Thought I would just check before I spend the time testing. Is it possible to do Sigma-delta Analog to Digital conversion when running the prop with internal clock RCSLOW ~20kHz? I just want to keep an eye on my battery voltage, not looking for a high-resolution solution. I'm pretty sure the answer is no way! But if someone with more experience thought there was a chance, I would give it a try.
The sigma-delta white paper
has everything running at 80Mhz.