Uses for an old Android device | Hacker News Reader

Uses for an old Android device

computerworld.com

138 pointsthund103 comments

Love these suggestions! I'm using an old Motorola X Pure as one of my CCTV cameras via the excellent free IP Webcam app for a couple years now, but with a twist:

I've done this before with an old LG phone, and it seems that leaving the battery in the phone for camera purposes is a bad idea. It turns in to a spicy pillow within a year. I believe it's the heat - from getting cooked in the sun through the window, from the CPU working hard to encode MJPEG stream, and from the wireless radio constantly transmitting that stream, all while being held near maximum SOC..

So what I did this time around was remove the battery completely! I found an old 5V USB phone charger, say 1000mA output, and used a diode to drop the voltage to ~4.2V or so. Nothing out of the usual for a phone to see soldered on it's battery terminals.

Now this worked, but I found that certain high-load situations would cause the phone to power off. Solution was to add say 5000uF of electrolytic capacitors to the output of my new power supply.

With that added, setting Android to sync automatically via my NTP server with a command through the ADB shell, setting it to always connect to my IoT VLAN WiFi, and setting IP Webcam to start after boot, this solution has been working perfectly for quite some time!

It was a fun project too, and I got to reuse an old phone, and old charger I never would have used again, and some random capacitors that have been rolling around in a parts box for years. :)

Bonus: I control the camera's "night vision" mode via Home Assistant automations (turn on/off around sunset/rise) through the JSON API the app provides. This also provides some sensors like temperature, etc. The video stream is fed to ZoneMinder, which HA streams from. Motion detection in ZM triggers object detection via HA, and I get reliable notifications while I'm away!

This is great. I've always wanted to do something similar for my phones' battery compartments, but don't have the tools or knowledge.

I'm curious, is it possible to create fake 'batteries' for devices that pass the current directly from the charger into the device? I'm imagining something that looks like a battery, but doesn't hold any charge so people can use their old phones exactly as you do and never have to worry about it pillowing.

I can see a market for something like that, albeit a very small one since it would be device specific. I'd buy one if it existed.

I would definitely be in the marker for such a fake battery as well, though I suspect the fact that modern phones don't have normal battery connectors (and instead rely on glue and ribbon cables to connect power) will make a standardized product quite difficult.

Still, though, a correctly set voltage regulator with a normal USB plug and a few easy solder joints to attach the device's battery connectors to would already make the process quite a lot easier.

The first model I designed and 3D printed was a dummy battery pack for an Android PDA. (We use cheap ones at work and the stock batteries puffed up after a year.) The idea should scale down to a phone with a removable pack, but may not be useful on devices with soldered batteries.

For some products, such things are already available.

For example, want to mains-power your Panasonic digital camera? [1] provides mains power in a battery form-factor. Just what you need for long term time-lapse photography.

[1] https://www.amazon.co.uk/dp/B01HGLXHVE/

Yeah, I have one for my Canon camera. I wish it existed for older phones too.

What does the addition of a capacitor do here?

Does it just give some buffer for the PSU in those high load situations?

That's exactly right - or at least it's my theory which has so far worked just fine. Seems that without the extra capacitance on the output of my power supply, the voltage can droop just enough to cause a reset in the CPU or somewhere in the phone's hardware during high-draw moments. The extra capacitance helps lessen the droop enough to keep things humming along. :)

I forgot to mention this, but the phone has also been loaded with LineageOS to get rid of a lot of the default crap that was on there. It boots way faster and IP Webcam seems to run more reliably this way!

Oh man ! I have an old android device hanging around.

I will give this a try. Will be a great experience to experiment with building simple circuit again.

Glad to see Unified Remote mentioned! I created it 12 years ago, back in 2010 when Android and smartphones were basically brand new. I still maintain it, although less frequent feature updates these days.

Thanks for your work! Is one of the first apps I purchased :)

Glad to hear! Appreciate the kind words :)

Thank you so much. I still use.

Shameless plug here: I made an open source coding framework / prototyping tool that works very well we old Android devices. I've used it for a lot of things. Made robots, radios, home controllers, cameras, etc out of old androids :)

Have a look if you want https://phonk.app

This is interesting - did you post on the frontpage as well?

Also I wonder if something like https://bun.sh/ could be used to get modern JS/TS support?

(Also your Discord invite is expired)

1) I did post it sometime ago but did not get too much traction :)

2) I never heard of bun.sh, I'll have a look!

3) I did not notice about the Discord link. Probably it has been like that for ages :/ I will replace it in the site. Meanwhile here you have a new up-to-date one https://discord.gg/Rt2mkWp

Thanks!

This is awesome.

thanks!

This is great! Would love to join the discord. A couple things that I'm curious about: can you make a script/app start by default, can you use a node library (murmur specifically), can you interface with peripherals (led and knobs). I'd like to turn my old androids into screen-less walkie talkies, and phonk feels like I might be able to avoid android studio, which would be a relief.

1) Yes, you can make a script that starts on device boot.

2) Sadly you cannot use node libs. The JS engine I use is pretty dated (Mozilla Rhino) and I dont have time these days to do big changes.

3) Yes, you can interface with Arduino compatible hardware via USB serial or Bluetooth / Bluetooth LE.

4) If you want to do something screen less, you can run a script as a service (background). A bunch of years ago, when the ESP modules were not common I used an Android device as a network interface for my Arduino :)

Also, here is the up-to-date Discord link https://discord.gg/Rt2mkWp

If the old Android device doesn't get security updates, then it isn't safe to keep it connected to the Internet. Someone can hack into it and turn on the mic and camera. Or use it for mining cryptocurrencies.

LineageOS helps ( if the phone is supported by it: https://lineageos.org )

This is my concern. I use my old pixel (3a) as an always-on Syncthing node but worry about the security implications.

But I haven't been able to find good info on what exactly the implications are. If I'm not worried about targeted attacks, does a device that is just a passive node pose a significant risk?

In other words, how much do security updates address targeted attacks (not my threat model) vs widespread attacks of non-updated phones?

This varies case by case, and widespread attacks definitely happen.

Perhaps the most famous one on Android was the Stagefright attack, which could take over your phone by sending you a malicious MMS (which you didn't even have to open), or by getting the system media player to play a malicious MP3/MP4.

That was a while ago and I haven't kept current on similar attacks. Running an unpatched system is a gamble that nothing like that is still waiting to be discovered.

> Perhaps the most famous one on Android was the Stagefright attack, which could take over your phone by sending you a malicious MMS (which you didn't even have to open), or my getting the system media player to play a malicious MP3/MP4.

Which I would assume is not an issue if I'm using an old Android phone without a SIM card, so there's no way to receive any type of sms/mms message

> This is my concern. I use my old pixel (3a) as an always-on Syncthing node but worry about the security implications.

Interesting, I've never thought of using an Android phone as a Syncthing node.

Is there a way for an Android phone to connect to Wifi, but not the internet?

I use Syncthing with local discovery only, which only needs the devices to be on the same Wifi network. Not having internet access and also not having a SIM card to get calls/sms/mms message should greatly reduce the risk of attack to the point where I wouldn't feel worried about it.

> Is there a way for an Android phone to connect to Wifi, but not the internet?

If you can manually set the IP address on it instead of letting the WiFi AP give it one, then you can just leave out the default gateway entry - The device will then have no idea how to route network data outside of your local LAN.

Alternatively, set up a different WiFi SSID that gives out IP addresses, but again without a default gateway address, and have your device(s) connect to that instead.

Or finally, if your router supports it, set a rule to block your device(s) (via it's MAC address) from accessing the internet.

all good ideas, thank you!

I think the first option might be the easiest because it doesn't involve having to change anything on the router.

It does seem possible on Android to set a static IP and remove the Gateway (or maybe set it to 127.0.0.1 if I can't leave it blank?)

https://service.uoregon.edu/TDClient/2030/Portal/KB/ArticleD...

The 3a will run Lineage, so you can get the latest OS updates. However, the vendor updates will not advance.

Lineage will try to scavenge firmware updates from other devices to upgrade what they can, but there might be problems with the wifi, bluetooth, or other firmware that can compromise the device.

This is less of a concern if your wifi connectivity is behind a NAT router, and Google is gone.

> If the old Android device doesn't get security updates, then it isn't safe to keep it connected to the Internet.

That can be mitigated somewhat by it being a local-only device with firewalls between it and the wider Internet (so it can call out as needed but nothing out can call in). There is still a risk of another device on your WAN, temporarily or otherwise being infected and passing on the problem - you could have an extra AP and keep such devices on their own leg of the network to reduce that risk. You'd still be prone to something that can attack an old unpatched device just by being in range of it, of course, so perhaps use some sort of exfiltration monitoring at your network edge (or the edge of that walled-off WAN) to hopefully detect an infection trying to propagate from the device.

That only works for the userland, mitigating security issues by replacing the main stock OS with Lineage.

Aren't most LOS roms based on ancient kernels (albeit mostly patched-up with security updates), that use ancient modules, with opaque BLOBS/Firmwares, that only sometimes get updated, if ever?

You could run "HighSecurityOS WhatEv" on your phone, as long as e.g. the Wireless-Interface runs something entirely independent of you with DMA rights, and probably faulty firmware, can you really trust your device? Or have I missed recent advancements in this problem space?

PostMarketOS aims to mainline more devices/phones, so maybe, even if your final OS of choice is Lineage (or derivative), I would check their HWCDB before checking, if Lineage works on a phone.

It seems like every Android device that I've had becomes ridiculously slow after a few years. Not even a factory reset helps. I'd be happy turning a few tablets into one of these ideas or even nothing more than glorified terminals if there were actually ROMs available for them. Lighter weight software that could give them new life like I've done for so many old PCs with a Linux distro.

I never had problems with devices becoming slow where a factory reset does not help, this sounds odd since a factory reset clears all configuration data. I tend to install some AOSP-derived distribution on devices which are supported (or which I port it to myself), for those for which I can not find a working distribution I pare down the factory distribution as much as I can by removing bloat and replacing obnoxious apps with functional ones from F-Droid. This makes it possible to use e.g. a Samsung Galaxy SIII from 2014 with Android 11 as a daily device for 'dangerous' work.

The problem is not with the data but what's under it: a flash memory chip the manufacturer cheaped out on.

Never had problems with those either, who made those Android devices with such short-lived eMMC chips? I'm using a number of old Android devices from both well-known manufacturers like Motorola, Samsung and Sony as well as lesser-known ones like Ainol, none of these suffer from memory-induced slowdowns. In my experience it is the battery and the touch screen which are most likely to give out first. The battery can be replaced, sometimes the touch screen can as well but I tend to just use those devices for purposes where I don't need a screen (which I often actually just disconnect to save power) such as MPD-based media players, a trailer camera and IP cameras.

A guess: You don't (re)write data on your phone storage much? This experience is common for my girlfriend who takes 50 GB of photos every few months, transfers them all to the PC and does it again, but uncommon for me who practically never uses the internal storage except for apps.

Not really, these devices all have seen intensive use and are still being used in that way. Some only have a tiny amount of flash on board (e.g. Motorola Defy only has 2GB, I have 5 of these running as media player, MPD player, trailer camera and IP cameras) yet they persevere. Some (e.g. Defy) even have been used with swap-to-eMMC for a while, I ended up disabling this because it is just too slow but it made it possible to run some apps which otherwise would not run on 512MB devices. In short, I have not had problems with flash wear - yet.

>who made those Android devices with such short-lived eMMC chips?

Asus/Google did, the Nexus 7 would brick itself after a 2-4 years from failing/worn out eMMC flash.

I gave my Galaxy Nexus to my dad, so it saw longer use than usual. After five years it was virtually unusable. It was already slow when I stopped using it.

My Nexus 5, which is sitting in a drawer nowadays, also becomes ever slower. Even my HP Veer, keeping the Nexus 5 company, isn’t getting any faster either—even though it never saw real use.

So yeah, basically all manufacturers “do it”. It’s not even about heavy use or anything.

Just because it is running Android 11 does not mean it has seen meaningful security fixes in the last half decade.

Sometimes it's Google services. I've had tremendous success with LineageOS (and CyanogenMod) over the years.

This x100!

I have an S8 and although I am a Dev, I am really a Luddite on my phone. I have some random apps, a Google account and things like WhatsApp and Telegram but otherwise not really anything of note.

However, I find things like the share photo button sometimes taking 5 seconds for the list of who to share with to come up. How? Sometimes I click an app and it sits there for as much as 10 seconds before something comes up, tbf, that might be the app but I fail to see how compiled apps can become slower and slower over time by this much.

I suspect the enemy at the gate is tracking/metrics type apps that are sending a constant stream of drissle to the internet to try and get "actionable data" for their Lords and Masters but just make everything appear crap. I also loathe the need to fiddle all the time. Google Authenticator, absolutely fine until they decide that we need to press something to reveal the code, now it's 2 clicks instead of 1 50% reduction in productivity! I think they have reverted it but honestly, leave things alone!

a prominent example of this was the first google nexus 7 tablet, née Asus Memo Pad. Therein somehow the NAND flash became used up in some strange fashion making write speed unbearable. This also could not be fixed with a factory reset.

Old android phones make great dashcams. Most of them have automatic gps address lookup, g-sensor shock detection, far better cameras and more storage than most dedicated devices. There's several dashcam apps on the play store.

I have an original Samsung edge with a cracked screen. I keep it because it has an ANT+ radio on it that actually works, and still use it for updating and tuning my old Quarq power meter on my bicycle. It also works seamlessly with the ODB II Bluetooth scanner for working on my car. I migrated to apple and overall I'm much less annoyed than I was with android, but their support for non typical hardware devices still lacks. Somewhat intentionally, I might add. The iPhone should 100% be able to communicate for example with that bluetooth device but it refuses to pair with it because that protocol is locked down.

Have you tried DEX on it?

Ideally https://news.ycombinator.com/item?id=27885176 but when $$$ are involved nothing happens... (Thanks to all the product managers and the coding supporters in hn that cripple OS)

Use it as an HD webcam! Or, at least, before Zoom turns your stream into a 360p mess:

https://play.google.com/store/apps/details?id=com.dev47apps....

I use this and it's fantastic.

I do the same with an old Pixel and recommend it as well.

I have an original HTC One that would be absolutely excellent as an universal remote (because it actually has an IR blaster), yet HTC almost went out of their way to kneecap that in the last firmware update it got years back and no third-party IR apps seem to work with it.

I suspect it will end up as a 3D printer display, but the browser on it is hilariously slow by today’s standards, and pretty much every 3D printer front-end brings along enough JavaScript to choke it…

Use them:

- for their original purpose with either an AOSP-derived distribution (LineageOS et al) or a debloated/pared-down factory distribution

- as a portable media player

- as a remote-controlled media player using MPD for Android

- as a trailer camera with its own Wifi network, no cables needed between trailer and car, better camera than commercial trailer cameras

- as IP camera

- as a mobile sensor platform for whatever you may come up with

- as a satellite navigator platform

- as a GPS tracker

. ... and much more

shout out /r/androidafterlife

I use em till they die.

Also, the article doesn't mention Remote Mouse, which is the only non-game app I ever paid money for, because it is so good

Depends on how old, but for frontend development you can hook the device to Chrome Dev Tools and debug on a real device, not emulated.

There is value in testing with the old device as you still want your website to work regardless of what device someone has, within reason.

I personally run a tor node on an old android phone

How?

I use termux to run a tor node and i use a 5W charger and Type-C Ethernet cable to get constant internet and stable battery.

The real challenge is keeping the battery charged and operating.

agreed, though Qi wireless charging will increasingly make it easier

You can either change it (not always that hard even with minimal soldering skills, it’s actually harder to find a decent battery), or use it plugged in. My wife’s old Kindle Fire is my permanently plugged-in, wall-mounted kitchen recipe book.

Someone in a different post mentioned the risk of fire/battery bulging if you leave your device plugged in like that. Is that a legitimate risk? I assumed that (while not great for battery life) there's some circuitry that's making sure it's not charging a whole lot.

Never thought of that, I’d assume/hope it has protective circuits… It’s been on there for close to 2 years with no issues.

You can use a plug with timer or even a smart plug that device itself turns on and off when battery level reaches certain levels.

Not sure how great constant charging and recharging would be either ;)

Chargie [1] allows this for USB-A. It could be controlled via an Android app.

My problem with repurposing an old Android device is the security issues. Firmware doesn't get updated anymore. An alternative OS like LineageOS or PostmarketOS takes care of most of the software issues, but not the firmware itself.

Another issue is that the battery is going to be years old, and on 'recent old' Android devices its much more difficult to remove the battery.

[1] https://chargie.org

modern devices often keep the battery at 80% level if charged for a long time, for this reason. (they say "to extend battery life" in notifications, and that might also be a side effect, but AFAIK the primary reason is to reduce the probability of bulging.

But many/most of these older devices discuss, do not - and my personal anecdote is that of the tens of phones+laptops I have owned myself and managed for family through the years - there were 4 cases of bulging: 3 were constantly-charging devices (as in, 3-5 years with hardly any time not charging), and one that was dropped from height and bulged immediately.

Never heard or seen anything like that at all. The fact that you are not even given an option despite decades of "this really is one of the most important things to billions of devices" makes me a bit hesitant to believe it.

Hmm, since this is Android, would a rooted phone running AccA† to limit maximum charge work?

† https://github.com/MatteCarra/AccA/

Maybe use a dummy battery? I use one for my 4g wifi modem. The battery got swollen so I replaced it with a dummy that connect directly to a USB charger.

If you go camping/offroading/overlanding one popular use case is getting an old Android w/GPS to use with Gaia GPS. You can use the Android Auto app but it's much less feature filled and you'll be using your phone to do a lot of things. Also AA on old/slower devices can be.. rough in my experience.

This is probably really niche for hn. Personally I use an ipad mini w/a Garmin GLONASS GPS receiver.

I've repurposed an old HTC of mine as a datalogger and display for my cars aftermarket ECU. It works really nicely as a digital dashboard.

which ECU? I am about to do the same for my Speeduino

I run a Haltech, I can run the phone straight through it's USB output. I would assume you'd be able to do similar with a speeduino

I discovered the other day that you can use your old android phone as a server for OctoPrint, a 3D printer controller that runs off a web interface. I am going to give this a try using my old OnePlus 3T.

https://github.com/feelfreelinux/octo4a

I have a bunch of android 4 and 4.4 devices that work nicely but you can't install a working browser on it.

I want to start using them as an always on display for kitchen/home assistant but I would need a browser for example, kiosk mode preferably.

What's stopping you from installing a browser app from APKPure, or one of the other repos?

Alternatively you could roll-your-own basic full screen browser via Android Studio and about 20 lines of Java.

Can I quickly derail the conversation to talk about APKPure?

I use their app instead of the Play Store and I have no complaints. Once in a blue moon it's missing an app, but never one I couldn't live without.

Having said that, why is APKPure? Who is funding them? Are they to be trusted? Have they stolen my passwords? Does anyone know?

That's an interesting question so I did a quick Duck and turned up a few things.

[1] Is APKPure safe to use? https://nordvpn.com/blog/is-apkpure-safe/

[2] "APKPure is not safe, distributes Trojans" (2021) https://www.kaspersky.com/blog/infected-apkpure/39273/

[3] Claims that APKPure is now owned by Blizzard Entertainment https://chimgadar.blogspot.com/

[4] Shows their 2014 seed round https://www.crunchbase.com/organization/glance-app/company_f...

[5] https://www.avg.com/en/signal/is-apkpure-safe

Short answer? I am not sure but then I use F-Droid which has the same pros and cons as APKPure so [shrug]

i have "tried" many but most dont work.....

i have tried to find old versions of apps but they almost always require andrdoid 5+ at least.

no, i have not rolled out own browser because i don't know how... maybe there is a need to build or maintain apps for old devices using old sdks and tools?

From a few months ago: “Repurposing an old Android phone as a web server” – https://news.ycombinator.com/item?id=31841051

PostmarketOS

I have searched for a way to use my Xiaomi Mi A1 phone. I want to use it as a personal cloud storage, but I haven't found out how to do it. Using it as a dedicated ebook reader maybe the best idea I can do with it.

Try installing termux, then install Apache and PHP inside termux, and finally run NextCloud server on it.

https://www.reddit.com/r/termux/comments/mkzoyd/showcase_ful...

Install Android 12 on it and give it to someone. It's a perfectly fine phone.

https://wiki.lineageos.org/devices/tissot/

https://wiki.postmarketos.org/wiki/Xiaomi_Mi_A1_(xiaomi-tiss...

It isn't that well supported in PostmarketOS (charging and OTG), but that sounds fairly fixable. Ideally you'd want both, then connect to a charger/ethernet combo.

You might be able to use the downstream kernel for that, or Termux on Android.

I use a old cellphone for music player when running. Smaller than new phone and without notification of hundred of apps on my main cell.

GSM module, GPS module, SOC, Operating system. I mean, these things are incredebly valuable. One thi g i can think of is drone brain

"Incredibly" valuable. Not anymore, they're common goods now. I bought a USB GPS module on Aliexpress the other day for a couple of USD. GSM modules also exist for USB. Virtually all of them run proprietary firmware. An old SoC is not very valuable, if you consider say Raspberry Pico and what you can do with such. The best thing to do with an old smartphone is IMO to recycle (= mostly downcycle) it. It still contains some valuable metals like cobalt and gold.

... and some can be totally reflashed with mainstream Linux:

https://liliputing.com/this-dirt-cheap-4g-lte-modem-on-a-usb...

I keep one one with team viewer running so I can connect to the bluetooth devices at the house.

I'm using mine as an alarm clock. Not network connected, so it can't spy on me.

So you also don't use a smartphone in general? Because otherwise having an extra device just for the alarm clock functionality, doesn't really stop the general spying on you... unless you are particularly worried about keeping your waking up times private.

The enemy must never know when he sleeps!

> Not network connected, so it can't spy on me.

In the age post-bluepwn and broadpwn, I'd assume otherwise. Especially considering that most OEM images come with admob, which even has ultrasonic RCEs that can be delivered by your TV's or radio's audio signal.

Opsec kinda mandates to destroy all broadcom chips :D

Want to use mine as a CCTV footage dump whenever online & offload to S3 otherwise

One problem is power draw. I figured out I can use an old phone with a removable battery without the battery but I still need a battery to power it up. However,if I do certain things that I presume need a burst of energy (wrong term?) that is enough to power cycle the phone. At least that's my guess because flash doesn't work.

Also do not use an old phone with a battery with screen turned on, capturing photos on repeat. The battery WILL swell up. It may take a few months but it will happen. Don't risk it.

You could connect power to the battery connector, like I did recently to a Nook: https://github.com/jonatron/trook/

I simply have a laptop (65W) USB C connected to the phone. I wasn't able to turn it on a month or so ago but tried it again after your reply and yes it still works. I use open camera to take a picture every so often (30s is one option). The phone is old and has a cracked display but the back is user removable so it is really nice. I attach the USB C cable, connect the (now very swollen) battery in, power on the phone, and remove the battery once the phone boots. As long as I don't do anything insane like try to use the flash, it works.

I appreciate the laugh at

> I tried acetone, because I had a bottle next to the alcohol, which went well.

Haha

can you please expand on this part though?

> Unfortunately, the micro-USB connector charges the battery, it doesn't power the device. This can be fixed by connecting a random 5V power supply to the battery connector instead.

Do I need a soldering iron for this? Thanks in advance.

Edit: do you know how we could get open camera or any camera app on Android to take pictures with the screen turned off? It really doesn't need the screen on all the time.

My idea was to simply have the phone screen off, one always running app tapping into the RTSP stream on WiFi then offload it every few minutes. Could have a smart power supply hooked up to drain the battery to low digits every now & then. Smart batteries with programmable functions & voltages would have been a boon for so many legacy electronics

old, scratched phone "requiring repair" is something you can inconspicuously keep on your table, with recording app, if you want to learn what people discuss in your absence.

Toss it.

Polluter.

Thats what iPhones are for.

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