2013 Persona possible 12 volt battery issue

Hello all. Need some help. My 2013 persons started doing some weird stuff. I went on an errand and when returning to the car, I hit the start button and nothing. I checked the overhead lights and barley lit, very dim. Checked headlights. Nothing. Sat there for about 5 minutes and then hit button again and had full power, car started. About an hour later stopped again and same thing again. Waited 5 min and full power. I suspected FOB battery and seemed to fix issue. Went home and checked power 5 times and no issues. Came out to car this morning and same no/low power and then full power. Went to work (35 mile ride) and same issue. Low/no power. Had a voltmeter on battery and showed 12.4 volts but at one point went to 11.9 under start up. When running it goes to 14 volts so alternator is charging. 12 volt Battery is original from factory and is 8 years old but seems good unless I am missing anything. Anyone else have similar issues. Thanks in advance.

 

I went to autozone. I had 12 volts idle, and when his meter put it under load , it tanked. Swapped battery and used car all night without issues.