My favourite battery-powered option for gathering information on the current state of my smart home are Aqara Zigbee sensors. For a limited time, you can equip every room in your home with motion, temperature and humidity, water leak, and vibration sensors at a discounted price. Aqara is currently offering their devices for $3.80 to $4.80 less than their usual price on Amazon Prime Day, which is happening now!

Motion sensors and smart thermometers for every room
Of all the Aqara sensors, the Aqara Motion Sensor and Aqara Humidity and Temperature Sensor are absolute must-haves for me. The motion sensor allows for easy and quick detection of presence in a room, while the temperature and humidity sensors inform you when it's time to adjust the heating or open a window. I also use the latter as a presence sensor in my bathroom, where the humidity increases significantly when someone is in the shower. Both sensors are powered by a single CR2450 coin-cell, which lasts for over a year thanks to the Zigbee protocol.
Preventing disasters with the Aqara Water Leak Sensor
The Aqara Water Leak Sensor is a reassuring addition to any home. Once installed, it will notify you in the event of a water leak, potentially saving you from costly damage. I have one placed under my washing machine, and it was triggered once, allowing me to shut off the water and machine before any damage was done.
The maligned Aqara Vibration Sensor
Another sensor I have in my arsenal is the Aqara Vibration Sensor. For full transparency, I do not recommend this sensor as a way to detect whether a washing machine or dryer is running, as it appears to require stronger vibrations to get triggered. It is more likely that you will be having success using it to detect whether a window has been broken. As with the previous mentioned Aqara Zigbee sensors, these are powered by a single coin-cell, which should last even longer as they are used less frequently.
How to integrate Aqara Zigbee sensors with Home Assistant
All four Aqara Zigbee sensors mentioned in this article are compatible with Zigbee2MQTT, ZHA, and the Aqara Hub. Pairing them couldn't be easier, thanks to an accessible yet inconspicuous button. Once paired with Zigbee2MQTT, the sensors are automatically discovered by Home Assistant, and likewise so with ZHA.