The well-reviewed Kidde KN-COPP-3 runs on electricity, but also has a battery backup that keeps working during power outages. This unit features a digital display, peak-level memory and a test/reset button. When the 9-volt battery needs replacing, the detector chirps and features an "Lb" on its display. This unit is rated highly by experts, who say Kidde stands out for the accuracy of its detectors. However, we did read reports from a small percentage of owners about false alarms. If you're good at replacing batteries regularly, you may be better off with the equally well-reviewed, battery-powered Kidde KN-COPP-B (*Est. $35).
We found the most reliable review of the Kidde KN-COPP-3 carbon monoxide detector in ConsumerReports.org, which tests and rates numerous carbon monoxide and smoke detectors. There are a substantial number of owner-written reviews at Amazon.com and PriceGrabber.com.
In this recent review, ConsumerReports.org editors test and rate 10 carbon monoxide detectors, including the Kidde KN-COPP-3. Editors give the highest rating to models that respond quickly to both high and low levels of CO.
Review: CO and Smoke Alarms, Editors of ConsumerReports.org, September 2009
The Kidde KN-COPP-3 receives mixed reviews from 90 owners at Amazon.com. Many approve of the plug-in design and digital display, but we did read a number of reports of false alarms and battery drainage within a week.
Review: Kidde KN-COPP-3 Nighthawk Plug-In Carbon Monoxide Alarm, Contributors to Amazon.com
The Kidde KN-COPP-3 is one of a handful of carbon monoxide detectors reviewed here. It receives mixed reviews from two owners who discuss several reasons why this model seems to use batteries rapidly. They speculate that it could be because it is plugged into an outlet that is being turned off by a light switch, or it may be that there was a product defect which has since been fixed by the company.
Review: Kidde Carbon Monoxide CO Gas Detector, Digital w/Battery Backup, Contributors to PriceGrabber.com