Reviews say the First Alert SA340CN (Est. $20) is a good pick for people who don't like to change batteries. Although some owners say the lithium battery, which is supposed to have a 10-year lifespan, lasted far less than a decade, the National Fire Protection Association Journal suggests any such failure is more of a consumer issue than a safety problem because the First Alert SA340CN chirps to indicate that the battery is low. Even so, the battery isn't user-replaceable, and you do have to buy a new unit eventually. It's important to note that the First Alert SA340CN is best at sensing fast-flaming fires and not as adept at detecting slowly smoldering blazes. For a detector that can sense both types of fires, you need a dual-mode model like the First Alert SA302CN (*Est. $25).
We found the best reviews at ConsumerGuide.com, which gives the First Alert SA340CN a rating of "excellent" for performance but doesn't explain its testing methods. A few other owner reviews are available online; those at Amazon.com provide a balanced mix of plusses and minuses, the latter mostly related to battery performance. A report in the National Fire Protection Association Journal is not a product review but rather an analysis of 10-year batteries in smoke detectors.
The First Alert SA340CN earns a Best Buy designation and a rating of "excellent" for performance, but it's unclear from the brief review how the alarm was tested. In addition to the extended battery life, ConsumerGuide.com praises the tamper-proof battery case for providing an extra measure of safety.
Review: First Alert SA340 Smoke Alarm with 10-Year Sealed Battery Review and Prices, Editors of ConsumerGuide.com, Jan. 24, 2007
The handful of reviewers at Amazon.com is evenly divided on the First Alert SA340CN smoke detector. Critics say the smoke detector's battery lasts well short of 10 years, and positive reviewers say the battery lasts as long as 12 years.
Review: First Alert SA10YR 10 Year Lithium Power Smoke Detector, Contributors to Amazon.com
3. National Fire Protection Association Journal
This is a general report on 10-year batteries in smoke detectors, not a review. Critics say that battery longevity is a marketing issue rather than a matter of safety because the detector chirps to alert users when the battery runs low.
Review: The 10-Year Battery, Alisa Wolf, January-February 1999