As
@Dana67Dart pointed out, the black wire is currently on "the big stud", which is the insulated stud and is where the charging current from the alternator originates. It, and the two field wires are all that should be connected. Do NOT connect either field terminal or wire directly to power or ground. The top stud, which your red wire is shown attached to in your first photo could be grounded, but it should not be necessary. Just stack your red wire with the black wire on that lower stud the black wire is already on. Make sure none of the ring terminals on that stud are touching anything else either. That would cause a short to ground and still pop the fuse.