u/Mobile_Syllabub8735

Hello!
Yesterday I was driving home and my voltage was running 13V at first then once I hit the highway my “non essentials” powered off and only the A/C was running.. Checked the voltage again and it was sitting at 11V I still had 10 miles to make home and as I was getting closer the voltage dropped to 10.9V. The Jeep ended up completely dying so I took the battery to get it charged up and they ran the test said battery was good and alternator was good. Checked grounding and everything was good. Checked the belt and it was good.. What other reasons could this have happened?