I am trying to estimate remaining battery life in a low power system. The battery is very well characterized so that reading the battery voltage will be sufficient for my needs to estimate remaining battery life.
However, the problem is that the system is comprised of low voltage chips (3.3V - 1.2V) and the battery voltage varies from 16V to 7V (dead). Any solution that I use to monitor the voltage must have negligible power overhead itself.
I am looking for
- A chip that can provide the voltage to a digital interface (I2C, SPI, etc.)
- A circuit solution that provides an ADC value that is accurate across the ~10V swing and can interface with a 1.8V microcontroller. (maybe resistor divider + zener + ADC)