That would be #29 AWG with diameter of 0.011", with a fusing current greater than 7 but less than 10 amps.
That is quite puzzling with respect to the whiz kid jason's data, that the bond wires will pass 25 amps but fuse at 26--How can that be?
The fusing current of 29 gage copper is greater than 10 but less than 14, but even that doesn't seem like it would have enough margin if the load were drawing 3 to 5 times the C rating of the cells. The 25 amps seems like the right amount of margin for the cells.
Is there another material that can carry 25 amps (and fuse at 26) in the #29 gage diameter?