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Which cell is good?
#1
Hello,

I'm about to make a first testing powerwall. I believe it will only work as a tester or for the lights at home. But not for high wattage devices. Currently i'm testing the batteries for their capacity. The range i have is from 1200 to 2100mah.

I don't have a lot of cells. It is only about ~300pcs. now. But i already confused, do you really go and check every single cell for it's specs? I've read that it is the best look at the specs what was the original capacity, what capacity is right now, and then to calculate what is the drop of mah from the original state. But even for the ~300pcs. this looks so time consuming. I see your photos with thousands of cells. And you look for the specs and calculate the percentage of each battery? 

Bit confusing which of those i should use and which of those not... :|

Thank you.
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#2
Many people only have a few different types of cells. And the cell database here is quite extensive myself I have only two types of cells lg(LGGBM261865) 2600mah, and Lishen (LS) (LS LR18650LA) 2000mah oh and two 24v lifepo4 batteries.

Later Floyd
when I first started I have many different types of cells.
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#3
Yes, you want to test 100% of the cells you plan to use in a power application if they are from reclaimed cells. Brand new cells, you'd randomly test to verify they are good. Usually when buying new cells in batches, they were probably manufactured together, so they are pretty close to having the same stuff in them.

Testing previously used cells, you check their capacity. If compared to the original capacity is more than 30% drop, you wouldn't want to use them in a large application, like a powerwall for example.

New    Used  %Drop
2200   1800  19%  81% of original
3000   1800  40$  60% of original

As you can see, even though they are both 1800mAh, one of them is better than the other as far as life left. This is why you should check what the original capacity was.
hbpowerwall likes this post
Proceed with caution. Knowledge is Power! Literally! Cool 
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#4
You're suggesting that out of your 300 cells you have 300 different types?    I don't think I've ever heard of that as (for example) an old laptop battery will have 6 or 9 cells of the same type when you break it open - so its hard to imagine each cell is different.   How did you get these 300 cells?
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#5
Ok. Understood. Cells are harvested them from laptops.
OffGridInTheCity you are right, they come in groups. So it's 300/5 i would say (in my case). But i was wondering what about people who have thousands of them Smile

Started to dig in the data base. But now i have a next question.

1. How do you deal with the cells that are NOT in the data base? or it is in the data base, but no capacity is provided, like this one: https://secondlifestorage.com/showthread.php?tid=4719

2. Another question. In the link above, the cell is "SF US18650V" while mine ones are "SF US18650GR". The last few letters are different :|
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#6
if not in the data base You can search the internet for info
http://www.datasheetcafe.com/us18650gr-d...cell-sony/
http://budgetlightforum.com/node/7750
found by searching for SF US18650GR on duckduckgo these were the 2nd and 3rd links
with these you have an idea of what the cells should be like.
a little more searching you might even find the actual data sheet. Smile

Later Floyd
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#7
(03-26-2020, 12:01 AM)powerX Wrote: Hello,

I'm about to make a first testing powerwall........................................ I see your photos with thousands of cells. And you look for the specs and calculate the percentage of each battery? 

Bit confusing which of those i should use and which of those not... :|

Thank you.
powerx

Ha yes we test every single one of them I have over 6000 of them tested and in a excel sheet.
Multiple criteria recorded and mAh results along with IR, Additionally  V and IR after at least a 30 day rest.
Small sample of my sheet.
these happen to be good cells


These not so good



US18650GR G* are Sony cells  the Prefix of the "GR" series is always US18650GR and then there is a number after that usually in the 2nd line which makes it a G5, G6, G8 etc.  The V is another series of Sony batteries.
Wolf
Korishan and OffGridInTheCity 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 01/23/2020
Total Number of Cells Recorded and processed                 6263
Total Cells required for PowIRwall  14S80P+1                  1200
Total Cells ≥2200mAh, ≥80%, ≥35mΩ, ≤75mΩ, ≥4.12V   3286
For Info Google Drive
Not your average Wolf       
            Cool
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#8
Thank you, playing with specs Smile

But now i see that there would be a very helpful upgrade of this page.
I have to enter each cell individual page, just to check the ah :| if on the main cell database page would be visible capacity as well, would be much easier and time consuming Smile

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#9
(03-27-2020, 11:10 AM)powerX Wrote: Thank you, playing with specs Smile

But now i see that there would be a very helpful upgrade of this page.
I have to enter each cell individual page, just to check the ah :| if on the main cell database page would be visible capacity as well, would be much easier and time consuming Smile
powerx

If you have excel then you can download my starter sheet https://drive.google.com/open?id=1W8CQa6...YUU1V-6Nsj

It has the database of all the cells that were available when I created it. Easy enough to add to also.


The second part of the sheet will pull all pertinent data from the Database sheet. All you have to do is enter a date if you so desire a cell number to keep track and the cell part number. The manufacture, wrap color mAh rating etc. will fill in automatically. Once you test the cell and enter the tested capacity it will calculate the SOH (State of Health) of the cell and give you a percentage.
I can't make it any easier than that.



Wolf
powerX 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 01/23/2020
Total Number of Cells Recorded and processed                 6263
Total Cells required for PowIRwall  14S80P+1                  1200
Total Cells ≥2200mAh, ≥80%, ≥35mΩ, ≤75mΩ, ≥4.12V   3286
For Info Google Drive
Not your average Wolf       
            Cool
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#10
thank you Wolf! Smile
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