TF18650 "thunderflames" battery goes up to 5.6V?

edit: a fact that might be significant: Before all of the below, this battery was drained to 2.8V @ about 1.6A while in a flashlight. It didn't cut-off, I just pulled it out, checked it and immediately put it to charger. Then this happened:

Same TF18650 thunderflames, last two charges...

Out of the (XTAR-WP6) charger: 5.6V... After a while: 4.8V... 4.6V... until after a while it sets to 4.19V...

Tested with two voltmeters, on the cheap one the voltage goes up and down (from 2V to 5.6V), on the better one it shows a lower value (a bit less than 5V) and does not go up and down.

This battery is now in my Solarforce w MF-XML dropin and working fine...

WTF? Any ideas?

Your charger has overcharged the battery. That cell has been compromised and should not be used any more. I also recommend getting a different charger.

Yeah charger is faulty..there's no way it should push a cell to 5.6a..protection should have kicked in on the cell though..either way toss the charger and cell

Protection on your Trustfire cell obviously doesn't work at all.

Question about charger:

Is it WP6 or WP6 II ?

WP6 II are excellent chargers.

Something is wrong here...

Somethings wrong... The pressure of the cell at 4.9v should be very high about 150PSI causing the CID to break. I think maybe there is something terribly wrong with either the battery or protection circuit.

thats happened to me with an unprotected cell and a tr001. it just kept charging and never cut off. got a replacement from the ebay seller. as for the cell i kept using it and it was ok. i would mark the cell and monitor it. maybe toss it like the others said just to be on the safe side.

I'm sure it is correct but have you double checked your readings and proved your meter? After that, how do other cells come off the charger? I would not use the cell and safely dispose immediately tho.

That is one reason I would never recommend li-ion batt with unknown cell specifications (datasheet).

Protection failed-OK. You've mentioned CID- but, nobody knows if this unknown cell has any ;)

Charger was purchased as a WP6-II but it seems to be a WP6 (no II is marked anywhere).

All my other cells (AWPs, TF blue) are coming off the charger at 4.19-4.20V. I think I might try - supervised - a LiMN unprotected 14500 to see if charger cuts off at 4.2V or not.

I think a 18650 cannot go this high in voltage without venting or - at least - swell and get very hot. I have the suspicion that the - probably faulty - battery's protection circuit "alters" the voltage I am reading? Can a protection circuit do that?

The II has threads in the plus connection, making it possible to use spacers:

Ah, thank you, then I have version II.

There is no way that WP6 II will charge to 5.6V.

Something else is cooking (beside that cell :) )

This part of your measurement is very interesting:

"Tested with two voltmeters, on the cheap one the voltage goes up and down (from 2V to 5.6V)"


Also when you said that cell settle at 4.19V - there is no magical way for cell to settle to 4.19V by itself.



That's why I suspect battery's protection circuit going crazy (and stepping up the voltage? pulsing out the voltage? I don't know if this is even possible). I know, I am describing something that is "impossible" and I hit my head on the wall to figure out what am I missing.

Unlikely it's the protection but it's a scrap cell now so remove it and see. I'd guess it's simply a faulty cell, the charger is prob fine, it's prob confused by the characteristics of the faulty cell and cannot terminate correctly. What's the reading of the charger with no cell inserted?

No cell charger voltage = -6V. But this doesn't mean anything, placing a battery (and after the light turns red), it shows 0.5V more than the cell voltage, e.g. if battery is @ 3.3V, it reads 3.8V on charger (or is it just the average, 4.2V + 3.3V / 2? Hmm... only one not charged button top battery is available at this time so I will check again in a couple of days). Also my Ultrafire charger is showing a big voltage number until a battery is placed, my old TF001 and some other noname ones I have, are showing 4.2V no matter what.

Interesting dilemma ...

Is it the charger , or is it the battery ,

Is 5v too much , well yes , but is the battery swelling ?

Swelling is usually a sign that the internal pressure is a wee bit high , just talk to the Lipo (RC) crowd .

If there was no associated swelling , and the battery did not heat up abnormally , and you want to track down the problem , then it should be ok , but be aware of the fact that this battery is potentially DANGEROUS!

Once a cell is placed in the current is limited thus limiting the voltage, this is why it drops on insertion. The charger will monitor the cell state at periods pre defined by the control program, it does this off charge. The cell can have such a low capacity/high internal impedance that it can rise massively in a time shorter than the monitor points. This ultimate voltage will be limited tho by the open circuit voltage of the charger. All this is IMO without knowing the charger in detail so I await correction but you see my question may mean something ;)

Right now I am charging an unprotected LiMN 14500 on this charger to see when the charger goes green (it is now @ 4.18V and still charging). So I can at least have a (not final) positive or negative on the charger.

Edit: That was fast... Charger turned green on the 14500, I will leave it there for 10-15 minutes and then volt meter the battery.

Edit 2: Unprotected battery came off the charger @ 4.19V.

Now let's see when I will find the courage to recharge the "thunderflames" one...

But, if the charger stops charging @4.19V... How can this thunderflames gone up to 5+? Arggh...

Jeansy, what you said makes sense to me but can a - charged twice - 18650 get so degraded?

WP6 II is very good charger, and I knew that you will get those results.

Even the cheap chargers Trustfire etc. cannot overcharge that battery to 5.6V -it is circuit design.

Even the top-branded cells get a dud once in a while.

Call it a manufacturing error, safely dispose of the cell, and go on about your business.

PLEASE DO NOT USE THE CELL FURTHER !!!

Even charging for testing may create a dangerous condition for this damaged example.