do smoke detectors work without power

Wondering do smoke detectors work without power? Keep reading!

To answer this question, we’ll first need to learn how the different types of smoke detectors operate and which detectors will be able to function without a battery.

The hardwired smoke detectors will function without power thanks to the backup battery that some units utilize. On the other hand, smoke detectors that only operate thanks to a battery, will continue to function just fine whenever the electricity is out.

Let’s now learn whether all smoke detectors work without power and which don’t.

Do ALL Smoke Detectors Work Without Power?

The short answer is No.

However, the long answer is that some hardwired smoke detectors do not include an integrated lithium battery and only depend on the electrical installation.

That type of smoke detector is not widely popular and even forbidden for installation in some locations.

Most smoke detectors and alarm systems utilize a backup battery.

Even when they are connected to the power via cable will continue to operate when the power is out.

Wireless Smoke Detectors Without Battery?

The wire-free smoke detectors only utilize a battery that should be frequently replaced for the function to continue normally.

They will not operate without the battery (power) but when everything is intact and there is no electricity, the device will continue to work.

Note: Wireless smoke detectors will not operate without the battery.

Which Smoke Detectors Won’t Work Without Power?

smoke detector without power

The answer depends on how we define “power”.

When the battery charge is low or the battery is dead, on a wireless smoke detector the operation is nearly over.

You’ll need a new battery for the wireless units to continue working.

The hardwired smoke detectors without a backup battery won’t work without power.

Some hardwired units will utilize a backup battery (if available), and continue to operate as normal even when the power is out.

Wired Smoke Detectors Without Battery?

Many people claim that they haven’t seen a hardwired smoke detector without a backup battery but here’s the catch.

Even when a smoke detector has a backup battery, over time the battery capacity degrades and starts chirping to indicate that replacement is necessary.

When left out, the chirping will disappear leaving the smoke detector without a backup in case of a power outage.

This is the occasion in which hardwired smoke detectors fail to go off since when the power is out they can’t continue to function. 


When Do Smoke Detectors Work Without Power?

when without power

A smoke detector will function normally during a power outage when the battery is intact and has been previously charged.

Once the power kicks back in, the backup battery is getting filled up and allows the detector to operate as normal when there is no electricity.

Nowadays most smoke detectors are using a backup battery so the devices can continue to operate when the power is out.

Let’s learn more about how long they will work this way:

How Long Hardwired Backup Battery Lasts?

The duration of the backup lithium battery of your hardwired smoke detector depends on what the battery condition is.

After a few years of usage and many power outages, the battery will be able to utilize less power than before shortening the lasting duration.

The integrated battery of a hardwired smoke detector will last up to 7 days without power.

This is only possible when the battery is new and hasn’t been worn out over the years.

In addition, the electricity should have been okay for at least several hours for the integrated battery to be entirely filled up, and ready for a 7 days standalone operation.

Note: Most of the hardwired smoke detectors’ batteries can be replaced.

Will A Hard Wired Smoke Detector Work Without A Battery?

detector hard wired

To answer this question, we’ll need to get familiar with the three types of hardwired smoke detectors and what their operation requires.

Then we’ll be able to tell the type of the device and whether or not the detector will work without a battery.

Hardwired Smoke Detectors Types:

Here are the different types of hardwired smoke detectors:

No Backup Battery

The hardwired smoke detector without a backup battery does not require a battery to function but won’t operate when the power is out.

Integrated Battery

In most cases, this is a lithium battery that cannot be replaced and lasts as long as the detector device.

The integrated battery taps power from the electrical installation and the detector will use that battery to operate when the power is out.

9V Backup Battery

This is a smoke detector that requires the battery to be inserted into the device which is also replaceable.

You won’t need to change the battery as frequently as the wireless smoke detector and the device will use the backup battery to operate when the power is out.

Note: Wireless smoke detectors won’t work without a battery but will operate without power.

Will My Smoke Detector Work Without Battery?

without battery detector

To find out whether your smoke detector will work when you remove the battery you’ll need to identify the type of your device. 

First, you’ll need to determine whether your unit is connected to the power via cable or it’s a wireless smoke detector, depending on the battery.

  • Detectors connected via cable will work without power if there is a backup battery.
  • A wireless smoke detector (battery-operated) will work without power.
  • Hardwired smoke detectors without a backup battery won’t work without power.

This is everything you need to know to be able to recognize the type of your smoke detector and understand whether or not the device will work without power.

Tip: For peace of mind you should test whether your smoke detector works without power.

Test Procedure:

In case the power is out and you’re wondering whether your smoke detector will work while you’re gone, there is an easy way to test the alarm.

  1. Press the Test/Hash button on your detector.
  2. Hold the button for at least 5 seconds.
  3. This should sound the alarm if the detector is working.

On carbon monoxide detectors, you’ll need to press the test button once to trigger the alarm and test whether the device is working when the power is out.

Hardwired Vs Wireless Smoke Detector?

People often wonder whether the investment into a hardwired smoke detector is worth the cost and the conclusion is simple.

The hardwired smoke detectors are better in contrast to the wireless units in every major aspect – compliance, safety, reliability, efficiency, and maintenance.

Wireless vs harwired

With hardwired smoke detectors:

  • You don’t need to change the battery.
  • They will work while the power is out.
  • Will still go off when the wired connection is impacted.
  • Last longer than its counterpart.

The only downside of the hardwired smoke detectors is that the “fire” or fault could interrupt the power supply before the detector goes off.

In case of a bad battery, the detector will fail. It’s also more expensive than wireless due to the installation of the electrical system.

Note: Hardwired smoke detectors' backup battery lasts 10 years, as long as the detector.

Quick Recap:

Hence, a smoke detector with a backup battery should operate normally when the power is out as long as the battery provides charge. The hardwired units without a backup battery won’t be able to go off or make any sound without power.

Read Next: Can A Candle Set Off A Smoke Detector?

Last Thoughts:

That was everything about do smoke detectors work without power. We made sure to cover the two general types, hardwired and wireless smoke detectors.

The recommendation here is to replace the battery of your smoke detectors every 6 months to prevent downtime.

We hope that this post was helpful and to discover more relevant guides, make sure to check our online blog.

Nicole B