The Victron Pylontech guide https://www.victronenergy.com/live/battery_compatibility:pylontech_phantom states:
When DVCC is enabled, the battery (via the CAN-bms) is responsible for the charge voltage. The Pylontech battery requests a charge voltage of 53.2V. We have however found that in practice this is too high. The Pylontech battery has 15 cells in series, so 53.2V equates to 3.55V per cell. This is very highly charged and makes the system prone to go overvoltage. It should also be noted that a LiFePO4 cell stores very little additional energy above 3.45V. For this reason we opted to override the BMS and cap the voltage at 52.4V. This sacrifices almost none of the capacity and greatly improves the stability of the system.
This makes a lot of sense. However, by error I found out that it is not implemented that way. The clamping seems to be implemented the wrong way round!
When I configure the absorption voltage in VEConfigure to 54 V, then it will charge the battery up to 54V and receive overvoltage alarm or destroy the batteries. The clamping to 52.4V is NOT THERE!
However, if I configure the absorption voltage in VEConfigure to 52.0 V, then it will ignore the 52.0 V and charge to 52.4 V. So, in fact, the clamping is implemented the wrong way. If the user sets something BELOW 52.4, shouldn't the user values be obeyed?
In fact, the same guide cited above says that the user should set the absorption voltage to 52.0V (see table!) If you do that, it has zero effect! The MP II will still charge to 52.4V absorption voltage.
I think this is a bug. If not, what would be the rationale behind this behavior?
I'm not sure where to report this type of bug, if not here please advise.
System Info: MultiPlus II 3kVA 48V, Pylontech US2000, AC coupled PV on AC_OUT, no other Victron devices except the MultiPlus, no DC connected chargers. Firmware v2.64, 20210227...