Robert, our detector units both have batteries in them as back-up, either AA or AAA. They will drive you crazy beeping if that battery runs down. Take your unit(s) off the wall and try replacing the battery if yours have one. PS When we are storing the RV and not using it, we take the units off the wall and take the batteries out, just because. No one would hear them beeping anyhow even if there was a problem.
Don't know if this will help you or not. An easy fix if it does.