I am building a digital hydrometer to monitor beer fermentation (similar to the iSpindel, tilt, rapt pill). It is a ESP32 with a mpu6050 accelero-gyro. The device is inserted in a PET Preform in your beer. As sugars ferments into alcohol the gravity (density) of the beer will reduce and the tilt angle of the device will reduce. This angle is monitored with the accelero-gyro and transformed into gravity with a statistical model. Data is send to ubidots every every 15 minutes.
Data send include temperature, tilt, gravity, alcohol by volume etc.
To save battery power, the ESP32 hibernation mode is used when it does not send data to the cloud.
The project is work in progress.