PreparedStates

Best carbon monoxide alarms for power outages (2026)

Ready.gov says to install carbon monoxide detectors with battery backup in central locations on every level of your home.

By PreparedStates editors · Updated October 22, 2026

Our picks

All 4 compared

1. Kidde Carbon Monoxide Alarm, 10-Year Battery, Digital Display Our top pick
10-year sealed lithium battery · Digital CO level · Carbon monoxide

Fit-and-forget, and works in an outage

4.5
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Our verdict
Our verdictResearched

A sealed 10-year battery means it keeps working when the power's out and never needs a battery swap, and the display shows the CO level so you can see a slow build-up.

Best for Fit-and-forget, and works in an outage

Good
  • Works without mains power
  • Shows the CO level
  • No battery changes for 10 years
Worth knowing
  • Replace the whole unit at 10 years

Who shouldn't buy it: Don't buy it if you want one alarm for smoke and CO: get a combination alarm.

2. First Alert CO605 Plug-In Carbon Monoxide Alarm with Battery Backup Runner-up
Plug-in with battery backup · None · Carbon monoxide

Plug in, with a battery for outages

4.0
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Our verdict
Our verdictResearched

Plugs into an outlet with a battery backup, which is exactly what Ready.gov asks for. Cheap and simple; no level display.

Best for Plug in, with a battery for outages

Good
  • Battery backup
  • Low price
Worth knowing
  • No CO level display
  • Needs a free outlet

Who shouldn't buy it: Don't buy it if you want to see CO levels.

3. First Alert 10-Year Battery Combination Smoke & Carbon Monoxide Alarm Also good
10-year sealed battery · None · Smoke and carbon monoxide

Smoke and CO in one ceiling unit

4.0
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Our verdict
Our verdictResearched

One sealed-battery alarm covering both smoke and carbon monoxide, handy where you'd otherwise fit two.

Best for Smoke and CO in one ceiling unit

Good
  • Smoke and CO
  • 10-year sealed battery
Worth knowing
  • No CO level display

Who shouldn't buy it: Don't buy it if you already have smoke alarms you like.

4. Kidde Carbon Monoxide Alarm, AA Battery
2 x AA batteries · LED lights · Carbon monoxide

The cheapest way to cover every level

3.5
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Our verdict
Our verdictResearched

A low-cost battery alarm to put on every level of the home, as Ready.gov advises. Batteries need changing.

Best for The cheapest way to cover every level

Good
  • Very cheap
  • Works in an outage
Worth knowing
  • Battery changes
  • No level display

Who shouldn't buy it: Don't buy it if you don't want to change batteries: get the 10-year model.

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Read this first
A CO alarm is a warning, not protection. Never run a generator, camp stove or charcoal grill indoors: Ready.gov says they should always be used outdoors and at least 20 feet away from windows.

Before you buy

Choose battery or battery-backup models so the alarm still works when the power's out, which is when CO risk is highest.

A digital display shows the CO level, so you can spot a slow build-up before it reaches alarm level.

Sealed 10-year-battery alarms never need new batteries; replace the whole unit when it reaches its end-of-life signal.

Fit one on every level and near sleeping areas, following the maker's instructions for placement.

How we choose

We verify every product's specifications against at least two independent sources, re-check its US price and stock on a schedule where we can track it automatically, and cross-check safety-relevant claims against official guidance. Every review is labelled Researched or Used and reviewed by us: where we've bought a product, or been sent it free, and used it ourselves, its review says which; where we haven't, our verdict is a considered spec-and-evidence comparison, not a hands-on test — and commissions never change a ranking either way. Read our full methodology →

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Common questions

Where should carbon monoxide alarms go?

Ready.gov says in central locations on every level of your home. Follow the maker's instructions, and put one near bedrooms so it will wake you.

Do carbon monoxide alarms work in a power outage?

Battery and battery-backup models do; hard-wired alarms without backup don't. Every alarm here keeps working without mains power.

Is a combination smoke and CO alarm as good?

It covers both in one unit, which is handy. If you already have good smoke alarms, a separate CO alarm with a display tells you more.

How long do CO alarms last?

Most are made to be replaced after about 7 to 10 years. Sealed-battery models signal when they reach end of life.