I too had issues with my Garmin strap that is about two years old. The HR would go much higher than what was accurate and I would change the battery and then after a month it would do the same thing. Then I decided to wash the strap separate from the load of my kit after a ride. I let is soak with warm water and a small amount of detergent overnight. That seems to solve my problem. I did this 6 months ago and everything is perfect. I think that the salt from natural perspiration causes the issues all of you have seen. I also short out the contacts of the internal battery contacts in the heart monitor.