New Panasonic Cell ncr18650bd 3200mah

[okashira]

Hm, on the topic of soldering cells... there seems to be a lot of debate on this subject...

I have 4 new PF's sitting in the fridge. I do some nice solder leads to two of them, cycle test them, and then do the same for un-soldered. Using this DC electronic load which is pretty accurate.
That should discover if any damage was done to the cells. Interest?

 

[cwah]

Hm, on the topic of soldering cells... there seems to be a lot of debate on this subject...

I have 4 new PF's sitting in the fridge. I do some nice solder leads to two of them, cycle test them, and then do the same for un-soldered. Using this DC electronic load which is pretty accurate.
That should discover if any damage was done to the cells. Interest?

Why did you put some cells in the fridge?? Is ir for the self discharge test I mentionned? You need to test that with high temp which is not something you can get from the fridge?

 

[riba2233]

That test would be really nice, but that's a lot of work, and results may not be too accurate, because you can solder better, faster, but someone will solder poorly...

 

[okashira]

Hm, on the topic of soldering cells... there seems to be a lot of debate on this subject...

I have 4 new PF's sitting in the fridge. I do some nice solder leads to two of them, cycle test them, and then do the same for un-soldered. Using this DC electronic load which is pretty accurate.
That should discover if any damage was done to the cells. Interest?

Why did you put some cells in the fridge?? Is ir for the self discharge test I mentionned? You need to test that with high temp which is not something you can get from the fridge?

Just for storage, didn't know how long before I would use them... I vacuum packed them to keep out the moisture.

 

[okashira]

That test would be really nice, but that's a lot of work, and results may not be too accurate, because you can solder better, faster, but someone will solder poorly...

I hope someone who's going to be soldering a pack of 200 cells can develop a repeatable way. Anyway, I will use the same method as I do to solder magnets, which is super easy...

 

[okashira]

first good 4-wire measurment... this is NKON PF rank 3 that I have shorted out a couple times

 

[bgt]

You can have them from here for crazy low price, if you are from EU:http://eu.nkon.nl/rechargeable/18650-size/panasonic-ncr18650pf-3-7v-2900mah.htmlSo, I've just tested Panasonic 18650BE, 4.2 to 2.5 V, 5A. I got 3176 mah, and the cell got slightly warm to the touch (a little bit more towards the 2.5 V). This is interesting because it got as warm as samsung 25R in the same test, which has almost the double less internal resistance. This is only a finger method thought.

Wow, thats a good price at this dealer

 

[riba2233]

Yep, even has samsung 29e for low price:

http://eu.nkon.nl/rechargeable/18650-size/panasonic-ncr18650a-1265.html


And new low price for samsung 25r:

http://eu.nkon.nl/rechargeable/18650-size/samsung-inr18650-25r.html

 

[bgt]

Yep, even has samsung 29e for low price:http://eu.nkon.nl/rechargeable/18650-size/panasonic-ncr18650a-1265.htmlAnd new low price for samsung 25r:http://eu.nkon.nl/rechargeable/18650-size/samsung-inr18650-25r.html

Have a 36V bottle battery with 50x 2.2A Samsung cells now but the Panasonic NCR18650PF cells looks to be a better choice. With a bit of cold weather the energy goes really down on the 2.2E Samsung cells. My Lifepo4 cells do way better with cold.

 

[okashira]

The PF's like the warmth.

I ran one at 10A:
It reached about 62°C by end of test. I taped a thermocouple to the wrapper of the cell.


Compared to 3A Overlayed:



I also messed this cell up again. I ran it again at 10A for a full 30 seconds after the test was done. Went down to 0.9V. Then proceeded to short it again, lol:



I will slowly charge it and see if it was damaged by another 3A test.

 

[riba2233]

Yep, they do. I got 2718 mah at 3A (ho heat), and 2861 at 5A (warm cell). Same goes for BE (2876 vs 3060 mah).

 

[okashira]

I did another 3A run on the cell I abused down to 0.9V under 10A load. (And shorted out again...)

This time I cut at 60mA (wasn't paying attention.) and had a 70 minute rest after charge. Same temperature (+/- 1C)
The difference between a 60ma and 100ma cut amounts to approximately 8mAh by my estimate.

Overall, the cell actually performed better. Less IR. However accounting for the extra 8mah charge, the cell lost 7mah to 2.8V, which amounts to a slight, but more then expected amount of damage for the past two cycles based on predicted cycle life.
Basically the abuse run to 0.9V did about 3 cycles of damage to the cell. And we ended up with less IR. Not bad at all. I imagine a LiPo would have been obliterated...

Was the lower IR because of the longer rest after charge? Well, that my friends is why you maintain consistent test conditions....

 

[okashira]

Fasttech delivered me some "B" grade PF's! Compared the the "D's" I got from NKON.


They were delivered at the following voltages:
PF, PF, BE, BE
3.6178 3.6186 3.6236 3.6221

 

[riba2233]

I see that you have C rank BE's, mine are D rank. Could you test them at 5A from 4.2 to 2.5V?

And I'm really curious to see the comparison between C and B rank PF's

 

[okashira]

I see that you have C rank BE's, mine are D rank. Could you test them at 5A from 4.2 to 2.5V?

And I'm really curious to see the comparison between C and B rank PF's

Did you do the 5A run on your first discharge of the brand new cell or did you do any break in or using the cell first (such as low current to break in the cell)?

 

[riba2233]

Nope, first discharge, and got 3176 mah from BE. But the second cell, after few cycles, does only 3060 mah in same conditions.

 

[okashira]

Here you are, 100ma cut at 4.201V and 60 minute rest

Since I never tested a PF at 5A, I did a linear interpolation to predict the PF's performance at 5A... light green dots on the chart.
The BE is right on with the PF...
That is of course my "Rank D" PF and "Rank C" BE
Will test "Rank B" PF later...
Also took manual temp readings of the BE and put them on the chart.

(I missed the first 44 seconds of data recording, thankfully I was able to note that I started 44 seconds into the discharge and offset the data appropriately.)

View attachment 2


edit:
I overlayed HJK's test of a Keeppower IMR 3200mah cell.

red and dark red is the two cells he tested, the black is my Rank C BE (cycle 1)

 

[riba2233]

Yep, that's pretty much what I've got. I'm only not sure about temperature, I would say that it wasn't as high as 45°C, but maybe my room was colder.

My thought about ranks - I would say that they mark consistency, greater mark, greater consistency. Mark A - all cells have 3200 mah; mark B - 3150-3200 mark C 3100-3200 mark D 3050-3200 etc... Or if you are Tesla, all cells have 3300 :lol:

 

[okashira]

Yep, that's pretty much what I've got. I'm only not sure about temperature, I would say that it wasn't as high as 45°C, but maybe my room was colder.

My thought about ranks - I would say that they mark consistency, greater mark, greater consistency. Mark A - all cells have 3200 mah; mark B - 3150-3200 mark C 3100-3200 mark D 3050-3200 etc... Or if you are Tesla, all cells have 3300 :lol:

I think it's probably AC-IR.
I doubt Panasonic does a capacity test on each cell. Would take too long

They probably charge to 3.63V resting voltage and do a quick ACIR measurement. MAYBE a DCIR measurement.
Then binned by ACIR.

We will find out as I have B and D PF's right here untouched.

 

[Cephalotus]

I read somewhere(?) that the cell ranks are about self discharge rates.

That would make sense because self discharge rate is the main factor for irreversible cell voltage drift. It is also easy and cheap to test. Just wait some time and measure the voltage at very high accuracity.

 

[riba2233]

Maybe, but I've recently received 53 pf's rank C, and all of them had exactly the same resting voltage, 3.61V. No exception.

 

[okashira]

The problem is, "waiting" is not something you want to do in a volume production environment like Panasonic's cell mfg.

I'd guess you would have to wait a bare minimum of 24 hours to let the voltage settle before you do your high accuracy voltage measurement.
There just wouldn't be enough storage to keep all the cells sitting in a fixture for 24 hours after charging so they can be measured again.
Theyd have to have some kind of automated storage and pull it back off the shelf after 24 hr to measure it.

I'm still going with DCIR/ACIR :-D



Thinking a little bit more. It is *possible* that Riba is still correct.
They could be charging the cells with a a high precision current supply for a set time.

Say they charge all cells with exactly 1.0000A for exactly 30.0000 minutes.
Wait 30 min.
Do a voltage measurement.
The cells that measure a *lower* voltage will actually be better cells, because that would indicate they have a higher total capacity (because the voltage went up less for the same charge)

DCIR can also easily be measured during the charging process. Just pulse the current and measure the voltage fluctuation.

 

[riba2233]

It's hard to tell, but we know that all cells leave factory with identical voltage, so they must be charging them at least to that particular voltage. I don't know whether they do one cycle as a part of QC process, but I wouldn't say it's impossible (maybe unlikely?), because I saw many Chinese manufacturers testing cells in large automated testing machines/closets.

 

[okashira]

It's hard to tell, but we know that all cells leave factory with identical voltage, so they must be charging them at least to that particular voltage. I don't know whether they do one cycle as a part of QC process, but I wouldn't say it's impossible (maybe unlikely?), because I saw many Chinese manufacturers testing cells in large automated testing machines/closets.

How do you know that all cells must leave the factory at the same voltage? I think that's your fallacy. It's too difficult to charge to a specified resting voltage, anyway.
It's much easier to apply a specified # of columbs to the cell with a precision current supply.

I know that my C grade BE's came in at a slightly different resting voltage then my B grade pf's.

Anyway here is a quick test of the PF B grade at 1A. haven't run 3a, 5a, 10a yet or an apples to apples. cleaned up the chart a little.

 

[riba2233]

Your results look pretty close to mine. I would love to see some rank A cells hehe

Yes, maybe I used wrong words. But, at least the cells from the same batch come at same voltage. That voltage changes due to self discharge of course, so that may be the reason or more likely one of the reasons you have different voltages for different batches.