Originally Posted by 
drivesafe
				
			 
			Hi Andrew, you may not have anything to worry about.
Every so often, the D4's BMS ( battery Management System ) will turn the alternator down to 12.2v, to carry out a discharge cycle of the cranking battery.
This involves the D4's electricals being used to discharge the cranking battery down to 12.2v, the theoretical 75% SoC point ( battery under load ).
Then the alternator will go up to 14.7v and stay there while the BMS evaluates the condition of the cranking battery.
From what you have just posted, it sounds like this is what is happening.
Just watch the voltage over the next few drives. It should stay up at 14.7v until the cranking battery is fully charged again.