I may be wrong, but it sounds like the cells may not be consistent after initial cycling from this particular manufacturer. Like not matched possibly? Matching isn't super important, but it makes me wonder how they are manufactured. Individual cells usually aren't that far out as to effect a rest time that much. But then again these cells are different than what we used to use in rc car racing. I had a battery sponsor and I got schooled on battery matching, but like said, I'm sure these have totally different characteristics. Just my random .02
Matt bought the same charger I have and that charger is supposed to balance the cells as it charges.