The gauge of the cable running from the alternator is a little low. It's possible to rewire this with heavier gauge but means the LHS engine cover needs to come off.
My preferred method of repair is to cut the cable back to good, and fit and crimp bullet connectors on. Apply electrolytic grease, connect and wrap in tape.
Soldering is all well and good, but it makes servicing a pain in the **** because you can't get the regulator/battery tray out of the way to do the belts etc. properly. It just hangs there and get's in the way
Not a big problem................but have a thought for your mechanic