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A project log for Minimalist Li-Ion Discharger/Capacity meter.

What you need to grade your scavenged cells for building balanced packs.

Daren SchwenkeDaren Schwenke 02/01/2019 at 03:250 Comments

I was down to the last 6 remaining cells to test.  Charged, and in the process of discharging.. almost done.

Then the power went out.  I was testing a cell welder.  Word of advice.... Don't run a space heater on the same circuit as your home-brew cell welder.  Duh...

So I charged those cells all the way back up, and discharged them again.  Unfortunately I remembered the approximate capacity numbers from when it terminated.

They are all coming in at about 200 mAh higher on the second cycle than they would have on the first.  I noticed this earlier on some of the other low-scoring cells also...

<EDIT>  Ok, not all of them are increasing, so I'm a little less paranoid now.  I'll probably still complete this task.

EDIT again... Two only increased slightly.  Two others went up by 100mAh.  Cycling more of them has resulted in all the low scoring cells going up 10-200mAh on the second cycle.. Too many variables....  I should just cycle all of them again and be done with it.

</EDIT>

This is not a problem with the capacity meter.  However, it likely means I will need to cycle about 1/3 of the cells again to make sure they are back to their actual capacity.  Now that I'm charging them in my two slot desk charger, and not all at once (temporarily wired into the BMS with a huge power supply), that is going to take forever.

But... I gotta do it.  Doing it.

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