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

Give your old smoke detector a lesson in communication with the Roost Smart Battery.

Andrew Gebhart Former senior producer
9 min read

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.


Roost Smart Battery

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.

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.

Roost packs smarts into a familiar 9V form (pictures)

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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.

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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.

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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."

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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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Like the initial setup, Roost made adding additional users extremely simple.

Screenshots by Ry Crist/CNET

Sounding the alarm

Once you're set up, the directions ask you to press the test button on your detector, to make sure your push notification will come through. It did. And after numerous tests both pressing the test button and submitting my detector to actual smoke, I can attest to the fact that the Roost Smart Battery reliably keeps you informed when your alarm sounds.

The notification on your phone even sounds like an alarm. It's loud, annoying, and perfect, as it clearly distinguishes its own alert from an ordinary text or email alert. However, Roost won't override your phone's vibration or silence settings, so if you turn your ringer off while at work, as I usually do, expect the notification from Roost to be just another ordinary buzz.

Pressing the test button on my alarm also revealed another small issue I have with Roost. It can't distinguish between when you're testing and when there's actually smoke. It knows if your alarm is sounding, but that's it.

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Roost can't tell the difference between a test alert and real smoke, but it will notify you in either case.

Tyler Lizenby/CNET

When the alarm sounds with Roost, tapping the notification will pull up the app, and the battery will show red with a ringing bell icon next to it. A pop up window will let you take a few actions -- call emergency, view monitors, snooze alarm, and view details.

Click the first option and the app will shift to your phone, with your emergency number already dialed, but you'll still need to hit send. Again, Roost defaults to 911 as your emergency number, but you can change that as you wish.

Choose the third option, and Roost will kill the power to the battery, thus shutting off the alarm if it's not also hardwired. The "View details" option just takes you to the main battery page. And "View Monitors" shows the names of your additional users, a button to call them, and a green status showing that they are in fact monitoring your alarm.

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Roost springs into action when your alarm sounds.

Screenshots by Andrew Gebhart/CNET

I found that status to be somewhat misleading. It doesn't mean the person has seen the alert or is taking action. It doesn't even mean the person's phone is on or connected so that you know he or she has received the alert. The monitors page will show a green monitoring status no matter what until the person decides to delete that particular alarm from their phone. It's helpful that you can call any monitor from this page, but it's less helpful than it could be if that monitoring status actually meant something.

Once the alarm stops, you will get another push notification with that update. If you want to use Roost to know when and if your alarm is sounding, you'll likely be happy with it. If you expect Roost to do anything more than that as a smart device, you might find it disappointing.

Roost vs. Nest

Part of the charm of Roost is its retrofit nature, but that nature brings inherent limitations with it. If you install Roost into an old, dirty smoke detector that's no longer great at detecting smoke, Roost won't make it better. If your Wi-Fi signal is slow or spotty, you might not get your notification promptly. Roost isn't a self-contained device, so it relies on its surroundings for performance more so than the $100 Nest Protect (second generation).

Complete with sensors to detect CO, smoke, humidity and even light, the Nest Protect 2.0 even includes an exclusive split spectrum sensor that can supposedly distinguish between fast and slow moving fires. The Nest Protect doesn't just add smarts to your smoke detector, it uses the latest technology in an effort to improve the basic functionality of the device as well.

In Roost's defense, any smoke detector you can buy off the shelf is certified for safety, and there's something to be said for not toying with the basics. But smoke detecting prowess aside, the Nest Protect also bests Roost in terms of smarts.

You can integrate the Nest Protect with any other Nest device you own, such as the Nest Learning Thermostat or the Nest Cam . It's also compatible with IFTTT -- the online smart home recipe maker -- opening the door to integrations with a wide range of other smart home products. For example, if your Nest Protect alarm sounds, you can have your ":="" philips'="" color-changing="" bulbs="" add="" apple="" homekit="" support"="" shortcode="link" asset-type="review" uuid="83016b03-1aba-4684-8959-883c9955f3fb" slug="philips-hue-bridge-2-0-with-apple-homekit-support" link-text="Philips Hue" section="products" title="" edition="us" data-key="link_bulk_key" api="{"id":"83016b03-1aba-4684-8959-883c9955f3fb","slug":"philips-hue-bridge-2-0-with-apple-homekit-support","contentType":null,"edition":"us","topic":{"slug":"smart-home"},"metaData":{"typeTitle":"First Take","hubTopicPathString":"Appliances^Smart Home","reviewType":"First Take"},"section":"reviews"}"> lights flash red and your Rachio Iro sprinkler system turn on through IFTTT.

As of yet, Roost doesn't offer any wider smart home integration. The Nest Protect 2.0 also lets you silence your alarm for those occasions when you burn the toast. Roost does promise this feature, and it works in theory, but not if your smoke detector is hardwired and the battery is just acting as a backup.

When it's all said and done, though, it's also important to remember that you can buy three Roost Smart Batteries for the price of one Nest Protect -- so comparing the two products is hardly an apples-to-apples affair.


If something's happening in my home while I'm out and about, I want to know. By connecting to your Wi-Fi and replacing an ordinary 9V battery in your smoke detector, the $35 Roost Smart Battery will keep you informed. That's the reason for Roost in the first place, and even a small touch like the notification sounding like an alarm helps it fulfill that purpose.

For such a simple device, Roost packs in plenty of similarly charming small touches. The app makes setup easy with illustrative, device-specific pictures. The app's also responsive and intuitive without being boring. The battery looks nice even though you'll never see it once it's installed. You can add other monitors for your battery with just a few button presses, and it dutifully fulfills its one basic task and lets you quickly call emergency services or your contacts when your smoke detector or carbon monoxide detector sounds.

The Roost Smart Battery is a budget friendly solution for adding brains to your smoke detectors, just don't expect the retrofit device to bring your alarms to the head of the class. The $100 second-generation Nest Protect still holds that position, and is a better option for those ready and willing to invest in the smart home. At $35, the Roost Smart Battery doesn't do as much as the Nest Protect, but it doesn't promise as much. And other than the snooze option not working on all types of smoke detectors, Roost fulfills its promises and is worth your consideration. With Roost, your dumb smoke detectors won't become geniuses, but they will become better communicators.


Roost Smart Battery

Score Breakdown

Features 6Usability 9Design 8Performance 8