M.S.
We have a very basic First Years monitor that has lasted for over 3 years now. After about 2 years of regular use, the battery in the main part got worse and worse at holding a charge. We had to leave it on the charging base or it would die in the middle of the night. My husband called the company to ask about replacement batteries, and they sent one, free of charge. So you might try calling Graco to see if they'll do the same for you.