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

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.

I still say “Sweet Smell Of Death” would be an awesome name for a thrash-metal band.

Just thinking out loud here… and getting strange looks from people around me.

Know the Nitefox UW360 flex-neck light-thingy? It comes with a magnetic-suck base (seriously!) and a ferric disk to act as a wider stabilising base, and to be able to stick it semi-permanently to another surface.

Well, what about something similar, a ferric disk that would stick to the magnetic-cap of the T1, and with a wider base and thus more surface area, wick away heat to the outside world?

Bugger, I just suggested that about a minute ago.

Doesn’t seem like a bad idea. See the UW360, ’though that’s not for heatsinking.

I’d imagine the T1’s cap has to make contact with a bottom surface, else there’d be an air-gap that’d seriously reduce its magnetic-suck action.

My protected cells are too long to fit this lantern.

I have 3 T1s …… I ran all 3 for several hours on high CW and the tailcaps on all remained as cool as the ‘outside’ of my fridge…… Not saying this couldn’t change in the future but if there is a heat problem then it seems it may be a QC problem and would not be occurring in ALL T1s.

Considering the majority of present owners of the T1 are not experiencing the same thing as the op while using the cell that came with the unit but from a known old cell (might’ve already high IR) , shouldn’t it be fair to Zanflare to have this thread’s title edited ?

In my case it was a used older cell that overheated & began to gas fumes due to the battery tube being hot from the LED that are attached to it inside. It may not happen to all 18650 cells, but its still a potential risk with a weak, older, cheaper, or damaged cell in the lantern. When it comes to lanterns in particular, i focus on all safety concerns and potential hazards. unlike flashlights, lanterns will more likely be left unattended for long periods of time running in a tent or house, resting on or near flammable material. (even when people are asleep) and even if just one out of 500 of them that has a bad cell it it that causes its battery to gas or go full-vent due to the heat and catch fire is a concern.

No doubt that most who have this lantern may never have a problem, but the risk is there because of the flaw in that design using the same battery tube metal as the LEDs direct heatsink. My personal feelings on this lantern is that Zanflare should either reduce the maximum mode amp load, or re-design the LEDs to be on a separate sleeve with an air-gap from them to the battery tube. ( but neither is likely as they woudl probably discontinue it and offer a new re-designed model.

Well, to be fair to Zanflare and the rest of the owners, such sweeping conclusion in this thread’s title (“Dangerous Flaw Discovered”) should be qualified with an additional note like “using a used, old cell, etc.” information.

No doubt you have good motives to bring this out to our attention yet one sample with such cell behavior from an old cell doesn’t necessarily require such sweeping conclusion.

I may be missing something but it seems to me if the “design” was the problem…. it would affect all the T1s. I definitely think if they implemented your suggestions the design would be safer but think it is a little unfair to blame the design if the problem is only caused because someone uses an old or defective battery. That’s like blaming a gas car’s design because you put kerosene in it. You could re-design the car so kerosene would work or simply use the proper fuel so you don’t create a problem where one does not exist.

it do not matter if its an old or new cell. the lantern has a flaw that directly heats up the cell with the LEDs. not everyone who may buy this lantern will understand what we know about Lithium Ion cells and LED lights. someday someone could put a cheap ultrafire cell on this lantern and it go bad. If a product i test has a potentially hazardous flaw, i will expose it and make sure people are aware of it.

and that would be “someone” at fault wouldnt it…… not the lantern?

your missing the point. the lantern has the flaw of heating the cell, that people are not aware of.

Would be fair though, to test it with the cell it came with and see if the problem still occurs.
And for good measure, test it with a Japan made cell.
Just to make sure it’s not your old battery.

Maybe I am, but again, if this IS a ‘design flaw’ then why does my tailcap remain cool after hours of continuous use when I use a decent battery?

maybe your particular lantern has a flaw and don’t run at full output like the others. LEDs will produce heat when running at higher modes. its fact. at 1 amp draw the tube inside my L1 gets so hit it almost burns my finger. The cap gets quite warm, but not as hot as the insides sides of the battery tube.