Roost Smart Battery review: The Roost Smart Battery has plenty to crow about

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The Good If you can install a battery, you can install the Roost Smart Battery into your existing smoke detector, and it will reliably send you push notifications when your alarm sounds. Both the battery and the app are attractively designed and easy to use.

The Bad Roost offers the option to "snooze" your alarm, but that won't work if your alarm is hardwired and the 9V is acting as a backup. Roost doesn't offer any interconnectivity to other smart devices.

The Bottom Line You won't get as many smarts with the Roost Smart Battery as you would with a wholesale connected replacement, but at $35, it's a viable and cost-effective option for simple, retrofit smarts.

7.6 Overall
  • Features 6
  • Usability 9
  • Design 8
  • Performance 8

While raising money on Kickstarter in 2014, a big part of the elevator pitch for Roost -- a startup based in Sunnyvale, California -- was that its Wi-Fi-enabled smoke alarm battery would forever banish the middle of the night "low-battery chirp" that's the nightmare of homeowners and apartment dwellers everywhere.

Does the Roost deliver? Well, we won't know if its smartphone-based low-power notifier works anytime soon, since its battery life is rated at five years. But we can tell you that the $35 unit -- which replaces the 9-volt battery in your standard smoke or carbon-monoxide detector -- works well on nearly all other accounts, delivering notifications to your smartphone wherever you are when a smoke or CO event is detected in your home.

At $35, it's an easier splurge than the similarly aimed $100 Nest Protect , and a more cost-friendly way to smarten up your whole home's worth of detectors as well. The Roost Smart Battery isn't as smart or feature rich as the Nest Protect 2.0, so it's not the perfect option for everyone, especially not those looking to build an interconnected smart home as Nest plays better with others. But for those looking for basic connectivity without hassle, I like the Roost Smart Battery. It really only does one thing, but that's all it's promising, and it fulfills that promise with polish and gusto.

Ruling the Roost

I found the Roost Smart Battery refreshing in a few ways. It's not flashy, but it is attractive. It didn't have to be attractive, since you'll never see it once you stick it in your smoke detector, but I appreciated the touch.

At a glance, you might think you're simply looking at a 9V battery. It's the same shape and size, with the same positive and negative terminals. It looks spiffy for a 9V, the sides all sport a clean white coat of paint, accented by a blue Roost logo on the front, and a blue top and bottom.

A familiar look with built-in smarts.

Tyler Lizenby/CNET

Inspect a little closer, and you'll begin to see there's more to Roost than initially meets the eye. A small port on the back acts as a microphone, and the bottom of the battery snaps free to reveal circuits. At its heart, Roost is a 9V, but it's a 9V that packs in a Wi-Fi antenna and a microphone.

You can buy the Roost Smart Battery, the first product from tech startup Roost, via the company's site, as well as from Amazon and Home Depot. One battery costs $35; a pack of two costs $65.

The reason the bottom of the Roost snaps off is so you can replace the power source. After its promised five-year lifespan is up, you'll get an alert instead of having to listen to chirps, and you can swap out the power source cheaply instead of having to pay for a whole new Roost. Snap off the bottom, pull out the power piece, and snap in a new $15 replacement, also available from the Roost site.

You can order and have Roost shipped to you in the UK and Australia via Roost's site, but for now, it's only certified to US safety standards. The price for one Roost converts to approximately £25 and AU$50 in the UK and Australia respectively. Two Roosts will run about £45 and AU$90, and the replacement pack cost equates to roughly £10 and AU$20.


To see the advantages Roost gives you over an ordinary battery, you'll need to download the Roost app -- available for free on the iOS and Android app stores. Thanks to the app's well-illustrated and helpful setup instructions, getting your battery connected to your home's router is almost as quick and easy as placing it into your smoke detector.

The iOS and Android apps for Roost are almost identical. I mostly tested Roost on my Samsung Galaxy S5 , but got a chance to try out the interface on the iPhone 6 Plus as well.

Roost includes pictures to help you through setup.

Screenshots by Andrew Gebhart/CNET

Open the app and you'll be prompted to create an account. Your phone number will double as your username, but Roost was able to send push notifications to my iPad as well. After your account is up and running, you'll click the button to add a battery. You'll indicate the location of the battery, then place your phone near it. Your phone will sound a tone and your battery will sync. That's it. Put that battery in your smoke detector, and you're good to go.

Even better, Roost uses pictures to show you exactly how to use your phone to complete the sync. The app knows if you're using an Android or iOS phone and will change the pictures accordingly, showing you how to turn up your phone's volume and where to place your phone's speaker in relation to the battery. My grandmother could set up the Roost Smart Battery, from start to finish.

A family friendly app

After you setup the Roost battery, there's not much else you can do with the app until your alarm sounds, but the interface remains friendly and intuitive. The main page lists your battery by the location you indicated during setup. Most of the time, you'll simply see a green circle with a check mark to the left of the battery name -- I set up mine in the "upstairs hallway." Underneath the location, you'll see a confirmation of that status -- "OK."

The main page, the menu, and the battery page of the Roost app.

Screenshots by Andrew Gebhart/CNET

From the main page of the app, you can press the menu button to adjust your profile or password, set your emergency contact -- which defaults to 911 -- and add monitors. Via the monitors button here and on your specific battery page, the Roost app charmed me again by making it just as easy to add family and friends to your battery as it is to get set up initially. Click the plus button and Roost will take you to your phone's contacts. Find the contact you want to add, and you'll go to a screen letting you select which smoke detectors you'd like the person to access. Click invite, and you're done.

Your contact will be sent a text with a link to download the app. I invited my colleague Ry to monitor my upstairs hallway alarm, and once he downloaded Roost, he had to press one button in the app to accept the invitation.

Tap the battery to see a few extra details, such as battery status and a list of the alarm's activity. You can also adjust the alarm's location and address settings from this page, and add more monitors.

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