What an Old Phone Smart Home Hub Can Do
An old phone smart home hub is a repurposed smartphone that runs Home Assistant, exposes its built-in sensors, and coordinates smart devices, automations, and basic network tasks as a dedicated always-on controller. Modern phones have processors, memory, and radios that rival small smart home hubs, so turning one into a DIY smart home hub is a practical way to repurpose old phone hardware instead of leaving it in a drawer. Using the Home Assistant Companion app, a single device can share over 100 data points with your smart home and manage automations for lighting, climate, presence, and security. This approach removes the need to buy extra hub hardware, since the phone becomes a sensor node, dashboard, and automation brain tied into your existing Wi-Fi and smart devices. The result is a cost-effective smart home automation setup managed from one repurposed device.
Prepare the Phone and Home Assistant Setup
Start by choosing a spare Android or iOS device with a stable battery and working Wi-Fi. Give it a factory reset, disable unnecessary apps, and set the screen timeout to a high value if you plan to mount it as a dashboard. Next, set up your Home Assistant server on an always-on machine such as a mini PC or similar box and ensure it’s reachable on your home network. Install the Home Assistant Companion app on the old phone and sign in with your Home Assistant account. Point the app to your server’s address and complete onboarding so the phone appears as a device with multiple entities. According to MakeUseOf, the Companion app can expose over 100 sensor data points, including battery level, light level, motion, connectivity, and more, giving you rich inputs for smart home automation from a single repurpose old phone project.
Build Core Smart Home Automations from Phone Sensors
Once the phone is paired, use its sensors to build smart home automation routines that replace dedicated hardware. Place the phone near a window and read its ambient light sensor in Home Assistant to control lighting scenes and blinds when lux drops below your chosen threshold, making your old phone smart home setup react to real room brightness instead of fixed schedules. Put the phone on top of a washing machine and use the accelerometer readings to detect vibration and inactivity, then send notifications when a cycle ends. Configure the battery entities, plug the charger into a smart plug, and automate charging to stop power around 80% and resume at 20%, extending battery health while the device stays online. Combined with presence and BLE beacon features, the phone doubles as a room-level presence sensor for more precise automation triggers.
Add Security Camera and Network Management Roles
To expand beyond sensors, install an IP camera app so the phone streams video over your LAN; Home Assistant can read this video feed through a built-in integration and expose a motion sensor entity alongside it. Use that entity to trigger porch lights, send alerts, or adjust behavior based on presence detection, turning a forgotten device into a security camera you control from your dashboard. In parallel, keep the phone connected to power via a smart plug and reuse the Companion app’s battery and charging state entities to automate its own power cycle. Android Police notes that a phone that’s always on can handle a couple of network tasks, making it a decent little server node. You can assign roles like lightweight dashboards, simple monitoring scripts, or presence-based network rules without installing more hardware on your rack.
Optimize Network Configuration and Daily Use
To make your DIY smart home hub reliable, fix the phone’s IP address in your router or Home Assistant network settings so automations always reach the same endpoint. Connect it to a stable 2.4GHz or mixed Wi-Fi network and keep it within strong signal range. If it also acts as a camera or dashboard, mount it in a covered, central spot where sensors stay useful but the device is safe from the elements. Disable system updates or schedule them for off-hours so automations are not interrupted. Use the Home Assistant dashboard to group entities from the phone—light sensor, motion, battery, BLE presence—into a dedicated view, making it easier to monitor. Over time, you can promote this repurposed device into a key part of your smart home automation stack, coordinating lighting, climate, and simple network actions without buying a separate smart home hub.