@Curtis63, I've used both solutions as suggested by @energia, depending on my power choices. One thing to keep in mind if you're using the ADC is what type of battery and the typical discharge curve. Also, you need to think about when and how often you check - right after a power-intensive action may yeld different results than letting a battery recover for some pre-determined time (again, dependent on how the battery responds to loads).  My systems are powered by LiPo cells, so the higher