Um, did my UF 16340s vent?

[MiniMag_Crazy_Greg]

While using my 2x16340/1x18650 UF C1 from DX, with UF 2x16340's (880 mAh), both reading 4.19-4.20v rested-charged state each when loaded into flashlight, I used it for 15 min, got hot, then I guess, protection cut in. Moon mode from one cell......I removed tail cap, and there was pressure inside tube. WHOOOOSSSHHHHHH:poof:, uh-ooh..........should I discard cells and hedge my bets on some AW cells?
TIA
Greg

EDIT**
Dyslexia strikes again!! Admins: My title of my post should be "...did my UF 16340...." not "16430"....thanks

 

[buickid]

Yeah, I'd discard them... Not worth whatever risk might be present. AW Cells are worth it!

 

[mdocod]

How *hot* did the light get, and what voltage do the cells read now after this incident?

I have a theory but need more to go on here before jumping to too many conclusions...

 

[old4570]

Hmm hot air expands , and if the flashlight is nice n tight , whoosh ...

My ultrafire A20 did this to me when I ran it on High for 10 minutes , got a bit on the warm side and hot air expands , nice n tight flashy .

 

[mdocod]

old4570,

That was my initial thoughts, but the "moon mode" behavior suggests a larger issue at hand. I'm leaning towards thermal expansion closed the gap on a short in the LED module.

 

[MiniMag_Crazy_Greg]

Thanks for all the replies. One cell reads 0 (zero) volts....and other is 3.72v......weird. :confused: The light got hot, but not too hot to handle. I purchased them from DX, does anyone think I should ask for the defective batteries be replaced? I've always used a dedicated 16340 charger and have had no problems at all with it, both cells charged 4 times at most.

 

[old4570]

0 zero volts ... There you go ..

 

[mdocod]

Ok, here's what I suspect....

1. 3.72V on the cell that didn't trip the PCB is ~20% remaining capacity. The other cell obviously tripped which means that these 2 cells are mis-matched in capacity by 20%. This has nothing to do with the problem going on but is worth pointing out because this type of inconsistency seems to be the mainstay of ultrafire, consistently inconsistent...

2. If you only ran it for 15 minutes before the cell tripped the PCB, then one of 2 things are likely happening:
A: The cells are severely underperforming and the normal load of this flashlight was a ~4C discharge rate for the cells, meaning the cells have less than 200mAH true capacity... Very bad..
B: The cells are close to expected capacity (~500mAH or slightly better at normal loads) but the flashlight is drawing ~1.5+ amps (3-4C) because something is wrong with the LED module, like a mild internal short or improper component installed on the regulator. This would explain a lot of the excess heat. In my experience, a normal Q5/R2 D26 style 6P size flashlight running ~3-4W power consumption will get warm after 10-15 minutes but not usually hot... Massive heat in the module could have destroyed the LED, produced various off-gassing by components on the regulator board, all sorts of possible things revolving around the concept of a short or excessive current draw seem very possible.

So it could be the cells (we already know they are very badly mismatched, maybe they are also severely underperforming, it would stand to reason IMO). It could also be the flashlight causing a problem.. It could be both.

-Eric

 

[MiniMag_Crazy_Greg]

Thanks mdocod!! I have a better understanding now. The "drop-in" in the flashlight has a label on it, "SUPER BRIGHT Q5." I always ran fine with one 18650, but not as bright as 2x 16340's. Would a nano charger solve my mismatched battery issue by charging them each individually to help ballance them? I have one of DX's 2 cell 16340 "digital Li charger," but cannot charge once cell at a time. I've always checked each cell's V on my DMM before use. As a side note, my 1cell Romisen RC-N3 often goes "moon mode." I guess some A&W cells are in my future. Thanks again everyone for their input.:grin2:

Greg

 

[Black Rose]

The cell mismatch problem cannot be addressed simply by charging....it's a problem with the cells themselves.

How old are the cells? Was one cell used more than the other?

 

[MiniMag_Crazy_Greg]

The cell mismatch problem cannot be addressed simply by charging....it's a problem with the cells themselves.

How old are the cells? Was one cell used more than the other?

They're less than 6 months old. I kept them in pairs as I received them from DX, I've purchased like 2 "pairs" of 16340-protected 3.6v, but then purchased a Romisen RC-N3 Q5 (1x16340 or 2xAA) [a great little EDC I might add :) ] so I've been using them "non-paired" and holding one cell aside till I have 2 to charge. So if I've learned anything from this post, same voltage does not mean that they are the same capacity mah-wise. Now, I see the advantages of alkaline/lithium primaries.......but also want to hug a few trees in my time :cool:, hence the rechargables.... Thanks again for your input!

 

[chmsam]

Remember also that a DMM does not measure cells under load like a proper battery tester does. A tester is more useful IMO.

 

[Illum]

there's a misconception that its bad when lithiums vent. If it vents, you should let out a sigh and smile.
Its DESIGNED to vent but NOT vent WITH FIRE, all the incidents involving a fire or charred remains of a battery concerns a failure in the safety vent to work properly.

I've had lithium primaries "burp" during discharge many times, haven't seen one from 13640s/17670s in my collection yet...

Generally, if it does vent, consider cocooning it [wrap tape around contacts to prevent shorting] and take it to a battery recycler

 

[mdocod]

Remember also that a DMM does not measure cells under load like a proper battery tester does. A tester is more useful IMO.

For LiCo chemistry an open circuit voltage reading is an accurate indicator of state-of-charge.

-Eric

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Greg,

You mentioned there that it always ran brighter with a single 18650...

This is very telling...
I think that there is something wrong with the regulator, it is running very inefficiently with higher input voltage and loading the cells really hard. OR... it was never designed to be used with 7.4V in the first place... Maybe they dropped the wrong module in your light... Or maybe it was only meant to be a 1x18650 version of the light and was accidentally advertised as a 3-9V style deal...

I really do think there is something "wrong" going on with the flashlight itself. AW cells might be better quality cells, but I don't think they would solve the problem...