The first set of batteries I got had 8 gauge wire. I thought maybe they were also for jump starting my car in an emergency. The only connectors that fit them were PRC6's and I hated them. Pain the the butt to get the cover to snap over the connector once you got it soldered up and the least little bit of solder on the outside of the plug and forget it.
I switched to XT60 and like them a lot better. Will carry most any load in the range we're talking about and much easier to use, lighter, and cheaper.
To fit the big cables, I just use a smaller slot on my wire stripper to trim a little of the wire off neatly and it fits right in.