Inverter changes 12 volts to 110/120 volts
Converter changes 110 volts to 12 volts
You might want to keep an eye on it and watch to see if it is over charging your battery when plugged into shore power. WFCO converters seem to be the low end of converters and the charging side goes bad and won't go into float mode. I had to replace my WFCO after 2 years of ownership of our Laredo. Went with a Progressive Industries one and have not had any problems since. The fan running means it needs to cool the converter down and if there is no load on it why would it be hot?