Vbat A6 electrically noisy #36
Description
Measuring the LiPo battery voltage is through a resistor divider 10M / 2.7M with a capacitor 100nF
Using this reference there is a lot of noise on the ADC.
Can the resistance's be changed to 1M / 270K for better noise immunity.
With 12.7M - the current drain 4.0V/12.7M = 0.31uA
With 1.27M - the current drain 4.0V/1.27M = 3.1uA - negligble in the overall power management
For an algorithm that detects the lowest battery voltage as an estimate for battery capacity, a windowed filter of 4 readings was implemented. The "Some Sw filtering" below used the lowest value read in the 4 to achieve some noise reduction
