I am developing a Bluetooth tracking device that uses a single CR2032 battery. Would it be worth using instead a rechargeable CR927 (40mA) battery and a small solar cell, the size they put in watches?
Using this battery might save some space and the main advantage will be that the device will need battery changing less often.
How should I design the circuit? Should I use a charge regulator?
All components are rated at 1.8 to 3.6V. The circuit uses up to 20mA in full active state, and around 40uA in sleep state.