I've wanted to build this myself for a long time but couldn't figure out how to overcome the spicy pillow problem.
Maybe I'm barking up the wrong tree, but I thought it was risky to leave a phone plugged in all the time. Does it need to be a modern version of Android OS that has the smart charging that stops at like 85%?
Yes that's what I do too! I didn't know that blogpost but I generally replace the battery with a DC-DC converter module from Ali. You can even tune the voltage and see the indicator change the battery charge level. I put them around 4 volt. The advantage of these modules is also that you don't need a beefy 5V power supply, you can simply grab a 12V or so (I have a full drawer of those from shucking external hard drives) and it will regulate it down nicely. They are 80 cents a piece (10 for 8 euro): https://es.aliexpress.com/item/1005007508685885.html and they can deliver up to 3A or so which is enough to handle the peaks. They're a bit bulky but I just tend to mount them elsewhere. Make sure you use a fairly thick cable to the phone then to minimise losses at that low voltage.
I didn't have to bother with the thermistor but some models need it yes. And some even have an i2c charge level module which is even harder to simulate though it can be done.
It's a statistical thing. Most phones don't explode their batteries. When you have a hundred or a thousand together, the chance that at least one has a battery explosion starts to reach concerning levels and you ask what you can do to avoid it.
It's not really. I've had a test bench with smartphones at work with open smartphone test farm and about 50% of them cracked their cases open after a year or two. It is not a joke. It really happens. None of them actually got to the point of exploding but it didn't exactly look "safe". Of course I replaced them when this happened. Sometimes it took a while because they were on a stand, we only controlled them remotely so it would take me cleaning the stand or something to notice something was off.
Still, it served our support team really well during the pandemic. They could test wifi setups at the office with different android versions even when they were in a country that was on lockdown themselves.
I left my ~$1k OnePlus phone on the wireless charger for after ATT told me I couldn't use it and forced their spyware Samsung phone on me, The battery puffed up after about a year.
I carefully charged a Motorola G Power 2020 to a 60% SoC (which should be very safe) and left it in the car, unplugged, as a spare. It puffed up in about 6 months.
An ignored Galaxy S7 puffed up while sitting on a shelf, unplugged, in a climate-controlled room.
Some other devices have been fine for far longer periods so it's not like I'm thinking it's endemic or anything (my Sony PSP is still working well-enough with its still-flat lipo cell from 2008), but it's certainly a concern.
Usually I replace a smartphone because it has some hardware fault that makes it unusable and it is hard to repair or the cost of repair vs capability is not very favorable.
Even if I was replacing smartphone before they died, I would probably sell them anyway. Do people really have various phones in working order waiting in a drawer?
Usually I replace my phone when the battery is almost dead and a full charge doesn't last more than a few hours. At that point the phone is usable but not good enough to sell. I usually keep it as an emergency backup phone
For some reason I tend to break screens way before the battery dies usually. I am not afraid to replace a battery or even a screen if phone is not totally out of date. Having said that there seems to always be a point when they start acting semi eratically or stop booting.
I had a totally outdated and probably insecure Samsung S6 edge 2 years ago that started rebooting randomly. I think that prior to that it was so old I could only install stuff from f-droid and aurora because roots certs installed on that old android version were too old for playstore to work. Too bad as you can't easily find smartphones in similar sizes anymore.
Knocking on wood my pixel 6a still going strong after 2 years.
I will upgrade when my device is many generations out of date. So no one really wants to buy one and I will then buy not the latest but a generation or two “out of date” so it’s cheaper. So I have a heap of phones over the years that no one wants. Not even me.
I try to get rid of my old stuff ASAP, it reduces clutter both physically and mentally.
I know many people who had their old phones and computers lying around because they didn't invest the time to transfer the data. Not long after, the phone was unusable either due to hardware problems or forgotten passwords, and the data is lost forever.
I take my previous phone kayaking. Once I have downloaded the appropriate maps over wifi, I can use it for navigation, logging and photography without being worried by the prospect of dropping it in the water.
I never sell anything, everything finds a new life.
I got a Sony Xperia Compact from maybe 2016. I use it as a bicycle navigator / recorder. Recently it stopped reading SIMs, probably rusty contacts, but all I need is wifi to update OSMAnd and send me the tracks I recorded.
I also have a very old tablet, maybe 2014. My SO uses it to view movies with VLC and TV via TVHeadend.
Oh wow, although I submitted it some days ago, I somehow got on the front page! Thanks for that!
Also as a note: this platform is nowhere near finished! I had this idea in my mind for a long time that I wanted to reuse my old phones and tablets as displays in my home. I also know that finding the right apps for these old platforms is a challenge in itself, that's why I went the route of creating an ES5 (that nobody writes anymore!) web app that most of these devices still support. The client's whole purpose is to display canvas and media files that the server dictates on-demand via websocket, while keeping a synchronized clock.
On Instagram I always saw these very cool widgets like retro clocks, split-flip boards, YouTube subscriber counters that I felt urged to buy. But I thought to myself that the old phones I already have could also do the same.
I am a long-time software engineer myself, but could never take the time to validate whether my ideas work. So I thought, why not try it out with Codex. After long prompting, supervising and correcting, I got a very usable solution that I now pleasantly use myself at home.
You can also vibe-code your widget if you want! You are not restricted to use the built-in ones. Just copy the "Canvas Widget Guide" you find under "Left Sidebar > Create > Smart Widget > Tutorial" and copy that article in ChatGPT or Claude while describing what your widget should display.
Then paste the code to "Create > Smart Widget > Edit the Code" in the Widget Details. (this flow should be more intuitive...)
You are able to send JSON data to your widget via an API.
An account is necessary to couple your devices to your wall. And auth is implemented via Better-Auth. I stopped Codex immediately when he tried to implement the login stuff from scratch. :)
Gotta get a lot of downvotes here but I don't care, I stand by my opinions: this is the best example that not all vibe-coded apps are "slop". If you have enough experience (or are smart enough to speed-run experience), good ideas, good attention to details and decent taste you can totally vibe-code cool things that are worth sharing. This true/false dichotomic attitude towards apps you see here from many HNers where "written by hand: good/vibe-coded: bad no matter what" really rubs me the wrong way.
I am interested to hear what features you guys want in the next iterations! While building ScreenWall, I actually had art installations, home dashboards and train depature info screens in mind. Interacting with the screens and triggering events across other screens is also in the pipeline. Would be cool, if you can give me some crazy ideas, so I can prepare the client runtime better.
I literally wanted to use RasberryPi to build this for my desktop since i loved those desk widgets showing cool info like the weather or time ... this is so cool!
Congrats, this looks very cool! I haven't tested it yet, but is it possible to make it work offline? I'd prefer devices running unsupported or unmaintained operating systems to avoid Internet access altogether.
The account mechanism is just used to scope the devices to „walls“. Otherwise I don‘t mine anything. But I share your sentiment, that this should maybe a self-hostable tool.
This is work in progress project of mine! I have so many ideas how I can make it better, but before I overengineer it just for myself (I think this is typicial engineer mentality), I wanted to submit it to HN before I lose my interest over time, like my other projects…
Working on ScreenWall (https://www.screenwall.app) because I had old phones sitting in a drawer doing nothing, and now I use them as passive widgets on my desk and wall. I use the browsers of the devices to join a shared "wall". From there I can push images, video, gifs, or a synced canvas to it (and any other old screens I add) without installing anything. Started as a one-device hack for my desk clock, but it scales to syncing multiple screens at once if you've got more than one old device lying around.