My system is an ESS with Multiplus II, Cerbo CX and two MPPT 250/70 and the smart shunt 500 in an 48V System LiFePO4 (no BMS).
The problem is, that due to any reason the DC Voltage shown / measured by the Multiplus is higher than the real DC-voltage. The shunt shows the correct voltage (checked with a voltmeter). The result of this mismatch is, that the Multiplus „thinks“ the batteries are full (state „Float“) and therefor the MPPTs are not charging .
When I switch off the Multiplus, the MPPTs are still not charging. But after rebooting the Cerbo both MPPTs are charging now to the proper voltage and SoC.
The system ran fine for more than half a year. Then one day this problem showed up. Updating to the latest firmware did not solve the problem. After increasing the Float Voltage from 54V to 54.3V it worked a while very good. But now the phenomenon started again.
Are there any ideas how to solve this?