Alternator voltage runs from 13.5 to 14.4. Maybe even a bit lower & higher than that in some vehicles and some circumstances. The alternator is not a well-regulated source for charging - that's not its primary function. Lead-acid batteries, whether flooded or AGM, tolerate the wide voltage range rather well. LiPO4 batteries are more sensitive to voltages and don't tolerate wide variations as well. However, the alternator isn't charging 24/7 either.
Former owner of 2004 American Tradition and several other RVs
Home is West Palm Beach, FL