Charging a lithium battery to 80% only?

I wish they would label it so that it shows 100% charge when it's actually charged 80%, and then give an option to 'overcharge' a configurable amount till 125% (the current 100%). That way it will make people aware that they are reducing the battery life by overcharging, and be picky when they overcharge.

But this won't happen because reduced battery life is a big direct and indirect(by reducing performance like Apple does with old iPhones) driver of phone upgrades.

by reducing performance like Apple does with old iPhones

What Apple did was clock down the CPU of iPhones with degraded batteries in order to reduce peak load which would otherwise result in crashes that would have made the device borderline unusable below some charge percentage.

Yes, they should have shipped the feature off by default and with a toggle, but the feature itself was amazing as it let already old phones last longer than they otherwise would have.

Apple deserves a lot of shit for their bullshit surrounding replacement parts, but this particular topic is something they get an undeserved amount of shit for in my opinion.

"What Apple did was clock down the CPU of iPhones with degraded batteries in order to reduce peak load"

It wasn't what Apple was doing that was the problem, it was the fact that they were initially quite secretive about it! People just started noticing their phones slowing down without explanation. Now days iOS tells if your battery no longer supports peak performance, which is the right thing to do.

"Yes, they should have shipped the feature off by default and with a toggle"

Oh, it should always have been on by default. Most people would much rather their phone run a little slower than risk random crashes and shutdowns! But iOS should have told you about this from the start.

I wonder how many products have components that downgrade under specific situations and they never explicitly tell the customer - and most customers don’t ask because it’s “complicated tech” they don’t want to know about it.

I think a lot of laptops do this because their cooling system is too weak for the CPU.

The Lenovo Thinkpad t480s comes to my mind: with factory settings, the CPU was unable to reach its advertised boost frequency nor maintain its max non-boost frequency for more than a few minutes. After 5 to 10 minutes, the machine was usually running at 300/400mhz under its advertised clock speed.

Undervolting helped a lot but could not fix the issue completely, under clocking was the only solution to maintain a consistent clock speed.

Thinkpads, for a long time have had a fan speed that's possible, but never reached by the firmware's automatic mode. On Linux, this sets the fan to its true maximum:

    # echo disengaged > /proc/acpi/ibm/fan

I use the thinkfan utility to run the fan more aggressively, including 'disengaged' over 70C.

How's your hearing? If any left.

I put in foam-tipped earbuds if I'm doing a big compile or something, but the Ryzen 6850u runs pretty cool most of the time.

Indeed, and for the t480s we could undervolt the CPU to help with thermals but these are not normally accessible to the end user.

So if you are an average user of a Lenovo laptop without technical skills, you probably have a machine that does not meet the advertised performance, and no way to fix it.

IMO, at least with x86, there is a point where it simply doesn’t make sense to cram higher clocks into a laptop. The last Intel MBP could be had with an i9, and IME if you left turbo enabled, even at idle the fans were annoyingly loud. If you pushed it, you’d get a quiet jet engine as they struggled to keep temps just below 95 C.

It was usually less annoying for me to just disable turbo, and only turn it on if I really needed the boost.

This is likely the case with all but gaming laptops. Most users won't care about performance under consistent, heavy workload, as much as it loading that .docx in 2 instead of 6 seconds. That burst of performance is what makes the system feel snappy and fast. If the user is happy, it was well worth the money too.

Clog the heatsink on just about any PC and it'll happily and silently thermal throttle itself.

That stretches the definition of silent. On MacOS you need command line utilities or third party software to observe throttling, but on Windows this information is easily viewable in the performance tab of the task manager, and Linux exposes this information in /proc.

Being buried away in technical debugging tools is 'silent' for 99.9% of users.

A common task that repair shops do to "fix a slow PC" is clean dust from the fans and heatsinks to reduce throttling. Users don't know or understand that this is happening, they just know their system is slow.

A lot of laptops do this when running on battery power. Do they pop up notices telling users they are running in reduced power mode?

I recall mine sometimes doing so if I unplug while it is on. Never occurs while it is booted on battery.

Laptops and phones also notoriously slow down to manage heat, and that is also never told to the user.

plenty. But normally the degradation is more gradual and automatic. For example, as the innards of your clothes dryer gets clogged up with lint, at some point the thermal cutout will cut in and out to briefly reduce the heat.

End result is your old clothes dryer starts taking longer and longer to dry clothes.

Maybe this is just me but I always assumed USB cables had indefinite lifespan until I happened to read a datasheet.

Maybe.

But you might overestimate technical understanding of people.

"Letting people know" comes with it's own challenges.

There are a lot of choices an OS makes without letting it's users know.

It would be quite overwhelming to communicate all. And in making choice what to communicate mistakes might be made.

Screaming disgrace is a bit exaggerated.

When this came out, most people were distrustful because it was a secret. It was seen as a way to force device upgrades, not save devices. If they had been transparent, even in documentation, (and allowed opt out) it would have curbed some of this backlash.

It may well have, but that doesn't mean the backlash was reasonable.

I believe it was perfectly reasonable based on the information at hand. Apple gave no reason to believe otherwise and behaved in a way that appeared deceptive.

I was an iPhone 6 user at the time and an Apple fan. I think the secrecy surrounding the move means that the backlash was reasonable.

Consider: a pop up saying "Your battery need replacing, it is operating in slow mode to avoid crashes" v people thinking "Damn, my phone is slow - I better buy a new phone"

People just started noticing their phones slowing down without explanation.

Also, Apple already had somewhat of a reputation; this was far from the first time they would do shitty things, blame the users, and/or refuse to communicate what's going on.

It's a classic case of 100% right and 100% fired: https://www.youtube.com/watch?v=nDO24U3hMkU

Well, duh. You're holding it wrong. /s

I never could get that to not work. No matter what I did the signal didn't degrade.

because by the time you tested they had already boosted signal power beyond all guidelines

Thin hands and hollow bones?

iPhones with degraded batteries have the tendency to shutdown on peak loads. Default is fine but only after a big fat pop-up with the option to deactivate it.

As if the typical user (not anyone that browsers hn) actually reads the _big fat popup_ and would just click through anyways. With no care or worry about what that pop up said or the implications.

Apple “You clicked a pop up that said you accepted random shutdowns and reboots due to a degraded battery instead of allowing us to degrade performance to enable a stable experience with a degraded battery.”

How would you explain the above to tech illiterate people? Increase suppose calls because you allowed a user to chose between degraded yet stable performance versus seemly random (to the user) reboots and shutdowns?

Because one looks like a hardware defect and the other like a problem of old age and is "easier" to accept for most people.

Apple's know-how in battery management is always a couple of generations ahead of its closest competitor.

My 2008 MacBook Pro was able to detect battery problems one year before they started to manifest physically. They did it by adding another controller and an independent firmware to the battery itself, but there was no better tech at that time.

M powered MacBooks added auto hold-off (discharge to 80%, keep it there) or postpone charge (because the battery is used too rarely), to the list of tricks they know, and these are just the visible ones to the user.

Apple's know-how in battery management is always a couple of generations ahead of its closest competitor.

M powered MacBooks added (...)

Things that Lenovo laptops have had for a generation?

IBM Thinkpads have "cap charge at n%" setting since 1999 or something, but it's not smart. You set it.

It was also present in HP and Dell's business notebooks for quite some time, but again, it's not smart. Just a pre-defined percentage.

Apple manages maximum charge capacity automatically depending on the way you use your computer.

Apple manages maximum charge capacity automatically depending on the way you use your computer.

Apple cannot predict where you are going to use laptop on AC power at home or whether you are going somewhere and need a full charge. So manual control is better.

That’s the weird part, they actually can. It’s supposedly one of the machine learning features, where it learns your schedule and makes daily accurate guesses of by when you’ll unplug and plug it back in.

... they actually can.

Yes, it does. Even my 7 years old iPhone X does it. I use some features at very specific times, and it suggests me "do you want to do X?" around the time I do that. So the models work well.

Also, the phone generally enables optimized charging if I put it to charge too early. Scheduling to finish a couple of hours before I wake.

I use some features at very specific times, and it suggests me "do you want to do X?" around the time I do that.

You're conceding that you have a predictable schedule. Folks on the other side of this (who believe it can't work nearly as well as manual control) don't have a predictable schedule. Think of it like {hybrid workers who use a desk all day the same 3 days a week, and are nomads the other 2 days a week, and the ML system can figure this out} vs {on-site workers who use a desk all day 5 days a week, but are nomads a few random days a year, which always catches the ML system off guard}.

Both are valid. A setting that caps it at 80% unless you hit a button for "I'm about to spend a lot more time unplugged than usual, so prepare the battery for that" is the only way to handle unpredictable circumstances. Just like preparing an EV for a road trip.

As said by me and others elsewhere on this thread, this is of course a valid requirement, and tools have been developed for permanently capping charging percentage on Macs for quite some time. I don't have an objection to that.

My Macs charge routine is way more hectic than my phone's which is very predictable, and both of them guesses what I'm trying to do correctly 99% of the time, and that's fine by me.

What I said is, it's working fine for me, but the system is open to tuning both out of the box (I need this now, please charge), or with some small tools (it was called Aldente IIRC), for differing, equally valid needs.

I don't think we're in disagreement here.

BTW, your nick reads ********. Is it hunter2 or something? ;)

There are apps for that if you want, and if it enables hold-off, you can always say "No, I need full charge now, so please charge".

I've had smart charging in other laptops for ages as well. I'm not saying Apple isn't doing good, I'm just disputing the "Apple is on another league" sentiment, when it's mostly based on a lack of knowledge of what's happening outside the Apple ecosystem.

My colleague just had to replace his HP Elitebook Notebook because the battery had bulged so much it had cracked open the case.

For this to be happening in 2023 means that some manufacturers at least, seem to be not managing this potential problem at all.

N=1 doesn't really tell you much of anything about anything.

Well, my wife's work supplied EliteBook's battery has been replaced today due to excessive swallowing, and it's definitely younger than my 2014 MacBook Pro.

Well, I didn't witness on any other current generation device, at least yet. I'm not a fanboy. I'll be happy if others are doing this in some form, esp. if it's independent of the OS itself.

It’s not new in Apple devices, either…

discharge to 80%, keep it there

Where? AFAIK this is a feature you need a third party app like Aldente for. The OS does not offer any way to control battery charging level. Yes, it tries to be smart and guess when you need full charge and sometimes decides to charge to only 80% but that doesnt work for all users except the ones with very regular routines and there is no manual control.

I meant the automatic one. My charge cycles are not very predictable, but periodically my Mac says that It'll hold-off charge, and uses battery until 80%, then uses power adapter. Then charges the battery fully later in the day if I'm connected.

Sometimes it flat out refuses the charge. Then I disconnect and use the battery until 30% or so. Then charge when convenient (clarification: It'd possibly charge if I hit a certain percentage, but I always disconnected voluntarily, to give a good use to battery. I lasts a day. Why not?).

My MacBook Air M1 has 165 cycles in 3 years, at 90% of design capacity. I think this is a very solid management of the battery for a computer used every day literally.

My MacBook Pro is at ~85% after 8 years. I don't remember total cycles now.

Why not?

I find running on battery, lots of things are throttled or disabled. CPU is slower for example. That's probably a good reason for why not.

I generally do mundane tasks like SSH sessions or zoom meetings when I'm on battery. Heavier tasks are always offloaded to my desktop system, most of the times, so running on battery here and there doesn't impact many things in my case.

A video call though isn't that mundane. Google Meet often has my cpu and fans spinning. I do prefer Zoom as it uses fewer resources. But of course, it will work on battery.

For an M1 powered MacBook Air, none of them creates a significant power spike on the system. I use both regularly, generally one hour at a time, and battery percentage doesn't take a noticeable hit after the call, and the computer doesn't warm up.

My 2008 MacBook Pro was able to detect battery problems one year before they started to manifest physically.

That may or may not be noteworthy. Despite half my family using MacBooks, and some having had major battery problems, I’ve never heard of such a notification as you describe (including at least one where I’d certainly have expected to hear about it). And the similar system SMART for storage devices is notoriously unreliable: I’ve personally had devices with dire warnings chug along merrily for plenty more years, and observed one or two failures that never received any warnings.

I used three batteries on that particular MacBook and it always shown a "! Service Battery" warning before things went bad. The battery life, and shape of the battery was indicative of anything, either.

Oh, don't bring up SMART. I remember long-testing >100 disks, and most of them passed (it took hours), and all of them failed within 10 days after facing real workloads. We needed a temporary storage for migrating things, but we lost no data, because it was just a copy operation.

They didn’t explain what it did. The feature was amazing, the presentation misleading.

No, Samsung and others spread a bunch of FUD that Apple was crippling their phones to force people to upgrade, and Reddit and HN apple-haters ate it up.

Still to this day people on HN repeat it like it's fact, and when you correct them, shift the goalposts to "well they didn't TELL people."

This is not a goalpost shift. It's THE argument. I'm not sure what arguments are there for alternative narratives.

Do we know they actually didn’t tell people? Does anyone read through the “What’s New” pop-ups after they upgrade the OS, or just blindly dismiss them?

Apple provides a very comprehensive user manual that ships as a pre-installed app on every phone. There are large headings describing the latest features right when you open it.

I don’t recall being unaware of this feature before it became a “scandal”, but I’m one of those weirdos that reads the release pop-ups.

Let's say you read that "what's new" pop-up and still update your phone because you expect it to work like before, but it doesn't because you're one of the lucky ones that had the clock speeds cut in half.

What do you do now? Your phone is laggy and there's no setting to disable the feature or a way to revert to an old iOS version. You go to the store and they don't tell you anything about a battery replacement, but instead suggest a new iPhone!

The feature was useful, the implementation wasn't. The issues weren't caused by the user not reading the changelog.

they don't tell you anything about a battery replacement, but instead suggest a new iPhone!

You keep repeating this, but battery replacements were a thing before this whole debacle. I got them a few times, I think they were like $79 (yes definitely more money than the sus extended batteries I'd buy off eBay for my HTC Evo). I realize society collectively forgot about them once the back stopped coming off the phone, but surely a tech savvy hackernews would realize that they couldn't use the same battery forever without replacement.

To replace the battery you need to know there's a problem with the battery. But the iPhone didn't tell me the issue was the battery. It happened after a software update if I remember correctly, so I did everything from formatting it to reducing the graphics load by using the accessibility settings... nothing worked. When I went to the nearest Apple store, the guy told me that I should probably get a new one.

I don't blame the guy for recommending a new phone, after all apparently Apple didn't inform all their stores about the change, so they probably had no idea that the fix was a cheap battery replacement.

Do we know they actually didn’t tell people? Does anyone read through the “What’s New” pop-ups after they upgrade the OS

I'm an avid reader of pop-ups and release notes. They didn't tell people.

No, Apple's throttling to prevent crashes is no more "planned obsolescence" than how Samsung (or any) laptops thermal throttle when the heat sinks get dirty.

Designing a product to fail gracefully is good engineering practice.

Apple made the right decision to make the phone go slower instead of crashing. Somewhere out there, there's someone making a 911 call on an iPhone with an old battery.

It's THE argument

From people I've talked to, it seems like the VAST majority of people are under the impression that Apple does this as a planned obsolescence practice.

In fact, this thread is the first one I've come across where most people seem to get the point of the feature

My iPhone was affected by this. Let me tell you my experience, without "Samsung FUD":

- The phone became slow, laggy animations, etc.

- I had no idea what was causing the problem.

- There was no way to return to an older iOS version or a way to disable the new behaviour.

- I went to an Apple store and was told that I probably should get a new phone.

I'm sure they had some good intentions, but in practice they degraded my experience too much and profited from new iPhone sales that didn't need to happen. Apple had to be sued first to add a setting to disable this feature and start offering cheap battery replacements (by then I had already moved on).

From the implementation of this feature to the way they handled it, it was all Apple. Samsung had nothing to do with my bad experience.

Not everyone was affected this much by the change, but some where. And that's a problem.

The fix had an impact on a core metric of the device: performance. This was the best technical solution to gain longevity, and it was in the interest of users. But doing it under the radar left everyone wondering if it had ulterior motives and let the rumor mill go crazy. Transparency is good even when everything is upsides & roses, and especially important when there are some compromises to be made.

Except they only HAD to do that because the battery simply did not have the capability to continue providing enough voltage and/or current by the time it got to about 20% degraded, which for many people could happen in just a few years. This only happened because they were putting stupidly small batteries in their phones to shave another millimeter off of the size that nobody cared about.

Either Apple did the proper QA of the battery to understand how it would behave as it got to end of life and knowingly put a battery into a $800 phone that wouldn't be functional before the phone would run out of software updates, or they FAILED to do proper longevity testing on the battery of a $800 phone.

It wasn't planned obsolescence when they added that code to keep the older phones working. It WAS planned obsolescence when they put a pitiful and underspecced battery into their $800 phone.

Some devices had a small performance hit, but some had had their clock speeds to less than half, making devices laggy even during normal usage.

By itself this is already a problem, but they also decided to not allow you to disable the feature or reverse to an older iOS version. I don't think they informed their Apple store employees either, at least I was told to buy a new phone. They had to be sued first to add a simple setting, ffs!

So yeah, I think the criticism is valid and deserved. I'm sure they had good intentions, but the implementation was shit and not only they created issues for some iPhone users, but also profited with new iPhone sales (not me, that was my last iPhone).

All the shit was deserved for altering phones without the consent of the consumer. I don't care how good they had in their hearts, get the user's consent first.

Almost nobody cares about saving batteries. Those are replaceable and cheap to replace every couple of years.

Innovating more battery life and leaving 20% battery life on the table sounds extremely pointless for what costs 20-30$ a year but lets you use the device all day instead of just shutting before the end of the day.

Those are replaceable and cheap to replace every couple of years.

If you specifically seek out devices with cheap replaceable batteries, sure. But this isn't the case with a lot of devices.

Replacing an iPhone battery is cheap, especially compared to replacing the whole phone: at the Apple Store it’s either $99, $69 or $49 and I’ve had other stores do it for like $40. That’s not too bad for a once every couple years cost.

Cheap for the wallet, but not the biosphere. Unless you mean to imply that people would get new phones less frequently?

It's well-established that iPhones have longer average lives than Android phones.

Really? If that is true, I wonder how much is due to the fact that the phones are more expensive so people take care of them more or delay their next purchase. It's not because the actual quality would be better.

If you pull statistics you also have to filter out the sub 150 dollar Andoid phones which may well have shorter average usage life.

If that is true, I wonder how much is due to the fact that the phones are more expensive so people take care of them more or delay their next purchase.

Delay because it's more expensive? How about delay because it's good enough? My iPhone XS is just fine thank you. There's no point in upgrading it yet.

Really? If that is true, I wonder how much is due to the fact that the phones are more expensive so people take care of them more or delay their next purchase.

Even if it were the case, it does not matter. What does matter is the amount of matter that ends up in landfills. As a matter of fact, we should be pushing for better built, longer lasting devices even if it means spending a bit more in the short term.

It's not because the actual quality would be better.

Second-hand iPhones are all over the place here in a way that Samsung Galaxies are not, even though they are more popular. You can argue that it is not a proof of high quality, but it is at least a proof that build quality is high enough that 4 years old devices are on average in a good enough state to retain a high resale value.

If you pull statistics you also have to filter out the sub 150 dollar Andoid phones which may well have shorter average usage life.

Which precisely is the problem. “But they were cheap” is a terrible excuse as we keep burning more non-renewable resources and shovel up heaps of electronic waste in landfills. Besides, we need to look at cost per year, not cost per device as a cheap device you have to change often is more costly over the long term. I am not saying only Apple devices can have high build quality, but it seems nobody is pushing OEMs towards that direction in Android-land.

Software support is an important one, and Apple has managed to slow down the RAM baseline inflation that Android seems to experience every other year. Even people who regularly upgrade usually trade in their old phones because they still have enough value to bother, so a lot more phones get used all the way to the end of their support.

How is that all that damaging? I’m sure those batteries are recycled in basically all cases and yes, I’d expect battery replacement does indeed forestall replacement for many phones.

The most common processes for recycling lithium ion and lithium polymer batteries are not environmentally friendly. They consume a lot of water and energy and produce toxic byproducts the require further processing and energy to be rendered safe.

https://pubs.acs.org/doi/10.1021/acsenergylett.1c02602

byproducts that require

It’s cheaper for the biosphere than replaceable batteries were, because you just switch out the battery and don’t need the plastic case for the replaceable part.

Yeah but then you have to buy an iPhone.

That's not snark. I want things from my phone that an iPhone can't give me.

The battery replacement ecosystem in Android land is pretty dismal.

It depends on your definition of dismal. Any phone repair shop can open phones and replace batteries. There are also disassembly videos for most models on YouTube. I looked at them, ordered parts and replaced the battery on my Samsung A40 when it started to discharge too quickly. I also replaced the camera after a hard crash on the floor broke the autofocus. Maybe not having Samsung shops makes all of that dismal but I actually prefer to have many small independent shops around the country.

Market fragmentation among Androids means that nobody stocks parts for anything and the margins are so low, a lot of shops will only do the brands they want to.

I couldn't find anyone to replace the battery in my Google Nexus phones, every time I tried, in a major metropolitan area. Ended up having to do it myself.

You can walk into nearly any cell phone shop in the world with an iPhone and walk out with a replaced battery because the staff know them and they stock parts for them.

I'm not sure that the problem is fragmentation inside an operating system. It's how widespread some brands are. I never had such problems with any Samsung phone I owned, even a Sony Xperia one years ago. I guess that it means that Apple, Samsung and even Sony (back at the time) are more mainstream than Google and for shops it's not worth to keep spare parts of Google phones. To be fair, the last time I had to replace a screen of a Samsung because it dropped down flat on the screen instead of on a corner, I had to wait one day for the replacement part to arrive to the shop. I put the SIM in the old phone or in my tablet and went back the next day. I'm not replacing the screen myself, it looks to require some extra skills compared to a battery.

It's always cost me around $40 to have an Android battery replaced at a "We repair phones" sort of place. That includes the cost of the battery.

The cost to replace the battery on iPhones, which most people would consider to be “difficult to replace” is only $100 directly from Apple. Really seems like paying an extra $100 every 2-3 years is a decent deal for something that has 20% more battery.

Even better - for some models it's $69 from Apple, and around $50 from third-party providers.

Source: I replaced my iPhone battery last week.

Really seems like paying an extra $100 every 2-3 years is a decent deal for something that has 20% more battery.

Maybe if you have a lot of money to waste, but people should have the option to choose

Does apple reslly replace the battery, or do they transfer your OS to a refurb and give you that? I'm very wary of apple repairs.

most recent phones and laptops have batteries that require advanced tools and chemicals to remove and replace

Laptops also? I didn't realise it had gotten this bad anywhere but in Macbooks.

Pretty much all thin modern laptops, Surface Pros etc use copious amounts of glue for different parts. With the worst offender iirc being the Surface Laptop which can't be opened at all without damaging the keyboard.

I'm an "almost nobody". I care about saving batteries. I get all the dead disposable vapes my friends will give me so I can recycle the batteries in them. Lithium is a limited resource and one day we're not going to have more to dig up out of the ground. There are others like me out there, I just need to find them.

The lithium is not disappearing though.

At some point in the future, we can start mining old landfill.

But yes, it's easier (and more efficient) to recycle before putting them in landfill.

Lithium is not a limited resource in the same way that Iron or Coal or Silicon are not limited. There is so much of it that we really cannot run out.

Cobalt, Neodynium and the other rare earth metals, though, those are highly valuable; and the processes to manufacture them are usually toxic. So do it for the rare earth elements, but don't do it for Lithium.

Let the user choose! Some people tether their phone a lot and use the battery only when out. For them 80% max is OK.

My Oneplus 5T got replaced because it has a small crack in the screen so it's impossible to disassemble without breaking the screen. I used ACC to only charge that to 90% so I could get three years out of the battery instead of just two.

I'll probably get a fairphone next so I don't need to worry about this. But the people with glued-in batteries definitely have to.

I'm pretty sure most (all?) manufacturers already do (the first part of) this. 100% can't be the point at which the battery literally stops taking new charge - if you did that they'd catch fire all the time.

It's just that the manufacturers idea of what "100%" should be generally skews more towards the immediate battery life end of the tradeoff, whereas some users prefer to have "100%" closer to the maximizing long term lifetime end of the scale.

Some devices do let you configure stuff like this - I know my android phone will let you cap max charge at an arbitrary level (although it won't report that level as 100%). Many laptop bioses will have a similar setting (good idea to set this to ~50% if you're using the laptop plugged in all the time, or just using it like a server with a builtin UPS).

You are right but I disagree.

Yes, devices do not charge batteries to 100% as that is directly damaging. And they don't discharge to 0% for the same reason.

So they charge to something slightly less. But that slightly less is for all intents and purposes the only definition of 100% we, as end users, have.

It's like saying that your CPU is actually only running at 70% clock frequency but overclocking it to 100% would require massive cooling and reduce the lifetime to months.

I agree a better definition and preferably one directly comparable to all brands and battery types were available, but I'm not aware of any and I'm sure that even if we had it you wouldn't trivially be able to get that information.

Noone should ever charge to more than 80%. That is short sighted and environmentally moronic. After less than two years a device will have more capacity at 80% than the same battery will have at 100% if it was charged to 100%.

While I agree with your general take and hate that my iphone can't be capped to 80% [0], and love that my otherwise crappy hp laptop can be capped to something like 85% (and reports both cap and max capacity), I don't agree with your final take.

To take the phone example, mine usually ends the day around 85%. I just don't use it too often. But I sometimes absolutely do and would trade months of battery life for not being left without battery in the middle of nowhere. And the 20% can make all the difference.

A few years ago, I rented a car in a foreign country on a foreign continent. It didn't come with a USB port, and I didn't have a cigar adaptor. When I arrived at my destination, at night, my phone's battery was 10%. I sure as hell am happy that it was charged to a "full" 100% instead of dying on me one hour earlier.

Sure, I could have grabbed an external battery or something. Not sure how much environmentally smarter that is, since it would basically rot away in a drawer somewhere, since I would basically never use it.

---

[0] Where does this 80% come from? Would it be even better if I stopped charging at 60%? I rarely use more than 20% of my phone's battery, so that would be largely enough, but I sometimes absolutely do and would hate to have to lug around external batteries "just in case".

Of course. All we're asking for is an optional "limit charge to 80%" feature. And, just like macOS has, you can have a very easily accessible "charge to full now" option for those times when you know you're going to need a full charge.

Don't forget, "100%" isn't really 100% any more after a year or two of charging to 100% all the time. You've probably lost 20% or so of your battery's capacity and it will be charging slower due to increased internal resistance.

"Where does this 80% come from? Would it be even better if I stopped charging at 60%?"

Yes, but only marginally better since there's diminishing returns. 80% is generally considered to be the sweet spot that best balances practicality with battery health.

just like macOS has

Can you please direct me to where this is possible in MacOS? I can't see any option to configure a charging cap except some "smart" option which has been on this whole time but always charges to 100%.

It's not possible to set a hard limit in macOS without third party utility like AlDente [1].

I was referring to the built-in "Optimised battery charging" feature. When this is active and has decided it will cap charging at 80% [2], you get a "charge to full now" option in the battery menu.

[1] https://apphousekitchen.com

[2] I do agree that this feature sucks and rarely actually works, unless you have a very predictable charging schedule.

Absolutely agree.

But my response was to the parent comment (emphasis mine):

Noone should ever charge to more than 80%. That is short sighted and environmentally moronic. After less than two years a device will have more capacity at 80% than the same battery will have at 100% if it was charged to 100%.

My point is that I find there are legitimate uses cases for sometimes charging to 100%. And, indeed, those cases are much better served if most of the time I only charge less. In my case, this could be much less (50% of my iphone's battery is more than enough 360 days a year – and I know beforehand when it's going to be one of those 5 remaining days)

But that 20% that makes all the difference will only make a difference when the phone is new.

Otherwise the opposite is true. Refraining to charge fully makes all the difference and saves you from a tough spot.

Which in turn is why (was a bigger problem before) the sentiment that it doesn't matter how good/bad battery life I have as long as it lasts me a day. Well, if you do a complete cycle every day a year old phone will not last a day anymore...

This used to be an easy problem to fix, by replacing the battery.

Shame that seems to be harder and harder to find on new phones.

I know my android phone will let you cap max charge at an arbitrary level

Yeah I used to have old Pixel phones as Home Assistant clients on my walls until they all started bulging one by one and I had to treat them as a fire hazard.

I now use Samsung tablets, ironically, that have a cap at 80% feature and they seem to be doing fine.

Are those cells 4.4v? Samsung makes great cells, and if you only charge them to 4.2V or less they should last quite a while. When charging to 100% means different things in different cases for the same battery technology then things get murky.

I now use Samsung tablets, ironically, that have a cap at 80% feature and they seem to be doing fine.

Yes, this feature is one of the most underrated features on Samsung devices. Massively underrated.

Because of the flatness of the voltage curve, limiting your charge to the middle range makes the state-of-charge estimation a much more difficult problem (less voltage signal). So there's actually a trade-off between longevity and accuracy of charge reporting.

iPhone 15 occasionally charges to 100% when 80% is set for this reason.

Many, many confused and complaining posts are to be found on Reddit and elsewhere about this even if it’s explained in the docs and I think next to the setting itself. It should show a notification when it goes to 100%.

I wish my Tesla did that

The Prius Prime supposedly does this. It charges to 80% internally but displays as 100%, although usually drivers have the display set to "miles remaining" rather than the battery percentage. I vaguely remember the manual referring to this.

As a non-battery engineer end user, I suppose all I care about is 100% usefulness. If the phone lasts more than a day under normal operation for a few years & doesn’t get too slow, I’m happy enough.

I think there's some confusion on what this actually looks like on the manufacturer's end.

When charging a lithium battery, your termination point is tied to only one value: voltage. 4.2v per cell is generally considered the maximum safe termination voltage. This is the theoretical 100% charge. And yes, if you keep pushing volts in, it will keep taking them until the call fails catastrophically.

Personally, I use 4.1 as my termination voltage. That's somewhere around 90-95%. You 'lose' a little of the maximum capacity, but lifespan is increased. I find it's fairly common for battery charge controllers to use either 4.1 or 4.2 as their default termination, but it's almost always selectable. You have to make a decision somewhere.

The flaw in this is that you're trading away a banner spec for something that users won't appreciate. You have to decrease the stated capacity and runtime of your battery in exchange for an indefinable amount of extra total lifetime. That's not something that consumers can/will take into account. They just look for the device with the most mAh or runtime.

I'm pretty sure most (all?) manufacturers already do (the first part of) this. 100% can't be the point at which the battery literally stops taking new charge - if you did that they'd catch fire all the time.

It's a really tiny amount, like 101% or 102% is the maximum. It becomes obvious on phones if you have an app that shows battery percentage over time - above 90% on a slower charger (like using USB instead of AC) it tapers off in a curve, even on a brand-new battery.

Almost everyone caps below max voltage, but a toggle between small margin and big margin is a lot less common. And if you have to reboot into the bios, it only half counts.

That way it will make people aware

These are all electronic devices. You can also just put big warnings in software instead of calling it 125%.

It's not any different from filling up a blender, water bottle, etc. to 80% instead of 100% to avoid creating a mess. Sooner or later people will know to avoid charging batteries to 100%.

that they are reducing the battery life by overcharging

Unfortunately their capitalist asses probably want you to reduce the battery life faster and buy a new device, which helps boost sales, boost revenue, boost shareholder happiness, boost stock price, and ultimately boost CEO net worth

Unfortunately their capitalist asses probably want you to reduce the battery life faster and buy a new device

This tactic would work great in a world with only one phone manufacturer.

My anecdotal evidence is that people tend to stick to the same brand when upgrading phones.

I think that depends on the brand. If they like the product, then yes. If the product has terrible battery life, probably not so much.

Well, there is one phone manufacturer and others.

There's only one iPhone manufacturer, and that seems to be extremely important to many people-- even extending to limiting their dating pool, apparently.

https://www.cnet.com/culture/iphone-or-android-your-phone-ch...

https://metro.co.uk/2021/12/26/owning-an-android-is-a-major-...

https://www.vogue.com/article/breathless-couples-who-are-not...

Some more responsible device manufacturers are doing this. For example, the industrial equipment I worked with charges batteries much more sustainably, also by charging it with less current.

Remember, there are multiple factors when it comes to batteries degrading. Voltage (how far the battery is charged) is one of them, but so is the charging current (how fast) and also the temperature during and outside of charging.

Personally, I usually use slower chargers for my laptops and phones to prolong the device lifetime.

I don't understand the obsession with fast charging. I can probably count the number of times I needed to charge my phone instantly on one hand. The other day I bought a MagSafe charger because my new phone doesn't fit properly on my old wireless charger, turns out it doesn't support the "legacy" 5W power bricks. Now it's sitting unused in the drawer because I don't want to charge with more than 5 watts.

Also an issue for travel-friendly charging solutions: there just aren't any truly lightweight USB-C cables that merely support the old USB2-era maximum currents that are perfectly fine for overnight charging. If you count grams, you're ent4irely better off with certain cable models of bulky A to micro-B + adapter.

And even voltage is just a rough proxy for the actual state of ions in the anode-cathode dance.

When voltage goes down with temperature, the charge state does not change. But drawing a certain amount of joules will be very different because at lower temperature you'll need more coulombs for the same amount of joules, aka VAh.

And at nontrivial discharge throughput, observed voltage will drop to much lower values than what a snapshot of the current ion-dance state would look like at steady state. This is the "smartphone SoC must not try performance bursts as it used to" scenario.

Top charge in a lithium battery is very arbitrary. Most batteries can tolerate going higher than the specified 4.2v, up to 4.3 or 4.35v - but the cycle life degradation is not worth the extra capacity.

This is exactly the answer. Especially with Li-Ion cells everything is a compromise. You can extend the life of the cell by a fair amount, but then it won't last as long before you have to re-charge. Similarly, if you charge it quicker, then it reduces the lifetime of the cell.

I honestly don't understand how people worry about their batteries in their devices so much. I give pretty much zero care into how I treat the battery in my devices other than to try to charge them before it drops down too low (which is where most of the damage occurs if you do it repeatedly) and I can only think of 1 or 2 times where my devices battery has worn out before I end up replacing it.

I replace my devices when the battery wears out because I can get a new phone in 5 minutes and the battery takes a week to replace in this forsaken country.

I've babied my iphone x battery (battery case ftw) and it's at "86%" after five years.

Even with all the nice features apple offers for battery management they still design their phones to have undersized batteries and encourage usage patterns that degrade the battery in ~2 years, when they could just slightly increase the thickness of the phone and increase the lifespan to ~5 years.

Very conservative depths of discharge and charging termination voltages can extend life spans into the 10,000 cycle ranges which is effectively forever for a device with a finite lifespan. And it wouldn't increase the weight of the phone too much: doubling battery capacity isn't doubling the size of the phone or even the battery itself. Just the active material in the battery.

Another reason is that batteries are ... small. Too small. If it charged to 80% from the get go, then your phone is already effectively living on reduced battery, it is already kinda broken because battery runs out too quickly.

This really depends on the person and use case. Pretty much the only time I get even close to depleting my phone or laptop battery is during air travel which happens like 2-3 times a year. Otherwise I charge the devices throughout the day at my desk where the laptop is plugged in 98% of the time anyways.

People that know about the 80% trick may then only charge it to 80% of the 80% which now shows 100% which would be 60% (if my morning fog brain is getting it right). But if they know it's actually only 80% when showing 100% they'll charge it to 100%. Then people will complain "they don't make phones like they used to".

80%80% would be 0.80.8 which is 0.64 -> 64%

Samsung phones have an option called 'Protect battery' which limits the charging to 85%.

But then the unscrupulous competitor advertising 100 hours will get customers and the responsible company advertising 80 hours doesn't, even if they advertise 20 hours overcharge?

The battery ages faster the more it is charged. It is approximately linear. Nothing special about 80%, you could draw the line anywhere.

With a jailbroken iPhone you can set some things like that up iirc. I had a 5 or 10% setting that would turn the screen off and make it appear battery powered down but it was still on. That way you retain your jailbreak.

There were more limitations on cpu speed also. Could turn on the super low power mode (which above setting did), custom max cpu frequency or temperature.

Idk about max battery charge but it was nice to be able to control those things. Could make a battery last much longer and phone would not heat up too much. I considered downgrading to get the many features back.

My wife's Galaxy Tab S7+ does this. It's configurable in the battery settings, 85% == 100% unless you disable the battery saving function.

Why even go that far? Just call 100% what is actually 80% on the battery and call it a day. We already get “actual formatted capacity less” when it comes to data storage, and EV batteries are generally under-provisioned.

Panasonic Let's Note series had an eco button that charges it up 80% only, man I love that series of laptops.

I've given up trying. If a device is willing to lie to me and only charge to 80% while saying it's charged, great, but all of this "try to stay in a range" logic flies in the face of reality.

Every device I use besides my cell phone, Nintendo Switch, and Nintendo 3DS has atrocious power drain when not in use. OS does not matter. Windows laptop, Linux laptop, ChromeOS laptop, Android Tablet, Amazon Tablet, you name it, if I set it down at 80% and come back 48 hours later it will be below 25%. So I just leave them plugged in when not in use, and to hell with battery longevity.

I just picked up my 2017 iPad Pro. It was last charged Nov 15. Been sitting by the bed mostly unused since. Currently at 80% charge. I haven’t experienced what you’re describing on an Apple device since they switched the laptops away from Intel chips.

In my experience, the OS does matter. I can’t believe how bad the rest of the industry is at this. Amazon’s Kindle line is incredible at this IME, but those are pretty atypical devices.

Screenshot from said iPad’s battery screen: https://postimg.cc/xcHpy5Sr

I have the exact opposite experience. My 2013 MBP can keep its charge for months while suspended/hibernated. My first-gen M1 MBA will deplete the battery in a week under the same conditions.

Does the latter have Power Nap enabled?

Don't have my MBP (late 2013) on hand to check, but IIRC the power nap was enabled only when plugged in.

That's the issue with regular PCs: most don't have the choice anymore to use S3 suspend. They default to "modern standby", the half-assed copy of Apple's power nap.

IIUC both Intel and AMD haven’t supported S3 on their CPUs for a couple generations now. The functionality is still technically in the firmware, but it’s broken to a varying extent.

Suspend and hibernate are not the same thing. The latter actually fully powers off the device. As far as the hardware is concerned, it's the same as "shutting down".

Windows does a similar thing on pcs with "modern standby": it will switch to hibernation if it's unplugged for a while. I don't know the specifics, but my work pc running windows 11 will be hibernated in the morning if I leave it unplugged going to bed.

My M2 Air will sit comfortably for weeks with little depletion at all. It's the only laptop I've ever owned where I comfortably walk out of the door without a charger with 35% battery.

My 2016 MBP drops from 65% to 30% in a month even when it's turned off.

And that's without power saving mode? Impressive!

Have you configured anything like "disable background network activity"?

Do you force close the apps?

Do you force close the apps?

Don't do this unless an app is unresponsive/not working correctly. It will just make apps slower to restart, using more power than it would if left to suspend/un-suspend as it's meant to.

Issues is: how can I know is app working correctly? I have 15 apps "in memory", my phone started lagging, what should I do?

If it's an iPhone, then iOS will suspend background apps in favor of foreground apps. If your phone is lagging it's almost certainly because the foreground app is resource-intensive.

If the foreground app requires more resources than are available due to background apps, it will suspend background apps to free up those resources.

Apps don't really have much they can do to get around this, assuming you're not jailbreaking or installing local profiles.

Well-built applications will have already saved state with every interaction. When they go to the background they will start unloading unnecessary resources and prepare for possible suspension by saving any additional data. Then when they're suspended, their state is saved to a snapshot that they can load in later so it's as though they never were suspended.

There _is_ more capacity in recent versions of iOS for an app to use background resources, and to start a background process automatically. Still, the system treats background processes with a lower priority and terminates them for using too much power way more aggressively.

TBC the discussion is around idle battery usage. Presumably, backgrounded apps will contribute to that. FWIW I do notice a difference, especially depending on what apps are open. Whether closing apps increases battery drain during reopening them for intentional activity is a different question.

I'd forgotten, I _do_ have a shortcut that runs late at night to turn off WiFi and enable low-power mode. I've had it for some time now and not thought about it. Another shortcut runs in the early morning to turn the WiFi on and disable low-power mode.

I didn't keep a great log of how the battery handled before that, but it does seem like I have to charge it less than I used to.

I only force close apps when they're clearly stuck.

An android device in standby in airplane mode will last a week in a single charge easily, in my experience. But if you have radio on, yeah, 2 days tops.

What device is that? It doesn't sound all that exceptional.

The longest I've had my iphone 14 pro unplugged was around 3 days, with very light use (I'd say 2 hours of active use, randomly browsing HN and reading a newspaper on its app). It barely went below 50%, with all radios on.

This is going to depend heavily on a number of factors. Background apps, processing notifications, screen brightness, signal strengths, etc. all play a role.

I recently picked up my Surface 3 for the first time since 2017. It had a 66% charge from the last time I used it...

It's not so much the OS as the device firmware, since the Surface 4 runs the same OS but has significantly worse battery performance.

That's a joke, right? The battery held a charge for 6 years?!

Which Kindle do you have?

A couple of years ago I finally upgraded to an Oasis and the Oasis battery life is significantly worse than my previous Paperwhite. It’s still good enough — I have to charge every two weeks — but the Paperwhite was better.

The Oasis is still my favorite Kindle (it’s my third).

I've got an Oasis 3rd gen (2019). My last Kindle before that was the 3rd gen "Kindle Keyboard" (2010). I'd say the Oasis has a longer-living battery than the old one, but I've always been pretty aggressive about turning off its radios and 'smart' features.

I love the Oasis, I'd like it if they made a slightly larger variant with USB-C. Basically the form of the Scribe, but I'd rather skip the pen input.

iPhone does not reflect these gains. I did own a Huawei and I felt those really had slow drain.

I'm not sure I've gone more than a day without looking at my iPhone in years probably (not great, I know..) but I've not had any notable standby drain issues. That is, I've never left it at something like 80% and come back to it hours later for it to be drastically lower.

I'm pretty religious about what apps are allowed background data, and notifications in general. But I never turn off any of the radios.

iPads feel like they last forever in standby. I remember there was a period of time where I was using my 6th gen mini very little (but I was using it) and it lasted me close to 3 weeks on a charge.

Even my iPad has horrible background drain. My iPhone is the only device I have that I can calmly leave at 15% when I go to bed and know my alarm will still work in the morning.

I had an iPad that I bought 5? years ago and I could leave that thing in sleep mode for literal weeks at a time and I'd still have a mostly full charge.

I "upgraded" to a Pro 2 years back and the first thing I noticed was it'd go from a 100% charge to 60% to even 40% overnight. All apps closed, freshly rebooted and did nothing but charge it the previous night before unplugging it.

A lot of comments online say "This doesn't happen. You're doing something. And it's certainly not wifi and bluetooth because those don't use battery while idle so do NOT turn those off!" I tried everything that was recommended, turning off iCloud, uninstalling random apps, etc.

Then I got into a habit of turning bluetooth off every night and my battery would only drain about 4-6% a day while idle. Turning off wifi as well and I get about 2-3% drain per night. I have no clue what Apple is doing, but when putting my iPad to sleep at night with any sort of wireless on, the device connects to every fucking thing it can find but wouldn't do while awake. I never even synced my Airpods with my iPad and made sure to delete them when they did connect, but still, if I leave bluetooth on before going to bed, my iPad will connect to my airpods while they're in the case, drain them to 0% (even after fully charging the Airpods before sleeping. It's not even possible to drain the case's battery with actual usage that fast!), then drain 40% of its own battery.

I can't make sense of it.

In short, turn all wireless off when you're done for the day. iPads/iPhones are annoying in that you can't turn them off from the drop down menu though, so you need to go through settings or make a shortcut.

The amount of background crap has been steadily increasing on Apple devices, you're probably right in your observation that it's related to wireless/Bluetooth.

I have a iPad 2 (yes, the one from 2011) which I keep around with the plan to turn it into a house-automation screen and I'm always surprised when I look at it every 2-5 months to see it still has a decent chunk of battery left. And it's in sleep, not turned off.

I just checked it, it's at 76% with a standby time of 562h (23.4 days). And this is with WiFi turned on.

Im really impressed, it's after all a 12 year old battery. And the device was in daily use for the first 4 years and then less frequently.

This is a side topic but I find it's a good example of forced obsolescence, because there is nothing wrong with it other than the fact that it does not support modern web standards or modern iOS apps which makes it trash for most people.

I have the same experience as you with the iPad 2 battery longevity, and was going to mention it before I saw your post. I keep it around with (the good old skeumorphic) iOS 6, for nostalgic reasons and for the old versions of some synthesizer apps. With WiFi turned off, it can last for months in standby.

Also using an iPad Pro that I got in 2018 (I think, the first 12.9 inch with the current look), it used to be better at it than it is now. In the beginning it would rarely drain now it drains ~20% overnight. Granted mine is older and has been heavily used. So the battery has had quite a few charging cycles by now.

It's still fine to work on though. So have no need to replace it, but it is a little annoying to find it at much less of a charge than what I would expect.

Yeah, same experience with iPhone. Can leave it at 20% then when I wake up it would drain like 5% or so.

So I just leave them plugged in

Isn't that exactly why you want a device that can self-limit? It doesn't need to lie.

If you leave it plugged in all the time, battery life doesn't matter. Self-limit or don't.

I'm rarely away from a power source for very long (and when I am, I'm not on my phone much). So I just leave it plugged in all the time. I've very rarely had my battery die on me, and like OP, I leave mine plugged in all the time. At night or while working, it's charging.

Even after a few years, I don't notice much of an impact. I'll sometimes notice it's getting low (again, if I'm out of my routine), and just charge it.

At night or while working, it's charging.

It doesn't have to be charging all the time. Some laptops have "intelligent" detection of the "usually plugged-in" state and won't keep the battery charged 100% at every moment, but will allow dropping it somewhat before charging again.

I suspect MacBooks are doing this quite aggressively (while lying about 100%), since their batteries tend to last (in terms of cycles) longer than windows laptops.

i thought that if the battery is charged the device will simply ignore the battery and run directly from the wire. so a fully charged battery should not be affected at all. repeatedly dropping down and recharging sounds like a bad idea.

Based on my limited understanding it's not that simple. At least some laptops still use battery power during power spikes even when plugged in.

repeatedly dropping down and recharging sounds like a bad idea.

I noticed this with my Dell Precision machine that it dropped to 99% and then re-charged to 100%. It was plugged-in 24/7. You can normally configure this in BIOS, but it was locked in my computer by my employer. Unsurprisingly, the battery swelled within a year.

OTOH, I'm not sure how much more damaging this is, given that even just keeping the battery at 100% for long periods of time is damaging.

It's plugged in when not in use. A single use that takes it away from an outlet can last a good while.

FWIW, I can't speak to other operating systems, but with Linux (maybe requiring cooperative hardware? I'm actually not sure) you can configure it to stop charging at a certain % if the charge controller doesn't have reserve.

I can find a link if you're interested; IIRC it was easy to setup and easy to temporarily disable if you need to fully charge for e.g. a long flight without outlets

https://linrunner.de/tlp/index.html

https://linrunner.de/tlp/settings/battery.html

This does require firmware support but it's pretty seamless in Plasma. It requires a root password which is slightly irritating. At one point I went through the PolicyKit contortions to allow normal users (me) to change it.

Most laptops come with some software bundled that helps configure this. Dell does I know. So did Lenovo.

I don't understand why devices can't switch to external power when plugged in. It's like they simultaneously charge and discharge the battery instead of bypassing it.

I think some do. I don't use my macbook anymore so don't have it on hand to check, but both my HP laptops (one running windows, the other linux) and my iphone seem to not fluctuate the battery charge if I leave them plugged in. The iphone doesn't even get warm, which can happen when it recharges from a drained battery.

The laptops won't even attempt to charge if the battery's above a certain threshold, like 95%. My linux laptop barely moves from my desk, so it regularly spends multiple days on end with the battery showing something like 96%.

Depends on the device. Some do. Some actually can't, because they are capable of drawing more peak power than their wall chargers provide.

My Microsoft Surface Pro 4 can do 100% to 0 in less than 48hrs, powered off the whole time. It's old now, but it became that way in the first 2-3 years, without even using it that much.

It's such a pain to use because when it's at zero, If I plug it in and power it on, it'll boot Windows, then at any moment will power off by itself, maybe because Windows doesn't want to run at low battery, maybe it's consuming more than what is being charged, idk. I have set the desktop background to 0x000000, removed all non-essential startup services, reinstalled it from scratch, etc.

So everytime I want to use it, I have to wait till it's 5-10% before powering it on.

The worst part is that if you look it up online, some ppl say it changed drastically after some Windows update, can't confirm because it's not my main PC, I don't remember the exact moment where it had this problem.

Similar with my Surface Pro 4. After a couple years of casual use (it was my "browse on the couch" computer) the battery was significantly degraded.

I think a big part of the problem is that "off" doesn't necessarily mean "off". If you just do "Shutdown" from the menu it is just some kind of suspend or hibernate state (I'm not sure which...PC hardware and Windows have a bunch of different "not fully on" states). It's still doing stuff that uses power. It's also doing periodic things like automatic updates.

The net result I believe is that even though from my point of view it was only being used occasionally, it was actually going through a battery cycle almost as often as if it had been my main computer.

I haven't used Windows in a while so don't remember all the details, but I think if you hold shift while invoking "Shutdown" it shuts down more than a shiftless "Shutdown". There are also command line commands that will shut down even more.

I never did find a way to shut it down enough that I could not use it for a week and still have a usable charge on it.

Hey, do you have occasional problems with disk encryption? Every so often when I open it I get some obnoxiously bright screen telling me I need to enter my Bitlocker recovery key. But if I cancel that it goes ahead and boots and has no trouble decrypting the disk.

If you shut down your Windows laptop or Linux laptop completely, or remove the battery, the battery will not drain.

I've accepted that manufacturers cannot or do not care or will not give me instant wake without atrocious power drain during sleep. Modern solid-state storage boots up really fast, and my browser, IDE, text editor and other tools are pretty good at restoring my working state after boot.

Windows laptops are embarrassing. I don't want to only use Apple, but why can't anyone else make a laptop that doesn't require a Human BMS? When I got my first Macbook for work, I was amazed to open it after a week of traveling to find it booted instantly at full charge. Meanwhile my old HP would play slack notifications in my backpack as it's going through the x-ray machine at the airport lmao

Do you leave your Nintendo Switch in standby mode or hold the power button for a few seconds for a full power off? If I don't do a full power off, the battery is gone after a few days in standby mode. It's really annoying when I forget to do it and am welcomed by a dead switch. My Switch is often outside of WiFi connectivity, and I wonder if it's constantly searching for a known network to latch onto.

My samsung tablet (wifi) has an average idle drain of 0.3% per hour, meaning what you see in 2 days would take a week. On windows laptops hibernation can also fix idle drain, but that is a bit of a hack.

The 3ds is atrocious though, even with wifi off. With wifi it can't even last a day.

I've found this to be true as well. Sample size of 1:

My Android tablet, Galaxy Tab S8 Ultra, loses something like 10%/day when on standby. I don't use it every day, so either I have to leave it plugged in the whole time, or have the foresight to charge it the day before I want to use it for something.

What /really/ annoys me is I have this really really old Android tablet. I think it's running Anrdoid 5 or 6 or something. It's only really good for light web reading and nothing else. When it's charged, it'll standby for literal months. It can lay in my drawer, forgotten, and then a month later I can pick it up and it'll be still above 60%. When in use the battery drops like a lead balloon, within the hour it's dead. But standby is fantastic. Why can't modern Android do that any more?

I had an Nintendo NDS, that thing was a beast in stand by power consumption, the battery was tiny I think no more than 2000mAh but every time I flipped it open it had power

FYI, on Apple Silicon Apple included a firmware-level "hard-switch" to limit the charge to 75/80% only. It was discovered by marcan while working on Asahi and in my experience it's much more convenient than the built-in ML-based solution (and also less hacky and bloated than AlDente).

See this discussion [0] on GitHub for the explanation and this snippet [1] for easy use.

This solution also works while the laptop is sleeping, the only limitation is that it doesn't survive reboots.

[0] https://github.com/actuallymentor/battery/pull/163

[1] https://github.com/actuallymentor/battery/pull/163#issuecomm...

I use the paid version of an app called Al Dente [1] to set the battery charging level to a specific limit. The app has a free mode. It has more features than what I stated, and works on Intel Macs and Apple Silicon Macs (limited only by what the underlying hardware allows).

[1]: https://apphousekitchen.com/

I don't know if they changed this, but I think AlDente follows a polling approach where it periodically checks the charge level and enable/disable the charging accordingly. Such solution is more hacky and it also could cause some sleep-related issues.

The SMC key discovered my marcan is nicer because it enables the same functionality without having to poll anything, as it's built into macOS.

Furthermore, I don't care about all the extra stuff they have put into AlDente, I just want to keep my battery at 80%.

I had such a switch in my old Samsung laptop. Works much better than software-based solutions, which are often simply unreliable.

Subscription pricing eh?

this switch is available to users on iPhone 15's

I know, I hope Apple will decide to expose it to everyone in the future, since it's already implemented..

It would be very easy to implement in software. Just display a green and yellow/red bar on the battery status icon and allow for people to say full is 80%, empty is 20%. Or something.

For me it is well worth going from charger to charger (they are everywhere, especially if you put some wireless chargers here and there) if that means the phone can still do a full day after 5 years.

I generally use phones until they stop working. I'm into my 3rd year with my iPhone 12 mini, the phone is still super fast, takes great pictures and still feels like "my new phone".

BCLM can set charging thresholds on Intel Macbooks https://github.com/zackelia/bclm

Nice, didn't know that!

Basically the SMC key that marcan discovered is the same thing for Apple Silicon

My older intel based macbook pro has started to tell me i use it mostly plugged in and won't charge higher than 80% on its own. There's also a 'charge now' button.

I'm not even on a recent Mac OS, it's still on Monterey. No extra apps to handle battery.

Of course, it doesn't look like a hard limit, but something triggered by usage patterns.

My problem with the built-in charging limiter is that if you are not extremely consistent in your usage patterns (I am not), it basically never kicks in. I much prefer a manual solution.

I've been using ACCA[0] for years to limit charge on my phone, usually to 60%, but higher when needed. I also limit the charging speed most of the time.

It performs like new despite the phone being over three years old. I'm determined to keep it usable as long as I can because I prefer its size and analog headphone jack over what's available now. Actually replacing the battery, however looks like a big hassle, so I'm determined to put that off for years.

[0] https://f-droid.org/packages/mattecarra.accapp/

I've been trying a similar experiment for several years now. I have a four year old iPhone, and for most of its life, the battery level has been kept between 30% and 70%. Settings => Battery => Battery Health and Charging says that the maximum capacity is 91%.

No idea whether that's better or worse than average, but I mention it so others can compare. I can say that this is the first time I've tried this experiment, and this phone has already outlasted any previous phone I've had.

Did you have an automated way to do that?

I wish I did but I haven't found one yet. I'm at my desk a lot, and that's usually when I charge it. I mostly use an old, low-current charger (originally for a bluetooth headset) so it charges slowly, about 5% per hour.

Which begs the question: if I charge my new Mac with an iPhone charger (8W), will it lengthen the battery life ?

I don't think so. You need 20V to charge a laptop

Probably not, seeing as that's not enough power to charge it up.

Answering peer comments: oh but it DOES work.

I forgot my charger in another town so I bought a USB-A/C cable and tried it out. Again, the iPhone charger is 8W. This is also the value reported by '/usr/sbin/system_profiler SPPowerDataType | grep Wattage'

When the Mac is open and in use (2023, M2) the iPhone charger can just about keep the charge level level, depending on usage.

But then when I close the Mac, it can easily take 10 hours to reach a full charge... but it does hit 100%.

So I am wondering if this is in fact a gentler way to charge the battery.

I have 2-year iPhone 13 Mini which I didn't care much about keeping some charging regime. It reports 100% capacity. I wouldn't trust this number. Another data point: 2-year MacBook Pro 16" which lives on my table (I don't think I've ever used it without charger), keeps its battery at 80% and reports 91% capacity.

I'm on the 12 Mini without any care with charging, it's at 89% capacity. I do have "Optimised Battery Charging On" apparently, not sure when that was added? Might've always been on not sure. From the description:

"To reduce battery ageing, iPhone learns from your daily charging routine so it can wait to finish charging past 80% until you need to use it."

So I imagine it stops charging or fast charging after 80%. And slow charges that last 20% for when it expects you to need the phone. Not sure how much this differs from only ever charging up to 80%.

I also use Carplay wired, so it's always charging in the car as well.

Just checked my iPhone 11 (work phone) it's at 86%, that's the normal sized model.

If phones with easily replaceable batteries arrive due to legislation, it would be one major win, less waste and more peace of mind.

I'm not so sure it would result in less waste. Apple will replace the batteries cheaply and recycle them; how many user-replaced batteries will go in the trash? How many extra batteries will people buy and never use, or replace their batteries before they actually need to?

I kinda wish my EV would just set the apparent 0% and 100% points at a level that guaranteed X cycles, where X corresponds to perhaps 200K miles. As capacity and fast charging infrastructure improves, it'll be less important for me to access the top 20% of the battery just to make a road trip feasible.

Hell, I'm okay with it just being a lie that I can control. Let me choose those points.

”I kinda wish my EV would just set the apparent 0% and 100% points at a level that guaranteed X cycles, where X corresponds to perhaps 200K miles.”

They already do! In most EVs, 0% is not really zero: you can typically drive another 20-40 miles before it finally dies.

Most EVs will easily have a battery life of 200K miles, with some capacity degradation. Active battery management such as limiting the max charge is more about preserving the battery life beyond this, and reducing degradation.

And all of this becomes less necessary with LFP battery chemistry, which is leas fussy about charge levels and less susceptible to degradation.

What happens if you actually do fully drain an EV on the road? How do you recover from that situation? Normally you’d just have to get a container of fuel delivered to you.

Most likely you get towed to the nearest charger on a flat-bed truck. But portable chargers (with batteries or diesel generators) on the back of trucks or vans also exist.

Some EVs also support power output (V2x) from their charge ports, allowing you to charge up one vehicle from another.

What exactly is the reason the car shouldn't be towed for regen? It seems a dead EV can just be towed to the midpoint between origin and the nearest charging station, then can be driven to the station using regen'd charge.

If the EV is truly dead then you may not even be able to put it in Drive mode until it’s plugged in, so regen wouldn’t be possible.

But sure, assuming you have enough power to put it in drive, there’s no reason that you can’t do this. There’s YouTube videos where people have tried it successfully.

My understanding is that manufacturers don’t support or recommend this method, though.

I find it a lot easier to keep my EV between 20 and 80% than my cell phone. Just plug in whenever you come home and set your top charge to 80%.

BMW i3 does that, kinda. I checked the raw data against the claimed battery size, and the in-car 0-100% was 20-80% of the battery.

My new Renault Megane E-tech does not do this. Instead it has an option to limit charging to a given percentage (if you set it to 100% it'll ask if it's just next charge) and the manual states that if you have less than 15km range the car might switch off at any moment without notice...

Let's just say I was mildly surprised about the latter.

Both cars had battery guarantees though, the Megane's is minimum 80% SOH after 8 years or 160000 km, with no reservations against charging to 100%.

There is so much confusion, misinformation and naive testing about this topic. I've only learned about this "80% battery thing" when researching EVs recently and it seems to have been (maybe) spawned by the Nissan Leaf many years ago.

And now it's appearing on HN seemingly once a week. What has changed? Is someone running an information(or disinformation) campaign? Blog or app to promote?

I've not spoken earlier for fear of being downvoted into oblivion: I am sorry to say, but this 80% nonsense is just ... terrible advice and is 90% wrong. Like "skipping a daily coffee will let you retire 10 years sooner" wrong. (And all these lovely graphs I see thrown around are from poorly setup and poorly controlled tests using small samples or maybe even they're faked idk).

To be horribly simplistic about it, the biggest factor in battery ageing is thermals. So if you want actionable advice on increasing the longevity of your battery (in the mobile phone context):

Don't let it get hot, which means things like:

* Take off that awful plastic insulator you call a phone case. (But we need phone cases)

* Charge it slowly. Lower charge rate = less heat = happier battery. (But people love charging their phone in 1 minute)

* Charge at human ambient temperature. (But on my bed, in the sun is easier)

I guess those are inconvenient and poor sound bites. I'm sorry, but consumer devices (especially phones) have poor thermals and the environment they're subjected to sucks. That's just a fact of life (and economics and physics).

Very simplistically, the only way "charge to 80% only" *might* be helping you is by keeping the battery cooler (In which case the above advice is much better).

Source?

14 years in electronic products (consumer and industrial) including Multi chemistry battery management system (BMS) designs.

Tesla charges battery to 80%. The supercharger charges it there in less than an hour and manages thermals. And it charges very slowly at the end.

Tesla battery lasts very well. Keeping battery between 20-80% is healthy.

Your comment kind of implies that 80% charge is irrelevant, but the things you mention PLUS the discharge depth or how full you charge also affect the equation from what I gather.

https://www.greencarreports.com/news/1110149_tesla-model-s-b...

"Your comment kind of implies that 80% charge is irrelevant"

I don't mean to merely imply that only charging up to 80% charge is (essentially) irrelevant. I mean to state that it is.

What actually happens at around 80% is that the charging regime changes. It's nothing to do with "making the battery age less". A lithium battery has two charging regimes: Constant Current and Constant Voltage. Up to about 80% a lithium battery is charged with constant current => charge speed is limited by the maximum output current of the charger => bigger charger faster charger speed => happy customer.

Above ~80% you switch to Constant Voltage. Charger now charges at a constant voltage and the charge current drops off following a log curve. The closer you get to 100% the lower the current => battery charges slower and slower the closer you get to 100%. This is a simple matter of physics and is the antithesis to "Fast Charging" which is why fast charging always talks about charging up to 80%.

"but the things you mention PLUS the discharge depth or how full you charge also affect the equation from what I gather."

Yes, depth of discharge (DoD) does affect battery ageing. But there's also a dozen other factors as well. Some affect the battery life more than DoD.

So yeah don't waste your life trying to compile custom kernels or whatever to only charge to 80% :) Just help the battery keep cool with what I posted earlier. It's all you can do. Worry about other things in life :)

I think people are confused because of the advice to not charge above 80% on fast DC chargers, but that is about the exponential reduction in safe charging speed at high state of charge, not battery degradation (excepting old versions of the Nissan Leaf with bad battery management).

If you fast charge to above 80% you are wasting your own time and the time of other people waiting to charge, so manufacturers usually quote fast charge times for a 10% to 80% charge, which is both more realistic and make the cars look better.

This post doesn't give any actual argument why you should charge your device only to 80%. If you use your phone for, say, four years, and charge it to 100% regularly, how much will the battery life deteriorate during those four years? I assume if the fully-charged capacity after three years is still at least 80% of the original, then regularly charging it fully was absolutely worth it. The point is that deterioration in battery capacity has to be compared to the loss of usable capacity if you only charge it to 80% voluntarily.

By the way, they also warn from fully discharging the battery, and recommend an charge range from 30% to 80%. This would mean you limit yourself to only 50% of the capacity. It is questionable whether gains in battery lifetime can outweigh this loss in realistic scenarios.

The main lesson seems to be that you shouldn't fully discharge your battery when you can avoid it easily, and not fully charge it if you know in advance that you won't need the full charge.

Bought my previous iphone in early 2018. Changed the battery this spring because its health reportedly fell below 80% of its maximum capacity.

I could not care less to be honest. Always charged to 100%. Dropped the phone multiple times throughout its lifetime. Fully discharged at random. Exposed to 50°C and direct sunlight as well as well below zero. 5 years is a good job done for a non-replaceable battery. And the cost of replacement was like 50usd or something in apple store.

The question is: why should I start bothering?..

If you were talking about the battery in your EV, the cost of replacement would be a bit higher. There are more things with batteries than iphones.

This post doesn't give any actual argument why you should charge your device only to 80%.

It does, it tells you the battery will degrade 5 times less compared to charging it to 100%. If that is worth it is up to you to decide. I charge my phone daily, it's usually around 40% at the end of day so charging it to 80% should only benefit me.

It does, it tells you the battery will degrade 5 times less compared to charging it to 100%.

The original question was whether the slower degradation of the battery is worth the immediate loss of 20% battery capacity, not whether the battery degrades slower.

It's highly dependent on the actual chemistry of the battery used.

If you can find the spec sheet from the battery manufacturer, it should tell how discharge/charge voltages affect lifespan.

Broadly, for lithium you can check out these charts: https://www.bing.com/images/search?q=dod+cycle+life+lithium+...

I recently bought a Pixel phone after having Samsung for a few years. Immediately the one thing that annoyed me was the lack for both limiting charge as well as enforcing slow charging. Both not only are useful for long term battery life but also, since I'm an occasional thruhiker (right now on my way to Mexico along The Continental Divide Trail), they make better use of my power bank. Without rooting the device these two features are not available (well, I can achieve slow charging by using a cable that only supports certain voltage and current)

By default my Pixel will slow charge when I set it down at the end of the day and be at 100% when my alarm goes off in the morning.

If you go to bed late, wake up early, need to charge for a few minutes at a party, etc, android slow charge at best doesn't work, and at worst works against you.

I have no idea how setting charging settings on our mobile computing devices is something that is not supported in 2023

Yes, It does that based on some none-transparent parameters. For example, right now my phone will try to slow charge at night. However, charging at night is impossible for me as the temperatures are too low (10f is nothing unusual right now on the divide). So, I have to set a fake alarm (or change my time zone) in hope that adaptive charging mode will trigger slow charging. It doesn't always work.

Use the adaptive charging setting

Read my previous comment. It's just a "smart" mode that gives you zero real control and won't work for my use case.

We just got a Tesla model Y. When we picked it up, they told us to charge it up to 100% at least once per week. Is there something different about these batteries?

Some models (RWD?) are equipped with LFP (lithium iron phosphate) batteries. Tesla recommends setting a charge limit of 100% and, as you mentioned, charging up to 100% at least once per week.

https://www.reddit.com/r/electricvehicles/comments/10ji8yk/l...

Yes - ours is RWD.

You probably have one with a LFP battery.

They have a different chemistry that is cheaper, have a lower energy density, are less powerful, don’t like cold, but that can often be charged to 100%.

The reason you need to charge it to 100% so often too is that it’s the voltage on a LFP battery is all over the place and the battery management system (BMS) has a hard time to keep track of the remaining capacity. Those system usually rely on the voltage but they can’t on this kind of battery. So charging to 100% will let the car know an accurate battery state of charge: full.

I have a model y with a classic LG lithium battery and I almost never charge to 100% and the car is discouraging charging that high in its user interface.

https://en.m.wikipedia.org/wiki/Lithium_iron_phosphate_batte...

The percentage is irrelevant, what matters is the charge termination voltage, which AFAIK is lower on all electric cars because you care about battery longevity. I.e. if the same cells were in a laptop, your car showing 100% might only be 80% in the laptop, and it's all good.

(What the actual charge termination voltage [and cell type] is, I sadly don't know and don't know where to find…)

Samsung phones have a good feature which limit charging to 85%. The only thing it's missing is the easy "I want full charge today" button, you need to go deep into settings to toggle this.

The other minor annoyance is that subjectively the battery charged to 100% seems to make a bigger difference than the reported 15% indicates - it seems like 30% or even more. Maybe some battery recalibration issue. But it doesn't bother me that much since 85% still carries me comfortably through the day.

You (or at least I) can add a quick toggle button called Protect Battery. This makes it as easy to toggle as all the other options like wifi, bluetooth, etc.

This is brilliant, thank you!

Indeed, very useful, thanks for the tip!

Pro tip: go to the settings app and type "prot" in the search bar at the top, the first search results will be "Protect battery", so you don't need to navigate to it step by step

Tesla suggests charging their new LFP type battery to 100% regularly. Why isn't this new type of battery more widely used?

https://en.wikipedia.org/wiki/Lithium_iron_phosphate_battery...

Patents only expired in 2022.

Because it has less energy density in favour of more stability.

The battery in my pixel 4xl failed two times under warranty and then a third where googles service provider wouldn't do it again for me. (The ribbon connector is actually what fails).

So I went to Amazon and bought a $14 kit that came with a battery AND tools. Did it myself in 15 minutes. (Whereas the UBreakIfix vendor took like 2 hours of my time between dropoff and pickup).

The Amazon battery has lasted longer than 3 Google official batteries did. Even so, I no longer worry about batteries when all these cheap kits and instructions exist.

You did all this in 15 minutes? https://www.youtube.com/watch?v=m1gVWGAw8do

Let me guess, the back cover wasn't stuck on very well from the repeated battery replacements.

Yes, 15 minutes or less. There's like 3 screws to undo on the battery clamp and 4-5 for the camera or whatever. That's it.

I suppose yes it was a not stuck together as well as a new phone.. I wouldn't know since a certified Google place had fixed it prior. So if it was stuck together like new, it would have taken me a few extra minutes with a heat gun. Still much much faster than having a pro do it for me.

Well that's comforting because I have my Pixel phone and a new third-party battery sitting in a box on my desk and I feel just a little intimidiated to tackle it. I will try it now.

I always try to keep between 20-80% with my iPhone and consequently always feel bad about my AirPods. The case is always as empty as possible, the pods as full as possible. They spend almost their entire life at 100% as a result of the charging case. Even though I always use them at a max of 1 hour or so at a time.

In other words: I first need to drain the case to the very bad 0% to get the pods to go down, otherwise they sit at 100% almost always because sometime I don't use them for days. I hope Apple designed for this...

I really wish I had more control over my device's charging cycles. I generally use phones until they really die (replaced my OnePlus 3 with an iPhone 12 mini because the power button broke and battery was down to 10 hrs or so), iPhone 12 mini still feels like my new phone and works great, I see myself using it for years to come (especially because I think it is the perfect size).

Perhaps I should get a non-charging AirPods case somewhere.

Well if it matters, I'm astounded at my airpod Pro's battery life. Going on four years of daily use, and I still get 3.5 hours straight hours out of them every night

The case is always as empty as possible, the pods as full as possible. They spend almost their entire life at 100% as a result of the charging case. Even though I always use them at a max of 1 hour or so at a time.

I wouldn't assume that Apple hasn't thought about this or that your earbuds are telling you the truth about their charge level. I have a Jabra headset that is four years old, and it is smart enough to profile my usage and optimize its charging. In normal use, I wear it during the workday and plug it in every night. In response, it slowly charges up to about 60% by morning, which is more than enough to get through the day. However, when I go on a trip and charge it less frequently, it responds by quickly and fully charging when I do get a chance to plug it in. (I only wish I could tell it when I'm about to leave on a trip, but the battery has lasted four years of almost daily use now, so it's a small price to pay.) If Jabra can do this, Apple can too.

On Android, I use a terminal script called Advanced Charging Controller (ACC) to automate keeping the battery under 80% and some other battery saving tweaks. It allows you to charge to any value (like 80%), then stop charging until it discharges to another set value, which triggers it to start charging again. That was you can keep it between something like 70% and 80% while you leave it charging over night. It also has settings to keep the batter under a specified temperature and trigger cool-down intervals if it gets to a particular temperature. It can use a job scheduler to switch between different profiles for different days, or events. There are also some frontend apps, which let the user control the script with a more friendly GUI ("AccA" or "ACC Settings").

Link to the script: https://github.com/VR-25/acc This does require root permissions, though.

AccA is awesome! I used it to repurpose my decade old Samsung Galaxy Grand Prime as a custom wall clock and alarm.

I couldn't figure out how to power it without a battery, and If I had plugged it in all time I was risking an exploded battery.

Enter AccA, it remains between 50-55% all the time, along with prioritizing battery-idle mode (which means the device tries to draw power directly from the external power source).

That is a good idea. Years back, I had a very old phone that I used as an alarm clock and media player. It would have been nice to not worry about charging. I did disable the mobile and wifi radios, which saved a tons of battery.

I'm in the "flashlight nerd" gang, and I've learned to store my long-term storage li-on batteries at near 50% capacity to extend their life tremendously. I've also implemented this strategy with my portable chargers, and they've lasted for years now at full capacity still.

Full half capacity?

The total capacity, meaning the battery's original mAh capacity.

I use a Chargie (chargie.org) hardware device to limit charge on my devices to 80%, and the batteries last nearly forever. Currently typing this on a 4 year old iPhone with like new battery function. I highly recommend these, I’ve been using them since they were first sold. I have no affiliation, but am a very satisfied customer.

For my Macbooks I use an app called Al Dente. I still have have 2016 MacBook with like new battery life.

People will ask is this worth it? Isn’t it a pain to have a device only charged to 80%?

It is totally worth it- because I only do it 80% thing when staying home, so when I travel my devices have full battery health and don’t run empty when I most need them.

Wow I didn't know chargie.org existed! I'm happy to finally see a device like this on the market.

I've had the same idea and created a device exactly like this as a high school project back in 2018, but didn't push it further

Is that really necessary? Don't basically all modern phones, laptops, tablets, etc all have battery protection software built-in?

I'm a simple man. My phone needs a charge I plug it in. When it's charged and/or I need it I unplug it.

I largely trust companies to get these basics right and haven't had an issue.

and haven't had an issue.

Every lithium battery in every device you’ve used has degraded. It’s not a manufacturing issue, it’s a chemistry issue.

If you haven’t had an issue, then you aren’t paying attention, or you don’t keep your devices for long enough for the degradation to be a problem. This doesn’t mean there’s no issue, this just means the issue doesn’t affect you personally.

A small change in charging habits could prolong the life of billions of devices, a huge win for the environment. You shouldn’t be so quick to dismiss the idea just because you personally aren’t affected.

If the company gives you a "battery saver" option, always enable it. If they don't, see if you can find 3rd party software to, or unplug it at 85%.

I wish my car can self-limit to 80%. Right now I have to set a timer to remind myself to unplug. If I forget to set the timer, I'm screwed. If at the exact moment it's inconvenient to go unplug, I'm screwed. Replacing the battery costs 18000 EUR.

What car do you have? I've been used-car shopping for an EV and every one I've looked at here let me limit charge.

Mercedes plug-in hybrid from 2015.

This is an excellent answer and explanation. It’s helpful for people that want a deeper understanding of what’s going on with lithium batteries and where the 80% recommendations come from.

But in terms of general advice that does the most good for the average person, I strongly recommend just doing whatever the manufacturer says. Just use the device and charge it when you want. Live. Some team at Apple, Tesla, Google, whatever, spent 9 figures plus figuring out how to charge the battery so that it meets lifetime guarantees under normal use. There’s too much bad advice out there. Don’t discharge fully every cycle/occasionally (that was NiCd specific, and it was bad advice then). Don’t obsess about turning things off, force quitting apps, putting your car in neutral, or whatever dumb thing your neighbor said.

That being said, the answer here is correct, but keep in mind how that works with the battery management your device already has. Tesla explicitly recommends a lower limit. Do it. Apple phones limit charge cap to 80% until before you wake up. That’s great.

I for one would at least like it to be configurable as much as possible so I can pick if, say, I want my laptop to only stay on storage voltage when I keep it constantly plugged in, or say my phone shutting down at 15% instead because the morons designing it have glued in the battery, or alternatively allow going lower for a bit more damage if I'm lost in a forest and need every mW I can get before it dies. Call it consumer choice.

I'm so fucking tired of every affordable BMS on the market being hardwired to cut charge at 4.3 V (beyond what the charger will even reach per cell, so you get no top balancing lmao) and allow going down to 2.5 V like bruh what are you even protecting at that point, staying at those extremes for any amount of time will destroy the battery anyway. It would've cost them 2 cents to replace fixed resistors with those screw potentiometers for range adjustment.

It feels like manufacturers decided to offset their lawnmowing to end users. I am not an expert in this field but 0% charge is not zero as far as I know. Completely drained battery cannot be charged and is usually unrecoverably dead. As for 100% again there is a speculation that 100% does not reflect the full charge and if it does, then the battery itself has safeguards to cut off power.

I want my device to plug in and out without much thinking as this is the scenario 99% of customers will follow. So the device I am charging should be smart enough to handle overheating, overcharging, its battery’s lifecycle, etc. and I believe it is possible to do without involving end users into this decision making.

If the lower threshold is 30% let it be so. Tell me via notification to connect a charger to help the precious energy cell stay safe and healthy. If the upper is 80% just lie to me saying that you are fully charged when in reality you are rotating the ions. Just be consistent in the average behavior and that’s it.

In a microfpv world (tiny drones) it used to be pretty common to overvolt li-ion batteries to fill them "beyond 100%". These days manufacturers sell you batteries rated to charge to 4.35V,but they don't last long this way.

Some mad people even charge huge 6c-2500mAh batteries like this, but it is insanity.

Does anyone know how limited charging works with balancing? As I understand balancing only happens when batteries reach their full capacity.

A bit of background: Batteries are made up of cells which have ever so slightly different voltages. If you have three 3.7v cells in series to make a 9.2V some cells will be 3.68V and another could be 3.72V. This is bad, because when you charge the battery it is charged as a whole unit - the BMS will simply stop charging when it reaches 9.2V (or whatever it is set to). Over time the difference between the cells will increase, which could ends up with one cell being 3.9V and another 3.5V. tThis will result in you damaging the higher cells (which if overcharged enough could cause a fire) and the lower cells will not be fully charged so the battery will have a lower capacity.

My understanding: Balancing is designed to fix this. The idea is that there is a resistor in series with each cell, and it turns on when that cell reaches the set point, e.g. 3.70V. That way when you charge the battery as a whole to 9.2V, you know each individual cell is also 3.70V.

This is a naive solution though, as for larger batteries you will have cells in parallel and you can't use this approach there. The better approach would be to charge each cell individually, but as I understand even large batteries like Powerwalls do not do this.

1. Balancing does not change the internal impedance of cells with different aging characteristics. You will be constrained by the weakest cell behaving more like a crude resister in the pack over time.

2. Balancing does ensure the capacity of all cells is maximized, but does not match each discharge characteristic under load.

Thus, the method can improve cell life under shallow changing, but can't atop unbalanced loading with random cell impedance mismatch.

There are good chargers and special meters that can help match a set of cells.

Best of luck =)

"Adaptive Charging" is the answer to this problem no?

My phone lowers the rate of charging so it's only at 100% by the time you wake up.

Even just making it easier to replace the battery ("right to repair") would mitigate this.

No. It's better but still stresses the battery when loading to 100%. Best is to load slowly (or so that the battery doesn't get too warm) to 80% or 90%.

As a consumer do I have to worry about this or will BMS handle things? My kid runs his 3DS until it shuts off and I was wondering what impact that kind of behaviour might have.

I wouldn’t expend any energy worrying about it. It’s meant to shut off before causing any damage. And even if you could slightly extend the life by babying the battery, who cares, you can trivially replace the 3DS battery for cheap.

The rule of thumb is you roughly double cycle life for every 0.1v lower you go (approx. 10% of charge).

I would only restrict the full charge level of you never need the full charge available anyway. Eg. I only use about 60% of my phone's battery, so I can comfortably restrict it to 85% and have plenty of leeway to avoid running out. If there's a decent chance you need the full battery, just use the full battery.

Also consider how long you expect to keep a device. A couple of years of daily charging is 700 cycles, so worth considering preserving battery lifetime if it suits you.

Iirc the chevy volt only lets you use around 60% of the battery pack under normal conditions.

Love my volt. 104K miles, 10 years old, no signs of battery performance degredation yet.

My last volt had 156k and same age and same performance (got totalled :( )

This seems to be good advice for single cells. But what about packs with cells wired in series and parallel? My understanding is, that packs always come with a battery management system (BMS) that will balance the cell voltages and therefore compensate for slight variations between cells that can manifest during use and charging. This seems to be necessary for both performance and longevity of the pack. Now the question is, do these BMSs work properly if you never or rarely charge your pack to 100%? I tend to charge packs to 100% to give the BMS a chance to do the balancing and then keep it off a charger for as long as possible. Not sure if my thinking is correct though. Maybe someone with more knowledge could chime in.

do these BMSs work properly if you never or rarely charge your pack to 100%

I'm no EE, but from the instructions I was given, the answer is no, the BMS requires 100% charge to kick in and "top up" the lower cells.

The recommendation was to do that every n=few charging cycles.

Pro Tip: Use this nifty charge limiter¹ on your macbooks to limit your laptop charging. I can see a noticeable improvement in my MBP battery life.

1: https://github.com/AppHouseKitchen/AlDente-Charge-Limiter

I think this [0] native approach is preferable

[0] https://github.com/actuallymentor/battery/pull/163

I've used the 80% max charge setting on a 15 pro since the first week or so. FWIW, it seems Apple has it charge to 100% occasionally (about once a month) even with the setting active.

I wish you could have iOS artificially adjust/map the visible battery level reading to your 0-80% limit (as 0-100%) - starting at 80% gives undue battery anxiety... but the other reason I use the 80% limit is that it still lasts DAYS and I don't have to think about charging it every day. That and battery longevity is nice on a phone that may go on for 5+ years.

Any BMS needs to charge fully to have the most accurate charge capacity, so it’s no surprise it automatically charges to 100% occasionally. Shouldn’t really matter for longevity if you’re doing it rarely.

Charge Li-Ion to 4.21V and that's that. The rest (over 4.25) is overcharging. If you see the voltages charged - it's clearly outside the spec. Using a voltage -> percentage table is just a gimmick that has managed to stick. The entire discussion is littered with percentages that aside being non-scientific, mean absolutely nothing at all as they are not comparable.

Most tool batteries, vacuum and mower robots - all charge below 4.2V - yet phones (and some laptops) are special.

Morealso charging it to '80%' means little as we have no clue what charge profile: constant voltage [how high]/current is used and when.

Neither too full nor too empty seems to be the sweet spot, but of course those who'd rather you buy a new one once in a while will optimise for other things than total cycle life energy.

The newish "high voltage" (>4.2V/cell) cells are an excellent example of this; they've come up with better material chemistries that resist degradation and would let cells last many times longer for the same capacity, but instead they just push the cells harder so they end up lasting roughly the same amount of time for a few tens of % increase in capacity.

Here are some good references on this with actual measurements, see e.g. table 4 on how many discharge cycles you can get out of a certain maximum voltage / charging level: https://batteryuniversity.com/article/bu-808-how-to-prolong-...

https://batteryuniversity.com/article/bu-204-how-do-lithium-... https://batteryuniversity.com/article/bu-501a-discharge-char...

On Thinkpads you can use tp_smapi to set charge start and stop thresholds https://wiki.archlinux.org/title/tp_smapi

One of my pet peeves is how people get so dismissive about limiting their battery charge. People will even get defensive, as if it is a personal attack or something. Empirical evidence has shown time and time again that it is a-matter-of-fact that stopping charge at 80% will prolong a lithium-ion battery. [1][2][3]

I mean, it’s one thing to be believe that it is “too inconvenient” or that “life’s too short to micromanage my phone battery”, and another to blatantly spread lies that stopping charge at 80% is a “myth” with no benefit. And maybe that “micromanagement” argument was true 5 years ago, but nowadays nearly every device can automatically limit charge levels, e.g.:

iPhone 15 and above

iPhone 14 and below with a smart-plug[4]

Most Samsung phones/tablets

Sony phones/tablets

Any rooted Android

Any decent EV

Windows: Asus, Dell, HP, Lenovo, and Microsoft laptops

MacOS through AlDente[5]

Linux: TLP for most manufacturers[6]

And honestly if your device can’t automatically limit charge, I concede it probably isn’t worth the micromanagement. But those kinds of devices have small, cheap, and easy to replace batteries anyway.

It’s a heck of a lot different to drive to the Apple Store and spend $250 for a MacBook battery versus the $30 battery and half hour of work for Nintendo Switch.

[1] https://batteryuniversity.com/article/bu-808-how-to-prolong-...

[2] https://accubattery.zendesk.com/hc/en-us/sections/202397985-...

[3] https://www.sciencedirect.com/science/article/pii/S235248471...

[4] https://forums.macrumors.com/threads/how-to-set-an-automatio...

[5]https://github.com/AppHouseKitchen/AlDente-Charge-Limiter

[6] https://linrunner.de/tlp/settings/bc-vendors.html

Most comments focus on consumer electronics where battery replacement is around $70-200. However the biggest impact is actually on EVs, where replacement costs are of much greater concern.

For large batteries supporting buildings or power plants, there's usually an optimization software that balances energy usage opportunity costs, and the amortized costs of battery degradation (personally built one in my previous job).

I can highly recommend ACC (and the ACCA app [1] for setup). It lets me limit my phone to 90% charge with the ability to ignore the limit temporarily when I need to. That's very useful for fixing the battery calibration, which can go bad when using ACC.

It has reduced my battery wear by 40-50% according to Accubattery's capacity graph.

[1] https://github.com/MatteCarra/AccA

I remove my laptop battery while using it at home. Its 12y old and still going strong.

I really want 80% limit feature on TWS earphones. It has small battery, perhaps fully utilize battery capacity for longer battery life, harder to replace battery (especially with waterproof). I'd like to have a 80%-100% slide switch on the case, but it would be too nerd feature.

" 100 % " is a matter of definition. It's planned obsolescence, simply put. What is generally agreed upon as " 100 % " is the voltage that makes the capacity drop to ~ 80 % after 300~350 full charge cycles. This means your device battery is at end-of-life after a full year of daily full charge cycles. Why we've defined it as such, I don't know. If we wanted our batteries to live longer we could simply change the definition of " 100 % " indicate 600 full charge cycles. In practice it would mean something like dropping the peak capacity voltage from 4.20 Volts to 4.10 Volts.

But where can I see real data and graphs about millions of batteries in phones and laptops, not these anecdata "i have a phone which lasted blah years".

Note: changing the chemistry is likely an option.

Lead-Acids prefer to sit at 100% or even slightly overcharged.

Figuring out the 80% point of li-ion is difficult due to the flat discharge curve.

Most of the devices that allow charge limiting don't have battery cutoff anyway, so you're discharging to 79% and charging to 80 over and over again. I've observed that in my ThinkPad. Fretting over ultimate lifespan doesn't seem worth it, especially at the wild charge rates devices have now.

This can't really be that big a deal. My framework laptop used to have a setting right in the bios about not charging past 60% if you plan to keep it plugged in all the time... at some point they just bug broke that feature and never bothered to fix it ever again. These are smart people and I trust that it can't really matter that much or they would have fixed it by now

Thanks, this post led to me finally getting around to limiting my Thinkpad's charging thresholds and discovering TLP (Linux power-tuning utility) in the process :)

For people who care about this, I would recommend float charging at 40%, slow charge to 60% before use, then slow discharge to 40%, preferably all done at 10 degrees C. And, for safety reasons, you should ideally have supervised charging in a fireproof bunker. Empty fireplaces and concrete basement floors can work in a pinch.

If you don't care, just use your device normally and buy a new one when the old one's cycle life starts to suffer.

If you want to be somewhere in the middle, try to plug it in reasonably soon after it dies, or ideally before it dies. Keep an eye on your devices on the first charge after you buy them, and on the first charge after a drop or impact, watching for smoke, burning plastic smell and swelling. Don't attempt to charge a swelled battery, and dispose of lithium ion batteries properly. Disclaimer: All the above advice is given without warranty, do your own research and don't rely on this advice for your safety.

I kept my XS max for about 5 years, and always charged it with a 5w pad overnight. Battery health after 5 years was 86% which is pretty decent.

1. All batteries have an aging characteristic whether they are charged or not (around 6% loss per year). For example, a home solar array or EV should prioritize the largest practical capacity budgets allow. Thus, the performance remains more consistent throughout the entire service life. This also reduces the discharge load stress on the cells reducing wear, and exposing greater energy capacity through efficiency gains.

2. There are several types of Lithium batteries with unique charge cycle limits. A common 4.2v cell is ideally rated for 8000 cycles if shallow cycled, and slow charged. Accordingly, deep cycling a LiPol or LiIon below 60% into the dead pre-conditioning zone or in the Constant-Current mode will reduce the life to well below 4000 cycles.

3. 80% or 100% full is meaningless because accessible energy depends on temperature (outside 4'C to 50'C is bad), chemistry, and loading. Typically, even the cheapest Lithium charge management ICs have a hysteresis built into the cycle, and will let the cells stand-by after charging until the cell internal resistance self-drains a bit of power in time before charging again.

4. Li batteries do not like trickle-charging or rapid-changing, and in a way the "100%" indication icon often means just that. Over-boosted the cell into the 112% capacity range to provide a short-term capacity boost. This wears out the cell 15% faster, but many tends to do this... so who would know the difference. I'd wager the Apple team added the 80% mode to turn off this boost trick, at the cost of "boosted" capacity.

5. There are consumer chargers for Lithium cells with temperature and impedance monitoring while charging. These are highly recommended if you have 21700 or 18650 cell based equipment. Unlike other options these chargers will show you a rapid impedance change when the cell has an internal problem (dendrite fusing in polymers etc.)

Read the manufacturers app notes for your cells. They will often disclose the conditions their chemistry is stable (Samsung and Sony are usually the best). There are so many various types of cells out there... most of them are crap.

This text is just a starting point, and should be assumed as another ill-informed internet opinion until validated under your own efforts. YMMV

Best regards =)

Another important rule: Never leave a lithium-ion battery at 100% charge (or <10% charge), or in an unventilated/hot area, for a long time. It makes battery swelling more likely.

https://www.washingtonpost.com/technology/2022/04/18/lithium... https://bgr.com/tech/samsung-galaxy-batteries-might-have-a-s... https://www.reddit.com/r/spicypillows/comments/gebotv/faq_wh...