The black/red wire is coming directly from the rectifier, you pull it out before it gets to the connecting block, attach with the spade connector to your new 10 or 12 gauge wire and run that directly to the battery terminal. What this cures is the new wire is big enough to cary the load for charging, and shorter than the small little stock wire that runs inside the wiring harness and is much longer, causing it to burn up prematurely because it gets too hot.
