Basically, the 110 volt outlets in your RV only work when:
1 - You are plugged in to a 110 volt power source (shore power)
2 - Your generator is running, which produces 110 volt power
The above is true in all older RV's, unless you have retro-fitted newer style batteries, inverters and other hi-tech electronics.
Since about 2010 some newer RV's have the new hi-tech batteries & electronics factory installed that will run 110 outlets via this battery bank OR with an under-hood generator running off the engine. But you will not find any of this technology factory installed in older RV's, as this technology did not exist at the time they were built.
I have an "old school" 1998 Coachmen, so I also have to be plugged in to shore power or use my generator for 110 volt.
Now: 1998 Coachmen Starflyte FRB 21' Class B+
Formerly: 1996 Coachmen M19-RD GMC 19' Class B