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Accept storage test v drop
Voltage drop of long term storage. I charged some batteries about a year ago and marked voltage level. What is an acceptable level of drop over a long period of time, I did some searching but find correct data.

Lithium and charged to 4.1 to 4.2
For new good cells, the drop is even below 1%/year from my tests.
Used cells can drop faster.

I consider acceptable the ones that were charged at 4.2 V and did not drop below 4.0 V after 1 year.
Note that the drop level depends a lot also on the type of the cell.
Many of even the used ones I have maintained 4.1-4.15 V after 1 year.

There is a direct link between V-drop over time and the general cell integrity. The ones dropping under 4.0 V (3.6-4) after 1 year I found to be very low capacity when tested, the ones ending up at around 3.3 even lower and the ones dropping below 3 were of 100-200mAh capacity.
CBlack, Generic, smileypete like this post
I had pretty good success so far as I charged to 4.1/2 ish and most stayed over 4.05 after almost a year in storage. I put cells below 4 but still have a higher charge and then only a couple really low volt ones.
So essentially, instead of waiting a year to find out if they drop 0.1V- 0.15V, if they drop by .1V after a month, they aren't worth much.
Proceed with caution. Knowledge is Power! Literally! Cool 
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