Thanks for the replies. I'm going to start with upgrading the stock wiring with the Big 7 kit from Paul. It's definitely not a belt, I can see how not charging at higher rpms would make it seem likely. While watching the installation video on the big 7 I noticed the alternator positive wire goes to a relay box just behind the battery that then distributes the power to the rest of the jeep. I think I remember my jeep not starting in the past and tapping on the box made it start it's been a while so I can't remember if it's same box.