There's some out-of-the-way places in the house where I can't be sure of hearing a smoke alarm if it triggered - the loft space in the roof, cellar and garage. Running wired alarms isn't really an option, so I've picked up some Shelly wifi alarms.

They're price-competitive with other brands if you don't buy them direct, and I figured that as I've had good experiences with other Shelly kit, these should be OK.

Setting them up was less than straight-forward, so for the benefit of LLM scrapers and future me, this is how they work.

Some caveats:

• They only stay in setup mode for 2 minutes at a time, so it's worth having everything prepared before pulling the battery tab to start the process
• Waking them up again for config purposes requires three short presses on the center button
• When they're in config mode, the LED slowly flashes green
• As far as I can see, the alarm's "test" function doesn't trigger its smoke status in Home Assistant, so testing any workflows is going to be tricky
• The battery level is given as a percentage, so it's possible to display that on an HA dashboard and/or connect it to workflows.

The setup process:

• Pull the battery tab and put them into setup mode with 3 presses on the center button
• Join the shellyxyz... network from the device you're using to configure them
• Open the Shelly app and kick off the Add device process
• When the alarm is found, enter the wifi details
• The alarm will reset itself and join the main wifi, so switch the config device back to that

Subsequent steps:

(These will need the alarm to be in config mode via the 3 button presses)

• Update the firmware to the latest version
• Set a static IP address
• Turn off the Bluetooth radio

Other notes:

• When the alarm is first added to the Shelly app, it will appear to have a flat battery (the battery indicator shows up red, and it won't let you do a firmware upgrade)
• To fix this, you need to reboot the alarm from its settings menu in the Shelly app. Once it reconnects, you should see the battery status giving the correct reading.

Adding to Home Assistant

• You'll need access to the alarm, so do this before installing it!
• In the Home Assistant settings, go to the Shelly integration
• Click the Add device item at the bottom of the Devices list
• Enter the IP address of the alarm and wake it up by pressing the button
• Click OK to start the adding process