good point, i don’t know if all protected cells have a thermo-cutoff sensor in the tail cap protection circuits, as i known them more for protection from over charging & over-discharging. I do have protected cells, and can do a test using one of them to maybe.
Two big factors limiting your temp here.
1) Ambient temperature, light will reach temperature equilibrium when it is X degrees hotter that the environment it loses heat to, so if it were 30C your light would get 16C hotter that it did under the same circumstances at 14C (difference could be from say 40C to 56C)
2) You had it hanging, so there is free air flow and convection current around the end of the battery tube. This is avoiding the biggest problem with this light, the lack of air cooling of the battery tube when sitting upright on an insulating surface like a wooden bedside table (which is also flammable)
30 seconds is quite some time for the tube to cool down and depending on the tube's emissivity the temperature measured by IR can be even higher than those 67°C, especially when you observed that the cell begins to vent gas. Thanks for keeping us updated, DBSAR.
This is an excellent idea for a light, especially that it has a first edition. The flaws can be detected and removed in the next iteration.
There are a very small number of lanterns that are good, and this is one of them. And it is cheap! A good business opportunity!
However, with few small corrections the T2 can be one of the best Lenterns on the market and the interest should be very large.
Namely:
1. Using Very High CRI leds. This is a must for a quality long term light. 9050 is the absolute minimum for a lantern. 9080 would make everyone happy. Nichia Optisolis 9090 will be the best thing and everyone will be talking about it. Very good lighting, and a good conversation piece and free word of mouth commercials. First lantern with near 100 CRI and similar discussions. BLF and CPF will be all over it.
2. Fixing the heat issue. Making the base 10mm taller with more metal, and a few ribs/fins will make the heat dissipation a lot better.
3. Making the battery tube to fit 26650, and a sock inside for a 18650 will be amazing. Even wider audience, and more runtime. More people happy, more sales.
4. Recess the touch button 5mm, to be harder to touch. Or place a better switch. Or place a On/Off slider switch underneath for lockout.
And that is it.
I will perform a new test of it with a 30Q Samsung later on friday. Will run it for 30 minutes on maximum mode, with the tint mixing set at medium blend, (roughly 4000K) meaning all the LEDs (both the W/W and C/W LEDs) will be on for the temperature tests to heat the center tube as it can. My goal here is to test this lantern to make sure it can operate safely, if it has a flaw with overheating the battery, then it needs to be addressed as a safety concern for the public using them, even if i have to sacrifice the lantern & a cell to a fire or vent to help make aware of/if there is a hazardous flaw to users.
- Using High CRI LED may be a moot point considering they have to go through a milky white lens which will surely alter the color and tint. IDK, maybe not?
2. An aluminum base would probably get the job done. Or increase the metal surface area on the bottom. Maybe a half plastic half aluminum base. Or they could just reduce max output (it’s a bright little suckered for sure) or add a temp sensor to step down output.
3. Maybe a 21700 would be a better option since we don’t need high drain cells. A 4800mah or 5000mah 21700 would equal, or almost equal, a good 26650. It would also keep the leds further away from the plastic lens, compared to 26650, to help it blend better. It could ship with the same cheap 18650 with thermal insulated (plastic) sleeve. Those that want to spend 10 bucks on a good, high capacity 21700 can then do so.
4. Buttons definitely need some tweaking along with UI. Needs to be simpler.
Thinkin’ about venting gas and sweet smell…the T1 could actually compete with this nice device:
Just kidding, of course! :smiling_imp: 
Both good points Zulumoose.
Which is why I felt it important to state my test conditions.
The first test has now run to completion. I got a further 55 mins or so on MAX CW and the tube and cell were still not “hot”. I’m topping off a protected Panny 3400 at the moment for another test.
Typically I have been using the lantern attached to a metal surface. I chose to let it hang so the magnetic cap could not use the metal as an additional heatsink.
Your idea of sitting it on an insulating surface might have to be part of my further testing but I’ll wait until I get my IR gun back again after the weekend.
I was just thinking about this earlier. Does the magnetic cap physically touch the metal surface?
If so, Zanflare could ship everybody a “fix it kit” to prevent thermal excess. It would be an 8” piece of square sheet metal. 
Hang the metal “heatsink” in your tent and attach the lantern to it. Makes for a super steady base when not hanging.
I’m just goofing around.
Goofing noted…
Checking using a steel ruler, it appears the tailcap and the plastic base are exactly flush when screwed down tight. You could always back the cap out a little if it wasn’t, as the threads are not anodized. So yes, the magnetic tailcap does physically touch the surface.
Having said that, I suspect that the amount of heat drawn out through a few threads and layer of paint over a circular contact surface only 20mm (3/4”) in diameter would be pretty minimal.
I just wanted to rule that possibility out for my tests.
The “fix it kit” could also be a bigger tailcap with fins, so it would screw directly on the heatsink.
I think we need some numbers here.
We humans feel pain at 55 degrees Celsius, and experience that as alarmingly hot. Electronics can withstand 250 degrees Celsius and more. Li-ion batteries are in between, thermal runaway starts only at over 150 degrees Celsius, but I guess degradations of the battery already starts at lower temperature. But still I reckon that a battery at 80 degrees Celsius (way too hot too touch) would not be unsafe? Anyone with more knowledge about that?
Btw, thanks for the very good hands-on review Den!
Exactly my point in my post in the gb thread.
HKJ frequently ends his tests with temperatures well over 50 Celsius degrees over ambient. Maybe the cell vented because it was somehow faulty?
ADDED:
Mooch frequently exceeds 80 degrees. Sometimes 90.
Quick browse and I found him going to 97:
All the HKJ reviews I’ve read he usually ends the amp draw tests early if they exceed 80°C. For a continous discharge rating it has to stay under that temp.
In those tests the battery chemistry is generating the heat, not it being heated by an external source. Maybe that’s an important distinction?
Based on Mooch’s background, he’d know for sure.
I PMed HKJ, maybe he’ll comment…
A member of the German TLF just checked his Zanflare T1 with the original batteries. He also used an IR thermometer. These are the results:
Discharge start @ 4.12V, maximum brightness in coldwhite:
o IR-temp. on tailcap: 0:00h 25°C, 0:15h 41°C, 0:30h 48°C, 0:45h 51°C, 1:00h 51°C
o IR-temp. after 1:00h on battery inner tube, max. 10s after interruption of operation / removal of battery: 53°C, 3.7V resting voltage
Test means nothing if we do not know the conditions of the test.
Ambient temp?
Airflow?
Orientation of lamp?
Material in contact with tailcap?
Ideally the test should be done without airflow at a known ambient temp in worst case scenario of lamp standing upright on an insulating surface like wood, or even worse on material, such as a tablecloth, blanket etc.
I doubt a cell vents below 90°C internal temperature. The internal temperature will depend on current draw and internal resistance in the battery (And of course ambient temperature). This means that the risk of a venting cell will be high when using a cell with a current draw that makes it hot when the tube also is warmed from the led.
I wonder how much the led heats up the interior of the battery tube at the top, leds can run above 100°C (The temperature of the tube may not tell the full story).
Thanks for the heads-up DBSAR.
After 10 days of daily usage of my three T1s, today, just before I read your post, my daughter bring me her T1 so I can recharge it and for the first time I noticed the very hot tail cap. Hasn’t happened until today even after hours on max so my guess - and its only a guess - maybe not all T1s have that issue?
I will keep my eyes open about this dangerous behavior.