I have 2 x AC1-3.7-E-G2-WL inverters connected in parallel with 1 x EP12 battery on each. This is working well but I want to add more capacity. Do I have to add another EP12 battery on each inverter to keep it balanced (so 2 batteries on each) or can I add a single EP12 to just one of the inverters therefor having 2 batteries on 1 and 1 on the other ?
You would need to install an EP12 on each, they can handle small imbalances in the stack size but having 2 + 1 will just cause you pain.