For monitoring a second battery in Ardupilot does the generic-smbus setting (or any other setting for that matter) support the use of the INA219 V/I/P monitoring chip please? I have some of these and if suitable for the firmware they are an ideal solution to my monitoring.
My monitor device is something like this:
FYI my Ardupilot FC is a Matek F765WING, with external GNSS receiver/magnetometer, 0.96" OLED and airspeed pressure sensors on the two existing I2C links.
If this is unsupported I will make arrangements to use analog inputs for V & I.