One of the most mature methods to achieve high accuracy and wide dynamic range shunt-based BMS battery current measurement is the use of high-resolution (ΔΣ) ADacs.
A typical implementation consists of a ΔΣADC with a resolution of at least 24 bits followed by a digital isolator.
The shunt is usually placed on the high-voltage terminal of the battery pack, and the ADC measures the shunt current with reference to the same high-voltage terminal. Because the splitter has a very low resistance value, the voltage drop at both ends of the splitter is very small. As a result, ADCs are capable of measuring small bidirectional voltage drops with high accuracy and dynamic range.
MORE: Can different batteries be maintained with the same BMS voltages?