I had historically been having issues getting stable and accurate voltage measurements. A scope on the 3.3V supply rail revealed a pretty noisy rail, probably due to the digital core chugging along at 60MHz. The ADC supposedly has some sort of internal bandgap reference, but since I switched to an external 3.0V linear regulator as the ADC reference I have had much better measurements. The voltage sensor board has two ranges: a 30V range and a 60V range. Currently I am using the 30V range and with the new voltage reference I have been getting very good readings. Next step is to work on measuring current, and the caluclinting power.