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Does internal resistance matter?
#41
Here is some more info on IR and capacity.

This time it's the Sanyo UR18650FM. I now have processed 115 of them and here are the results.
This is actually not a bad battery, Look for 80% capacity if you stay below 60mΩ IR. 90% capacity if lower than 50mΩ IR. No heaters or SDs at this time.



Wolf
If 18 X 650 = 2200+mAh then we have power! 
May all your Cells have an IR of 75mΩ or less Smile
Last count as of 6/10/2019
Total Number of Cells                          5940
Cells  >80% of Capacity                      4334
Cells <80% of Capacity                       1605
Cells ≥2200mAh & ≥ 80% & ≤75mΩ    2800 +236
For Info Google Drive
Not your average Wolf       
            Cool



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#42
Another set of cells that I am pretty confident on the crossover point for.

The UR18650ZT 53mΩ anything above that and there is a rapid falloff in capacity.

 

All these charts are on my drive in a folder called graphs 


Wolf
LEDSchlucker likes this post
If 18 X 650 = 2200+mAh then we have power! 
May all your Cells have an IR of 75mΩ or less Smile
Last count as of 6/10/2019
Total Number of Cells                          5940
Cells  >80% of Capacity                      4334
Cells <80% of Capacity                       1605
Cells ≥2200mAh & ≥ 80% & ≤75mΩ    2800 +236
For Info Google Drive
Not your average Wolf       
            Cool



Reply
#43
(206) ICR18650-26* tested  Includes the following suffixes


Chart results indicate anything above 58mΩ looks to be a loser.



Wolf
bournevexed likes this post
If 18 X 650 = 2200+mAh then we have power! 
May all your Cells have an IR of 75mΩ or less Smile
Last count as of 6/10/2019
Total Number of Cells                          5940
Cells  >80% of Capacity                      4334
Cells <80% of Capacity                       1605
Cells ≥2200mAh & ≥ 80% & ≤75mΩ    2800 +236
For Info Google Drive
Not your average Wolf       
            Cool



Reply
#44
@wolf, the (data) hunters (you)/they are.(i know the real wolfs/dog packs), you are just a normal wolf, hunting and curios, said from somebody like me, its a good compliment!!!!!

I would like to see a chart of some cells that did not make it to your pw.
Incl to high or to low ir, to low soh, ect ect.
I am working on a data sheet that is running from the other side, the ones that did not make it by a LONG shot.
I agree on the time and effort, this is second place.
But what if those...lets ?exaggerate?...400mohms cells still can hold 6 amps (?exaggerate?)....but there discharge must be under 150mah to deliver that 6 amps?
And your pw is big enough to drain just 100mah from each cell???
So can you use those "bin" cells....IF you're PW is big enough?
the same applies to heaters, i think, if they can have a charge at 100 or even 50mah, would they be heaters?
Those kind of cells i going to use in my pw if its big enough, mainly as a test, no vamps or sd are allowed btw.
I am going to use even 1300mah cells with has more than 650mah left, just to see what is going to happen.


I agree that ir is REALLY important...according to the remaining cell live and what happened to them in there previous live, but can we decide to prolong their life to offer them an easier life to serve us better?

I going to build a wall that will be above 90% soh and below 70 ohms to suit my needs. basic setup.
After this, the rejected (1400 of them because i want 48v at 100p a pack) below 80%soh and worse, to test, what if i can gain "only" 50 amps per pack?

Its 50 amps...despite my "normal" packs are at 280 amps at minimum? its 50 extra?

And how the heck you get that "ohm" sign?

Thanks in advance, and sorry if some of my questions seems stupid to the readers, just hoping to get some answers
Still learning English. Learning Li ion and solar technology.
+/- 3500 Li ion cells harvested, none checked and counting.

Time is our enemy, must work to, the sun is our friend, must relax to.
With best regards
Reply
#45
(06-08-2019, 07:50 PM)100kwh-hunter Wrote: I would like to see a chart of some cells that did not make it to your pw.
Incl to high or to low ir, to low soh, ect ect.
I am working on a data sheet that is running from the other side, the ones that did not make it by a LONG shot.
I agree on the time and effort, this is second place.
Well you can always download my Excel sheet and sort the data to your liking. Tongue
Quote:........................ what if those...lets ?exaggerate?...400mohms cells still can hold 6 amps (?exaggerate?)....but there discharge must be under 150mah to deliver that 6 amps?....................................

All that may be true but at this point I want to build a wall that will not give me any trouble. Or at least a minimal amount.
My main interest was how to get the best cells and how to expedite the harvest. Once the powerball is built in all its glory after that I can experiment....................


Quote:And how the heck you get that "ohm" sign?

Alt 234 Ω Hold down the Alt Key and type 234

https://coolsymbol.com/alt-codes-alt-key...mbols.html

Wolf
If 18 X 650 = 2200+mAh then we have power! 
May all your Cells have an IR of 75mΩ or less Smile
Last count as of 6/10/2019
Total Number of Cells                          5940
Cells  >80% of Capacity                      4334
Cells <80% of Capacity                       1605
Cells ≥2200mAh & ≥ 80% & ≤75mΩ    2800 +236
For Info Google Drive
Not your average Wolf       
            Cool



Reply
#46
I'm going with a hard cap at 120. Less than 100 for a high drain pack. If any get hot and never finish charging they are removed. Any that drop in voltage beyond 4.14. Any cells with less than 85% capacity are removed. I have one pack going on 4 years now.
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#47
(06-10-2019, 09:54 AM)joblessalex Wrote: I'm going with a hard cap at 120. Less than 100 for a high drain pack. If any get hot and never finish charging they are removed. Any that drop in voltage beyond 4.14. Any cells with less than 85% capacity are removed. I have one pack going on 4 years now.

What are you using to measure IR?

I find that most name brand cells, Samsung, Sanyo, Panasonic, etc if they are over 90mΩ are not usable.
Matter of fact most cell over 75mΩ usually do not perform well especially above 85% of remaining capacity.
My testing cap is at 90mΩ for some cells mostly Sony (which I will not be using in my powerwall) and LGs and really that is to high for my powerwall anyway as I am keeping my IR on all cells for it at 30mΩ to 75mΩ.
All these measurements are made with a YR1030 4 wire 1kHz AC meter.
Staying below 90mΩ has virtually eliminated any hot cells "heaters", vamp cells (ones that never finish charging) and SDs. Although an occasional SD sneaks in there once in a while.

Wolf
If 18 X 650 = 2200+mAh then we have power! 
May all your Cells have an IR of 75mΩ or less Smile
Last count as of 6/10/2019
Total Number of Cells                          5940
Cells  >80% of Capacity                      4334
Cells <80% of Capacity                       1605
Cells ≥2200mAh & ≥ 80% & ≤75mΩ    2800 +236
For Info Google Drive
Not your average Wolf       
            Cool



Reply
#48
IR does matter, @wolf your data is a box of gold! and a big box i mean
Still learning English. Learning Li ion and solar technology.
+/- 3500 Li ion cells harvested, none checked and counting.

Time is our enemy, must work to, the sun is our friend, must relax to.
With best regards
Reply
#49
@100kWh-hunter

Yep after just shy of 6000 cells recorded there are some nuggets to be gleaned from that information. Big Grin

After my holiday I will continue although not with an accelerated rate as previous.
Just fine tuning the IR by part number sheet.

BTW
LG LABB41865 cells recover from a laptop pack with cell voltage well below 2 Volts IR was very acceptable. Charged on a CC/CV charging board at 50mA per cell to 4.18V. Took 3 days. Cell was initially tested on a Foxnovo tester twice and then transferred to the SKYRC for a total of 8 cycles the 9th is happening right now. Pretty good results for a sub 2 Volt battery. IR was the deciding factor to try to recover these cells.
I also have many that had an unacceptable high IR that didn't get this far.
I can now concentrate on documenting the failures also.

Wolf
If 18 X 650 = 2200+mAh then we have power! 
May all your Cells have an IR of 75mΩ or less Smile
Last count as of 6/10/2019
Total Number of Cells                          5940
Cells  >80% of Capacity                      4334
Cells <80% of Capacity                       1605
Cells ≥2200mAh & ≥ 80% & ≤75mΩ    2800 +236
For Info Google Drive
Not your average Wolf       
            Cool



Reply
#50
@joblessalex.
Why don't you use above 90% in separate packs and 80-90% in other packs?
So what i am trying to ask is, why don't you make two separate packs/systems at different soh%?

I am trying to harvest enough to make my first pack 14s100p of soly above 90%, 2650mah a cell, with a ir as good as new!
The second one will be slight less and reach 1400 of them, or i must harvest again a 1400 above 90%.

It is clear that i still don't fully understand, except the segregation part, hope you will understand my jibber chaotic jabber.

Best

@wolf.
The alt does not work on my laptop. maybe i have to install dosbox?Smile
Still learning English. Learning Li ion and solar technology.
+/- 3500 Li ion cells harvested, none checked and counting.

Time is our enemy, must work to, the sun is our friend, must relax to.
With best regards
Reply


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