"dpb" wrote in message ...

Interesting they actually build in circuitry to indicate when they need
changing and the recommendation is to ignore it...

Not that changing early is going the wrong direction, but has also always
seemed somewhat overkill to me too unless have unit(s) that don't have the
warning or have been ignored (hard to do if can hear at all or just yanked
them) in the past.

When the circuitry decides the battery needs replacing at 3:00 AM, you'll
probably think it would have been a good idea to replace it last Saturday
night. You are also assuming the circuitry works and that it did not sound
for three days while you were away on vacation and now it is completely dead
but you don't know it. .