labeled, but there is a graded output bar pictogram over the first four levels (i.e., shows the direction to turn to raise or lower the output). There are firm detents at each level, with a slight click as you enter into each one.

TN30045.jpg

TN30046.jpg

TN30048.jpg

TN30049.jpg


There is a metal battery carrier that holds 3x 18650 cells. The positive contact plate is slightly raised, so all types of 18650 cells should work fine (i.e., true flat-tops, wide and small button-tops). Longer cells may be a bit tight, but my protected 3100mAh cells all fit. The carrier can be inserted either orientation into the handle. Note that particularly wide cells may be a tight fit into the handle.

TN30036.jpg

(from my TN30 review, but it looks the same here - the battery/body handles are the same).

The light can tailstand stably, and the tailcap cut-outs facilitate access to the switch. Switch is a forward clicky switch (i.e., press for momentary, click for locked-on). Switch feel is fairly typical, with a definite click. But there's more to it than meets the eye ... :whistle:

TN30051.jpg


There is a double set of springs in the base, in addition to the spring in the head. The double-set of springs in the tail is a tip-off that something interesting is going on with the tail-switch and the battery carrier. Here is what the tail switch looks like in detail:

TN30064.jpg

TN30065.jpg


There is clearly a circuit along with the forward clicky switch. This is presumably to provide some sort of assist to the switch, modifying the load on it. The dual springs is how it draws power from the battery carrier, irrespective of the head. Scroll down to my Standby Drain section for more info.

User Interface

Turn the light off/on by the tailcap clicky – press for momentary, press and release (i.e., click) for constant on.

Change output modes by turning the control ring in the head. Arranged from left-to-right (looking down at the light, held in traditional flashlight carry), the modes are level 1 (moonlight) > level 2 > level 3 > level 4 > level 5 > level 6 (max) > standby > tactical strobe.

No light is produced on standby, but a miniscule current will be drawn to allow the circuit to respond to a ring turn (see below). As always, I recommend you store the light clicked-off at the tailcap, or locked-out by a head twist.

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



As always, videos were recorded in 720p, but YouTube typically defaults to 360p. Once the video is running, you can click on the configuration settings icon and select the higher 480p to 720p options. You can also run full-screen. :)

PWM/Strobe

There is no sign of PWM on any level – I believe the light is current-controlled. :)

TN30-Strobe1.gif


Strobe is an oscillating frequency strobe, switching between 6.9Hz and 14.6Hz on my sample. Each frequency lasts for about 2/3 of a sec. Here is a blow-up of each strobe frequency individually:

TN30-Strobe2.gif

TN30-Strobe3.gif


There is a bit of a ramp-up to the peak strobe output, but it is not something you could see in practice. Strobe is quite blazingly fast to the eye.

Standby Drain

The "Stand By" mode on the control ring is just that - due to the electronic ring control, the TN31 will always be drawing a small current when fully connected and the tailcap switch is clicked on.

I measured this current as 96uA. Since the cells are arranged in series, for 2600mAh 18650s that that would translate into a little over 3 years before the cells were fully drained. Note this is slightly higher the 65uA standby current listed in the manual, but that may just be natural variation (e.g., my TN30 was 114uA, in comparison). This is quite reasonable for a standby current.

There is a secondary circuit in the tailcap that has its own standby drain. You don't often see physical clicky switches in these sorts of high-powered lights, likely due to their inability to handle the typical current flows. In this case, the physical forward clicky is connected to its own circuit that presumably provides some sort of assist to the switch, modifying the load on it.

I tried to measure the current draw on the tail switch, but my DMM's uA/mA port seems to have gone on the fritz since my earlier measures of the head standby draw were taken. While I'm waiting for a replacement, HKJ reports between 20-50 uA standby drain on the tail switch (scroll down the thread for commentary).

This means that whenever the battery carrier is loaded with cells and in contact to the tailswitch, a miniscule current will be drawn (i.e., it would take at least 6 years to drain the cells, even at its highest point). But to break this current, you would need to remove the carrier from the handle.

Beamshots:

TN31042.jpg

TN31023.jpg


The emitter was well-centered at the base of a very large and deep reflector. The reflector is smooth finished, and should provide excellent throw. And as you can tell from the reflections of the blind in my office, there is a very nice anti-glare coating on the lens.

And now, what you have all been waiting for. ;) All lights are on their respective max battery sources (3xAW protected 18650 for then TN30/31), 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.

TN30-Beam001.jpg
TN31-Beam001.jpg

Cat3-Beam001.jpg
7G5V2-Beam001.jpg


TN30-Beam002.jpg
TN31-Beam002.jpg

Cat3-Beam002.jpg
7G5V2-Beam002.jpg


TN30-Beam003.jpg
TN31-Beam003.jpg

Cat3-Beam003.jpg
7G5V2-Beam003.jpg


TN30-Beam004.jpg
TN31-Beam004.jpg

Cat3-Beam004.jpg
7G5V2-Beam004.jpg


Output and throw on the TN31 is clearly extreme – greater than my other single-emitter "thrower" lights. Scroll down for a comparison of estimated lumens and throw.

Beam profile is pretty clean, although there were some slight irregularities in the corona around the hotspot.

For outdoor beamshots, these are 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).

Note: Sorry, I mis-labeled the TN31 as a 3xXM-L light in the outdoor pics below. :sssh: Rest assured, the TN31 is actually a 1xXM-L light.


TN30-TN31.gif


The TN30 (3xXM-L) produces a lot more light than the TN31 (1xXM-L), with a wider spillbeam. But the dedicated throw of the more focused TN31 is impressive. Let's see how it does against other "thrower" lights in the 1xXM-L class:

TN31-7G5V2-CatV3.gif


Ok, it clearly out-throws the competition, including the earlier Thrunite Catapult. :eek:oo:

Let's see how it does against a throw king, the Olight SR90:

TN31-SR90.gif


While not quite in the same category, it is getting pretty close for both throw and output. This is a very impressive showing for a 1xXM-L, 3x18650 light. :thumbsup:

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 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 http://www.flashlightreviews.ca/FL1.htm 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).

TN30-FL-1-Summary-New.gif


UPDATE AUGUST 20, 2012: I have revised the summary table above to reflect the results of my new NIST-calibrated lightmeter.

As the beamshots indicated, the TN31 out-throws other lights in the single XM-L class, but a pretty measurable margin. Output is also higher than the 2x18650 lights, which typically max out around ~800 lumens. The TM31 appears to be able to deliver ~1100 lumens, at least initially - the light has a slight step-down after 69 secs (see my runtimes for more info).

Lowest output is slightly lower than 0.5 lumens in my testing. In fact, here is a breakdown of the estimated lumen values for both the TN30 and TN31 in my testing:

TN30-TN31-Lumens.gif


As you can see, the reported output and throw specs from Thrunite seem remarkably consistent with my testing. I suspect Thrunite did indeed get these tested in a properly-calibrated integrating sphere. :thumbsup:

Output/Runtime Comparison:

TN30-Hi18650.gif


TN30-Med18650.gif


Output/runtime performance was quite good for the TN31 when taking into account the 3x18650 battery source. It was certainly well in keeping with other current-controlled lights at these levels.

You will note the TN30 typically outlasts it at lower levels, but that's because the 3xXM-L emitters are each being driven to a lower level for comparable output (i.e., emitters are more efficient at lower drive levels).

As with the TN30, the light steps down slightly after exactly 69 secs of runtime. Unlike the TN30, however, the TN31 remain perfectly stabilized throughout the remaining Max output run. Flat regulation is evident at all output levels. :)

Although it doesn't show in the runtimes above, the TN31 would flash a few warning flashes shortly before hitting the built-in battery protection circuit shut-down.

One quirk – instead of shutting off when the battery protection circuit was reached, the light dropped down to a moonlight mode (similar to Level 1). :thinking: Not sure why this happened, but it was a consistent observation. And this was different from the TN30, which completely shut-off (as expected).

In terms of reported ANSI FL-1 runtimes, the Thrunite numbers seem pretty good, though perhaps slightly inflated at some levels. Remember that my runtimes are done on 2200mAh cells. On 3100mAh cells, I would expect runtimes fairly close to the reported Thrunite specs.

Here is a Hi mode runtime comparison, on 3100mAh and 2200mAh batteries:

TN30-Hi18650-Comparison.gif


No real surprises here - the 3100mAh cells perform better.

Oh, and those little blips near the end of the L6 run on the TN30 are from the low-battery warning system of the light.

Here is a comparison of the TN31 to typical single-emitter 2x18650 lights:

TN31-2x18650Hi.gif


As you can see, the extra 18650 provides a lot of extra runtime. But it also allows for greater overall output on the highest level. :eek:oo:

UPDATE MAY 23, 2012: At a user's request, I have done a comparison of no cooling and fan cooling on max output on the TN31. I even measured surface temperature on the no-cooling run. On AW 18650-2200mAh, this is what I got:

TN31-cooling.gif


Note the left Y-axis is estimated lumens converted from my lightbox (for the two output runs). The right y-axis is the surface temperature in degrees centigrade (celcius), measured with a probe attached to the base of the head for the no cooling run only. Hard to put those numbers in context since I don't usually measure temp, but subjectively I can tell you the light got quite hot.

As you can see, the lack of cooling caused a small drop in output over time - but nothing you could ever see visually. With fan cooling, output dropped from ~1150 estimated lumens at activation to ~1050 lumens right after timed step-down, and never dropped below ~1000 lumens. With no cooling, output dropped from ~1150 estimated lumens to ~1050 lumens as before, then gradually dropped to the ~900-950 lumen range. This resulted in marginally longe runtime.

As always, take my lumen estimates with a grain of salt - they are based on a calibration of my lightbox to ceiling bounce values of other heavy output lights of known calibrated lumens. But they do seem remarkably consistent with Thrunite specs.

Also, note that my office was quite warm for this test (i.e., resting temp for the light was 28 degrees), and no cooling was applied (although a window was open in the room). Frankly, I can't imagine a real-world scenario that would be worse than indoors with poor ventilation, as done here.

Either way, you would never be able to see any of this visually.

Potential Issues

Due to the electronic control ring in the head, the light has a stand-by current when in "Stand By" mode. But this current is very low (96uA), and will not be problem for regular use (i.e. will take about 3 years to drain three fully charged 18650 2600mAh cells). You can break this current by clicking the tailswitch off, or loosening the head from the body.

However, there is a second standby current due a circuit in the tail to assist the physical switch. The tail circuit draws its power directly from the battery carrier, irrespective to the state of the head (i.e., the purpose of those dual springs in the tail). The current draw is miniscule (i.e., over 6 years to fully drain the cells), but the only way to break it is to remove the battery carrier from the handle.

Only 3x 318650 Li-ion cells may be used in the light (i.e., doesn't support multiple CR123A primary cells)

Light uses a battery carrier, and very long or wide cells may be a bit tight. But all cells I tested worked in the carrier, including protected flat-top cells.

The individual levels are not specifically labeled on the head of the light, so you may need to "count" detents to figure out what level you are set to.

Light drops to a low moonlight level, similar to level 1, once the batteries reach the end of their runs. Not sure why this occurred, but it was a consistent finding.

Preliminary Observations

Move over Catapult, Thrunite has a new throw king – the TN31. With about twice the raw lux at 1m, that translates into ~50% more overall throw for the TN31. :bow:

The TN31 is the best throwing – and highest output – single XM-L light I've tested to date. The beam pattern is fairly smooth and even, with good spill and an incredibly bright hotspot. This is one of the largest reflectors I have ever seen. :eek:oo:

Like its sister light, the TN30, output/runtime performance was very good, with the current-control circuitry providing excellent runtimes at all levels tested. Stabilization was quite good as well, with perfectly flat regulation on all levels. :thumbsup:

The TN30 does have a relative runtime advantage when run at comparable output levels, but that's because the triple emitters would each be driven to a lower level (and emitters are more efficient at lower currents). The beam pattern is quite different of course, with lesser throw and a lot artifacts from the overlapping beam wells on the TN30.

In terms of the interface, the control ring worked well in my testing. I particularly liked the clear and firm detents at every level. The six output levels are well spaced (and very accurate to the specs), giving you plenty of output and runtime options. I am also glad to see strobe was placed after a standby mode. A good implementation of a control ring. :)

I like the use of the physical clicky switch, but its implementation is a little unusual here - there is actually a second circuit in the tailcap that seems to provide some sort of powered assist to it. The standby current draw is tiny though.

For those looking for maximum throw and output in a single XM-L emitter, I think you've found answer for the moment. :rolleyes: While not quite in the same category yet as Olight SR90 on both measures, it is getting close. When you consider the max runtime is pretty comparable on those two lights – despite the TN31 having half the battery pack capacity and size – that is a pretty impressive showing. :eek:oo:

----

TN31 provided by Thrunite for review.
 
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peterharvey73

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Great review as always Selfbuilt.

The TN31 with a single XM-L U2 and a 79mm bezel diameter only has 1147 lumens OTF, yet how come it has amassed 595 meters of throw?
Has it been de-domed or something?
Or is it by a combination of boosting the OTF from 800 to 1147 lumens, plus enlargening the bezel diameter from 60 odd millimeters to 79 millimeters???
Is this XM-L U2 driven much higher than the regular Cree recommended 3 amps to yield that many lumens?

Similarly, the TN30 achieves a massive throw of 400 meters, over the Nitecore TM11 of just 286 meters.
At 64mm, the TN30's bezel diameter is hardly any bigger than the TM11 at 60mm.
So is the TN30's massive throw due to being driven hard to produce the 3000 OTF lumens output?
Though the Nitecore TN11's spill still seems to be wider?
 
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BLUE LED

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Thank you for the review. I am waiting patiently for my TN31 to arrive. I am glad that it is well regulated and throws like a champ. The long runtime on maximum is also impressive. The low low is also rather unexpected for a high output thrower :)

I think the pics should state single XM-L.
 

HKJ

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A nice review as usual, but you got the switch wrong. It does not turn the power 100% off, it has some electronic assistance that needs a small amount of power.
 

selfbuilt

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Or is it by a combination of boosting the OTF from 800 to 1147 lumens, plus enlargening the bezel diameter from 60 odd millimeters to 79 millimeters???
Similarly, the TN30 achieves a massive throw of 400 meters, over the Nitecore TM11 of just 286 meters.
At 64mm, the TN30's bezel diameter is hardly any bigger than the TM11 at 60mm.
The greater output is part of the reason for greater throw. But a lot of it is also bound to be due to the reflector. Note that it is a lot more than just the overall reflector width - depth and overall shape/design matter greatly.

For example, the TM11 and TN30 have similar sized heads, but the reflector well geometry is completely different. The individual TN30 reflector wells are more than twice as deep (looks closer to 3x as deep), with the 3 emitters much closer together. This obviously gives good throw. Note that the TN30 reflector wells are not as deep as Xtar S1, which is an even better relative thrower.

A nice review as usual, but you got the switch wrong. It does not turn the power 100% off, it has some electronic assistance that needs a small amount of power.
Interesting. Do you have a measure of its current draw, or a suggestion as to how I can measure it? I'm guessing it has to do with the large spring in the base making separate contact with the carrier?

FYI, when I was measuring the ring standby current in th head (96-114 uA for the two lights), I tried turning the light off at the clicky - it dropped my current reading to zero (i.e. undetectable on my DMM's uAmA port). For all intents and purposes, it looked to me like the switch completely cut the circuit.

But of course, I wasn't measuring between the tailcap and the carrier. I was suspicious of why the secondary spring was there, but couldn't get any specific reading.
 

HKJ

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Interesting. Do you have a measure of its current draw, or a suggestion as to how I can measure it? I'm guessing it has to do with the large spring in the base making separate contact with the carrier?

I measured 20uA to 50uA, depending on on/off status. If you open the back you can also see the electronic. I did that in my review.


FYI, when I was measuring the ring standby current in th head (96-114 uA for the two lights), I tried turning the light off at the clicky - it dropped my current reading to zero (i.e. undetectable on my DMM's uAmA port). For all intents and purposes, it looked to me like the switch completely cut the circuit.

But of course, I wasn't measuring between the tailcap and the carrier. I was suspicious of why the secondary spring was there, but couldn't get any specific reading.

The two springs are to supply current to the tailcap circuit, you need to measure the current from the battery to them.
When off the current to the head is zero (or at least well below the uA range).
 

selfbuilt

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I measured 20uA to 50uA, depending on on/off status. If you open the back you can also see the electronic. I did that in my review.
There was a bit of blue lock-tight on the threads, but I got it open. I see what you mean, there is clearly a circuit there. That clearly explains the presence of the second spring. I'll update the review with pics later and a revised description.

Unfortunately, my DMM's uAmA port seems to be on the fritz all of the sudden, I am not able to get any readings on any light. Not sure how that happened, but I will see about getting a replacement fuse to see if it helps. So, until I get a replacement, I will go with your estimates as to the current draw. :)
 

light36

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Wow great review as always , after reading your review of the Trunite TN31 i am ordering one . Selfbuilt your reviews are always tops !!!!.
 

orbital

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88.7K!!!!!!!!!

___________________________________


 

ergotelis

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TN31 should be giving more than 4amp to the led, more likely 4,5-5 in order to produce 1100OTF. In a copper base for sure.
To be honest, with such a big reflector and this drive current, i was expecting higher lux numbers.
At similar sized trustfire X7/X8 reflectors,a lot of members managed with a [email protected],5amp about 90,000 lux(and me too).
At higher driving levels, some members archieved 110,000+ lux.
 

candle lamp

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Another excellent review. Eric! :thumbsup:
Thanks a lot for your efforts & time always.
It's an amazing thrower king light now.
How do feel about inserting the battery carrier into the battery tube? Is it too tight or suitable fit?
 

selfbuilt

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How do feel about inserting the battery carrier into the battery tube? Is it too tight or suitable fit?
It was fine on my samples, as long as you are careful to make sure the batteries are all firmly installed in the carrier. Tolerances are tight, but not unreasonable for the cells i tried.
 

jasonck08

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Great review as always.

Also can someone assist in identifying the reason for the circuitry on the tail switch?

I see what appears to be a couple small N-channel mosfets, 2 resistors, and a few diods of some sort? Reverse polarity diodes perhaps?
 

HKJ

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Also can someone assist in identifying the reason for the circuitry on the tail switch?

I see what appears to be a couple small N-channel mosfets, 2 resistors, and a few diods of some sort? Reverse polarity diodes perhaps?

As I wrote in my review it is probably to reduce the wear on the mechanical switch. This is mostly useful in the TN30, but because the TN31 uses the same body it gets the same construction.
 

selfbuilt

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Some concern was expressed in another thread about a thermal step-down in output if no cooling was applied. I have tested this on AW 18650-2200mAh, and here's what I got:

TN31-cooling.gif


Note the left Y-axis is estimated lumens converted from my lightbox (for the two output runs). The right y-axis is the surface temperature in degrees centigrade (celcius), measured with a probe attached to the base of the head for the no cooling run only. Hard to put those numbers in context since I don't usually measure temp, but subjectively I can tell you the light got quite hot.

As you can see, the lack of cooling caused a small drop in output over time - but nothing you could ever see visually.

With fan cooling, output dropped from ~1150 estimated lumens at activation to ~1050 lumens right after timed step-down, and never dropped below ~1000 lumens.

With no cooling, output dropped from ~1150 estimated lumens to ~1050 lumens as before, then gradually dropped to the ~900-950 lumen range. This resulted in marginally longe runtime.

As always, take my lumen estimates with a grain of salt - they are based on a calibration of my lightbox to ceiling bounce values of other heavy output lights of known calibrated lumens. But they do seem remarkably consistent with Thrunite specs.

Also, note that my office was quite warm for this test (i.e., resting temp for the light was 28 degrees), and no cooling was applied (although a window was open in the room). Frankly, I can't imagine a real-world scenario that would be worse than indoors with poor ventilation, as done here.

Either way, you would never be able to see any of this visually.
 

selfbuilt

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My response to another thread on this light, about comparing lumen estimates between reviewers:

None of us have permanent access to true NIST-calibrated and maintained integrating spheres of appropriate size for all lights. And even if we did, there are still plenty of factors that can lead to spurious results. Plus, you must understand the natural variation between samples, runs, etc. Manufacturers are not required to report these variations (i.e., ANSI FL-1 just requires reporting of the average of 3 samples - no variance measures reported, and 3 is not large number to start with). Given all the adjustment errors involved, no one should infer any sort of true accuracy to the implied level of precision some people seem to like to report for their own boxes.

Keep in mind, precision is based only on your ability to get reliable repeated measures of the same light in the same box, over and over again - it tells you nothing about how representative that one sample is, or how accurate the box is (i.e., it can only be used for relative internal comparisons).

My own lumen estimates were developed based on a comparison of my ceiling bounce readings for specific lights where the same model was measured in true integrating sphere. I make no claim to the accuracy of my numbers (as suggested by my relatively low precision in reporting - 2 sig figs with a half digit variance on the second digit). But here is a table comparing my estimates to manufacturer specs for a number of high-output lights:

HiOutput-Lumens.gif


The main anomaly is the SR90, but that is presumably explained by the very early testing sample I received (note the dates). I am quite confident that currently shipping SR90s meet or exceed the current ANSI FL-1 rated spec from the manufacturer, due to improved output bins on the SST-90.

The point here is that my values are directly based on the relative performance of my sample lights in my ceiling bounce room, linearly adjusted to estimated lumens by a conversion multiplication factor. It is quite possible that my values are not accurate - but the relative proportionate readings are surprisingly consistent with manufacturer specs.

Put it another way, if my TN31 were really 800, or 900, or 1000 ANSI FL-1 lumens, etc., then you would have to adjust all my other lumen estimates down by the same percentage as they are based on a linear conversion of direct ceiling bounce readings (i.e., the lights are all proportionately relative to each other). Of course, it is possible that someone else has a 800 lumen TM31 - I have no idea of what normal variation is, given my single sample. But is also quite likely that their "lumen estimate" calibration differs from mine.

You have to compare any one individual's lumen values against only the other lights they have tested. You cannot compare across reviewers and samples unless you do a detail correlation analysis of all figures they report for common lights to see how much they personally differ (as I did here for my basic lightbox lumens).
 

TEEJ

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Excellent points.

I would add, as someone, in a past life who has also worked in a laboratory setting doing performance testing...ONE sample is not TYPICALLY representative of the entire product output.

This means that, exactly as Selfbuilt mentioned, ALL lights will have a RANGE of performance, just like not all Mustangs roll off the factory floor with exactly the same 1/4 mile time/speed, etc.

There are ALWAYS variations in a batch, and between batches, runs, etc.

So, generally, unless a factory's QA/QC or raw materials, etc, are really inconsistent, MOST of the product will fall into a reasonable RANGE of performance...with some outliers/salients occurring at either end of that bell curve.

So if one guy measures 1,000 lumens for light A, and 2,000 for light B....and another guy measures the same MODEL light and gets 900 for A and 1800 for B, that actually AGREES. It can mean that if YOU buy one of those lights, the output might be anywhere between those two #'s. If you KNOW they made a bin upgrade, driver changes, etc...sure, assume the LATEST reviews might have had the latest version, etc.


Personally, I trust an unbiased third party reviewer like Selfbuilt, TurboBB, HJK, etc, over a manufacturer claim.....and even if the number itself is not "accurate", it doesn't really matter, because its still proportional to the other lights' numbers from the same reviewer...and that reviewer's numbers relative to the OTHER reviewers, and so forth.

There is a system of checks and balances.

For example, NO ONE here REALLY knows what "1,000 Lumens" looks like the way a musician has perfect pitch and can hear the frequency accurately, etc. What we THINK is "1,000 Lumens" is a product of what we were TOLD was "1,000 Lumens"..and COMPARING that to what we see, etc.

So if you have a "1,000 lumen light" based on the reviews, etc...and its not able to light up things as much as you want it to...you know you want MORE THAN 1,000 L for its replacement. If SB says the light you HAVE is 1,000 L, and another light he reviewed is 2,000 L, you KNOW its about twice as bright...and will light up MORE THAN your "1,000 L" light, and so forth.

The fact that your "1,000 L light" was putting out 1,200 or 800 L doesn't matter, the fact that the "2,000 L Light" is putting out 2,200 or 1,800 L doesn't matter, because it doesn't impact your decision process...the data essentially means the same thing.

:D


If the reviewers DID have a calibrated IS, that would be great of course, but, the LIGHTS will still vary...and they would need to be sent perhaps several lights from different batches, etc...to establish a performance curve....otherwise, they are STILL only able to say what the ONE light they were sent did....and hope its at least representative of the range a consumer might be shipped.
 
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