Britannia
Wannabe
Yes. AGM.
Ran for 4 hours and stopped for fuel. Dead.
Alternator is putting out 14.2 volts.
Ill check the terminals at the actual battery when I stop.
Can you check the voltage at the starter battery when the alternator is putting out 14.2 V? If it's low then there's a problem with the charging system. Yet another possibility is that the duo charger has died. You can check the voltage going into and out of that unit when the alternator or shore charger is running. If the output voltage is low then it could be dead. Check those two fuses too.
Richard