The estimated average battery life of the Polar Power Output Sensor is 300 riding hours. To change the battery, please follow these instructions carefully.

1. The battery for the power output sensor is in the bike mount unit.
   
   
2. Open the battery cover on the right side of the bike mount with the aid of a coin. Push the battery cover gently and turn counterclockwise.
   
   
3. Remove the old battery and insert a new one, minus side up (battery type CR 123A). A flashing light in the power sensor indicates a correct replacement of the battery.
   
   
4. Put the cover back into place. Push the battery cover gently and turn clockwise until the arrow points to the arrow next to the "close" text.
   
   
5. Test the sensor by checking that a red indicator light flashes in the power sensor when the spoke magnet passes the speed sensor.
   
   
6. Do not throw away the old battery with normal waste; take it to a place where problem waste is handled.