In article ,
"John" writes:
I had a new one from BG in May2004. Model SF350EN

Label says "Replace Unit by May 2009"

A few weeks ago it started to chirp a "Low Battery" warning (at 3:00 in the
morning of course). I removed the irremovable battery cover and put in 3 new
(but cheap) AAA batteries. After only a few weeks the alarm sounded again so
I fitted some better ones (but not Duracell's). Today it was chirping its
Low Battery alarm at 4:00am.

Question:
Should I get some Duracell's - or does the unit intentionally die after 5
years (in my case 4 years and 7 months?

Carbon monoxide sensing elements have a limited life.
I would not assume that simply replacing the battery
(even if you do get it to work) means the CO detector
is doing anything useful.

Are you sure the chirp means "Low Battery" and not
"Low CO level"?

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]