Aqara’s cord-free presence sensor runs for up to three years on battery power

The $50 sensor runs on two coin cell batteries so you don’t need a nearby power source for installation.

How I use this hidden Android security feature to easily turn off sensors - and where to enable it

Open the Settings app. You can do this by either tapping Settings within the App Drawer, or tapping the gear icon in the Notification Shade. From within Settings, tap "About phone," and then scroll to ...