I am currently planning a system with three MPPTs, one Phoenix charger, a Cerbo GX and a Smart Shunt (or BMV-712 Smart) with an external battery temperature sensor. The battery is a lead-acid battery.
Maybe, in some future the lead-acid battery will be replaced by a LiFePO4 battery. From my understanding LiFePO4 batteries require a dedicated BMS which is either integrated into the battery (most vendors) or is external to the battery (e.g. Victron's own LiFePO4 plus Lynx Smart BMS or smallBMS). However, in all cases the BMS must be compatible with the Cerbo GX. The BMS communicates with the Cerbo GX and reports the internal cell status, SoC, temperature and requests the optimal charging voltage/current from the Cerbo GX.
Does this imply that the Smart Shunt (or BMV-712) becomes unnecessary? IMHO, the BMS should be able to report all the values (and more) which the Smart Shunt does report. Is there anything I miss?
Addendum on Sep 23rd 2023 due to answers up to now
Reading the answers I confuses me even more.
Until a few weeks ago, I had been thinking that lead-acid and LiFePO4 batteries were basically the same, i.e. "dumb" energy storages. Of course, I was aware of the fact that they are using different cell chemistry, that due to that difference in cell chemistry both have their specific advantages and disadvantages and that they require different charging strategies (i.e. different bulk, absorption, floating voltages, different charging current, etc.). However, I had been under the impression, that one could simply throw out a lead-acid battery, drop in a LiFePO4 battery, adjust the configuration of the Cerbo to the new battery according to the specifications of the battery and that would be it.
Then I learned that LiFePO4 batteries are sensible snowflakes which require their own tailor-made BMS which is either integral part of the battery or must be added externally. Without a BMS LiFePO4 batteries would die, explode or do other unpleasant things.
I also learned that the Cerbo GX stops being the controller of the charging process, but that the BMS takes over (of course, assuming that the BMS and the Cerbo are compatible). That's why I conjectures that a SmartShunt (or BMV-712) becomes unnecessary, because the BMS takes precedence anyway.
Now, the answers up to now are basically saying that one should keep the SmartShunt in place, because the built-in BMS of most batteries are less reliable and more inaccurate than a SmartShunt. That's confusing. I thought the whole purpose of a BMS was to cherish the poor LiFePO4 in the first place. Why do I need a BMS if not for that reason?! Moreover, if (most) BMS are that bad should I even connect them to the Cerbo GX at all or just keep them disconnected and let the Cerbo GX continue to use the SmartShunt?
