Polar CS300 User Manual

ENG

Wrist Unit Battery
Do not open the wrist unit yourself. To ensure water resistance properties 
and the use of qualified components, the wrist unit battery should be 
replaced by an authorized Polar Service Center only. At the same time, a 
full periodic check of the cycling computer will be done.
Note: 
•   and Battery low are displayed when 10-15% of the cycling
  computer battery capacity is left. The backlight and cycling computer  
 sounds are automatically deactivated when these are displayed.
•  Excessive use of the backlight drains the cycling computer’s battery
  more rapidly.
•  In cold conditions, the low battery indicator may appear, and
 disappear again when you return to a warmer environment.

Speed Sensor Battery
Contact your authorized Polar Service Center to replace the speed sensor. 

Transmitter Battery
If your transmitter stops working, it might be due to the battery running
out. To change the battery, you need a coin, sealing ring, and battery
(CR 2025).

1.  Open the battery cover of the connector with a  

  coin by turning it counter clockwise from CLOSE  

  to OPEN.

2.  Remove the battery cover, lift the battery and  

  replace it with a new one. 

3.  Remove the sealing ring of the battery cover and  

  replace it with a new one.

4.  Place the negative ( -) side of the battery against the bottom.

5.  Place the cover with the arrow pointing to OPEN. Make sure that the  

  sealing ring is placed correctly in its groove.

6.  Gently press the cover deep enough so that its exterior surface is on  

  the same level as the connector’s surface.

7.  Turn the cover with the coin clockwise until the arrow points to CLOSE.  

  Make sure that the cover is closed properly!