tennille wrote:
I don't expect to be able to run the unit off the inverter. My question is why would having the house batteries connected be necessary when plugged in to shore power and is this normal.
It's normal, or at least not abnormal, to need to have the house batteries in place and connected. Many things are 12V only. Depending on the converter, it may be possible to run them off of converter power without a battery connected; however, many converters don't work well (or at all) without a battery. Even if you have one that produces clean power of a reasonable voltage without a battery, having a battery hooked up allows for better handling of transient high-current needs when the converter output could conceivably sag.
Some (mostly older) converters produce
very unclean power on their own and rely on the battery to clean it up.