In 2017, I purchased six First Alert Smoke Alarms with Voice (Model SA511) for our house. These are battery powered units that run for about a year before the 2 AA’s need to be replaced.

Sometime in the past   (late 2018? 2019?) one of them kept false alarming, and no amount of compressed air, battery changes, resetting, etc would keep it from alarming, so after several calls to First Alert, they replaced it under warranty.

More recently, (in June 2020 and November 2020) the units in my garage and utility room off of the garage both failed with a “Detector Error in <location>. Check Manual” error message (followed by three short “berrps” in rapid succession).

In both cases, the First Alert customer support people sent me a replacement (Model SA511B) unit.   The SA511 units do not have the “F” first alert “shield” logo above the “First Alert” text on the front, while the “B” units do. (Although the “B” units simply say Model No. SA511 on the back, with no B marking in the model number.)

The SA511 “B” units include the F-Shield icon above the “First Alert” name.

My failed   units were all manufactured on March 27th of 2017. They have a 10 year warranty, but I’m wondering if there is a systematic problem with the original SA511 units (or perhaps just the ones manufactured on certain dates?) as I’ve seen 1/3 of my total units fail due to the “Detector error”   (and another due to the false alarm issue).