Kidde KN-COSM-B-RF Review

The Kidde KN-COSM-B-RF is a battery-powered smart smoke detector that’s easy to install, connect and use to monitor potential dangers in your home.

Our Verdict

Despite its poor performance in our detection tests, the Kidde KN-COSM-B-RF provides adequate protection for you, your home and your family.


  • The Kidde KN-COSM-B-RF is battery powered and doesn't require wiring to install.


  • The smart functions of this detector only work if you have a Wink smart home hub.
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The Kidde KN-COSM-B-RF is a battery-powered smart smoke detector that’s easy to install, connect and use to monitor potential dangers in your home. When you connect a few of these units together wirelessly, they work together to ensure every room is notified when one detects a threat. The detector also has a voice alarm that lets you know how to proceed. However, it took a relatively long time for an alarm to sound in our detection tests, and you can’t hardwire the device to your home’s electrical system.

For our detection tests, we sprayed simulated smoke from an aerosol can 5, 10 and 15 feet away from the detector. When we sprayed the smoke from the 5-foot mark, the alarm sounded in 23 seconds. This is the slowest response time we recorded during our testing phase. Additionally, it failed to detect the test smoke from the 10- and 15-foot marks.

In our detection tests, the Kidde KN-COSM-B-RF performed the worst of all the devices we reviewed. We believe its failures in our tests may stem from the ionization sensor it uses to detect smoke. In fact, it's the only smart smoke alarm we've tested that primarily uses an ionization sensor. The simulated smoke we used in our tests is more suited for testing photoelectric sensors.

This doesn’t mean the Kidde KN-COSM-B-RF can’t detect smoke from a distant source – it just takes longer before enough has accumulated to activate the alarm, which is a known flaw in ionization-type smoke sensors. Instead, this detector is better for spotting rapid ionization in the air that accompanies flaming fires without as much smoke. This makes it very important to have both main types of smoke sensors in your home: photoelectric and ionization. This alarm can also detect when carbon monoxide builds up in your home.

When the smoke alarm goes off, it not only blares a tone, but it also provides voice instructions, telling you where the threat is and how to proceed. Every networked alarm sounds when one detects a problem, so everyone in the house knows they need to evacuate.

When we tested this smoke detector, we found it the easiest to install of all the devices we evaluated. This is because it is completely battery powered, so you don’t have to hardwire it into your home’s electrical grid. As such, you can put it nearly anywhere in your home. It’s convenient, but a hardwired connection, while more difficult to install, provides an extra layer of security if the battery dies.

This smoke detector can wirelessly connect to others like it, which allows a series of them to work together to provide more comprehensive protection. You can link up to 12 in the same network and the detectors don't need an app for this function.

If you have a Wink smart hub, you can connect the Kidde KN-COSM-B-RF to your Wi-Fi and get alerts on your smartphone, which allows you to monitor your home remotely and receive mobile alerts when the alarm detects danger. This is very convenient if you’re away from home when an emergency occurs. The mobile app, while nice, doesn't allow you to remotely hush the unit if it goes off, a feature found in every other smart smoke detector we tested.

Although this Kidde smoke alarm is easy to install, connect and use, there may be times when you need technical assistance. You can consult the FAQs section on the company’s website to get quick answers to common questions. If your problem isn’t covered there, you can also contact the company via email. It would be nice to see more help options such as phone and live chat support.

This smoke alarm has a device lifetime of 10 years, matched by a warranty of the same length. This is quite impressive, considering more expensive smart smoke detectors such as the Nest Protect and Halo+ have much more limited warranty coverage.