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

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?

The point of this thread was that DBSAR had a battery vent in his lantern at 65°C or maybe lower. We are not sure the actual temperature. I think we all suspect that his battery, even though it seemed to work fine, was damaged internally. Maybe it was due to it’s age, or maybe it had been over discharged at some point. We don’t really know. We don’t even know why his latern got that hot to begin with.

Maybe the lantern only got up to 55°C and then the battery got so hot internally that it heated the lantern up instead of the other way around.

My country also routinely goes up to 35-40c (even 44c in some provinces during the summer months) and I don’t think the ambient temp is linear in adding to the cell in this case, but perhaps by a few degrees…can somebody more knowledgeable correct me on this?

I haven’t noticed any substantial difference even in my modded, much hotter lights in Turbo at 26c and 35c.

The chips I have seen datasheets on do not include any over temperature protection.

That’s odd, I see this data a lot in battery ads. I don’t have too many protected cells. I’ve got a Panny B 3400 from KeepPower, but I notice it doesn’t mention temperature protection, just over charge, over discharge, over current, and short-circuit.

My others are Panny GA 3500 from Evva.
It says:
Built-in Seiko IC and Three MOSFETs to protect battery from over charge, over discharge, short circuit, over temperature and low temperature.

I’ve looked at a lot of the protection circuit details on many batteries in the last couple years and it seems like most do mention over temperature protection. Obviously that’s not a standard feature across all protection circuits. I thought it was. Well, that’s a bummer.

They may mean the PTC protection, not the chip.

What is PTC protection?

I think they ought to change that design.

It can potentially be dangerous as the battery temperature can be quite close the limits and a not perfect battery or a little bit more outside temperature can cross them.

Also, for our purposes, venting equals explosion as there are no safety vent-holes to T1 - or any other flashlight that I know of - to relieve the pressure (as there are on many ecigs exactly for this reason).

What is PTC protection?
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That is a ring inside the battery that will change to high resistance if it gets too hot, this will basically disconnect the battery. It is not used in all batteries.

You can see it in this tear-down: Disassembly of some UltraFire batteries

This is not true. The T1 battery tube is not sealed. If pressure were to build up, it would go through the positive end of the battery tube, through the pcb and into the white plastic housing. Then the white plastic would break relieving the pressure. So it would not be any kind of pipe bomb if that’s what your thinking.

On flashlights I have seen some pictures where it vents through the driver board and then through the switch hole.

But that wouldn’t address low temperatures and PTC tripping would kill the cell. Sounds like the typical marketing department over hype on nonexistent or features they don’t understand.

KuoH

Is the tube even that thick or is it just a thin piece of sheet metal rolled into a tube with a crimped side? I wouldn’t think they’d waste that much material and add weight by using a thick walled tube like a flashlight.

KuoH

I think the wall thickness of the battery tube is quite thick. Maybe at least 5mm thick. You can tell because there’s a threaded screw hole at the top.

DBSAR, do you have any more pictures of the lights internals or of the plastic part that’s removed?

Must have been a bad battery. I heated a Samsung 25r up in a Emisar D4, installing it backwards testing for reverse polarity protection. It heated up to measure 215ºF on the outside of the battery tube. No telling what the actual temp of the 25r was. By the time I got it apart, the battery was still at 180ºF with no venting. PTC, that HKJ mentioned, may have prevented it from thermal runaway and exploding though.

I think he Vented! :open_mouth:

Whatever breaks after a vent (tube, plastic housing) will break in a way we can’t predict if we don’t test it. Even a flying piece of plastic can be as good as a knife if it hits right, and that is if you are right about the tube having an easy way out for the gases. If a battery vents, it will increase the pressure inside a closed cylinder. So, no, no vent holes = possible pipe bomb.

Also, flashlights do explode from time to time (mobile phones and laptops too), it’s a risk we all take and we can’t be sure that they will vent through the driver board or switch hole or use any other “easy way out”. They are not designed to fail, they have all kinds of protections, and still, they sometimes do. Seems like the T1 works close to the battery fail limits without any thermal protection and I would prefer it not to.

That’s just my opinion and, of course, I could be wrong.

He certainly did, LOL!