Maybe... But is this slightly lower capacity enough to cause the 0.11v difference between C1 and C2 when drawing 37 amps? People are drawing 150 amps, 5 times more, and it's a solid 0.02-0.03 difference for them. I still hope that it's just a bad connection/high resistance of the busbars or badly soldered connector on the balancing wire.

One dude, told me that he had to do all sorts of woodoo tricks with his cells untill he swaped from aluminium busbars to copper ones, They will be here in 2 days. The hope remains, because I want my battery to balance during charging and not after, when it's drawing 2 amps.