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

Keep in mind the heat has to get out some how. The battery tube and tail cap is about the only way it can do that.

I’m off work and can do some tests on my two lights. I only have a temp probe from my DMM, though. I guess I can insulate my finger and hold it up against what I’m measuring. Will that work?

I need a good IR thermal reader that’s not too pricey.

Okay, here is how I tested my two lights. One used the stock battery and the other an Evva brand protected Panny B 3400mah (69mm). Both fully charged.

Ambient was 25°C. Lamps where laid in their side.

I let them run about 10 to 12 minutes at a time, then checked the tail cap temp, the inner battery tube temp and the battery temp (the negative electrode was the hottest part). I probably lost a good bit of heat just from checking every 10 minutes so at the 40 minute mark I decided to let it run 20 minutes continous to try and max out the temps.

I took amp draws before the test with each cell and ran all tests on the CW setting as that seems to pull the highest amps.

Here’s how and where I measured. The bare aluminum on the tail cap seemed to be the hottest part.

The two batteries.

All the temps seemed to be pretty accurate. They steadily climbed and then stated to level off. There are a couple measurements at 30 minutes that are a couple degrees cooler than before. Those might be anomalies. It’s tricky getting the probe to press against things hard enough so they might be about 2° too low.

Anyway, here are the results:

I hope you guys can understand them.
Max tail cap temp was 54°C.
Max battery tube inner wall was 55°C.
Max battery temps were 52°C. It was hard to hold them. This might be a safe battery temp, but I still don’t like it. I’m certainly not used to it.

I stopped testing after 60 minutes since the temps were leveling off. If they had run for 60 minutes continous (no interrupting to check temps) I think all temps might have gone one or maybe 2 degrees higher. I’m not sure. Both batteries were in the 3.6v range after the tests so their output might have have been going down. Total runtime was probably closer to 75 minutes. After recharging both batteries, the capacity added to each was right at 1480mah.

About the battery temps, it seems like the heat shrink acts as an insulator not only electrically, but also thermally. I suspect most of the heat is going through the tail cap, up the spring and into the bottom of the battery. It’s an all metal heat path so conduction is good.

Some of the heat probably comes through the plastic heat shrink, but not most of it. It’s just not a good conductor. This is my theory, at least.

The positive electrode was the coolest. It only makes contact with the upper circuit board, not the battery tube.

52°C is not a problem. It actually improves performance, especially in the cold.

Not good test conditions, the problem is obviously going to be more evident when the light is standing on a non thermally conductive surface, not lying on its side generating a convection current past the hot spot with cool air.

Below are my temperature measurements, using a fully charged Samsung 30Q cell. I ran the test for 60 minutes, measuring every 10 minutes with an IR thermometer. The measurement is the highest temperature observed on the base of the lantern, which was not actually the tail cap but a spot on the base just to the side of the tail cap, for some reason. Temperatures leveled off and started dropping from about 60 mins onward.

I ran the test twice:
(1) Base Temp 1 lantern position:

(2) Base Temp 2 lantern position:

The lantern was sitting on top of a speaker cabinet. Starting/ambient temp was 25 deg. C.

Thanks Pete, that looks like another well done & documented test… with decent results as far as the lantern goes.

Same goes for you JasonWW… well done with excellent documentation. :THUMBS-UP:

Sorry. Maybe I’ll do that the time time I’ve got a chance to measure again.

Maybe I’ll just let it run 40-50 minutes straight on a hard wood surface then measure the battery temp.

The most important thing is the battery temp, right?

Is it safe to assume the battery temp is always going to be a few degrees cooler than the tail cap temp? That’s what it seemed like on my tests.

So I’m guessing Petes batteries got up to 53°C or 54°C?

My battery temp did not exceed 50 deg C.

So your batteries ran at least five to six degrees cooler than your tail cap temperatures? Interesting.

Was the hottest part of the battery the negative base plate?

My T1 arrived today. Now fully-charged in the office, I will simulate the above 60-min test with my ir meter later tonight when I’m home.

Would you believe that the ‘Weather Station’ clock/thermometer/humidity/barometer is a product of Henry Xu of Opus?

Photo below shows the closeness of the ir’s reading to the Inside Temp of the Weather Station.

Later tonight I will start the 60min temp reading test…

Started the discharge test at 8:17 @ room temp of 26.8cel : (lantern standing on wood table during the duration of the test, except when taking temps)

After 17min., IR temp reading at 43.7c:

After 36min. : 52.3c

After 48min: 55.9c

After 1hr, 1min.: Temp started to decrease by 1.2degrees to 54.7c

After 1hr, 2min: Temp steadily decreasing to 53.1c

Removed cell while light is still on, cell temp 51.4c, Cell voltage: 3.66v

Definitely just fairly warm for electrical components standards, so it’s safe to use using even with the unknown OEM cell that came with it.

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…. :THUMBS-UP: . :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. :FACEPALM:

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.