DBSAR Lantern Mini-Review: -Zanflare T1 (UPDATE: Second T1 failed!

Well it appears, from Pete’s results, that the battery tube gets hotter when the light is upside down, which seems odd. This would seem to indicate that the heat concentrating at the tail cap is not due to that being the bottleneck of heat dissipation. If that were the case the light would cool more effectively upside down.

This makes me think that the outside diffuser is dissipating much more heat than it is given credit for, obviously it won’t appear as hot, as it has a much larger surface area. Maybe not such a bad design then, just slightly overpowered for its overall heat dissipation capability?

Just concluded a discharge temperature test on post 114. :beer:

My bad. I must have measured cell temp incorrectly before. I re-ran the test (lantern in position 1), and after 60 minutes, lantern base was at 56 deg C, and cell temp was 56 deg C as well. This was the temp on lower half of the cell. The upper half was cooler.

Cell was at 3.83V at the time of measurement.

Thanks tatasal for posting your test results. Good info & well documented…. :+1: . :beer:


DBSAR, what kind of conclusions have you made about this temperature related issue on the T1?

In our own tests it seems most of the battery tubes never exceeded 60°C and the batteries themself seemed to range from 50°C to 56°C. (I haven’t had time to sort through all the posts)

You reported 67°C in your battery tube, right? Do you think your T1 was an anomaly or maybe we should test these lights in a hotter environment?

I looked at a few battery data sheets to see what kind of temperature related info I could find. It seems there is a regulation Per UL1642 that says cells have to withstand 130°C without exploding or burning. Edit: I see that the Panny B has an 80°C limit.

An operating range of up to 60°C surface temp seems to be the norm for most cells.

Do you think this means the T1 was built within the safety specs and your T1 had an issue? Even as hot as your battery tube got, your battery should not have been anywhere close to its danger limit.

Samsung 35E:

3.12 Operating Temperature (Cell Surface Temperature) Charge: 0 to 45°C - Discharge: –10 to 60°C

9.4 Heating Test
Test method: To heat the standard charged cell at heating rate of 5°C per minute up to 130°C and keep the cell in oven for 10 minutes. Criteria: No fire, and no explosion.

Sony VTC6:

2.6 Allowable Environment Temperature Charge 0~+60℃ -
Discharge –20~+60℃

2.8.2 Discharge Conditions
Discharge at cell surface temperature below 80℃.

I couldn’t see a max heating test.


2.9 Operating Temperature Charge 0 ~ 45℃ Discharge –20 ~ 60℃

4.5.4 Heating Test
Cells are charged per 4.1.1 and heated in a circulating air oven at a rate of 5ºC per minute to 130ºC. At 130ºC, oven is to remain for 10 minutes before test is discontinued (Per UL1642).
Specification: No explode, No fire

Samsung 30Q:

3.11 Operating temperature (surface temperature) Charge : 0 to 50℃ (recommended recharge release < 45℃) Discharge: –20 to 75℃

9.4 Heating test
Test method: To heat up the standard charged cell at heating rate 5℃ per minute up to 130℃ and keep the cell in oven for 10 minutes. Criteria: No fire, and no explosion.

Sanyo/Panasonic 3400B and 3500GA

5.12 Operating Temperature
Charge 0 ~ +40℃
Discharge –20 ~ +60℃

(2) High Temperature
“Do not use or place the battery near fire, a heater or a high temperatures (more than 80℃).”
The battery’s polyolefin separator may get damaged from the heat and could cause an internal short circuit. This may cause the battery to catch on fire, smoke, explode, or
cause heat generation.

It looks like Wimpy Water got removed from the forum (I wonder what he did). I wish he was here so he could apologize for accusing me of sweeping these temperature related issues under the carpet. He was way paranoid. :person_facepalming:

In this test venting is allowed, i.e. the cell is not usable after this.
The 60°C rating is not really maximum there is some safety included. This can be seen from some cells where the specifications allows up to maybe 80°C when using thermal cut-off.

The Wimp got wimped.

I don’t know what specific rule he broke, but it was obvious that he was more interested in trolling than content. He deliberately threw around insults and slipped provocative comments into his posts on a regular basis.

Ah, so venting is allowed. That makes sense. 130°C is pretty rediculous.

Yeah, 60°C is normal. They even store the cells at 60°C for a month to make sure they hold their charge.

What is interesting is the Sanyo/Panasonic data says the “polyolefin separator may get damaged” above 80°C. I wonder if this kind of separator is common among all the other brands of batteries as well. This might be considered the true temperature limit before venting. What do you think?

The “No fire, No explosion” means venting is allowed. A venting is a undramatically event to prevent explosion. But it can be dramatically if there is anything that can ignite the venting gas (Like sparks).

This is surface temperature, the inside will be warmer.

I guess it depends where the heat is coming from. If the heat is from an external source like battery tube or heater then I don’t think the interior will be warmer.

If the heat is from high discharge, then the inside will be warmer.

I’m glad your on this thrwad. I guess someone pointed you in this direction? Edit: Oh yes, post #39. I forgot.

I guess it depends where the heat is coming from. If the heat is from an external source like battery tube or heater then I don’t think the interior will be warmer.

If the battery powers it, the battery will get hot and this means the battery will be warmer.
The reason I use relative temperature in my battery test is because the temperature is above ambient and if the battery is inside a hot tube, the tube temperature is ambient.


I think my general conclusion is the Zanflare T1 is not a defective or dangerous device. It seems to keep the batteries within a safe operating range.

No device is 100% safe. If you use a Li-ion battery that is abused by being over discharged, over charged, dropped, etc… then it will be more susceptible to over heating and venting.

Most devices may still be able to use these abused cells because the devices heat range is limited. In the T1, the heat range is higher than most devices, so that makes it more likely to push a bad battery to its thermal limits and cause it to vent. It doesn’t mean the device is bad, it means the battery was bad.

So I guess the moral of the story is to heed all Li-ion battery precautions. If you’ve got a battery that gets really hot while being recharged at a nice safe rate or doesn’t seem to terminate charging, that battery may be damaged inside. Get rid of it in a safe manner.

Be cautious of laptop pulls or old batteries. Test them out thoroughly before using them in your devices. If it acts funny, can’t hold a charge or runs hot for unknown reasons, it’s better to get rid of it than risk it venting on you.

I had a brand new 16340 battery act funny on me a while back. It would not terminate a slow charge and it got really hot in the process. I had the manufacturer send me a replacement. Better safe than sorry.

This is my opinion on the matter. What do you guys think? Have you drawn any conclusions yet or do we need to do more testing?

I’m curious if the battery temps will exceed 60°C in a 35°C ambient environment.

I pretty much agree with you Jason. I feel like it is safe enough to use given the results you & others have posted, as well as what I have experienced using mine.

No problems to date…… :+1: . :wink:

The T1 is definitely safe to use even in the brightest mode till the cell goes down in voltage, goes a notch down as the cell depletes with lower brightness until the LVP kicks in.

Tried it again today for confirmation.

Edit: I once experienced my Klarus Mi7Ti with a 14500 accidentally turn-on inside a holster (from my Eagletac D25A) and went into turbo until the holster was melting and nearly burned it. I never held a light as hot as it was, it was scalding hot.

Yet the light and the cell are still alive up to today.

Thanks to all for contributing data points to this thread.

I’m not yet prepared to rule this as “safe under all conditions” but I don’t plan to try to heat my house to 35+ C just for testing purposes. I’ll sure be keeping an eye on this as we move into summer down here.

If the cell can reach the mid 50s in a 25 deg ambient, then I think there is some cause for concern when you start adding another 10-15 on top of that. (Yes, I’ve experienced temps of 35-40C indoors on a summer night.)

Lithium ion won’t go into thermal runaway until the 115C (240ºF) range. You’re plenty safe. The temps everyone is posting is with the lantern on full brightness anyway.

Protected cells are still a viable solution. I’m not sure if the o-ring was able to be compressed using my 69mm cell. You don’t need to fully compress it unless your outside where it might get wet. I think a thicker o-ring would get compressed. Or you could double up the o-rings.

HKJ, have you ever tested the thermal limits of a protected cell to see if it kicks in at a certain temperature?