Best battery smoke and carbon monoxide detector

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Best Overall Smoke Detector

First Alert SCO7CN

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Smoke Sensor Type: Photoelectric | Battery-Powered or Hardwired: 2xAA Batteries

REASONS TO BUY

Voice and siren when the alarm is triggered

Very loud siren

Integrated CO sensor

REASONS TO AVOID

Programming requires a bit of effort

No option to link to other alarms

For a top-notch battery-powered option and our favorite overall smoke detector, check out the First Alert SCO7CN. This alarm is straightforward to install and emits a traditional alarm and a spoken call to evacuate. It detects both smoke and carbon monoxide and tells you the maximum amount of carbon monoxide detected after an alarm has been triggered (in parts per million/ppm). The alarm is incredibly loud.

Though it's a great basic alarm, it lacks bells and whistles. For example, you can't link it with other alarms to create an interconnected system, and it doesn't have an escape light. The initial setup is a bit more involved, as the programming process to set the alarm's location is far from intuitive. All told, though, this is a great battery-powered alarm and is an excellent choice if you need a dual smoke/carbon monoxide alarm that will let you know the location of the alarm.

This unit will warn you about smoke and increased CO levels with the traditional sirens and spoken commands, including the location of the alarm if you have preprogrammed it.

Credit: David Wise

Another Great Option

First Alert SCO5CN

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Smoke Sensor Type: Photoelectric | Battery-Powered or Hardwired: 2xAA Batteries

REASONS TO BUY

Combo CO2/smoke sensor

82 dBa siren

Low battery signal mute

REASONS TO AVOID

Not as responsive to flaming fires

Not linkable

For those who don't need the voice warning, the First Alert SCO5CN is a great premium battery-powered combination smoke and CO alarm that doesn't include the extra chatter. This unit has a photoelectric sensor to help detect fires when they are still smoldering and an electrochemical CO sensor. It is super quick and easy to install, and the siren is loud to alert you in the case of fire or carbon monoxide accumulation. Thanks to a slide-out battery drawer, you can change the batteries without removing the alarm from its mount, and we appreciate that you can mute the low battery chirp for 8 hours — perfect for those instances where that chirp starts in the middle of the night.

Our biggest complaint with this alarm is its inability to be set up in an interconnected system, where one alarm sounding will trigger all of the alarms. It also only has a single type of smoke sensor, so you'll need to purchase an additional type with an ionization sensor to meet the National Fire Protection Association's recommendations. Due to this, some other options are better if you only want a single brand and model of smoke detector throughout your home. Despite that, we think this is a great battery-powered combo smoke/CO alarm, particularly if you don't want to mess with programming locations for voice prompts and just want a simple siren.

This combination smoke/CO sensor is ready to go in minutes.

Credit: David Wise

An Easy and Inexpensive Interconnected Option

Kidde 21026044 Wireless

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Smoke Sensor Type: Ionization | Battery-Powered or Hardwired: 3xAA Batteries

REASONS TO BUY

Hassle-free wireless interconnect system

Very easy to install

REASONS TO AVOID

"Hush" function can be finicky

No way to identify the initiating alarm

If you don't have a hardwired detector system and have always wanted to add a series of interconnected alarms, then the Kidde 21026044 Wireless is a great option. This battery-powered alarm is straightforward to install, with a series of eight switches on the back that let you select a unique wireless code for your alarm system. Any other alarm set with the same code will automatically go off when any interconnected alarm is activated. However, there is a limit of 24 total Kidde devices, with 18 being units that trigger an alarm (12 can be smoke alarms). Many building codes require an interconnected alarm system for new construction. This model's wireless interconnectivity could be a much easier and less expensive option than running wires throughout your home.

We discovered that the "Hush" button could be a little finicky. You should be able to hit this button on the initiating alarm, and it should silence all of the others, but we found that it took a few tries before the other alarms would silence. There is also no straightforward way to precisely know which alarm triggered the others because there aren't voice announcements like some other systems have. Although these aren't trivial flaws, the Kidde 21026044 is one of our favorite battery-powered options for setting up an interlinked alarm system, especially when you're shopping on a budget.

The Kidde 21026044 makes it extremely easy to set up an interconnected system.

Credit: David Wise

Best on a Tight Budget

Kidde i9050

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Smoke Sensor Type: Ionization | Battery-Powered or Hardwired: 9-Volt Battery

REASONS TO BUY

Inexpensive

Tamper-resistant locking pins

REASONS TO AVOID

Harder to push "Hush" button

Limited features

If you are on a tight budget and on the hunt for a bare-bones smoke alarm, the Kidde i9050 is a great option. This ionization smoke alarm is quick to install and has all the basic features you may want, allowing you to minimize the amount you need to spend if you are replacing all the alarms in your home. The locking pins are also a nice feature to reduce the chance of theft or someone tampering with the alarm.

However, when it comes to advanced features, the Kidde i9050 is quite limited. It can't be linked to other alarms, so be sure to check local regulations to ensure that your overall system complies. You may need to add additional photoelectric smoke alarms or carbon monoxide detectors to your home. Still, if you're shopping on a limited budget, then the Kidde i9050 is one of the top models we recommend.

The Kidde i9050 is a fantastic option if you are shopping on a restricted budget.

Credit: David Wise

Best for Smart Functions

First Alert OneLink Alexa Safe & Sound

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Smoke Sensor Type: Photoelectric | Battery-Powered or Wired: Hardwired with Lithium Battery Backup

REASONS TO BUY

Integrated speaker and Alexa voice assistant

Tons of features

REASONS TO AVOID

Expensive

Can be challenging to attach to the mounting plate

If you are looking for a new smoke alarm that packs as many smart features as possible, then the First Alert OneLink Alexa Safe & Sound is a fine option. This top-tier smoke alarm can act not only as a smoke and carbon monoxide sensor but also includes a built-in Alexa-enabled speaker. It will send notifications to your phone if an alarm is triggered, allowing you to remotely monitor your home while you're away or hush false alarms right from your smartphone. You can play music with streaming services like Spotify or iHeartRadio, and the speaker sounds pretty good for being in a smoke detector. There is also a customizable night light that you can automatically turn on in the evening.

Regrettably, all of these features combine to make this product one of the more expensive options we tested. It also makes installation more challenging because you need to wire it in place and pair it to the OneLink and Amazon Alexa apps. It's expensive enough that you probably aren't going to want to install one in every room of the house. You can still connect the Safe & Sound to other compatible non-smart smoke sensors or other Safe & Sound units to get an interconnected alarm system for quite a bit less. It's a great choice if you want to add more Alexa-enabled speakers to your home and want a smart smoke detector for your Alexa or Apple HomeKit system, but otherwise, it may have more smarts than most people want or need in a smoke alarm.

The Safe & Sound comes with just about any smart feature you could hope for in a smoke alarm.

Credit: David Wise

Best for Hardwired Comprehensive Smoke Sensing

First Alert 3120B Hardwire Dual

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Smoke Sensor Type: Photoelectric & Ionization | Battery-Powered or Hardwired: Hardwired

REASONS TO BUY

Dual smoke sensors for flaming and smoldering fires

Easy install for a hardwired alarm

REASONS TO AVOID

The mounting plate isn't our favorite

No CO sensor

The National Fire Protection Association (NFPA) recommends having a mix of photoelectric and ionization smoke alarms in your home for the best chance of an early alert to any problem. While most smoke alarms only have a single sensor, the First Alert 3120B Hardwire Dual has both to cover all your bases. The alarm includes a pre-stripped wiring adapter and provides the option to interlink with other compatible alarms so that any alarm will trigger all of them. It also has a battery backup in case your power goes out.

We wish this model had an integrated carbon monoxide sensor since that could further reduce the need for additional alarm units. It's also worth noting that not all hardwired smoke alarms are compatible with each other when creating an interconnected system, so you are going to want to double-check if you are just trying to replace a single alarm. Regardless, the First Alert 3120B Hardwire Dual is an excellent option for anyone looking for dual smoke sensors in a simple package.

The BRK 3120B has both types of sensors, giving you the best shot of early detection of both flaming and smoldering fires.

Credit: David Wise

Another Great Battery-Powered Combo Alarm

Kidde 21026043 KN-COSM-BA

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Smoke Sensor Type: Ionization | Battery-Powered or Hardwired: Battery-Operated

REASONS TO BUY

Voice alerts

Integrated CO detector

Can't be installed without batteries

REASONS TO AVOID

Not compatible to connect with other units

Doesn't announce location when triggered

If you liked the looks of the First Alert SCO7CN but need a new ionization smoke alarm, then the Kidde 21026043 KN-COSM-BA is a fantastic option for you. This unit is powered by three AA batteries and features an integrated carbon monoxide detector. It's a breeze to install and features not only the typical carbon monoxide and smoke alarm patterns - but also voice commands warning you to evacuate. This unit can also inform you of the peak concentration of carbon monoxide measured once it hits a level of 100 ppm or higher. We recommend only checking this after any potential danger has cleared and the source of carbon monoxide has been mitigated.

Although the Kidde 21026043 KN-COSM-BA is a solid standalone option, it cannot link to other smoke detectors. It also cannot be programmed with a location, so it won't immediately alert you to the location of the triggered alarm. Still, this model is one of the better combo smoke/carbon monoxide alarms if you need a battery-powered unit and are looking for another ionization sensor.

This alarm also has voice alerts but can't be programmed with a location.

Credit: David Wise

Best for Google/Nest Smart Homes

Nest Protect

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Smoke Sensor Type: Split-Spectrum | Battery-Powered or Hardwired: Both options available

REASONS TO BUY

Motion-activated night light

Heads-up feature to warn you of an imminent alarm

Comprehensive smoke-sensing abilities

REASONS TO AVOID

Expensive

Limited smart home interactions available

If you already have a Google-based smart home and want to add an intelligent smoke detector to the mix, then the Nest Protect is an excellent choice. Available in both battery-powered and hardwired versions, this smoke alarm easily integrates with your existing Nest products. It lets you remotely keep an eye on things, alerting you with push notifications if an alarm sounds. Even better, it can automatically activate a Nest camera so you can see what's going on or turn off your heating system if it detects elevated levels of carbon monoxide. The Nest Protect has smoke sensors for both flaming and smoldering fires and a motion-activated light to help you during a power outage.

Unfortunately, the Nest Protect is one of the more expensive smoke alarms we have tested to date. It also isn't compatible with triggering any other smoke detectors, so be prepared to spend a serious chunk of money if you're hoping to get an interconnected alarm system and a Protect unit in every room. There aren't many options to use the Protect as a trigger for other smart devices, like having your lights turn on if an alarm is initiated, though this can change as smart systems get updated. The Nest Protect is one of our favorite options if you already have a Nest system and want a smart smoke alarm, but you need to be prepared to pay for it.

The Nest Protect seamlessly integrates into Google/Nest smart homes.

Credit: David Wise

A Less Expensive Apple HomeKit/Alexa Option

Onelink Smart Smoke + Carbon Monoxide

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Smoke Sensor Type: Photoelectric | Battery-Powered or Hardwired: Both options available

REASONS TO BUY

Can silence/monitor remotely

Compatible with specific non-smart smoke alarms for an interconnected system (wired only)

REASONS TO AVOID

Not the most extensive set of smart features we have seen

Longer setup process

The Onelink Smart Smoke + Carbon Monoxide smoke alarm is a slightly more budget-friendly option than many other smart smoke detectors on the market. It has all the necessary features you would want, like the ability to test/silence the siren right from your smartphone or alert you that an alarm has sounded if you aren't home. It's available in both battery and AC-powered versions, and both can connect to other compatible alarms to create an interconnected system. This is especially handy with the hardwired version, as you can wire it into an existing First Alert or BRK hardwired alarm system, adding smart features at a much lower cost than buying a smart smoke alarm for each room in your home.

Although we found this product does well with the basic smart features, it seems a little limited when it comes to more advanced features. It is Alexa and Apple HomeKit compatible, but we found it difficult to set this product to trigger other actions, such as turning on the lights when an alarm sounds or turning off your heater if it detects increased levels of carbon monoxide. The remote monitoring will also only work if your home wireless network is powered up and functioning, so you might want to consider higher-end professional monitoring services if you need a more reliable setup. It is an excellent option if you're hoping to add some smart features to your smoke alarm system, but you're trying to save some cash.

This alarm is a good way to add smart features to an Alexa or HomeKit smart home.

Credit: David Wise

A Combination Hardwired Option

First Alert SC9120B

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Smoke Sensor Type: Ionization | Battery-Powered or Hardwired: Hardwired

REASONS TO BUY

Smoke and CO sensors

Can connect with compatible BRK and First Alert alarms

Battery backup

REASONS TO AVOID

Visually obtrusive mounting bracket

The First Alert SC9120B is the perfect option if you need a hardwired alarm that is not only a smoke detector but also a carbon monoxide sensor. This smoke detector has a 9-volt battery backup to provide alerts even when your electricity is out. It can connect to other hardwired alarms to maximize your early warning in the case of an emergency, and it's not too much of a hassle to install with the included pre-stripped wiring adapter. It also has a latching alarm, so you can identify which unit initiated the alarm even after the siren has subsided.

This alarm is a fairly run-of-the-mill combination smoke and carbon monoxide hardwired alarm. It has a slightly larger mounting/trim plate than some of the other models, which can be handy if you want to cover up any damage near your electrical box, but it's more noticeable than we would prefer for most installations. The First Alert SC9120B is one of our favorites if you want a hardwired smoke alarm that doubles as a carbon monoxide detector.

We found the trim plate on this model stands out a bit more compared to other alarms.

Credit: David Wise

A Light to Guide You

X-Sense Escape Light SD01

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Smoke Sensor Type: Photoelectric | Battery-Powered or Hardwired: 10-year Lithium Battery

REASONS TO BUY

No batteries to replace

Quick install

Integrated evacuation light

REASONS TO AVOID

Can't connect to other alarms

No CO sensor

We think the X-Sense Escape Light SD01 is a decent all-around smoke alarm. It is one of the fastest of the entire group to install since it comes with a preinstalled 10-year battery. You only need to mount the bracket to the wall, attach the alarm, and you're all done. It automatically activates once installed in the mounting bracket and has an LED indicator to alert you that the unit is functioning normally. Additionally, this alarm has a bright LED escape light that will illuminate whenever an alarm is triggered to help guide your evacuation.

Unfortunately, while the X-Sense SD01 handles the basic functions of a smoke alarm well, it is a little limited when it comes to additional features. It isn't a combination smoke/carbon monoxide alarm, so you will need to get a separate alarm to meet your carbon monoxide sensing needs. You also can't directly connect this with other alarms to make an interconnected system, and it has to be disposed of properly once the battery is depleted. The batteries aren't replaceable, so we are a little concerned about the escape light prematurely draining them if you are prone to accidentally setting off the smoke alarm from things like burning popcorn or toast.

The integrated evacuation light can guide your escape if the alarm is strategically placed.

Credit: David Wise

Why You Should Trust Us

Our expert smoke detector reviewer, David Wise, has made a career of professionally reviewing and evaluating a wide variety of consumer products and electronics. He has a formal education as a mechanical engineer and is a DIY enthusiast, utilizing this experience in the creation and execution of our rigorous side-by-side testing and evaluation process for smoke alarms.

We rated and compared performance by installing them in various locations around the house, looking at the amount of effort it took to install them, all the different features these products have, and how well they can integrate into an existing alarm system. Throughout our testing, we triggered alarm after alarm while listening to siren after siren (after siren!) to assess each model's performance.

Analysis and Test Results

We broke down our testing and evaluation process into a series of different rating metrics. We use each product's weighted performance in each metric to determine our overall rankings, but recommend you pay closer attention to the metrics that are most important to you.

Ease of Installation

As it's one of the first things you will have to tackle when getting a new smoke detector, we started by rating and scoring the hassle it took to get each smoke alarm installed and configured. Generally, we have found that the battery-powered models are a bit easier to install, as you just need to attach the mounting bracket to the wall, insert batteries, and clip on the alarm. This is true for the First Alert SCO7CN, the First Alert SCO5CN, the Kidde i9050, the Kidde 21026043 KN-COSM-BA, or the X-Sense Escape Light. The X-Sense is particularly easy to install, as you don't even need to install batteries. A 10-year lithium battery is built right in, which will activate the first time the sensor is attached to the mounting plate.

We generally found battery-powered models to be a bit faster and easier to install.

Credit: David Wise

There are a few other battery-operated models, but they each offer wireless connectivity, so they take a little more time and effort to configure. The Kidde 21026044 Wireless is the easiest of these. You just need to pick a code with the eight switches on the back, and any alarm that shares the same code should automatically connect (up to a limit of 24 interconnected devices with 12 being smoke alarms).

It only takes a second or two to get this alarm ready to link to compatible models.

Credit: David Wise

The battery-operated Nest Protect and the OneLink Smart Smoke + Carbon Monoxide are easy to install. Still, it takes a little more time to get their smart features up and running because you usually need to download an app, make an account, and pair it to your mobile device. You need to do the same thing with the First Alert OneLink Alexa Safe & Sound, but it takes some extra time to wire it up to power, so it has one of the most involved installations of our test group. The wired versions of the Nest Protect and the OneLink are about the same level of difficulty to install as the First Alert OneLink Alexa Safe & Sound.

It can take a little bit of time to get the Safe & Sound installed and paired correctly.

Credit: David Wise

The remaining hardwired alarms aren't too hard to install, provided your home is already set up for a hardwired system. Most of them, such as the First Alert 3120B Hardwire Dual and the First Alert BRK SC9120B, come with a pre-stripped wiring harness, so it should be quick and easy to remove your old alarm and attach the new ones with a pair of wire nuts. You will need to strip the other wire and do a little more work if you have an interconnected system, but it isn't a huge hassle.

Detection Sensor Type

Next, we compared the types of detection sensors present in each of these products. Smoke alarms come with two different types of sensors: ionization and photoelectric. Ionization sensors use a tiny trace amount of radioactive material to detect smoke — nothing to be concerned about — and are generally more sensitive to flaming fires. Photoelectric sensors rely on a light source and sensor and are typically triggered faster by smoldering fires. To give you the best chance of early detection, the National Fire Protection Association recommends having both types of sensors in your home.

Luckily, some smoke detectors, like the Nest Protect and the First Alert 3120B Hardwire Dual, include both types of sensors in a single unit, giving you the best chance of detecting both flaming and smoldering fires. The Nest Protect also has an integrated carbon monoxide sensor.

The BRK 3120B has dual sensors for smoke and a battery backup but lacks a CO sensor.

Credit: David Wise

A handful of other smoke detectors also have integrated carbon monoxide sensors, even though they only have a single type of smoke-sensing sensor. The First Alert BRK SC9120B and the Kidde 21026043 KN-COSM-BA have ionization smoke sensors, as well as carbon monoxide detectors. The First Alert SCO7CN, the First Alert SCO5CN, the First Alert OneLink Alexa Safe & Sound, and the OneLink Smart Smoke + Carbon Monoxide all have photoelectric smoke sensors, in addition to a carbon monoxide sensor.

The SC9120B doubles as both a smoke and CO alarm.

Credit: David Wise

Interconnect Abilities

Many new building codes are mandating an interconnected smoke alarm system so that any alarm detecting smoke will trigger all of the others to sound. Luckily, many of the products we tested have this ability, which is common among hardwired alarms, like First Alert's 3120B Hardwire Dual and BRK SC9120B. These units have a dedicated wire just for linking to other units. However, you need to check that the wiring in your house and your other alarms are compatible. Usually, they will only work with other alarms from the same manufacturer.

The OneLink Safe & Sound includes a wiring adapter that can make install a breeze if you already had certain types of First Alert alarms installed.

Credit: David Wise

The hardwired version of the OneLink Smart Smoke + Carbon Monoxide and the First Alert OneLink Alexa Safe & Sound can also do this, with the bonus of being able to link with non-smart compatible alarms. This lets you save some money by adding only a single smart alarm to achieve a smart system. The wired and wireless Nest Protect can link to each other but not too different alarms.

The wireless interlink capabilities are one of our favorite features of this alarm.

Credit: David Wise

The Kidde 21026044 Wireless can also be linked and is one of the simplest and least expensive ways to set up a connected system, even if you don't have hardwired alarms. You just pick your code, and each alarm should automatically link. You need to locate the initiating alarm for the "Hush" feature to automatically connect to the other blaring alarms.

Other Features

Finally, we compared any additional features these products have. Some of these products will give you verbal warnings in addition to the typical siren alarm. All of the smart smoke alarms, including the Nest Protect, the First Alert OneLink Alexa Safe & Sound, and the OneLink Smart Smoke + Carbon Monoxide, will inform you of the type of alarm triggered and the location of the initiating alarm.

The First Alert SCO7CN and the Kidde 21026043 KN-COSM-BA also have voice alerts, and the First Alert SCO7CN has the bonus of having a programmable location that it will announce when an alarm is triggered so you know precisely which one went off.

It is very handy when the triggering alarm announces its location if you have multiple units installed around your house.

Credit: David Wise

A few other models also have integrated lights, though for different purposes. The X-Sense Escape Light SD01 has an evacuation light that will illuminate when an alarm is triggered to help guide your way out. The Nest Protect and the First Alert OneLink Alexa Safe & Sound both have LED ring lights, with the Nest Protect's lighting up automatically as a nightlight based on motion. The First Alert OneLink Alexa Safe & Sound will light up based on ambient light and gives you the option to customize the color.

Conclusion

Hopefully, you have found this review helpful and informative for picking the next smoke detector for your home, regardless of if you are looking for a bare-bones budget option or a deluxe model with smart features. Whether you have a hardwired system or need a battery-powered model, we sincerely hope that one of these products is the perfect match for your needs and budget. Additionally, you should check any local regulations and the guidance by the NFPA to ensure that whatever system you choose is in full compliance for maximum safety and peace of mind.

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