Thanks for the info. If I read the datasheet correctly though, the INA217, which is designed as an amplifier, has a way too small range for the voltage I am using.
" Signal input terminals Voltage(2) (V–) – 0.5 (V+) + 0.5 V
Current(2) 10 mA "
That would make sense for an amplifier, but I don't see how it can be used as a voltage sensor for up to 18V.
What am I missing? A search for Arduino and INA217 only gets amplifier circuits. INA217 and voltage measurement gets nothing.