I use a RTC DS2032 with button cell CR2032; I desoldered the charging resistor.
Daily I want to measure the coin cell voltage via an analog input. Now I measure 3.325 V with a DVM and adjusted the gain of the ADC to get the same result in my Arduino Nano. I want to create a warning sign “change button cell”.
In the datasheet of the CR2032 i never can find such a high voltage for this cell
- What is a save low level voltage for the DS3231 (it works between 2.3 and 5.5 V)?
- What is a good formula to calculate the rest capacity of the coin cell?