Using Ruuvi sensors in high humidity may occasionally cause a leakage pathway that drains the battery prematurely. Remove the battery from the Ruuvi sensor. After the power is switched off, try to remove as much moisture as possible from the device. Use a soft cloth and soak up all the moisture. Use a cotton swab for the small parts. Blow dry the PCB gently with compressed air. Placing the PCB into silica gel to dry for a day or two can also help. Check the PCB for visible physical damage. Replace the battery with a new one.
Battery is low quality
Make sure that you are using high quality batteries. CR2477 button-type batteries are recommended. If you are using the device in extreme temperatures, please use a battery suited for these operating conditions.
A damaged component inside the sensors might cause the battery to drain faster than expected. Check warranty terms to see if your device could be eligible for replacement under warranty.