See All Carbon Monoxide Detectors

Kidde KN-COPP-3

*Est. $45
June 2013
by ConsumerSearch
Kidde KN-COPP-3

  • Easy setup
  • Easy-to-read digital readout
  • Ability to monitor peak CO levels
  • Attractive
  • Short battery life in backup mode
  • 24-hour safety hotline not always available
Where to Buy

Bottom Line

Professional testers and individual owners praise the Kidde KN-COPP-3, a plug-in carbon monoxide detector, for its accuracy and easy installation. This model will run on battery backup if the power goes out, but owners complain it will not run on battery power for long. However, numerous owner testimonials on and recount how the Kidde KN-COPP-3 saved their lives.


A lifesaver. Professional testers laud the Kidde KN-COPP-3 for its excellent ability to detect high CO levels, and grateful owners extol the unit's lifesaving detection abilities in their heart-pounding online reviews. The detector switches to a 9-volt backup battery during power outages. The Kidde KN-COPP-3 has a loyal following. Many reviewers have purchased multiple units or are repeat customers. Owners love that it displays a continuous readout of CO levels and gives few false alerts. The detector is not designed to perform quick checks for the presence of carbon monoxide as a fire department's wand would.

However, one Amazon user took advantage of the unit's digital readout and battery backup and walked the detector around the house to look for the CO source; when he walked into the garage, the reading more than doubled. The unit will not display CO levels under 30 parts per million, but stores them in its memory as long as it's not reset or unplugged.

Ease Of Use

No second guessing. Users say this Kidde model is easy to install and use. Carbon monoxide levels are continuously displayed in easy-to-read red LED numbers on the digital screen, and the 85-decibel horn is loud enough. The CO detector can be plugged directly into an outlet, used on a tabletop or mounted on the wall. Users find the 6-foot extension cord especially handy since the detector is large (6 inches long and about 4 inches wide) and will take up an entire outlet.

Also, a pullout slide support on the back of the unit helps keep it steady when plugged into an outlet. And while not as important as its safety features, many owners say the detector is an attractive unit. The instruction manual is easy to read, but users give the company's 24-hour safety hotline a thumbs-down for keeping banker's hours.


Eats through batteries. Like the First Alert CO615, the Kidde KN-COPP-3 will not operate unless the backup battery, which comes with the detector, is installed. In the event of a power outage, the 9-volt battery will only continue to keep the unit running for 20 hours. This quick battery drain rules out the possibility of habitually unplugging the unit during the day to free up the outlet for other things, as some owners try to do. In addition, some owners grouse, the detector needs a fully charged battery to function properly.

A handful of the low Amazon ratings stem from a defect in some units related to the low battery indicator. But a limited five-year manufacturer's warranty covers those lemons. The detector's sensors wear out at about seven years. At that point, the detector will chirp its end-of-life alarm and display an error code indicating the unit should be replaced. While this is a common safety feature among CO detectors, it irks some users enough to rate their detectors poorly.

Where To Buy
Kidde KN-COPP-3 Nighthawk Plug-In Carbon Monoxide Alarm with Battery Backup and Digital Display

 (725 reviews)
Buy new: $69.99 $37.38   47 Used & new from $19.41

In Stock. Eligible for FREE Super Saver Shipping

Featured StoresStore RatingNotesTotal Price
eBayeBay rated 3.83 (1281 reviews)1,281 store reviewsIn Stock. Buy it new & now! with eBay Buyer Protection$55.99

Our Sources


The Kidde KN-COPP-3 is included in's latest roundup of carbon monoxide testers. Ten detectors were tested for their responses to high and low CO levels, as well as the display/voice features.

Review: CO & Smoke Alarms, Editors of, February 2011


Several reviews contain stories of human and mechanical errors setting off dangerous CO levels and triggering their detectors to sound. More than 270 owners reviewed the Kidde KN-COPP-3, with about 56 percent giving it a perfect score. Owners who gave the detector 1 star complained of the quick battery drain during battery-backup mode or they owned models with a battery defect.

Review: Kidde KN-COPP-3 Nighthawk Plug-in Carbon Monoxide Alarm with Battery Backup and Digital Display, Contributors to, As of May 2013


Over 20 owners reviewed the Kidde KN-COPP-3, giving it an overall score of 4.6 out of 5. Only one owner rated the unit 2 out of 5 stars, and did so because he did not like the detector's built-in self-destruct feature.

Review: Kidde Carbon Monoxide Alarm Plug-In with Digital Display 9-Volt Backup, Contributors to, As of May 2013

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