As promised, I have made a small change to the source to support either the INA-220 or the INA-226 chip. These are pin compatible chips, and either CAN be used, though the INA-226 is an improved chip.
If you are doing a 12v system, either will be fine. As with a 24v system (though to support 24v, the INA-220 will need some pre-scaling divider resisters, which the INA-226 can support a 24v system directly). For 26/48v, the higher native voltage of the INA-226 (36v vs. 28v), plus its higher input impedance makes for a slightly more stable and accurate measurement chip.
You can read a bit more about this here: SmartDCgenerator.blogspot.com/....improved-voltage-sensing-chip
Now, a WORD OF CAUTION: Because I am away from the boat these days, I have NOT BEEN ABLE TO TEST THIS CODE ON ACTUAL HARDWARE!!! As such, I left the prior version (v0.1.3) on the google drive as well as the new v0.1.4 version.
Also note that I revised the order of the parameters for the #define AMP_SHUNT definition, from mv/Amps to Amps/mV