Alright, a couple things:
Using a nickel strip like shown in either of these photos
is not a good idea. Even with a very stiff deck, the battery can flex enough to cause the nickel strip to fail, either at the bend (in the case of the upper photo) or at the welds (in the case of the lower one).
Using nickel strip for series connections like this if generally fine for brick-style batteries where flexion is nonexistant, but for flat batteries it’s not a good idea at all.
You should use flexible, high-strand-count copper wire for all series connections, including the ones in the middle there where you show nickel in this photo.
As for current ratings and ampacity, here’s a bunch of info.
Check the Battery Builders’ Club thread for more tips and tricks, and pictures of batteries built using these best-practice methods.