How do you recognize a real panasonic 18650pf battery

D

Drokz

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Jun 30, 2013
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Antwerp, Belgium
hello ,

Ive bought new 80X Panasonic 18650PF cell.
they came yesterday with every cell 3.61V.

I have already 1 cell discharged, and charged first to 4.1 V but there was going 1780mah in, then further charged to 4 .2V, 245mah en charging ended.
so the cell are 2900mah, and 2750mah minimum. really weird that charged till 4.2V only 2025mah in.... :?

come this because they in really long storage time? OR should they "wake" up?
OR they NOT real Panasonic 18650PF cells.....????

normaly i charge never till 4.2V.

the intention is to make a 18S4P pack. So 64.8 V 11.6 Amp
So iam making 3packs with 6S4p, because my chargers cant take more then 6S :p
With these 18650 brackets :
18650bracket_01.jpg
 
What voltage (at what amps) did you discharge to before your charge test?
Post a picture of the cells?
Where did you buy them?
 
you should charge to full charge of 4.20V and then discharge to resting voltage at 3V in order to have an accurate measurement of the capacity. you need to discharge at .1C to make it legal i think, as they do for the ratings on lead acid batteries.
 
dnmun said:
you should charge to full charge of 4.20V and then discharge to resting voltage at 3V in order to have an accurate measurement of the capacity. you need to discharge at .1C to make it legal i think, as they do for the ratings on lead acid batteries.
Click to expand...

Wouldn't he also want to do a high current discharge to verify it wasn't a repackaged low power battery? Or at least try to measure the internal resistance (ie measure sag under load)
 
okashira said:
What voltage (at what amps) did you discharge to before your charge test?
Post a picture of the cells?
Where did you buy them?
Click to expand...

first i discharge hem with 0.5amp till 3.1V, then charge with 1amp till first to 4.1V = 1780Mah




I buy them by http://www.Nkon.nl

dnmun said:
you should charge to full charge of 4.20V and then discharge to resting voltage at 3V in order to have an accurate measurement of the capacity. you need to discharge at .1C to make it legal i think, as they do for the ratings on lead acid batteries.
Click to expand...

searching @ google, i find the next results ; Minimum Capacity: 2750mAh (0.54A discharge at 20°C)

Wouldn't he also want to do a high current discharge to verify it wasn't a repackaged low power battery? Or at least try to measure the internal resistance (ie measure sag under load)
Click to expand...

i have no internal resistance meter...
 
Interesting. Where are you located, out of curiosity?

I just ordered 10 PF's from Nkon myself, and I am in the US.

3.1V is a pretty reasonable discharge voltage for 0.5A on that cell. You should get most of the capacity at that point.
They are rated for discharge to 2.5V, but at that current, you won't get much between 3.1V and 2.5V (in fact I would consider 2.5V kinda overdischarge at low amps)

But before you can officially complain, you will need to:

-charge to 4.2V with a 60-100mA cut off.
-Rest 1 minute (cell voltage should be ~4.17-4.185V) [[[4.17 RESTING is typically "full charge" voltage for NCO chem, but these are NCA so slightly different]]]
-So a full discharge to 2.5V (do 1A-2A if you can...) and record your mAh.

I would complain to NKON.nl if they are below 2800mah.
 
I note that the box says "Rank D"
What does that mean, mr. flathill? ;)
 
okashira said:
I note that the box says "Rank D"
What does that mean, mr. flathill? ;)
Click to expand...

You can also see the rank/grade stamped on the battery itself at the end of the battery next to the date code. I think someone (flathill?) has said in another thread that the grade has to do with factory sorting according to self discharge rate. A is best, F is worst...but don't know for sure.

EDIT: looking at pictures of -be batteries on the web, I see letters all the way to H...so don't know what it means.
 
Hi Guys !

The second charge is much better !
the same i decharge to 3.1V @ 0.5Amp = 2340mah
(the charger will decharge LI-ion till 3.1V)

then i decharge in Life mode ;
It will decharge to 2.8V @ 0.3amp = 280mah

===== 2620mah....


@riba2233

I dont have a charger then decharge to 2.5V .... euuhmm... I dont believe that less then 3V, good is for litium .
 
okashira said:
Interesting. Where are you located, out of curiosity?
Click to expand...

Iam located to Essen, Antwerp, Belgium

- i have charge with 100mA to 4.2V
- rest 1 minute (cell voltage 4.12 a 4.13)
- the results are 2620mah... but with 0.5amp and 0.3amp decharge modes...


i think that litium a few 3 - 5 cycles are need for the full power MAH te become.

so, is it best to te cells that have arrived @ 3.61V to first to cylce (every cell)?????

or build an pack (6S4P) en connect balance leads, en then cylce them???
 
Drokz said:
okashira said:
Interesting. Where are you located, out of curiosity?
Click to expand...

Iam located to Essen, Antwerp, Belgium

- i have charge with 100mA to 4.2V
- rest 1 minute (cell voltage 4.12 a 4.13)
- the results are 2620mah... but with 0.5amp and 0.3amp decharge modes...


i think that litium a few 3 - 5 cycles are need for the full power MAH te become.

so, is it best to te cells that have arrived @ 3.61V to first to cylce (every cell)?????

or build an pack (6S4P) en connect balance leads, en then cylce them???
Click to expand...


I don't see a problem with cycling before or after building your pack.

4.12-4.13 seems slightly low for full charge. maybe if you went to 4.16-4.17 it would have a little more.

These cells are good for low voltage, you can go to 2.5V for a cycle test. (dont do it under very small load though. at least 1 amp.)

0.5A is a pretty small load for these cells, so I would not go to 2.5V on them.

between 2.8 and 2.5, probably only like 40 mah, so you are looking at 2660, still seems low. Maybe do 50ma cut off charge.

3.6V is a good voltage to store them until you use them.


And check your temperature too. They might put out a few more mah if you warm them up to 30°C
 
Drokz said:
hello,

I have tested further, @ 17°c roomtempature goes 2840mah in the cell @ 1amp charge rate (2.8V - 4.2V)
Click to expand...

You charged the cell from 2.8-4.2 and got 2840, or was that discharge from 4.2 - 2.8?
 
Drokz said:
charged 2.8 to 4.2.....
Click to expand...

2.8V unloaded resting voltage is pretty low. (too low IMHO)
that is why you don't want to go to 2.5V under light load...
 
Ahh, gotcha.

3.25 is more reasonable.

I am surprised by the recovery. 0.2A is such a small load. Yet the cell still rebounded by 3.25-2.8 = 0.45V = 16%!

You might say the internal DC impedance is equivalent to 0.45 / 0.2 = 2.25 ohms at that rest voltage! No wonder they tend to heat up toward the end of the drain.

I think they are rated for like 0.025 ohm impedance normally. That is an increase of 1000%.

Of course, some of that recovery is due to continued chemical reactions in the cell after the load was removed. I am sure the actual heating rate was less then 0.2^2 * 2.25 = 0.09 watt during the end of the discharge...?
 
I hope they are not fake.

Discharge test should be from fully charged (4.2V) to 2.5V cut off at 3A (1C)

You should get around 2800mah:
http://budgetlightforum.com/node/29051

I hope you can make it, or just raise a complain for fake cells!
 
riba2233 said:
I'm sure that they are not fake if they are from nkon. Maybe it has something to do with cells grades... I will get my PF from nkon soon so I will to the same test.
Click to expand...

How can you be sure? He doesn't want to tell me his supplier so there is a lack of transparency. I'd question legitimacy of the cells without good source background
 
Drokz said:
are the batteries already arrived?
Click to expand...

Are you asking me? Yeah, let me do a proper test soon...
They certainty "feel" like quality cells. :p
 
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