This applies to all types of solar inverters regardless of size. The number of batteries you can connect to an inverter cannot be more than 12 times the inverter charging current. A 20A charger can handle 240ah battery maximum. The formula is A x 12 = battery capacity (ah). If it is a 40A charger the limit is 480ah.
If there are three 12V 200ah batteries, the battery voltage is 36V (12V x 3 = 36). An inverter with a 36V can recharge these batteries. The maximum capacity is 600ah 9200 x 3 = 600). Battery Parallel Connection. If the battery bank is connected in parallel, the battery bank capacity increases but the battery voltage is the same as each cell.
TL:DR if you have the battery data sheet, respect that. If you don't, then limit yourself to C/10 current and 13.8v charging voltage. The maximum charging current for a lead acid will be given in the data sheet. Some batteries are more robust than others. If you don't have the data sheet, then C/10 should be reasonably safe, in your case, 15A.
The Inverter will continue to try to charge the battery even if the mains voltage is low. However, the charging process will take longer. The inverter must pull more current from the mains to supply adequate power to charge the battery. It is critical to remember that different batteries have different voltage requirements.
So if the battery current limit is 20 amps, and there are two batteries in parallel, the inverter must provide 40 amps (20A x 2 batteries). This is not the case if the battery bank is configured in a series, because all the batteries have a similar current. Connect Batteries in a Series.
Charging Time of Battery = Battery Ah ÷ Charging Current T = Ah ÷ A and Required Charging Current for battery = Battery Ah x 10% A = Ah x 10% Where, T = Time in hrs. Example: Calculate the suitable charging current in Amps and the needed charging time in hrs for a 12V, 120Ah battery. Solution: Battery Charging Current: