W/o telling us what converter/charger you have, I don't know why anyone would tell you to change it. Most any converter/charger in any later model RV is well capable of charging any kind of battery. (AGM or otherwise) If you want faster charging on generator, you may want a larger converter, and large converters require larger wire to the batteries.
I made the other (AGM) statement only to let you know you get less amp hrs per dollar w/ AGMs. If you have the need for them, that's a good reason to go w/ them.
And did you know that if one 6 volt battery has 220 amp hrs, that two of those same batteries connected in series, still has only 220 amp hrs ? But that is still probably double the amp hrs in your single 12v battery.
And as was said, you can get more elaborate w/ a transfer switch etc etc, even adding a sub panel separating the stuff that should not be operated on inverter, but then you are getting more complicated.
Also be informed if you are thinking of using a lot of battery power to operate such things as hi powered sound system, and you are expecting solar to keep up w/ recharging, you will need to be thinking 4-6 more panels added to what you have.
RJsfishin wrote:
You're making it complicated.
Change to AGM if you don't want the most amps for the bucks.
Add the solar.
Don't change anything else, except turn off your converter/charger when shore power is connected to inverter.