In article ,
Steve Walker writes:

I've never seen the point in the alarms with fixed batteries, unless it is
to prevent people taking the batteries out because of nuisance alarms. If
that is the case, they'll simply throw the whole thing away or pull
connections out!

It's because research shows a significant proportion of battery
alarms never get the battery replaced, so after the first year,
they sit there disabled.

Our alarms have replaceable batteries, a simple button test and if the
battery gets low, the alarm starts beeping at irregular intervals -
although it can take a few days to work out what's beeping, as they are so
infrequent and we have many other things, including children's toys that
beep.

Mine are all PP3 replaceable battary types, but they all have a
PP3-sized module in them which powers them from the 12V burglar
alarm, and generates a signal back to the alarm when they start
drawing enough power for the sounder. So I never have to change
any smoke detector batteries.

When I put some in my parents' home, I fitted them with the
lithum (10 year) PP3s, so we don't have to arse around with
battery changing. Since then, they've had an extention and also
have mains interlinked ones, but I didn't bother removing the
battery ones.

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