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Comment by lockhouse | Hacker News Reader

Honest and tangentially related question…has anyone else noticed that Apple devices hold their battery life in suspend mode way better than Windows, Android, or Linux ones do?

My kids mostly only use their Kindle Fire tablets on the weekends and even if they get fully charged Sunday night, they’re running on fumes by Friday, even if they’ve been completely unused in the interim.

Meanwhile, I have an iPhone from my employer that I usually top off once a week, but it’s still well over 80% most of the time during the same period.

What magic is Apple using here?

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A couple things:

1. On Windows and Linux, devices have to handle a huge number of hardware configurations. Not everything can go into the same "deep sleep" mode with the same instructions, so developers implement different "idle" states that may or may not discharge the battery quickly. Too many sales efforts focus on making a laptop 'boot' from idle in seconds, and too few focus on making it usable after being off for days. Look up "S3 Deep Sleep", "Modern Standby", and the bevy of options described at https://learn.microsoft.com/en-us/windows-hardware/drivers/k... to learn more. Apple only supports a small list of hardware platforms, and can make deep sleep work and resume quickly and reliably on just that list. Even the Kindle Fire is not totally vertically integrated between the MediaTek processor and Android OS and Amazon UI, there's bound to have been a lot of finger-pointing and little leadership pushing for microamp-level sleep capabilities.

2. Android/Windows/Linux allow users to install applications that do things that consume battery in the background - for example, my Tile bluetooth locators and Garmin smartwatch work great with my Android phones. They wake up a sleeping phone and force it to use a little power to grab a location data point or send my watch an updated weather forecast. Apple doesn't let third-party developers do the same.

I'd bet that if you pushed and held the power button on your Kindle tablet on Sunday night for 3 seconds and chose a full "Shut Down", and then held the button again Friday for 2 seconds, it would have the same battery level as it had when you turned it off. It's just because it's been checking for system/app updates and otherwise running code while 'sleeping' unused that the batteries are low, in spite of the fact that no humans were using it.

Is it even possible to fully turn off a Kindle anymore? I want to do exactly what you’re saying to prevent the draining of the battery, but the only options that appear after holding the power button are “Cancel” “Restart” and “Screen Off”. Holding the power button longer just seems to restart the device :/

I they need them always on so that they can gather up data from Amazon smart TVs that were never connected to the internet (project Sidewalk).

Kindles have an airplane mode. I use mine only for sideloading so it hasn't connected to the internet in years.

I always just shut down my Windows/Linux machines, sleep in all its forms has never worked properly. It's far better for my sanity to just turn it off knowing I can just turn it back on.

Especially in this day and age of blazing fast (read: several gigabytes per second) SSDs, cold boot speed for most people is a non-issue.

I set my laptops to hibernate when the lid closes. Entire RAM written to disk, then a full powerdown. Do turn off wake timers and wake on USB (sometimes disabled in true hibernation but not always).

I don't use hibernate either: /Usually/ it works fine, but once in a while Windows just derps getting back up necessitating a full reboot. I don't want to deal with inconsistent shit like that, I'd rather just go for a proper shut down and cold boot so I can expect consistency and therefore reliability.

It's the magic of "not being allowed to run anything".

If you kill -9 all your Linux processes then you'll be great at idle use as well.

Now hunting down all the processes that might be turning on your radios, CPUs and I/O devices is the hard part on OSes where you can actually run things in the background, since you easily get into tragedy of the commons situations.

For comparison, consider a Kindle (linux device, battery lasts for weeks) or a Garmin watch (battery life is about 3-10x better than Apple watch) to see how different can outcomes be if you control what processes run.

Processes don't run while a computer is in suspend mode.

Of course they do on modern computers (so do peripheral microcontrollers).

Most modern laptops and devices don't go into full suspend states anymore, they just do a much lighter standby similar to phones and tablets. Windows calls this "Modern Standby" while Apple just does it since Apple Sillicon.

Even so, periodically they will wake up and run tasks just like phones (e.g. Power Nap on Apples, no idea what Windows calls it). Linux has a headache here because it's mostly not prepared to disable all their processes and peripherals correctly during those states so something keeps waking up and running.

Linux assuredly does not periodically wake from standby to run random background tasks. I welcome a reference to the contrary. (Android notwithstanding -- I know phones and tablets do not truly suspend -- I am responding to the suggestion of manually managing background tasks which generally implies a non-handheld OS.)

I wasn't aware macOS enables Power Nap permanently on Apple silicon, interesting.

I have quite an old samsung tablet that, when I keep wifi and bluetooth turned off in LineageOS, has just this week surprised me as I had fully charged it and hadn't used it in about a month or so, it still had 70% battery life left. It may have even been closer to two months, I can't be sure.

But if I leave the wifi on, even with syncthing/etc not running at all, it will last about as long as you'd expect an unused android tablet to.

I'm sure it's many tricks adding to one great feat, but I've always guessed that many of these devices could probably be better optimized for what is ironically their primary use case: using low amounts of power in standby while still able to relay important information as needed.

But if that's any part of the apple magic, how does the trick work, and why aren't more devices doing similar things?

For Android just leave battery saver permanently enabled at 100% charge. You lose animations and haptic feedback but it cuts down on radio usage and extends battery life.

No magic whatsoever and this is not an Apple-thing. Tune your device well and you can achieve this on not just Android but old Android devices. Just like your employer-provided iPhone I have some devices which are rarely used but still kept charged for when they're needed. Unlike your employer-provided iPhone these devices are old in gadget-terms, e.g. a Samsung Galaxy Tab 3 10.1" from 2013 which is used occasionally but mostly just dozes its way through "life". I just checked its battery, it tells me the last charge was 5 days ago and the battery is at 73%. This is the original battery, 10 years old. I did an experiment with a Motorola Defy+ some years ago to see how long the thing would last on a single charge, doing absolutely nothing which turned out to be 26 days The key here is that all my devices run either AOSP-derived distributions like CyanogenMod (the Defy's - I have 5 of them, 3 in regular use) or LineageOS (the Galaxy's). They do not have any Google apps installed, some of them use microG as a substitute for those few apps which need it. They mostly run free software except for the few commercial/proprietary things needed - mostly banking and electronic-ID related - which also means there is no background traffic to commercial entities who desire to profit from my data.

If you think a bit about this it isn't that strange, really. Compared to iThings most Android devices have relatively high-capacity batteries while the rest of the hardware is quite similar. The higher battery capacities tend to be (ab)used to enable a host of data-hungry apps to run on the things, sending their spoils off to their masters. If you kill those apps and their means of subsistence you're left with a device with a lot of battery to spare.

I believe Macs readily hibernate, moreso than Windows or Linux laptops do (if at all). macOS has a few tricks to make it seem more responsive coming out of hibernation (such as showing a fake image of the desktop before it becomes responsive) which lets it get away with this. (I can't find anything to back this up right now, but I remember reading this somewhere, and my experience with at least some versions of macOS match this.)

On the other hand, my Linux laptop (Dell XPS 15) lasts much longer while awake and runs far cooler than any other device I own. There simply is less crud running in the background keeping it active. (Disabling off-chip graphics, disabling full-disk indexing, and applying all suggestions from Intel PowerTOP play a big part here. vs. on my Mac, I'm forced to force-enable off-chip graphics, else input lag is horrendous.)

My experience is the opposite. My company gave me an M1 mac that I leave plugged while I work. It is at 100% when I shut it down Friday afternoon, and its at around 40% when I boot it up on Monday morning.

I suspect the battery is defective, but like I said I leave it docked when I work anyway so I don't really care.

That sounds like a software config issue. Any chance you have "Wake for network access" set to "Always" instead of "Only on Power Adapter?"

Even if it shows as set to "Only on Power Adapter" change it to something else and then change it back. I once had a case where the UI state for a setting was inconsistent with the underlying system state.

I have an android tablet that I use every couple of weeks. There's no noticeable battery discharge between uses. I think I've maybe charged it once ever.

The "magic" is no features. For example All day events can have a notification at 9:00AM and that's it. You can't change it. You can't have 100 events with different notification times. The phone only has to wake up at 9:00, check the events and that"s it. There are many, many examples like this on the iPhone.

That's just a stupid limitation of the UI on the iPhone. On a Mac you can set a custom time, which triggers just fine on an iPhone.

> For example All day events can have a notification at 9:00AM and that's it.

That's a bizarre limitation that they should fix, but I don't think it implies anything about how iPhones work in standby. Alarms, timers, reminders, push notifications, etc. seem to work fine in standby (although I'm sure standby battery life is affected by how often those are happening).

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