> I've read about so many instances where people used wall mounted iPads and Android tablets where the batteries would swell after a period of use.

Made that mistake myself. I now have a wall mounted iPad with the charger plugged into a timer powerpoint that only switches on for 1hr a day. Been running like that for 5+ years now without issue. (I'd planned for that to just be a proof of concept, and to use a wifi powerpoint that'd turn on when the battery dropped to 20% and back off where it hit 80%. The easy solution has turned out to be "good enough" and has remained in production, like that cronjob perl script from 2004...)

That is a great idea. I wish I had thought of that myself (even though I already do something similar with a USB powered cordless phone that stops charging when I sleep my system).

One of my use cases is to monitor my surveillance cameras, which drains my batteries quickly, but I have unused wemo switches that I could put on a schedule to just cycle power more frequently for intermittent charging.

Really cool! Could you give specifics about the typical low and high of the battery cycle, please? (from XX% to XX%).

I'd been intending to aim for 20%-80% cycles, because I read that's "good for lithium batteries".

The timer switch I grabbed to do my proof of concept only has 15min resolution (it's a weird old mechanical one where you move plastic pins in the stop/start time rings). I recall setting it to 45mins because the docs says the iPad gets 80% charge in 1 hour, and it'd occasionally run down and switch off, so I bumped it up to 1hr and haven't touched it since.

I just checked now, it charged for an hour overnight finishing ~10.5 hours ago, and is currently saying 59% charge. I honestly have no idea how low or high the charge level gets, just that I haven't needed to wake it back up from a shutdown in over 4 years...

I've come to doubt the details there are important. Don't leave it on charge 24x7, that'll kill it fairly quickly (~9 months in one data point of mine). Charge it long enough and regularly enough to keep it running, but at the low end of that spectrum. Keep in mind my goal here is less "extend the life of the battery", and more " prevent the battery from swelling up and damaging the device/catching fire", but I suspect there's a fair bit of crossover between those goals, since I've not needed to increase the charge time in response to any battery capacity decrease over 5 years (which in retrospect surprises me somewhat).

If I was aiming to maintain the best possible range in an electric vehicle, I'd probably pay much more attention to max charge and min discharge levels, but "the simplest possible thing" has been working well enough for me to just leave it alone.

If it dies on me tomorrow, I'll be happy enough with the use I got out of it and the tradeoff of time I spent futzing with it.

(Note: I'm also quite familiar with abusing LiPo batteries way past safe limits, I raced FPV quadcopters 5-6 years back, and in my worst excesses, I'd be aiming to completely drain a flight pack in ~2 minutes. They'd end up too hot to touch, and start to decline to the point of not being race competitive within 20 or 25 cycles. They'd also catch into unextinguishable fire in big crashes and occasionally while charging. I have a healthy fear/respect of high capacity and high current LiPo batteries...)

I have a six year old phone that still runs on the original battery. The capacity is pretty low but still lasts for 2-3 hours of active usage. Just charge it for an hour per day and you'll be fine.

I've had an iPad 2 on my wall for home automation which I just removed because we are moving. Now I'm afraid to open it and see what the battery did after all those years on a charger.

> What I'd like to know is if it will work with the battery compartment empty on AC power only.

The Pinebook laptops can work without a battery while connected to AC, but not out of the box. A simple hardware mod is necessary to enable this, that's documented by Pine.

That is unusual. I have never had a laptop that would not work without a battery present.

It’s really not, especially for high end models if you are stressing your hardware and it’s not an awfully thermally limited design you’ll drain the battery even when you are connected to the charger.

You have 60W chargers usually for systems with max power draw of the CPU+GPU that can reach around 200W peak and in the mid to high 1XXW sustained if you have a DTR/high-performance “mobile” CPU + dGPU.

Even if your laptop comes with a 90W charger it’s still a problem because it’s not enough to power a 65W series H CPU and a high end GPU that draws another 80-120W.

Most laptops will always use the battery directly and trickle charge it due to the power draw.

Power(hungry)ful modern gaming/DTR style laptops can use both concurrently, heck older gaming laptops used to come with multiple power supplies that were needed simply because even the battery wasn’t enough at the time to serve as a buffer, so you had to plug in 2 power adapters to power the laptop fully.

Even without this constraint having a single power path is cheaper and simpler to design so most manufacturers just only draw from the battery and have a separate charging circuit that charges it without having to add power balancing and switching circuitry.

IBM thinkpads used to advertise that you can switch the battery while the laptop was plugged into the charger most laptops of that period didn’t support this either.

If you go even further it was even more of a headache because older laptops used LiPo batteries which were even more finicky.

> older gaming laptops used to come with multiple power supplies

Some curious digging found two examples (with pictures):

https://www.gamersnexus.net/news-pc/2612-why-2-power-adapter...

https://hothardware.com/reviews/dell-alienware-area-51m-revi...

I have a couple of old ThinkPads that work but seem to throttle heavily, I've attributed it to need for better burst draw handling.

Also one of their older W models that will only run on battery if a standard 90W power supply is connected and will only charge the battery if the device is off. Running on external power is only supported with the 135W or (stock) 170W PSU.

MBPs at some point switched to drawing power faster than it could be provided by the plug alone. Of course, you can't tell nowadays whether laptops will work without a battery, because most batteries are non-removeable.

I don't think I've ever seen that behavior with a MacBook Pro of any vintage -- and I've had an MBP of one stripe or another since at least 2007, using the date of the 2007 MacBook Pro gathering dust bunnies nearby -- except when I use the wrong power supply with it, e.g., a 13" MBP power supply with a 15" one, or my MacBook Air's power supply with any MBP now.

I wouldn't doubt it's possible to draw more power than the adapter can give you if you're pushing the MBP full-bore, but I'm pretty sure that under normal power loads, this doesn't happen.

Try mining cryptocurrency, running prime95, playing fps shooters, or even dota on high settings. You will notice the battery draining while plugged in. You also see it if you are on an airplane, but that is usually because the charger tries to pull too much and overheats and gives up ghost. Macbooks have underpowered chargers.

> Macbooks have underpowered chargers.

My 16” shipped with a 96 watt charger, and I’ve not seen a laptop with a higher powered one. I’d have to contend with that assertion.

I had 180W for my old HP laptop, and recently ~135W (or 170W) for Thinkpad W541.

<100W adapters were mostly for potato laptops, until USB-C came into picture which supported up to 100W and now manfucaturers adapted (and probably wait for 200W PD).

Newer Dells pull 180W from a paired USB-C dock connector.

Nice to see workarounds.

I must say that I love that I just plug out the laptop power adapter and plug it into my phone (or mouse) and it charges. Even when it comes with lower performance of the laptop.

Are all other laptops you've seen potato? My Dell XPS 15", 130 watts.

My current Dell laptop uses a 240 watt charger

ThinkPad P73 has 230 Watt charger.

I suspect that this is the reason why MBPs now refuse to boot on low battery. You used to be able to start up the machine when your battery was at 0% (as long as you were plugged in), but newer MBPs complain and don't boot up until you recharge to 10% or so.

They just bumped the power adapter on the 2019 MBP up a little bit. I've seen people say that if they max all cores and leave it that way it will drain the battery even if it's plugged in. I haven't attempted that, and I've never seen the behavior under any other circumstance.

I've run into it a few times with mine (2017 15" MVP, 3.1GHz Quad i7, 16GB RAM, Radeon Pro 560). I had an issue the other day where a virtual machine got stuck in a loop while testing some background jobs. Each time I tested it, another infinite job booted up. Eventually, I had like 30 of them running when I took off my headphones and heard the fans. Checked my battery and I was down to 65% despite being plugged in. I'm guessing that happened over the course of an hour or so.

I've also had it happen a few times when running unit tests for a different project in Docker, but that's likely just because Docker for Mac makes Electron look resource efficient.

It does, just launch any game that uses 3D (tried Starcraft 2 and WoW) - you will see that battery will drain when you have power adapter plugged in - MacBook Pro from (AFAIR) 2018.

That's unusual for modern machines. It was de rigeur from the first portables up to about 2005, as I recall.

I was rudely surprised by my first Core 2-era machine that wouldn't boot without a battery installed, because prior to that, from Pentium-based Toughbooks back to the 486-based Noteflex back to various 8088 and even pre-x86 machines (PC8201A, club100 represent!), they were all absolutely fine running from the power inlet alone with no battery.

The Zenith MiniSport was the sole exception because the power jack was actually physically on the battery, but you could still gut an old dead battery and make a dummy, and it would run from the brick just fine. (This is documented in the very first issue of Brian Mork's excellent Minisport Laptop Hacker zine, available wherever fine textfiles are sold.)

Lenovos etc. don't care, but I've seen this first hand with some Acer and Asus laptops. It has nothing to do w/peak power consumption, that is a wholly different problem, of a different class of devices.

some Lenovo devices do throttle though. If you do not have a battery and are using the 65W not 90W lenovo chargers on an X220, it will throttle your power.

I went with raspberry pi + LCD. Even though there are many LCD options I recommend going with their official pi touch display, it just works without headaches. I did use their official enclosure, but it doesn't really seem to be well designed for wall mount (some 3d printing and magnets helped).

I think going with an android tablet is fine and headache free. I just don't like aesthetics of that solution.

> I think going with an android tablet is fine and headache free.

The problem with many tablets is that leaving them plugged can cause batteries to swell, which can end up being a huge headache.

I've heard stories of offices that used iPads as wall mounted displays having this problem, so I don't think any particular make or model is immune to this issue.

I considered Pi+Monitor, but for me, something like the Pinetab is a cleaner, simpler solution. And at $99 without the keyboard, that's a pretty decent price.

> I considered Pi+Monitor, but for me, something like the Pinetab is a cleaner, simpler solution. And at $99 without the keyboard, that's a pretty decent price.

Of course you should go for what is easier for you, and the pinetab does sound easier, however I'd argue that it is not cleaner.

Separating the screen and main unit will allow for a more serviceable solution, changing either piece if it breaks, or upgrading the main unit if you need more power/different connectivity.

Yep, this was the first thing I thought of. Hoping to do the same thing.