hey all hopefully someone here can help me out with this issue searched the forum and couldnt really find anything. so i have a 2013 f350 dual alternator set up. so the last month i have had an intermittent battery light an p0620 code. checked batteries and they are 12.5v with truck off. so in the beginning the light would only come on while in drive and when im stopped at a light then voltage would bounce between 13.8 and 14 start moving light would go out and voltage would go back up to 14.2-14.3 so i figured alternator issue so i tired to find diagnostic process to figure out which alternator didn't come up with much. I checked connections at the battery all were clean, i checked connections at alternators and top passenger alt had a little corrosion on the pin nothing crazy cleaned it and reconnected. drove around some days no light some days light would come on. then it wouldnt come on when stopped but switched to it would flash on when accelerating moderately. i load tested my batteries and one was ok at 100% charge and the other was marginal at 100% charge, i had thought about changing the batteries but i would hate to spend the money and have it be something else like one of the alternators being bad hence why im trying to make sure its 100% the batteries. so then no light for a while seemed to be fine. this morning started my truck to drive to training for work and battery light was on and stayed on the whole 15 to 20 min ride and said battery voltage was 14.3-14.4. so im kinda scratching my head without just throwing parts at it. i about broke down and went to ford to get 2 new batteries and get the upgraded 850 cca ones. if anyone has any insight that would be awesome besides throwing parts at it or bringing it to ford and hoping they find it quick before racking up a large bill. im currently 3 hrs from home for a week so no tools but if its something that i can get by for the week till i can get home to my tools that would be awesome. thanks in advance and sorry for the long post.