Thrunite TN31 drops from 1147 lumens to 809 under its temperature control.

I nearly pulled the trigger on the TN31 until I discovered that the temperature control on this flashlight can take the lumens down to 809 or so from 1147.

So is this really an 800 lumen light but when the conditions are right it can run at 1147 lumens.

What is the general opinion about this, and has anyone else seen this documented or experienced this kickdown themselves?

I really wanted to buy this light until I read an article on the temp control.

The step down doesn't bother me, as it is still an excellent thrower with good runtimes. Therefore I consider this to be a really useful torch and a welcome addition to my collection.

Pretty much most high performance, hard driven lights step down to protect the vitals.

Its like runner...we say a man can run at 30 mpg or so, but only for a few hundred yards...but they might be able to run at 15 mph for a mile or more, etc.

If you make the race 100 miles, the average mph goes down some more...and then you ask..How fast can a man run?

The answer is typically the sprint speed....not the average on a 100 mile distance.


So, its really a "30 mph Runner" essentially.

On the other hand, if you need something delivered 100 miles away in less than 4 hours...a guy running that far to deliver it won't work.




If you use a light to see things far enough away that the stepped down range is inadequate to see what you need to, in the level of detail you need to see it in...long enough...then, sure, you need a more powerful light.

In terms of the timed step-down, I found it dropped by just under ~100 lumens in my testing (at around 70 secs into the run).

Check out my full TN31 review for more info on the light. I didn't post lumen estimates for after the drop-down in the review, but it was still ~1000 lumens by my estimate.

Under cooling, it stayed fully-regulated at this level. It's possible that output would have dropped further over time with no cooling (i.e., if there is a thermal sensor). But as others have said, this would be a sensible precaution.

There is a timed step down of about 100lms roughly a minute after turn on but this was in my testing with a fan used. Also, I measured current draw to only be 1.48A @ 12.56V so it's not really being driven all that hard. The temp (under 37.8C) reached during runtime testing corroborates this. I graphed the entire runtime w/actual measured lumens (on my PVC LMD) along w/the temp so you can check the review for further details.

I'll try a test run w/out a fan in the future but in the meanwhile do you have a source to the article indicating the steep drop?

Thx!,
Tim

Just got mine yesterday, and all I've got to say is WOW! All the throw of my SR90 in a MUCH smaller package. Amazing light.

Pull the trigger. You will not regret it.

And by the way, thanks once again Mr. Euro Exit/Egress Sign for yet another outstanding review. I can't help but buy a light when you show that it comes out on top of the competition.

turboBB said:

in the meanwhile do you have a source to the article indicating the steep drop?

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I would be curious to see it too.

Flight_Deck said:

thanks once again Mr. Euro Exit/Egress Sign for yet another outstanding review. I can't help but buy a light when you show that it comes out on top of the competition.

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Ha, not too many in North America get that ... It is actually quite common world wide (although some countries include flames to help spur him on). :laughing:

turboBB said:

There is a timed step down of about 100lms roughly a minute after turn on but this was in my testing with a fan used. Also, I measured current draw to only be 1.48A @ 12.56V so it's not really being driven all that hard. The temp (under 37.8C) reached during runtime testing corroborates this. I graphed the entire runtime w/actual measured lumens (on my PVC LMD) along w/the temp so you can check the review for further details.

I'll try a test run w/out a fan in the future but in the meanwhile do you have a source to the article indicating the steep drop?

Thx!,
Tim

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I don't think I can link to the article in question due to restrictions on CPF.

But it did come from another review site on lights.

Some reviewers use fans when testing lights but this test was done in the real world where you don't carry fans and batteries on your person just to cool the light being tested to get the best results.



Cheers

I appreciate your POV re: the use of fans but consider also that in the real world, there may be other elements to aid in cooling, which chief among them would be ones hand. While I can't speak for every reviewer, I honestly don't have the time nor inclanation to sit around with my hand to keep the light cool thus a fan is employed. This is to say nothing of what would happen to the output curve whenever I'm not able to maintain my posture perfectly still (ie, "Hmmm... was the bump/reduction casued by the circuit or did I lean over to pass gas 30 minutes into this run...")

Until I can ascertain just how hot a light might get, I don't intend on allowing it to potentially overheat (or worse) on the very first run thus preventing me from being able to complete a review. This is why I also graph the temperature with the runtime and if necessary will revisit a run without the aid of a fan if conditions call for it (e.g. check my EYE30 review).

In either case, this has got my curiosity piqued so as mentioned, I'll conduct a run without a fan just to see what happens.

Cheers,
Tim

Curious to see your results Tim. I've just done it myself on AW 18650-2200mAh, and here's what I got:



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 said:

Curious to see your results Tim. I've just done it myself on AW 18650-2200mAh, and here's what I got:

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.

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You should know the reviewer "mev" of this light at another well known site.

Could he be that far out in his testing.

I am sorry if I have heaped rubbish on the TN31 for no reason if his test light was faulty or the batteries not being fully charged.

I just want to know if this is a good flashlight.

I especially want a good thrower and this seemed to be it.

I have the Dereelight Aspheric with the EZ900 Led and the Olight SR90.

I was going to put the TN31 up against them.

Let's see if this issue can be put to bed once and for all.


Cheers

I'm sure lots of guys use their throwers on high continuous for long periods of time. But I also imagine there are many like me who use the light on a lower mode and then need to take a look around as far as their light will let them see and then drop back into a lower mode.
I was using my TN31 the other night in the jungle like that. It was fine on the lowest mode (.5 lumens) for hiking, (though I often had it on the 21 lumen mode). I was actually in a position without gps (long story) where I could have gotten lost (wouldn't have been the first time of the end of the world to spend the night out). There were tons of animal/"orang asli" trails going in many directions as well as clearings every little bit. With no moon in the clearings, the throw is really good for getting your bearings. I'd turn it on high, made out some hills/ridgelines and the angle they were running at about 500m away and that was extremely helpful to find my way back. Those "bursts" that helped me get my bearings in the clearings only need to be a 15 seconds or so so I was getting the max I think may be possible with a single XM-L light.

I'm not saying it's as good as a XML light that continuously runs at 1140 lumens, but I don't think a single XML can be driven that hard continuously without watercooling or something fancy like that. You can think of it as a 950 lumen light that does 1140 lumen bursts and I'm glad it has the option to do 1140 bursts if that makes sense. I'm guessing the scorpion is the same way; for max/turbo you have to continuously press down the tail cap button. I'm betting they're hoping someone doesn't continue to do that for an hour. I think it's a great option to have - a turbo boost mode that is over and beyond what the flashlight is capable of safely running at continuously.

So basically the TN31 is just a larger TK35 with a third battery.

Thanks, you just saved me some money.

utlgoa said:

So basically the TN31 is just a larger TK35 with a third battery.
Thanks, you just saved me some money.

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No, it isn't. Direct output comparisons in my lightbox and ceiling bounce show the TN31 has ~40-45% more output than my TK35 at 30 secs into the run (although that drops down to <35% after the intial step-down of the TN31). See my TN31 review for output summary values of both lights.

You need to compare relative output measures within individual testing methodologies, not across reviewers (see comments below).

In the case of the TK35, I imagine that difference has dropped slightly with the new TK35 recently released (with improved output bin). But keep in mind, the average successive Cree output bin increase is only ~7% more output (and normal variance could make that anywhere from 1-14% for any given two samples).

EDIT: Also, throw is hugely different - my TN31 clocks in at nearly ~90K lux @1m, vs my TK35 at a little over ~20K lux @1m. That is over twice the relative beam distance (i.e., overall "throw")

Oztorchfreak said:

Could he be that far out in his testing.
I am sorry if I have heaped rubbish on the TN31 for no reason if his test light was faulty or the batteries not being fully charged.

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I can't comment on any other reviewer's methodology, but I suspect the issue is simply one of lumen estimate variation (i.e., it has nothing to do with thermal drop-down, just different baseline estimates).

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:



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).

Having both the TK35, and now the TN31...coming into it I wasn't expecting TOO much difference. Hours later after charging up the batteries and waiting for dark, my jaw hit the floor. The tn31 can THROW, and its very obviously putting out more light doing a simple ceiling bounce... If you want a thrower, and have the cash...its awesome.

edit: Wanted to add, the tk35 is still my "go to" light, the tn31 is a pretty beefy sucker. Secondly, i'm using Callies in the tk35 and Redilast in the TN31 so same cell's. Also something I notice, using ultrafire in the TK (I have 4 as backups) the light seems to heat up MUCH quicker, if anyone can explain this it would be great....anywho BUY QUALITY BATTERIES.

Oztorchfreak said:

I nearly pulled the trigger on the TN31 until I discovered that the temperature control on this flashlight can take the lumens down to 809 or so from 1147.

So is this really an 800 lumen light but when the conditions are right it can run at 1147 lumens.

What is the general opinion about this, and has anyone else seen this documented or experienced this kickdown themselves?

I really wanted to buy this light until I read an article on the temp control.

Click to expand...

Thermal stepdown used to bother me as it didn't seem honest to post the light hghest lumens at a temporary time. Some lights don't advertise or keep that part of the lights stepdown info on the down low.

I just accept it now. The ZL steps down but you can just turn if off and back on for another 5 minutes of it's highest setting. Other lights do this too and i dont mind it too much just gotta remember it's there for a reason so don't letthe light get to hot.

I used to; and still some what do think all lights should advertise ANSI ratings with the highest mode after step down as it's actual lumens. Since there is "turbo mode" i am content with that but many lights don't label that. For me it's a headup before i buy a light. I have actually this on these forums and now days inaccept it and just look forward to the next light. I am lookin forwars to new emitters now.

I had a mate come over and he had his Thrunite TN31 with him.

I was so astounded that this new light out throws every light I have even the Olight M3X except for the Olight SR90.

It was so good I bought one.

I got it today and it is a beauty in output, quality and handling.

The beam is just a real pointy thrower with a nice white colour without any strage tinges to it.

I don't know where the original reviewer got his figures from but this is beautiful torch with a fair bit of spill.

It came in an Aluminium Case, spare o-rings, holster, and six CR123 batteries.

It runs better on 18650 batteries but the CR123s work nearly as well.

The battery carrier is tough and easy to load.

I love it so far.

I am sorry for starting a debate on this torch based on one reviewers findings.

If you have the cash get it you will not be disappointed.


Cheers

I really like my TN31, as it is a very good thrower. I did notice quite a big gap between the stainless steel bezel and the aluminium head. I found that it is easy to unscrew this. Is this true of other TN31's?

I used to hate the temp contolled governors on high power lights until a flashlight in my coat pocket somehow turned on and was red hot when I noticed it. Had it been bedtime it could have easily burned my house down. I like temp controlled governors now. I certainly like them better than time controlled governors. With those you could be out skiing at low temp and still have the light needlessly lower output because 5 minutes have passed.

recDNA said:

I used to hate the temp contolled governors on high power lights until a flashlight in my coat pocket somehow turned on and was red hot when I noticed it. Had it been bedtime it could have easily burned my house down. I like temp controlled governors now. I certainly like them better than time controlled governors. With those you could be out skiing at low temp and still have the light needlessly lower output because 5 minutes have passed.

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yikes, which light was that? did the LED get damaged?

Craig