I have a Victron MultiPlus-II 48/5000 connected to a 5 kWh Felicity battery and, after about a month of working perfectly, the following problem has appeared.
Problem description
With grid power available, the MultiPlus remains idle. The loads are supplied from the grid and the battery does not discharge.
When I disconnect the grid, AC-out immediately loses voltage, the transfer relay click is not heard, and all the LEDs on the MultiPlus turn off.
If I manually force inverter mode using the physical switch in position I, the unit does invert and supplies the loads, so the inverter and the battery appear to be working correctly. In that case it stops using the grid.
Checks performed
I removed ESS and reloaded the configuration, but the behavior did not change.
I completely disconnected the Cerbo GX to rule out any external control, but the problem remains the same.
I read and resent the VE.Bus configuration using VEConfigure.
I removed the assistants and uploaded the configuration again to rule out any control conflicts.
When forcing inverter mode with the physical switch, the unit does power the loads, so the inverter and battery seem to be functioning correctly.
However, when grid power disappears, the transfer relay does not click, so the automatic switch to inverter mode does not occur.
At this point I am not sure what else to check, so I would greatly appreciate any help or suggestions you might have.