The AC input on the EG4 is designed for either Utility or Generator. Users have reported issues with some types of generator/inverter combinations such that the inverter does not qualify the AC and will not accept it. Make sure you are using the correct voltage for your inverter model and give it a try. Using the internal charger in the EG4 is the cleanest method to charge batteries from an AC source rather than using a separate charger. Although, there is nothing wrong with having a separate charger on-hand in case you need it sometime.
