I have detectors that ‘chirp’ and have perfectly fine batteries. This is when you need a lawyer to go after the companies that make the cheap detectors. I had 3 like that from a batch of 5. The company DIDNT CARE.
They replaced them after I paid to ship them back — with more that did the same thing !!
CCS or something like that
Have you noticed after 5 years the smoke detectors outside cover turn an ugly shade of brown? And it says “Do not paint” on them. LOL. I smell planned obsolescence.