Part of the plan in the previous post showed me attempting to sense the voltage level of the VCC supply by feeding it into an external ADC. Well I’ve just discovered, thanks to Tzapu’s (he of “WifiManger” fame) Minimalist temperature sensor project, that the ADC on the ESP8266 can be configured at boot to read the internal voltage at VCC. This would mean that using an external ADC would be essential, but then seeing as the ESP’s A0 only goes from 0-1v it isn’t a devastating loss to not have it available.
Tzapu is also using a current regulator (with a 18650) cell to power it. This will also require some investigation.