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

my previous test was with the factor included cell, so i was running it tonight with a 3000mah cell to test run times, and it got really hot. ( i could not put my finger in the tube it was so hot) when i took the bottom cap off the tube & cap was really, really hot, and from a photo i seen they use that tube as the heat sink for the LEDs! - a very, very dangerous design…

i ran it for another 20 minutes with the original 2600mah cell, then measured the inside surface of the battery tube at 67 degrees Celsius. (on maximum mode in W/W which i measured at 0.89 amps on the tail cap. (the cool white mode on max pulls 1.02 amps.)

Oh crap.

I would ask for a refund ASAP. That is a very dangerous design.

This would have not happened if they had put a least a small aluminium plate.

Now I know why it was too cheap. That’s because it is too cheap.

No one should be jumping on the bandwagon until they get all the facts first.

We need to hear from the manufacturer about their thermal limit tests. It’s possible DBSAR has a malfunctioning unit. Probably not, but we need to gather up all the facts and data before condemning a product.

It is actually not that bad of a design seeing as most flashlights are made similarly. If you leave a flashlight running long enough the heat near the LED will travel down through the length of the battery tube and it will heat up the battery just the same. I guess the big difference between a flashlight and this lantern is that one has an exposed battery tube so that the surrounding air can pull heat away from it. The lantern doesn’t have any way to circulate the air around it’s battery tube.

It’s quite possible that this entire situation can be fixed/corrected by using a simple insulating sleeve around the inner battery tube to prevent a battery from touching the metal walls and absorbing that heat.

A long-term solution would be for the driver design to be tweaked to step down the brightness at a certain temperature.

That link is taking me back to post #11.

Not to be deliberately contrary but I’m doing a test at the moment with the OEM cell.
So far I’ve run the light for 65 mins on MAX WW. The battery is no more than mildly warm and the inside of the battery tube is the same.

The lantern is hanging by the metal handle and nothing is touching the tailcap to act as a heatsink.

However, ambient temp here (winter) is only 14C (57F) today. What might happen over our 40C (104F) summers is anyone’s guess.

Obviously more testing to be done. I just kicked it to MAX CW about 10 mins ago.
A spot check reveals the resting voltage (straight out of lantern) is only 3.60V so it may be a bit pointless to continue without a recharge, but I’ll let it go for now.
I will try again with a freshly charged Panny 3400 or similar when the current cell cuts out.

With the greatest respect Den is it possible you have a higher ambient there or perhaps as JasonWW suggested, there may be some variation between batches or perhaps even a faulty unit?

With so many of these having been sold through the group buys, I hope a few other users can run some tests and report back too.

EDIT: Sorry, but I can only give subjective temps at present as my IR thermometer is elsewhere.

I have never had any flashlight (factory or modified) heat a battery as hot as this in my T1 did last night. The LEDs are in direct contact with the battery tube wall, (no flashlight does this.) this is the first time i have any light heat the cell up so hot to the point it began to gas. (the sweet smell before it begins its thermal runaway and vent.) I’m not condemning this light, i’m expressing a potential dangerous design flaw if consumers use a damaged or old cell in such a design where the battery tube is “directly” heated by the LEDs at high modes,
which i will stand by my decision is a very bad, flawed design to do that in the first place. (same scenario as lighting a propane camp stove that rests on its propane tank that feeds it)
Its ok for most if us who are experienced with LithiumIon cells and its characteristics and limitations, but this is a potential safety issue to the un-trained public. from past experience I testing cells to the point of venting flames, i know the warning smell all to well before a LiIon goes nuclear. Lithium Ion becomes unstable at high temps, and the potential with this design exposes that risk. I heated a running flashlight with a 18650 cell in it to the point of it exploding. (see my video from a few years back) the design of this light as a flaw that needs to be addressed, as its using the LEDs to heat the battery tube directly. Zanflare can easily fix this issue in a few ways, one is like you said is to tweat it down to a maximum of 0.65 amps draw, ( i did just that after with my T1 using a amp meter and ramped it down to 0.66 amps ( about 80% from max on the W/W mode) and the battery tube stabilized at a 55 to 57 degree temperature after 40 minutes. ( still to hot for my thoughts, but less than running on maximum.) another fix is to have a “shell tube” outside the battery tube for the LEDs to contact, leaving an air-gap from the LEDs and the battery center tube, preventing the conduction of heat to the battery.
in reality no flashlights i ever seen has hot running LEDs all around the sides of the battery tube/body in direct contact with it. Also, nobody is going to walk around, holding a modded flashlight that manages to conduct enough heat to the battery body for a hour or more continuously. Lets get realistic here… Metal at 65+ decrees C is very uncomfortable and nearly impossible to hold in a bare hand for more than a few seconds, let alone a hour. In this case of a lantern, it can sit there on a table or hanging in a warm tent, for a couple hours getting hot, cooking the cell at temperatures beyond what we can endure for a few seconds on a bare hand. There are reasons why Tesla liquid cools their massive 18650 cell banks… this cell chemistry is not stable, nor safe at extreme temperatures for long periods of time.

I will perform another test tomorrow or next week using the factory cell and my temp-meter at the maximum modes, (but will do this in the garage this time.) when i did the test last night with the cell over heating, the temperature inside the tube was to hot to put a finger in. I did a test after only running it at roughly 80% with the factory cell, and got a 67 degree Celsius in the tube. (higher than i care to continue using it continuously at that temp or higher.

How did you measure the temperature inside the tube? Did you measure 67°C right after you took out the battery? If so, actual temperature in operation might be even above those 67°C as the tube immediately cools down when you turn off the light.

Another short-term fix would be to swap out the factory battery for a protected 18650.

One of the things the protection circuit protects against is overheating.

I’m not around my Lantern at the moment, but if you wanted to test out a protected cell in it, I would be really interested in the results. I don’t even know what the protection circuit would do in case of a over temp situation. I guess cut all power to the cell. I’ve never actually tested that.

i measured it maybe 30 seconds after i removed the cell, (second test with original cell) using a infrared-type temp meter i use for all my heat testing)

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.

  1. 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: :smiley:

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. :stuck_out_tongue:

Hang the metal “heatsink” in your tent and attach the lantern to it. Makes for a super steady base when not hanging. :smiley:

I’m just goofing around.