Indeed it is. Depending upon the model (you didn't post it) it could be a variety of different failures such as a bad stator, shorted rotor, but most likely the voltage regulator. That being said, an hours worth of troubleshooting with a meter will confirm/deny this before throwing parts at it.
How handy are you with a multimeter?
94-Newmar Kountry Star 40-KSDP
Spartan/Cummins 8.3C-300HP/Allison 3060 WTEC-II/25yr RV Tech RVIA Certified/Onan-Cummins Certified