I’ve been building/playing with a small-scale system (1200W solar-in) of a Multiplus 2000VA, MPPT 150|70 VE.Can, Cerbo GX (with 7” LCD and wireless KB/mouse) and a SmartShunt connected to a battery system running a JK BMS with LCD display and app access.
After a few months of playing and tweaking, it seems that I rarely even look at the SmartShunt data and the Cerbo seems to be able to calculate all relevant current flows in the system to the point where the SmartShunt seems extremely redundant (eg: I remove the VE.direct cable from the SmartShunt and the important data is not really effected…), at least for general day-to-day use. Also, although not amazingly accurate, the JK BMS gives a decent sense of battery SoC.
Other than an arguably better estimation of SoC, what value does the SmartShunt add to the system described above?
The smart shunt will give a more accurate reading of current and SOC than any other component in a system, and in a system without a BMS, the Cerbo will be using the shunt data in preference to or in conjunction with the inverter and MPPT current readings.
If you have a good BMS, then that too has a calibrated shunt incorporated, so that will render the shunt redundant.
The BMS on my Fogstar battery has a mind of its own and is often 50% away from the smart shunt.
The reason is that the BMS does not recognise small currents under about 1amp whereas the shunt does. My system has a quiescent draw of about half amp for the control gear that is not registered by the BMS.
What I am saying and Fogstar agreed is I should ignore the BMS soc and rely on the shunt.