I am building a system that will have 4 x MPPT 250/85, 3 x Phoenix 48/5000 inverters in parallel and a Pylontech 48V battery bank. I will not be using a backup generator source but I do have a RV parked in my driveway with a 12V 6.6 kWh battery and an Easysolar 12/1600/70 installed. This is wasted capacity when we are not using the RV, so I may as well put it to good use.
Obviously, the 12V battery in the RV and the 48V Pylontech battery in the house need to have some method of interfacing. 12VDC to 48VDC conversion is not the answer, so I looked into using the 240V output of the Easysolar to run a 48V charger for the Pylontech batteries. Naturally, I want this to be controllable to ensure that my very expensive batteries don't overcharge. I can already ensure that the RV batteries don't over-discharge as that system is fully integrated into Home Assistant and customisable via automations.
I looked into Skylla 48V chargers but they are essentially dumb units and don't appear to be controllable by the Pylontech battey BMS and Cerbo GX. Next option is to use a Multiplus in charge-only mode. The Multiplus 48/1600/20 matches well with the output of the Easysolar in the RV and has a VE Bus connection but I cannot definitively find out whether its output would be controlled by the Pylontech BMS in the same manner that the MPPTs are.
Any help would be much appreciated.