On Monday, December 10, 2018 at 8:47:17 PM UTC-5, Ed Pawlowski wrote:
On 12/10/2018 6:44 PM, bmay wrote:
replying to Berma, bmay wrote:
If they are hardwired to AC why did the batteries even come in the play

Because the batteries are there for backup in a power outage. They
notify you when week even if hard wired. Would you want to wait until a
power outage in a blizzard to find you need batteries?

What I can't figure out is why in some of them with both AC and batteries,
the batteries last a year or less? You would think those batteries
would last about their shelf life. A friend's house, new construction,
has that problem. They chirp and there are so many that it's hard
to figure out which one it even is. There are a bunch of them and in
all, the batteries last maybe a year. I was wondering if instead of them
being really low, there is some clock in there that forces you to replace
them every year? Makes no sense to me.