THE BROKEN PHONE IN YOUR DRAWER CAN REPLACE AN 80 DOLLARS SERVER - AND IT IDLES AT 1 WATT
That cracked phone in your drawer has an octa-core CPU, more RAM than a Raspberry Pi, and idles at 1 watt — Hardware Haven turned one into a working home server.
by Hardware Haven
AutomationEnergy
- difficulty
- ●●●○○
- time
- a weekend
- license
- license not specified
- repo
- repo ACTIVE102 stars
●●●○○ · a weekend · license not specified · 102 stars · repo ACTIVE
Partner
COMPAREE VERDICT
This is a proof-of-concept demo, not a ready-to-follow guide. Hardware Haven showed that a drawer phone can replace a Raspberry Pi for home automation — the Xiaomi Mi A1 in the video idles at about 1 watt running Home Assistant under postmarketOS, and the specs (octa-core, 6-8 GB RAM, 128+ GB storage) genuinely beat an 80 dollars Pi. The environmental case is real: 5.3 billion phones were wasted in 2022 alone (WEEE Forum), and most have usable ARM hardware inside. But the video does not walk you through the diode mod or the postmarketOS install, and there is no BOM or schematic. You will need to cross-reference the postmarketOS device wiki, understand basic ARM bootloader unlocking, solder a diode into the charge controller without a circuit diagram, and troubleshoot kernel modules for GPIO and power management. The clustering guide on blog.denv.it is excellent if you want to run Immich or Jellyfin across several phones, but it starts after postmarketOS is live. This is for someone who has installed Linux on embedded ARM hardware before and is comfortable reverse-engineering a voltage mod from a 35-second video clip. If you have never unlocked a phone bootloader or soldered to a charge IC, you will waste your weekend and possibly kill the phone. The one thing most likely to go wrong: your specific phone model is not on the postmarketOS support list, or the kernel lacks the drivers you need, and you only discover this after buying a USB OTG adapter and a diode.
IN THE REPO
NOT IN THE REPO
- —No repository or files exist — this is a YouTube video demonstration by Hardware Haven, not a packaged project with step-by-step instructions.
- —postmarketOS install process is documented on the postmarketOS wiki for 250+ devices, but you must confirm your specific phone model is supported before buying parts.
- —The diode mod to bypass a swollen battery is shown on video but not written up with part numbers or schematics.
- —A separate written guide exists for clustering multiple phones into a k3s setup (blog.denv.it), but it assumes postmarketOS is already running.
- —postmarketOS is GPL-licensed free software; the clustering guide appears under CC BY-SA 4.0.
- —Hackaday covered the build in August 2025 as a proof-of-concept, not a polished tutorial.
Can I build this?
Build at your own risk. Projects involve tools, electronics and sometimes mains voltage — follow the creator’s safety notes.
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Videos
Hardware Haven — drawer phone home server demo
Proof-of-concept demo showing battery removal, diode power mod, postmarketOS install and Home Assistant running. Not a step-by-step tutorial.
Gallery
Start here
Navigation into the creator’s own docs — we don’t rewrite the guide, we route you to the source.
- 1.Confirm your phone model is on the postmarketOS device list(Do this before buying any parts. If your phone is not supported or support is partial, the project stops here.)
- 2.Read the Hackaday coverage to understand what the build involves (This gives context but is not a build guide.)
- 3.Watch the Hardware Haven video to see the diode mod and boot process (Pause and screenshot the diode placement; there is no schematic.)
- 4.Follow the postmarketOS install guide for your specific device(This is where the actual install happens. Device-specific quirks are documented in the wiki.)
- 5.If clustering multiple phones, read the k3s guide after postmarketOS is stable (Written guide for running Immich and Jellyfin across several phones. Assumes postmarketOS is already working.)
Resources
Documentation, files and community threads for this build — we link straight to the original sources and never rehost the creator’s files.
KNOWN ISSUES
- Buying a phone before confirming postmarketOS support. Many devices have partial support (no GPU acceleration, no cameras, no modem) and are listed as 'community' tier, which means basic features may not work.
- Leaving the swollen battery in. The video is clear: remove it. A swollen lithium cell is a fire waiting to happen.
- Soldering the diode without a multimeter check. If you wire 5V to the wrong pad on the charge controller, the phone is bricked.
- Expecting the video to include part numbers or a schematic. It does not. You will have to identify the diode type and rating yourself.
- Assuming the clustering guide is plug-and-play. It requires working knowledge of k3s, persistent volumes, and ARM container images.
- Underestimating bootloader unlock difficulty. Some manufacturers (Xiaomi included) require an account, a waiting period, and Windows-only unlocking tools.
Will my phone work?
Only if it is on the postmarketOS device list. Check the wiki first. Even listed devices may have missing features like GPU acceleration or camera support.
Can I skip the diode and just plug in USB power?
No. Most phones refuse to boot without a battery unless you trick the charge controller. The diode mod does that by feeding voltage into the charge output. Skipping it means the phone will not turn on.
What diode do I need?
The video does not specify. A Schottky diode rated for at least 2A and low forward voltage drop (e.g. 1N5819) is a common choice for this type of mod, but confirm with your phone's charge controller datasheet if you can find it.
How much does this actually save versus a Raspberry Pi?
A Raspberry Pi 5 with 8 GB RAM costs around $80 plus the cost of a case and SD card. An old phone costs nothing if you already own one, and idles at about 1 watt versus the Pi's 2-4 watts. The environmental saving is larger than the financial one.
Can I run this 24/7?
Yes, if the phone is designed to run on continuous power and the charge controller accepts the diode mod. The video shows Home Assistant running, which implies it is stable, but long-term thermal behavior and flash wear are not tested.
Community builds
No community builds yet — be the first, we feature the best ones.
Discussion1
FROM THE COMPAREE TEAM
The video shows a 1-watt idle on a Xiaomi Mi A1 running postmarketOS — but postmarketOS support varies wildly by device, and the diode mod is shown without a schematic. If you have an old Android phone in a drawer, what model is it, and have you checked if it is on the supported list?
Hardware Haven
Hardware Haven demonstrated the build on YouTube as a proof-of-concept for e-waste reduction. The video shows a working 1-watt home server running postmarketOS and Home Assistant on a retired Xiaomi Mi A1.
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DISCLAIMER
- Comparee is not the author of the projects featured here. All rights to each project belong to its creator — every page links to the original source, and we never host creators’ files.
- Information is provided without warranty and may become outdated as projects evolve. Prices are indicative bands only — always check the creator’s parts list for current costs.
- Building and operating any project is at your own responsibility. Protective equipment, safe workshop practice and compliance with local regulations are the builder’s responsibility.
CompareeTEAM3d ago
Practical notes from our verification: Hardware Haven's video is a proof-of-concept, not a tutorial — the diode mod is shown on camera but without part numbers or a wiring diagram, and the postmarketOS install is summarized in seconds. The clustering guide on blog.denv.it is genuinely useful if you want to run Immich or Jellyfin across multiple phones, but it assumes postmarketOS is already stable and you understand k3s. The Hackaday article linked in our sources provides context but no build steps. The 1-watt idle measurement is real (shown on a power meter in the video), and the specs claim (octa-core, 6-8 GB RAM) matches typical mid-range phones from 2017-2020. The biggest trap: many phones on the postmarketOS device list have partial support, meaning no GPU, no cameras, or no modem — fine for a headless server, but you must confirm before you start. No repository, no BOM, no schematic — this is inspiration, not a packaged project.