Got a OTA update yesterday that said something about improving battery charging in these trucks. Might ask them to manually do the update on your truck and see if it helps.
I had a constant issue with low charge on my truck. Even had dealer replace battery under warrant. I’m convinced the motorcraft batteries are trash. Upgraded with the biggest top of the line Interstate battery I could fit. Haven’t had an issue since.
Side note, that 775cca battery is actually pretty small for these trucks. The big interstates are like 950cca but the more important number is the 94 amp hour. Smaller AH ratings will drain much faster thus giving you low voltage. I’m assuming your battery is in the 70ah range which is drastically smaller. Put an Interstate MTZ H8 and don’t waste your time with the dealer.