Charging a lithium battery to 80% only?
electronics.stackexchange.com
electronics.stackexchange.com
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.
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.
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.
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).
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.
Yes, this feature is one of the most underrated features on Samsung devices. Massively underrated.
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%.
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.
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[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".
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.
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%.
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.
I suspect quite a few people do that so it probably is net-good overall, but agree it doesn’t work well if you’re moving around a lot.
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)
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...
Shame that seems to be harder and harder to find on new phones.
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%.
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.
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.
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.
If you specifically seek out devices with cheap replaceable batteries, sure. But this isn't the case with a lot of devices.
If you pull statistics you also have to filter out the sub 150 dollar Andoid phones which may well have shorter average usage life.
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.
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.
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.
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.
Source: I replaced my iPhone battery last week.
Maybe if you have a lot of money to waste, but people should have the option to choose
Also, we're talking in the context of a $1000-1200 phone for the base config. 10% of that cost for a replaced battery does not seem outrageous to me.
As someone else pointed out, the cheaper phones Apple sells have correspondingly cheaper battery repair costs.
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.
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.
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.
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
This tactic would work great in a world with only one phone manufacturer.
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...
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.
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.
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.
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.
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."
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.
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.
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.
I don't blame him 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.
They knew that old devices (especially common with the well-selling iPhone 6) would fail at peak demand, and wanted to address that, but they probably didn't have an accurate figure of exactly how many devices would be covered by the feature as initially configured.
That it took them as long as it did to react to the resulting situation is unfortunate, but could probably be explained by corporate culture at Apple, they don't generally like to admit mistakes (see the Trash Can Mac Pro press meeting a few years back).
In the end it was just a huge PR fuckup, if they had properly considered how many devices would be affected they would have realised they needed to communicate more clearly, they could have avoided lawsuits and honestly if they had played their cards right from the get go they would probably have received praise instead of backlash, but instead here we are 7 years later still explaining how battery chemistry affects integrated circuits on technical forums.
I'm an avid reader of pop-ups and release notes. They didn't tell people.
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
Notably, this will no longer be an issue on modern iPhones because they have much more reasonable batteries.
Apple underspecced the batteries in iPhones and then hid the software kludge they made to hide that fact. That's why the reaction is warranted.
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.
- 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.
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.
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.
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.
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.
FWIW, the performance and CPU features are the same on Mx based MacBooks whether they're plugged in or not.
> M powered MacBooks added (...)
Things that Lenovo laptops have had for a generation?
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.
For this to be happening in 2023 means that some manufacturers at least, seem to be not managing this potential problem at all.
Every company makes big mistakes. Also Apple once built laptops with self-cooking GPUs, a couple ones very fragile keyboards, a series with too-sensitive screen coatings.
We can write tons of problems with every producer. The most important metric is whether they're learning from that or not. As far as I can see Samsung and Apple learnt their lessons.
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.
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.
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.
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? ;)
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.
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.
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.
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.
It was usually less annoying for me to just disable turbo, and only turn it on if I really needed the boost.
# echo disengaged > /proc/acpi/ibm/fan
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.
End result is your old clothes dryer starts taking longer and longer to dry clothes.
Laptops and phones also notoriously slow down to manage heat, and that is also never told to the user.
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.
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
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?
That would be transparent and also allow decisions, if AppleCare also allowed for free battery replacement after receiving that message it would be a PR boon, not a kerfuffle.
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.
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"
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).
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.
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 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
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.
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.
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.
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'm pretty religious about what apps are allowed background data, and notifications in general. But I never turn off any of the radios.
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.
Have you configured anything like "disable background network activity"?
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.
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.
>I have 15 apps "in memory", my phone started lagging
I wish I could tell you... I have 60+ apps 'in memory/suspended' always. I only close an app if there's an issue. I restart my phone maybe once a month, usually from a software update.
The only ways I've seen my phone (iPhone 13, so two years old) lag is: - playing a demanding game and it gets too hot/throttles - using music via bluetooth + GPS + charging at the same time (gets too hot) - when opening 15+ new tabs in Safari simultaneously (like a group of bookmarks), weirdly makes the whole iOS UI stutter for a bit.
I haven't been able to make it lag otherwise.
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.
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.
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.
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.
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 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.
I'm not joking, I have an iPad Pro and the main reason why I NEVER use it is because EVERY time I pick it up and try to use it, the battery is completely drained. To the point, where you have to charge it for five minutes just so that you can power it up again.
In those five minutes I lose interest, so I don't use the iPad. At some point, I remove it from the charger. A week later, I pick it up again.... aaaaand it's dead again.
Isn't that exactly why you want a device that can self-limit? It doesn't need to lie.
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.
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.
> 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.
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?
The 3ds is atrocious though, even with wifi off. With wifi it can't even last a day.
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%.
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.
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.
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.
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...
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".
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'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.
Why oh why can‘t Apple just add a hard 80% limit switch somewhere in the battery settings. What happened to thinking of nature, guys?
Basically the SMC key that marcan discovered is the same thing for Apple Silicon
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'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.
Link to the script: https://github.com/VR-25/acc This does require root permissions, though.
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).
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.
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.
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.
"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.
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.
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.
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.
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?..
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.
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.
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+...
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.
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
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.
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 :( )
I have no idea how setting charging settings on our mobile computing devices is something that is not supported in 2023
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.
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 =)
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.
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.
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 =)
It has reduced my battery wear by 40-50% according to Accubattery's capacity graph.
I don't know how they did it, but it even works when the phone isn't booted.
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 largely trust companies to get these basics right 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.
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...
https://www.reddit.com/r/electricvehicles/comments/10ji8yk/l...
(What the actual charge termination voltage [and cell type] is, I sadly don't know and don't know where to find…)
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.
With careful management, you can as much as triple or quadruple the usable lifespan of a regular lithium battery consumer device.
I was under the impression all phones already do this.
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
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.
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.
Some mad people even charge huge 6c-2500mAh batteries like this, but it is insanity.
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...
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.
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.
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.
Let me guess, the back cover wasn't stuck on very well from the repeated battery replacements.
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.
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).
Hell, I'm okay with it just being a lie that I can control. Let me choose those points.
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%.
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.
Some EVs also support power output (V2x) from their charge ports, allowing you to charge up one vehicle from another.
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.
1: https://github.com/AppHouseKitchen/AlDente-Charge-Limiter
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.
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
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).
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.
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...
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 :)