Some lamps use the enclosed tube for heating in cold weather
Fenix CL25R
Wow. Paranoid much?
Plainly speaking, I’m not following your logic here. The more you try to explain it, the less sense it makes.
In the best interest of everyone here, I’m just going to skip your posts from now on.
I hope you found my earlier suggestions about using a USB cord for a nightlight helpful.
I think that is more of a clever marketing phrase and not a real “feature”. Unless what they meant to say was that in very cold climates the battery tube getting warm will heat up the battery so it performs at its best. (It’s known that lithium-ion battery’s perform very poorly at cold temperatures)
It is using the same basic design as the T1. I assume the CL25R would have the same battery heating (or over heating) issue as the T1 were it not for their thermal protection circuit that reduces output if it gets too hot.
From the Fenix website:
Isn’t that what i said then?
Testing with the old cell, with the cell it came with, and with a Japan made cell.
I have some old laptop pulls i don’t use anymore, and although they keep their charge and have a decent capacity, they can get quite hot under load.
Although this light probably draws only some 1.3 Amperes max, an old low drain cell may heat itself up a little, additional to the poor thermal path of the light itself…
Anyway, meanwhile DBSAR did test it with an ‘old cell’, the stock cell (or not?) and a Japan made cell, and it still gets quite hot.
I’m thinking about the spring now, in the tailcap.
I’ve read reports of crappy springs, probably iron, with the chrome / nickel flaking off.
Dunno if those may get hot while conducting 1.3 Amperes.
Calm down, there is no conspiracy here. DBSAR and JasonWW are well-known users with thousands of posts. For sure they don’t have a secret agenda to trash or promote Gearbest/Zanflare or some other company.
There is clearly a serious issue in some units that needs to be fixed, but not all units are affected. OTOH a Convoy S2+, with a 8x7135 driver on high, heats as fast or even faster (edit: source) and we don’t hear about batteries flaming inside them, so the cell likely had some defect to start with (i.e. the issue only becomes critical if the lantern has this overheating problem and the cell is weak). However, since people are likely to put any 18650 cell on the lantern, including fake no-name 9800mah cells that belong to the trash, this issue that affects some units needs to be addressed.
There has been a lot of these sold. What we need is some accurate readings from other users. Im guessing the temps will be acceptable unless it is a defective unit or a defective battery is used and if that is the case, it would be on the User. Improvements could be made and a disclaimer should be included.
Just tested the Fenix CL25R (NCR-GA battery). After 20 minutes, the cap heats up to 91ºF (32C). So yeah, I think it is a feature for cold weather. Even in warm weather, it’s still 140ºF+ away from any thermal runaway potential.
In post 40 are readings from a german forum
That’s lower than even I thought it would be(51°C after an hour)………. and definitely acceptable
Hi, as the administrator of this forum I can assure you that there are indeed both manufacturers and affiliates here in this forum. We make no attempts to hide that fact. Whether that affects any particular user’s judgment and/or opinions is up to each individual:
So please drop the “deep forum” conspiracy theories. And please stop arguing:
Thanks.
Boy……. sure got quiet all of a sudden 
……… Anyone else have temps?
Guess we’re all now homeless from our burned-down houses after the testing. :smiling_imp:
If anyone wants to modify theirs without destroying it I’ve managed to get the diffusor top off and retain 3 of the 4 locking tabs.
Wrap your thumb and index finger around the white section right above the black base.
With your other hand, crush your index finger into the diffusor while lifting up slightly.
Work your way around the light a couple times and it will eventually pop free.
The adhesive is very weak and you will hear it separating. Be careful when it does pop free because that’s when one of the tabs may break.
Sorry if this has already been addressed.
I was thinking of putting an insulating layer and a heatsink between the emitter strips and the battery tube. Or gutting it and doing something else with it.
With some of the issues I’ve seen it’s not good for gifting but could be a nice host.
edit: this thing looks like a sci-fi prop from a few years ago with the cover off! Kinda harsh on the eyes but may leave it like this for a while.
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. :+1: