I’ve created a device using a ThingShield and a remote sensor powered by a CR2032 button cell battery. The sensor can return the voltage being provided by the battery.
Standard devices report State of Charge – a percentage of full battery charge. Is there a standard algorithm for calculating state of charge for a CR2032 battery? What voltage would be considered 100%? At what voltage would it be considered time to replace? Or dead?
I just posted some info regarding this on another thread here:
The real challenge is the variability in batteries and your ability to read the voltage accurately. The battery will have some internal resistance, meaning that every time you read the voltage the voltage will depend highly on the amount of current your device is drawing. You can get to within about 10% by reading the unloaded voltage and using a curve like the one in this datasheet labelled Continuous Discharge Characteristics. In the post above I outline a model that could work to estimate the remaining power in the device to higher accuracy.
Looks like it has been a bit since you’ve posted your question… hope this is still helpful!