[retiredguy123]

Originally Posted by DALEPQ

Just as an F.Y.I.
Had to replace battery in a detector that was beeping, we were "Seasonal" so had to have a handyman do it.
He advised that if one battery is needing to be replaced, then all batteries need to be replaced.
The reason he gave, was that all the detectors are inter-connected, and when a new battery is put into one, it has a higher output than the other ones. Thus, that difference
will cause the other ones to begin beeping.
He did then put in all new batteries in all the detectors, problem solved.
Will have new batteries put in again in all detectors, before we leave again.
Also, the Fire Dept. used to do the replacement as a no-charge service, they stopped
because of Covid, anybody know if they have re-started doing battery replacements?

Your handyman's explanation is not correct. The smoke detectors are powered by the house electric current. The batteries are only for backup purposes, if there is a power outage. The detector will automatically detect a low or dead battery and the detector will start to beep every 15-30 seconds or so until you replace the battery. Although it may be a good idea to replace all of the batteries at the same time, it is not necessary. You can replace the battery in the detector that is beeping and that will resolve your beeping problem until another battery gets low or is dead.