To answer the OPs question, a WFCO ( brand) Converter is the electronic device that converts the 110VAC from shore power into 12VDC to charge the battery and help run the 12V appliances in the RV, It is usually in the same compartment as your fuse /breaker/distribution panel. FR uses WFCO converters in a many of their products as they are cost effective. If you ever have to replace it, many people use Progressive products as they are higher quality and have some nice additional features.
2015 Freedom Express 248RBS
TV 2015 Silverado HD2500 Duramax
TST Tire Monitors
Honda 2000I + Companion
2 100W solar panels