This site is now in read-only archive mode. Please move all discussion, and create a new account at the new Victron Community site.
I am not too sure what you want to calculate.
Three (3) 12V 220Ah batteries should be connected in parallel to maintain a system Voltage of 12V to use with a 12V inverter. You will have 660Ah in that case.
If the MultiPlus is charging at 70A from 50% SOC then it will take ~5 hours or more to reach 100%.
You can connect as many batteries as you want, @isaac coffie. So long as they are in parallel, maintaining 12v, the number of batteries connected is irrelevant other than increasing the time needed to charge the bank. Your inverter neither knows nor cares how many batteries are connected in parallel to it.
A lead acid battery should be charged with 10-15% of the capacity. -> 100Ah battery -> 10-15A charging current
Your Multi can charge with 70A max. -> up to 700Ah of batterys.
Additional resources still need to be added for this topic
11 People are following this question.