Why Your Old Phone Makes a Great Smart Home Hub
That old phone in your drawer is far more than digital clutter. Packed with sensors, Wi‑Fi, and a touchscreen, it’s already everything you need for an always‑on smart home hub. Instead of buying dedicated hardware, you can use a Home Assistant setup to turn it into a central controller for lights, climate, entertainment, and more. Because this device is no longer your daily driver, you’re not draining your primary phone’s battery or tying up its screen with dashboards. It simply lives on a stand, powered and ready 24/7. Most recent Android and iOS models work fine, and even older devices handle smart home automation tasks comfortably as long as they can run the Home Assistant Companion app and a modern browser. The result is an old phone smart home control center that rivals purpose‑built hubs, without extra cost or complexity.
Step 1: Prepare the Old Device and Install Home Assistant Companion
Start by wiping unnecessary apps and data from your retired phone so it has as much free storage and memory as possible. Update the operating system to the latest version it supports, then connect it to reliable Wi‑Fi and disable mobile data to avoid distractions. Next, set up your Home Assistant server on a PC, mini‑PC, or NAS, then create your user account. On the old phone, install the official Home Assistant Companion app for Android or iOS and sign in with the same account. Once connected, the app exposes over 100 data points from your phone to Home Assistant, including sensors for light, motion, location, and battery state. This instantly turns your device into a sensor hub and dashboard endpoint. Place the phone where it has a good view of the room, and keep the screen timeout long so your smart home interface is always just a tap away.
Step 2: Build Practical Automations with Built‑In Sensors
With the Companion app online, you can now create powerful smart home automation routines without extra hardware. Use the ambient light sensor to measure lux levels in your living room and trigger lamps or blinds when the room actually darkens, instead of blindly following sunset times. Repurpose the accelerometer by resting the phone on a non‑smart washing machine or dryer; when vibration stops, Home Assistant can send a notification or flash a light to signal the cycle is done. Presence detection becomes possible too, as the phone’s location and connectivity can help determine whether someone is home or if a room is occupied. Each sensor can be combined with others and with existing smart plugs, bulbs, or thermostats, giving you hands‑free control over lights, temperature, and appliances using the device you already own.
Step 3: Protect Battery Health and Keep the Hub Always On
A dedicated smart home hub must stay powered, but leaving a phone plugged in 24/7 can degrade its battery over time. Home Assistant solves this by exposing detailed battery information from the Companion app, including charge level, state, and charger status. Plug the phone into a smart plug and automate charging: for example, turn the plug on when the battery drops below 20% and off again when it rises above 80%. This keeps the phone alive without constantly topping it off. Alternatively, create an automation that switches a lamp or sends a notification when your hub device needs charging, reminding you to plug it in manually. Combine this with a simple stand or wall mount and a long cable, and your old phone becomes a neat, semi‑permanent fixture—always ready to control your smart home without risking an early battery failure.
Step 4: Add a TV‑Style Dashboard and Integrate Other Ecosystems
To make your old phone feel like a true control center, design a full‑screen Home Assistant dashboard with buttons for lights, media, and scenes, then set it as the default view in the Companion app. On Android, you can go further by installing an Android TV‑style launcher such as ATV Launcher to give the device a streamlined, remote‑friendly interface focused on apps and tiles. This can turn the phone into both a control panel and a content hub that mirrors an Android TV experience. From there, link Home Assistant to Google Home or Alexa so voice assistants can trigger the same automations, keeping everything in sync. Because the phone is dedicated and always connected, it acts as a bridge between your existing smart home platforms, giving you a consistent, responsive smart home automation experience across rooms, screens, and devices.
