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Processing Low V Cells
#1
I started this to show how to process Low V cells. At least how I do it and have had a reasonable good success rate.

As you all know we run into those packs that just have a bunch of < 1V cells. What to do?
First off we know the cell is mechanically OK as there is some V so no CID trip or PTC issues.
At <1 V there is not much charge to worry about so I line them up in my 20P cell holder.
These are Sanyo UR18650FM all of them were <1V

I have a CC/CV  Buck Power Supply hooked up to my modified Server Power Supply for 12V input and  I set my CC/CV Buck to 4.2V and 1A.
That equates to 50mA per cell.
This picture shows some of the Sony "greens" being charged US18650GR G8 The ones that are in Sony green cells suck thread


Next I watch the V build up and check the cell temperatures by hand.
(Thermal Imaging camera coming today If you want one that is a good unit and at a great price I got this one. https://perfectprime.com/collections/the...cts/ir0018)
After about 1 to 2 hrs you will notice some cells getting a little warmer than the others. I will have Thermal images in the future but for now I use a thermal gun and most cells will run around 22°C to 25°C. Then you get to the 27°C and up cells. At this point you will notice on the DMM that the V has somewhat stalled at a certain V and doesn't seem to rise anymore.
That means the high temp cells are absorbing all the A and are sucking the V down.
So I removed the "hot cells"  and immediately the V started to rise. You can view the video here (Too big to post here)
Now you will see that the rise is in the thousands of a volt so it would not show up on a regular DMM. 
As the offending cells have been pulled out the remaining ones are now able to absorb a charge. What is to note though is that the IR of the  "hot" cells wasn't bad at least not in the ionosphere.
 
I will make more detailed pictures and possibly more short videos of this process. as it continues.

Hope this explains some things.

Wolf
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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
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#2


^^ I do something similar - but instead of 20P, I do 4P with a TP4056. Ends up being about 25mA/cell until 2.93V. 

I've had very little success with <1V cells, though. A lot of them will test very well initially, but most end up being self-dischargers and a lot will lose a lot of capacity on a second or third test. The 10% that were found at less than 1V, don't self discharge, and hold a decent capacity must not have been at that voltage very long, but I have no way of knowing that. Also, brand seems to make a difference as the Sanyos are particularly bad at less than 1V.
Formerly known as Dallski
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#3
Good Idea, In my case the 20p board serves as a discharger also.
I just have a rash of UR18650FM cells and a lot of them are below 1V so I decided to experiment.
We will see what happens.
So far the results aren't stellar
 
I will find out what their reading is after 30 days.
I may set some aside and do a series of C/D cycles on them to see what their longevity is.
On another note in the Sony Green cells suck thread those cells seem to have come around.
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
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#4
I know people will ignore me as I ignored others' warning: Testing low voltage cells is only useful if you can't get your hands on cells very often. I'm bulk checking voltages of cells I tested 3 months ago, most are very good. I got to a pack that had low initial voltages, but tested with decent capacity. These are the Sanyo UR18650ZT rated at 2800mAh new. Well, 5 out of 6 have self-discharged significantly, while 1 is ok. I'm going to re-test the one non-self-discharger and see what capacity it has now. I won't be surprised if its lost a lot of capacity.



With my generics, I'm just putting my <1V cells in a box by themselves. Not going to bother testing <1V cells anymore. Easier to take to the recycler since I don't have to worry about discharging the cells!
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Formerly known as Dallski
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#5
These cells were somewhat low V cells all in the ≥2V but <3V. Initial IR test showed good promise so all got charged at CC/CV 50mA, 4.2V.
All got stuffed into my three testers. 
Results are pretty enlightening. All above 90% and pretty even across the board on all testers.
Kinda says that all my testers are really close to each other as far as their results in mAh is concerned.
Nice to see in living color. 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       
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#6
(02-21-2019, 05:20 AM)Dallski Wrote: I know people will ignore me as I ignored others' warning: Testing low voltage cells is only useful if you can't get your hands on cells very often. I'm bulk checking voltages of cells I tested 3 months ago, most are very good. I got to a pack that had low initial voltages, but tested with decent capacity. These are the Sanyo UR18650ZT rated at 2800mAh new. Well, 5 out of 6 have self-discharged significantly, while 1 is ok. I'm going to re-test the one non-self-discharger and see what capacity it has now. I won't be surprised if its lost a lot of capacity.



With my generics, I'm just putting my <1V cells in a box by themselves. Not going to bother testing <1V cells anymore. Easier to take to the recycler since I don't have to worry about discharging the cells!

I can report some strange positive things about Low-V cells, See my lucky thread, pls.
https://secondlifestorage.com/t-I-though...3#pid50123


In this case  Bike blocks, It may be a special case.
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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#7
Hi Cherry67, I just read your lucky thread. I've got my own research. And I've read a lot of Wolf's research on this topic, as well. I believe we can all agree that the proper way to recover cells that have less than 1 Volt at the time of discovery is to charge them with as small a current as possible for the entire duration of their first recovery charge. That will not recover all cells, as some are permanently damaged from being in a low voltage state for too long. Just yesterday I was "trickle" charging four LG cells from their original voltage up to just 3.5V at 25mA per cell, and I noticed the 0.8V cells held their voltage, but the ones that were at only 0.05V were already self discharging after just 24 hours. You cannot recover all cells, you can just have a better chance of recovering the ones that are not super damaged.
Formerly known as Dallski
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#8
Dallski, i agree to most what you say, but what i do is still slightly different.
I use much lower currents now for <3 Volt, and moderate charging to full then. 100 - 300 mA.
But, i dont believe that ist the last word in this issue.
What i have is 3 blocks 10s6p coming Up from 0.6, 0.8 and 1.1 V/cell, each Block 100 % successful and total in synch. That ist so totally different from the usual 70 % success rate that it triggers my interest.
1 Block would be Chance, 2 ist Strange, but 3 ist an indicator there ist Something in it.

I'll Just want to know WHAT.
There are so many possible Parameters...

Sorry i will Update later.
Patience typing mobile is Up.
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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#9
(06-04-2019, 04:23 AM)Dallski Wrote: ................... Just yesterday I was "trickle" charging four LG cells from their original voltage up to just 3.5V at 25mA per cell, and I noticed the 0.8V cells held their voltage, but the ones that were at only 0.05V were already self discharging after just 24 hours. You cannot recover all cells, you can just have a better chance of recovering the ones that are not super damaged.

@Dallski

That is correct you cannot recover all cells BUT if you take an IR reading of the cell (no matter what the voltage) you will find that the ones that have a low IR reading your chances are improved dramatically.
I just charged a lot of LGABB41865 9 of them had a V of <2V some of them below 1V using the 4.2V 50mA per cell CC/CV.
The ones with the V in yellow where those cells . It took 3 days for them to come up to 4.18V.
The other 6 came out of the pack with 4.05V which went into the charger/testers right away.

The IR was perfect on the cells, no heaters, and the results were very good.
So just another feather in the IR cap.
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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#10
Wolf, you are probably right. If I had more used cells, I probably would invest in a proper IR tester. It all comes back to IR, with a few exceptions as you have found.

Cherry, the reason I keep currents low for the whole first charge is because I think it prevents plating. I dont remember the specifics, but i believe high currents on low voltage cells produces plating on the cathode or anode of the cell. While it doesnt seem to affect the first test after charging, it does seem to cause the cell to self-discharge over time. I dont have the hard data on that, though, I have just had a lot of bad luck with <1V cells and I think it's because I was just throwing them in the TP4056 and charging them at 1A after they got to 2.92V. I lost a lot of cells that tested well initially. But then again, they could have been high IR cells to begin with, so who knows?
Formerly known as Dallski
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