There is some majors design flaws in that meter. First, the shunt resistor is almost useless since it does not take the AH as a cumulative value to know the State of charge (SoC). Voltage is a poor variable to determine SoC because Voltage varie depending of the load connected to batteries. The AH capacity, Watts and Energy (watt*hours) whether the battery is draining or charging is cumulating... So these variables are useless.
Very good instrument , i need it a lot , thanks .