The usual configurations for House Batteries are two Six Volts, One Twelve Volt, Two Twelves or Four Sixes. Four Six Volt batteries will provide more power longer than two Twelves. With four Sixes, you wire pairs in series and then these in parallel. (See RV Electrical Power Section.)
When you are not connected to ‘shore power’, the batteries can provide both Twelve Volts DC and 115 Volt A/C house current to the RV as long as they maintain a charge. How long they can provide power depends on how much power you draw from them. The Inverter provides 120 VAC power from the 12 VDC from the batteries. Generally, the inverter will not power the air conditioner. When running on battery power through the Inverter you may find that certain outlets, such as the Microwave, may not be powered. This is to prevent you from stressing the batteries.
House batteries are a different breed than starter Chassis batteries. They discharge slowly, a little at a time over a long period of time and they charge the same way. These batteries are charged by a battery charger contained in the Inverter/Converter distribution box. When buying House batteries look for Deep Cycle. These are sometimes referred to as Golf Cart Batteries. They are designed to discharge down to a level of 10% when needed and then to slowly charge back up to a full charge state. They should automatically charge anytime you are connected to Shore Power.