[dladd]

fwiw, I have three 2-3' long sections of #2 cable in my battery loop (the rest are all 2/0) and I sometimes pull 500 battery amps for brief periods. No heating that I can feel. My steady current is more like 130a on the highway (1c), just very brief bursts up to 500a when getting on the freeway. I do plan to replace them soon, I'm curious to see if I experience any less voltage sag after replacing the sections of #2 cable with 2/0.

I'm very impressed with anyone who builds their own controller, especially AC! My stuff is all off the shelf.

 

[dladd]

Are the #2 segments sequential? If you have some meters it'd be interesting to put one across the #2 segments and another across the same number of batteries connected with 2/0.

these aren't battery interconnects, I use the standard CALB copper pieces for that. These are the cables between sets of cells which are in the trunk, but a few feet apart. One goes from my lower set of cells to the circuit breaker. One goes from the circuit breaker to the upper set of cells. The third returns from the upper set of cells to the fuse. Those cables are all soon to be replaced, it's on my never ending to-do list. The main front to back cables, and all motor cables are already 2/0.