This is an automotive Voltage monitor. Draws 7mA in deep sleep mode.
This board was soldered with an iron because I didn’t feel like grabbing the solder paste and setting up my air station for a few small components. I think I prefer the air station for the tidy solder joints it gives.
Eagle files are here:
Here is a simple program to read the voltage. Note that it relies on the resistors being correctly set up (460k/1M) and may need to be calibrated. Note that while the base ESP modules work with a 1V comparator for the ADC, some development boards work with 3.3V (or supply voltage). It only writes to the serial, full HTTP integration will be coming shortly.