Write down the appliances that you intend to connect to your 12 volt battery bank system. The appliances need to have an operating load of 220-volts, although each appliance has a different amperage associated with it, including a peak amp rating and a normal operating amp rating. You need to be sure the power inverter used exceeds the peak amp rating by at least 10 percent and your battery bank can sustain the amp-hours, calculated by multiplying the amperage of the appliances by the time each one is used.
Install and wire your battery bank system. If you use 12-volt deep-cycle batteries, all of your batteries should be identical in their specifications and in their age. You need 10 12-volt batteries, wired into a series circuit with 8-gauge AWG cable. Make sure there are at least 2-3 inches between each battery.
Solder eyelets onto the ends of the 8-gauge AWG cable if you do not have access to pre-made battery cables. Connect the 8-gauge cable or battery cables to the batteries in a series circuit configuration, connecting opposing terminals of adjacent batteries, so that the positive terminal of one battery is connected to the negative terminal of the other battery. Continue this pattern until all of the batteries are connected and one positive terminal and one negative terminal, from two different batteries, are remaining.
Connect the input cables for the 120-volt AC power inverter to the two remaining battery terminals. Do not turn the inverter on because you still need to connect the other inverter. Consult the owner's manual or the manufacturer for which specific types of cables should be used to connect the battery bank to the power inverter as well as which type of wire should be used to connect two identical power inverters into a series configuration.
Connect the second power inverter into a series circuit with the first power inverter, so it doubles the voltage of the system, pumping it up to 220 volts. Turn on the power inverters and plug in your appliances.