I installed a three-phase system with 3 MultiPlus-II inverters (48V/6500V/100A) and the Dyness batteries were going into protection mode and not starting. The starter light would come ON, but after some strange sounds and lights ON and OFF on the MPPT(250/100 TR VE Can), the batteries would go dead.
Could you please provide more details about your Dyness batteries?
The MultiPlus-II 48/6k5 requires a minimum battery capacity of 250+Ah (approximately 12.8 kWh). Therefore, for a 3-phase system, you would need at least 750+Ah (approximately 38.4 kWh) of battery capacity.