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Does internal resistance matter?
#21
Cherry,
Good to hear from you again!
No bows necessary. Tongue

Do to your influence I have become a rank ameture at Excel (Always wanted to learn it  Smile )

I enjoy doing this and it's interesting when you go from a hypothesis to an unproven theory at this point.
With enough data I believe we will have a proven theory and than can have a working law.
I know that there is all kinds of research out there that tests cells to their limits and records the data.
But these cells are all in a controlled environment and I dare say that most of them if not all the studies that have been done are on new cells that they grow old in a controlled environment.

We are harvesting/salvaging cells that we have absolutely no idea what kind of "Environment" they have gone through.
So I/we are I believe in a somewhat uncharted territory. I have not seen anyone else that has collected this type of data anywhere.
If someone else knows if anyone has done this please let me know!

Ps I have updated the Charts folder on google drive.


That's it for now.

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 8/7/2019
Total Number of Cells Recorded and processed                 6149
Total Cells required for PowIRwall                                   2856
Total Cells ≥2200mAh, ≥80%, ≥35mΩ, ≤75mΩ, ≥4.12V   2760
For Info Google Drive
Not your average Wolf       
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#22
(01-11-2019, 01:21 PM)Wolf Wrote: We are harvesting/salvaging cells that we have absolutely no idea what kind of "Environment" they have gone through.
So I/we are I believe in a somewhat uncharted territory. I have not seen anyone else that has collected this type of data anywhere.
If someone else knows if anyone has done this please let me know!
This is exactly what i have to hold under daromers nose since - i have forgotten how long, but you bring it to a nice point.
daromer, see you soon Big Grin .
1 kWp in Test
4 kWh battery target - plus Mobile Home battery
Ultra low cost
Electronics ? No clue. Am machinery engineer.
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#23
Your data isnt new as i Said Wink i allready know the end result. Why do you think i have done some pointers on what to look at and how you should present it Wink

Controlled environment or not you Will soon see... I shall not tell just yet. Big Grin
The Ultimate DIY Solar and build place
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Current: 10kW Mpp Hybrid | 4kW PIP4048 | 2x PCM60x | 83kWh LiFePo4 | 10kWh 14s 18650 |  66*260W Poly
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#24
(01-11-2019, 03:36 PM)daromer Wrote: Your data isnt new as i Said Wink i allready know the end result. Why do you think i have done some pointers on what to look at and how you should present it Wink

Controlled environment or not you Will soon see... I shall not tell just yet. Big Grin

Daromer,
I'm sure the data isn't new but why isn't it published anywhere? Regarding used / salvaged / harvested cells!!
I can find all kind of stuff on new cells but can you find a universal chart that says if the IR of this model and manufacturers battery is X or above don't even bother with it.  Well can you? If you can then stop me from doing this madness ""(as you already know the end result)""  Smile and just let us know what the IR cutoffs are for each individual brand and model  and I think all of us would be happy and harvesting will be much faster. If not then I will continue on my quest to find the holy grail on each manufacturer and model and I guarantee that I will share it with everyone so their harvesting process can proceed knowing that there is a very good chance that the battery they are putting into the tester will give a good result.

When I started out doing this I had 1 OPUS tester and a bunch of laptop batteries and no clue what to do and or look for. IR what? Trusting the OPUS with an IR reading is like trusting a fox in a henhouse. Yea its a lesson learned that needs to be shared. I would faithfully put my 4 batteries in each morning and evening and record the results getting depressed when the mAhs didn't come back with anything worth saving. When I did get a good batch of cells I was wondering what made them better. So I kept reading and studying on the Internet and this board and several others. It all came down to IR so how do you measure it correctly? I think everyone knows the answer to that by now if they have been following my posts. (If not read cherry67, daromer and my posts)
I did read the boards FAQs before I stuck my nose into this board to comment and to contribute.
So in conclusion the point is to share the knowledge with everyone in this community and that is what I am doing. I hope to come up with a simple harvesting plan that identifies the cells you keep to test and have a very good chance of a good mAh result and the cells you send to the recycler or sell on ebay to some unsuspecting person. Na I would never do that. I would have full disclosure as I have all the info an each cell anyway. Smile

Happy enlightened and successful harvesting everyone.

Wolf
100kwh-hunter and Kna like 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 8/7/2019
Total Number of Cells Recorded and processed                 6149
Total Cells required for PowIRwall                                   2856
Total Cells ≥2200mAh, ≥80%, ≥35mΩ, ≤75mΩ, ≥4.12V   2760
For Info Google Drive
Not your average Wolf       
            Cool
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#25
The data you bring out can be found in many scientific papers regarding degradation over time. Does it matter if its controlled environment or yours? No it doesnt. The data is the same as long as you take into account the conditions.

The reason you dont find the data you are looking for is that you arent looking for the right data. You are looking for the data in above format meanwhile the scientific papers out there are a bit more technical Tongue
You dont find specific charts with all models and brand compare to IR because people that do 2nd hand cells test both capacity and IR not the one or other. The ones working with it get batteris of known cycle count and can directly estimate capacity left.

Why do I know that? I have some insigt into it Wink

With that said what you build up is an more easy way for some users to do their first analysis of what they got.

If you have read my comments you have seen that I have from the first day told people not to even go with the IR of the cheap testers and therefore IR comparing is useless.

Why dont I go by IR if i know that you can get rid of some cells??  Because the times it takes to meassure the IR is equal or more than just putting it into my testing rig. Sad but true Tongue It cost some money to do the charge but its actually nothing comparing to doing what you guys do. Note that there are not table for all 1000s of types out there but most manufactures do have degradation tests where they both mention it by formulas and some tables.

Perhaps i should not add this yet here but I can post one link so far Tongue
https://journals.plos.org/plosone/articl...ne.0185922

If you spend some minutes you can find MANY more of them out there Big Grin Perhaps its not what you have looked for but they do contain the data you are producing.


NOTE THAT I still think the work you guys do is Awesome because it have things that others dont in terms of its done on DIY basis and with a different goal!
Kna likes this post
The Ultimate DIY Solar and build place
YouTube / Forum system setup / My webpage  Diy Tech & Repairs

Current: 10kW Mpp Hybrid | 4kW PIP4048 | 2x PCM60x | 83kWh LiFePo4 | 10kWh 14s 18650 |  66*260W Poly
Upcoming: 14S 18650~30kWh | Automatic trip breakers, and alot more
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#26
Daromer,

I like it good paper and it is not that technically challenging.  Tongue
I guess I got to get me an Xray machine or steal one from my dentist Big Grin
But seriously that is more information that proves IR is important.
Now as far as time savings boy I don't know I had 100 or so cells they where all ICR18650-22F I did an IR test of all of them and it took me maybe a half hour to sort them into 60mΩ or less. Plugged 46 of those into the testers and wella all of them had good capacity. The other 54 cells are sitting in a bin when I have time to test. But you see I didn't have to test them because I know from others that I tested anything over 60mΩ is not a plausible candidate for me.
54 divided by 4 is 13.5 testers dedicated to finding out the cells are not up to snuff. I don't have 100 testers just laying around waiting to be stuffed with any cell. I want the cells that will most likely give me the best results to occupy my testers. Big Grin

13.5 testers running for 6 to 8 hours seems like a waste of time to me. Now think about the guys that have 1,2,or maybe 3 testers as their budget is limited
Testing 54 cells that may or may not be good with 3 testers let's say 6 hrs each test  that would be 4.5 X 6 = 27 hrs if you are not sleeping to find out all the cells over 60mΩ are not up to snuff. Shure seems like a waste of time to me. I know I am wasting time with testing all the cells no matter what the IR is but it is for a good cause Smile .
Here is the sheet of the ICR18650-22F results. Kind of undeniable results. Also see the 60mΩ at the bottom just getting by Tongue



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 8/7/2019
Total Number of Cells Recorded and processed                 6149
Total Cells required for PowIRwall                                   2856
Total Cells ≥2200mAh, ≥80%, ≥35mΩ, ≤75mΩ, ≥4.12V   2760
For Info Google Drive
Not your average Wolf       
            Cool
Reply
#27
I test all cells. I don't have a lot. BUT doing IR Kelvin tells me which ones are probably going to die or cause problems later. I will put the 80mR and over (yeah that's my line, a bit high but..) at the front of the pack so I can get to them. I have tested my cells at 0.5A. Now I test at 1A. Going through cells that seemed OK at 0.5 are pretty bad at 1A. I was wondering why some cells were OK at 95mR and others shit but it is consistent with manufacturer. So sorting by manufacturer seems really important. I can tell straight away that a green one with 90mR will be shit. While the reds can be the full heater OR quite good. R dependant. Pink and browns are fully sick even at 95. So I bought my 20 buck kelvin and it is super quick to check. I clean the copper probes. I use quite a bit of pressure as it can vary a bit. The swiper may not work for me as I think the contact pressure might be too unreliable. As I will start with a high current setup 0.5 - 1A surge batt this is important. But some of you guys have massive walls and IR might not be that important. I love reading all you guys banter and the time and obsessive (as we all are really) sucking of knowledge is the new 'mans shed'.
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#28
Applause.
100kwh-hunter likes this post
1 kWp in Test
4 kWh battery target - plus Mobile Home battery
Ultra low cost
Electronics ? No clue. Am machinery engineer.
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#29
OK guys and Daromer,

I re-read the study that you so kindly gave us a link to.
Here is the problem I see with it at least from my perspective and with us as DIYers in mind.
First of, obviously we don't have Xray machines just hanging around in our back pocket. Tongue
Second a test on 70 cells and 22 of those had ∞ IR (did these cells have any voltage in them? or was the CID tripped?)so the test was really only on lets see 70 - 22 = 48 wow that is one huge dataset wish I had that so I could make predictions on whether a cell is good or not.  Big Grin

I now have 762 tested cells in my database and I don't think I need an Xray machine to figure out which ones are good or not.
Oh and by the way the ∞ IR ones didn't even make it into the sheet. Smile 
Also the amount of data that was collected is minimal at best even with all the formulas etc.
Find me a study that has 2000 cells in it and then I might be more inclined to accept the results. Big Grin



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 8/7/2019
Total Number of Cells Recorded and processed                 6149
Total Cells required for PowIRwall                                   2856
Total Cells ≥2200mAh, ≥80%, ≥35mΩ, ≤75mΩ, ≥4.12V   2760
For Info Google Drive
Not your average Wolf       
            Cool
Reply
#30
That was only 1 Link. You can find papers testing 10 000 cells to. They Will all show the same result. The xray is not needed but its a way to show what happens.
The Ultimate DIY Solar and build place
YouTube / Forum system setup / My webpage  Diy Tech & Repairs

Current: 10kW Mpp Hybrid | 4kW PIP4048 | 2x PCM60x | 83kWh LiFePo4 | 10kWh 14s 18650 |  66*260W Poly
Upcoming: 14S 18650~30kWh | Automatic trip breakers, and alot more
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