I have a 2010 Outlook with 208000 miles. It's runs great but recently have been having a issue with the battery gauge only reading around 13 volts. It will hold steady at about 14.5 volts for 30 mins and then drop to 13 and stay there. No battery light is on or anything like that and if I let it sit overnight it will do the same thing the next day. Changed the battery and had the alternator tested. I'm driving myself crazy trying to figure this out

 

I would get a second opinion about the alternator health. The voltage should always stay 14.2 to 14.5.

 

Ditto on the alternator. Especially if it's the original. I think it's a brush issue, but I'm NOT a mechanic.