Polar makes a series of popular heart monitor watches that can help you to achieve maximum levels of cardiovascular fitness and prevent you from overtraining by alerting you when your heart rate is too high. Designed to be worn like a watch, it is sized for men, women and in a unisex styling. Many athletes choose the Polar F4 series for their workouts. The Polar F4 works as a receiver for the chest strap transmitter. You can change the Polar F4 battery yourself with a few simple tools. You'll have to wait until you remove the old battery to purchase a new one since Polar recommends that you only have it serviced by an agent and does not list the battery types for the various number models in the F4 series.
Place your Polar F4 watch face down on your work surface. Look closely at the back of the watch and find the small indent in the metal part of the face; this is the lifting point for the back of the watch.
Pry the back of the watch face off by inserting the tip of a pen knife into the lifting point and lifting the back up. The back of the watch is only pressed into place and will come off easily this way.
Grab the small clip that is extending across the surface of the battery with a pair of tweezers. Slide the tweezers toward the end that hooks down into the watch. Pull the hook end of the clip out of the watch and remove the clip from the battery.
Insert the tip of your pen knife between the battery and the edge of the watch face (do not insert the tip between the edge of the battery and the internal parts of the watch) and pry the battery out of place.
Match the old battery with a new one at an electronics store. The store will be able to read the writing imprinted on the battery to make sure that you get the correct battery type for your heart monitor. The F series of Polar watches includes many different number models, all of which use a different battery. Match your old battery and you will not go wrong.
Press the new battery into the watch making sure that the writing on the battery is facing up.
Press the holding clip back into place. Handle the clip with tweezers only, since it is very thin and can be bent or lost easily. Once it is in place, press the back of the watch on.