Polar Pacer HRM changing battery?

It is. you have to send the entire unit to Polar (in New York, I believe). Check the web for their address. They are very good to work with. The older ones used to be user servicable, and you may be able to change out the watch battery if you are careful (they seem to be making them tougher and tougher to do by yourself). Pricing is about $10 to $15, I believe. Good luck.