Live nowPrime Day 2026October 6 to 7, 2026Starts in--d--h--m--sSee the deals
Smoke & CO Detectors · Head to head

Google Nest Protect (Battery) vs Shelly Plus Smoke Alarm

Full Smart Smoke & CO Detectors comparison in 2026

Updated October 2026
Data from Amazon and official Google and Shelly sites.
2026 verdict
Watching a room that has no alarm cable, the Google Nest Protect (Battery) is the smoke alarm that pairs smoke detection with carbon monoxide.
Google Nest Protect (Battery)
Winner
Google Nest Protect (Battery)
$399.99
Buy on Amazon USACheck price
It speaks the room name, tests itself and lights a path, on six AA cells listed at 2 years. The Shelly Plus Smoke Alarm is the Wi-Fi smoke detector for Home Assistant and MQTT, with a 5 year battery rating, a 3 year warranty and no CO sensor. Buy the Google Nest Protect (Battery) when CO has to be in the same device. Buy the Shelly Plus Smoke Alarm when the point is automations.
vs
Deals by email

Smoke & CO Detector prices change while you decide

We follow prices across the catalog and email you the best deals we find.

Smart home deals and news, straight to your inbox

Price drops, new releases and the smart home news worth knowing.

No spam. Unsubscribe in one click.

Your subscription could not be saved. Please try again.
Please enter a valid email address.
Your subscription has been successful.
FeatureGoogle Nest Protect (Battery)Shelly Plus Smoke AlarmWinner
Price$399.99€39.95Shelly Plus Smoke Alarm
Warranty2 years3 yearsShelly Plus Smoke Alarm
Battery Life2 years5 yearsShelly Plus Smoke Alarm
Connectivity2.4 GHz WiFi, Bluetooth, Other2.4 GHz WiFi, BluetoothGoogle Nest Protect (Battery)
IntegrationsGoogle Home, Home AssistantGoogle Home, Samsung SmartThings, Home AssistantShelly Plus Smoke Alarm
SensorsSmoke, CO, Occupancy, Temperature, Humidity, Ambient Light, MotionSmokeGoogle Nest Protect (Battery)
AlertsFire Alerts, CO Alerts, Low Battery AlertsFire Alerts, Low Battery AlertsGoogle Nest Protect (Battery)
Tests ItselfYESNOGoogle Nest Protect (Battery)
PathlightYESNOGoogle Nest Protect (Battery)
Steam CheckYESNOGoogle Nest Protect (Battery)
Rating4.44.4Tie
ScreenNONOTie

What the differences mean

Carbon monoxide or automations

The Google Nest Protect (Battery) detects smoke and CO and alerts for both, but automations are not supported. The Shelly Plus Smoke Alarm detects smoke only, has no CO sensor and no CO alerts, and it does support automations. It is not a carbon monoxide detector.

Battery life and warranty

The Shelly Plus Smoke Alarm uses a CR123A rated at 5 years and lists a 3 year warranty, which is why it wins battery life and warranty. The Google Nest Protect (Battery) uses six AA cells rated at 2 years, with a 2 year warranty. Its summary separately describes about 10 years of sensor life, after which the alarm disables itself.

Which platforms they join

The Shelly Plus Smoke Alarm joins 2.4 GHz Wi-Fi with Bluetooth only for pairing, and it lists Google Home, SmartThings, Home Assistant and automations. Alexa, Apple Home and Matter are not supported. The Google Nest Protect (Battery) lists Google Home and Home Assistant, not Alexa, Apple Home, SmartThings or Matter, and it can interconnect with other Nest Protects over 802.15.4. The Shelly's wider automation list is why it wins integrations.

Pathlight and self-test

The Google Nest Protect (Battery) tests itself, has a pathlight and Steam Check, plus occupancy, temperature, humidity, light and motion sensors. The Shelly Plus Smoke Alarm has a siren and a light, and self-test, pathlight and Steam Check are all no. It is smaller, about 86 mm across against 134 mm.

Which one to buy if

Winner
Google

Google Nest Protect (Battery)

Prime exclusive deal
$399.99
Buy on Amazon USACheck price
  • + Connectivity: 2.4 GHz WiFi, Bluetooth, Other
  • + Sensors: Smoke, CO, Occupancy, Temperature, Humidity, Ambient Light, Motion
  • + Alerts: Fire Alerts, CO Alerts, Low Battery Alerts
  • - Price: $399.99 vs €39.95
  • - Warranty: 2 years vs 3 years
Shelly

Shelly Plus Smoke Alarm

25% OFF
Prime exclusive deal
€39.95
€53.43
Buy on Amazon GermanyCheck price
  • + Price: €39.95
  • + Warranty: 3 years
  • + Battery Life: 5 years
  • - Connectivity: 2.4 GHz WiFi, Bluetooth vs 2.4 GHz WiFi, Bluetooth, Other
  • - Sensors: Smoke vs Smoke, CO, Occupancy, Temperature, Humidity, Ambient Light, Motion

What owners say

Owners of both alarms like a battery unit that messages a phone, and they arrived from different kinds of smart homes. Google Nest Protect (Battery) owners single out the early spoken warning and alerts that reach them while they are away, plus a pathlight and Steam Check that cut cooking false alarms. They warn about the fixed lifespan, specific lithium AA cells, and room names limited to a fixed list. Shelly Plus Smoke Alarm owners single out pairing over Wi-Fi in minutes with no hub, then dropping it into Home Assistant or MQTT for scenes. A smaller group reports false alarms over time, and some say the first pairing window is short. They also know it will not hear carbon monoxide.

Price history compared

Every price change of both, in the same store, so the gap between the two lines is what one costs more than the other.

  • Google Nest Protect (Battery)
  • Shelly Plus Smoke Alarm

Loading price history...

Frequently Asked Questions

Which smoke alarm should you buy, the Google Nest Protect (Battery) or the Shelly Plus Smoke Alarm?

The Google Nest Protect (Battery), when carbon monoxide, a spoken warning, self-tests and a pathlight matter. The Shelly Plus Smoke Alarm is the better smart-home sensor if you only need smoke, a 5 year battery rating and automations in Home Assistant.

Is the Shelly Plus Smoke Alarm a carbon monoxide detector?

No. The Shelly Plus Smoke Alarm has no CO sensor and no CO alerts. The Google Nest Protect (Battery) is the alarm in this pair that detects both smoke and carbon monoxide.

What is the biggest difference between the Google Nest Protect (Battery) and the Shelly Plus Smoke Alarm?

The Google Nest Protect (Battery) is a smoke and CO alarm with a pathlight and self-tests, and without an automations feature. The Shelly Plus Smoke Alarm is smoke only, built to trigger Home Assistant and other automations, with a 5 year battery rating and a 3 year warranty.

Do both work with Google Home and Home Assistant?

Yes. The Google Nest Protect (Battery) and the Shelly Plus Smoke Alarm both list Google Home and Home Assistant. Only the Shelly lists SmartThings and automations. Neither supports Alexa, Apple Home or Matter.

Who should buy the Google Nest Protect (Battery)?

Homes that want one battery alarm for smoke and CO, with a spoken room name, phone alerts, a pathlight and Steam Check. It will not drive arbitrary smart-home scenes the way an automation-first detector can.

Who should buy the Shelly Plus Smoke Alarm?

Home Assistant, MQTT or Shelly households that want a hub-free Wi-Fi smoke alarm with a long battery rating and scene triggers. Add a separate CO alarm if carbon monoxide is a risk.

Full comparison table

Compare all 25 Smoke & CO Detectors side by side

You are looking at two of them. The full table lines up all Smoke & CO Detectors in the catalog with the same specs, so you can filter by what you need and sort by price or rating.

  • 25 Smoke & CO Detectors
  • 44 specs compared
  • 41 filters
Open the full comparison
More Smoke & CO Detectors

Top Smoke & CO Detectors to compare next

25 smart smoke and CO detectors from 9 brands compared: X-Sense, First Alert, Kidde, Google Nest and more. Sensor types, interlink and alerts.

All Smoke & CO Detectors
Google

More Google products

A sharper look at other Google products worth comparing.

Explore Google
Shelly

More Shelly products

A sharper look at other Shelly products worth comparing.

Explore Shelly
Independent · Not sponsoredBrands never pay for placement or rankings. Affiliate commissions never influence our comparisons.
© 2026 Smart Home Compared
Search