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Cellphones Power

Ask Slashdot: What's the Best Way to Charge Your Smartphone Battery? 142

Posted by EditorDavid from the battery-up dept.
To stop their smartphone battery from swelling, long-time Slashdot reader shanen bought a Samsung Galaxy with a "restrictive charging option." But what setting should they use? The way this battery protection option worked was to stop charging the phone at 85%. That left me enough charge for my normal daily travels, which rarely took the phone below 50%, and the battery remained unswollen after a year, which included a month of quite heavy tethering, too. Unfortunately... After a recent upgrade, now my Galaxy has three options for the battery where it had two. The 85% option is still there, but it has been lowered to 80%. I've been using that for now and it still seems good enough. However my main concern is with the best option to maximize the overall lifespan of the smartphone...

The other old option says something about using AI to control the battery charging, but I don't trust it and think it is just the old approach that causes phones to die quickly... The new third option is the one that is interesting me. This seems to be a kind of flutter charge where the phone will charge to 100% and then stop until it has dropped to 95% before charging again, even if it remains plugged in. This sounds attractive and would give me more battery insurance when I'm traveling, but maybe it reduces the overall lifetime of the phone?
They tried getting answers from Samsung, but "I think I have been flagged as a low-profit customer." And of course, this raises several other questions? (Are other smartphones better? Have iPhones solved the battery-swelling issue?) And most importantly: is there a way to charge batteries without reducing their lifespan?

Share your own thoughts and experiences in the comments.

What's the best way to charge your smartphone battery?
This discussion has been archived. No new comments can be posted.

Ask Slashdot: What's the Best Way to Charge Your Smartphone Battery? More

Ask Slashdot: What's the Best Way to Charge Your Smartphone Battery?

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  • Phones are usually scrap before the battery (Score:3, Informative)

    by internetd00du ( 7659518 ) on Sunday June 30, 2024 @03:09PM (#64590433)

    I say this as someone who complains about non user replaceable batteries all time... all of the phones me or my family have had, ended up too slow to keep using way before the battery had issues.

    I was that guy who bought spare batteries for my old school Google nexus one. One was still sealed. I throw the lot into battery recycling and the phone into ewaste. It was too slow to even use as an alarm clock.

    I know modern phones are faster and have more storage, but after 5 or 6 years, they're just useless in terms of performance. I buy a phone I can afford to easily replace and don't worry about the battery cycles.

    • Agree. I buy cheap Samsung phones (usually around $100). I've never had a battery fail. I have had a CPU fail and have had the microphone fail.
      I usually keep my phones until they die or if an app I need fails to function with an old version of Android.

      The newer phones are glued together and very difficult to disassemble to replace the battery but I don't care. I just buy another cheepo phone.

    • Re: (Score:2)

      by dskoll ( 99328 )

      I've had the opposite experience. My previous phone (Nokia N-900) lasted for two batteries (which were easily user-replaceable) before it got too slow/clunky to use.

      My current phone (a Motorola) is still fine, but the battery's starting to go bad. This battery unfortunately is not easily user-replaceable so I probably will end up getting a new phone even though a new battery would have been good enough.

      • Re: (Score:2)

        by tlhIngan ( 30335 )

        This battery unfortunately is not easily user-replaceable so I probably will end up getting a new phone even though a new battery would have been good enough.

        Have you checked at the mall kiosk? Just because *you* can't easily replace it doesn't mean those places can't replace it. And often it can be done far cheaper and quicker than you doing it yourself.

        They have the tools and experience and you're really only looking at a $30-50 expense.

        Generally speaking, if you don't drain the battery a lot, then keepin

        • Re: (Score:2)

          by dskoll ( 99328 )

          Last time I looked, the cost to change the battery was closer to $100-$150, which is expensive enough to give me pause.

      • This battery unfortunately is not easily user-replaceable so I probably will end up getting a new phone

        I know. I throw away my car too every time it needs an oil change because I can't do it myself and no one in the world offers a service to maintain or repair cars. This is getting expensive. /s

        Hint: it costs about $40 in labour to get someone to replace the phone battery for you. Not everything in the world needs to be done yourself. We have an entire industry known as "the service industry" to do things you don't want to or are not capable of doing. Go down to your local mall's electronic kiosk and invest

    • >"Phones are usually scrap before the battery [dies]"

      1) Battery decline isn't just binary (works, dead), it is progressive over time.

      2) So taking care of the battery is useful even if you keep it only 2 or 3 years. You will have longer runtime, if needed, during that period you have it and use it, making for a better experience.

      3) Having a good condition battery means as a used device, it will last longer (if you give it to someone, sell it, etc).

      • Re: (Score:2)

        by edwdig ( 47888 )

        It's kinda true, kinda not. I've found my laptops get a steady gradual decline in battery life over the years, then it just suddenly falls off a cliff and the battery is unusable. Doesn't really matter how I treat the battery. I've had laptops that I would take the battery out of when I didn't need it, I had batteries I left in all the time and kept it plugged in pretty much constantly. My first laptop battery died after 2 years Modern laptop batteries seem to die after 5 or 6. What I do really doesn't seem

      • All good points

    • It was too slow to even use as an alarm clock.

      No it wasn't. The Nexus One is still a powerful and useful phone... if you could have decent software on it. Planned Obsolescence sucks balls.

    • This doesn't reflect my personal experience: My current phone is 4 years old. It's still plenty fast for everything I do on it (just social media, browsing and some calls). The battery it's still in pretty good shape (I tend to keep it between 20 and 80%) but if the battery were to degrade or die I would still replace it before buying a new phone.
      Granted, it's an Android and it's OS will eventually too far behind the curve to be my main device, but if it still works I'm sure I'll be able to find valid uses

    • Re: (Score:2)

      by CAIMLAS ( 41445 )

      You must be an Android user.

      I've got an iPhone Xs, which I've had since shortly after release, in 2018. That's 5+ years, which is about 4 years longer than I ever got out of an Android phone.

      The battery was never fantastic for my use cases, particularly when traveling for work, when I'd often have to use an external power bank by the end of the day - especially if I had to tether. It'd be down to 20-30% by dinner, and I'd have hours before I could call it a night.

      I ended up recently getting a $30 battery ca

  • Does the speed of charging matter? When I'm at my desk, I sometimes plug my phone into the USB-C charger for my spare laptop since it's just sitting there, and it charges extremely fast. Normally I use a wireless charger that maxes out at around 15W, and certainly a bit lower with the losses involved. Would there be some value to saving some of the older 5W USB chargers to charge even more slowly? (I assume not.)

    • Re:Speed of Charging (Score:5, Informative)

      by drinkypoo ( 153816 ) <drink@hyperlogos.org> on Sunday June 30, 2024 @03:43PM (#64590507) Homepage Journal

      Yes, absolutely it matters.

      For maximum battery life you should always slow charge.

      Here's why: Higher charge rates mean the battery heats up. That alone is bad, especially with NCM batteries, because their electrolyte releases oxygen when overheated. But they also don't heat up uniformly. And part of that is in turn due to lithium islanding.

      We discussed some fundamental research on this here on Slashdot, where a team made a lithium cell in a transparent vessel and then studied it during different types of charging and discharging. During either operation, lithium migrates through the electrolyte in the direction of current flow. And this happens most when the current flow is greater, as you would imagine. Perhaps it is in part due to the heating effect, which you would expect to cause more mobility of components.

      The "islanding" is lithium becoming physically separated from other lithium, or in particular from the anode. One of the most interesting outcomes of that experiment is that the islanding can be to some degree reversed by rapidly discharging. So if you want to minimize islanding, you want to slow charge; And to if it is possible to also repair it (I don't recall what kind of discharge rates they were using, so I don't know how effective this might actually be) what you logically want to do is occasionally rapidly discharge the battery, perhaps by benchmarking, and to a safe [dis]charge level chosen to minimize long-term damage as deep discharges seem to significantly decrease battery lifespan. And if (as the experiment indicated) charge rates are sufficient to cause islanding, it seems likely that most devices are capable of discharge rates that can repair it.

      • Re: (Score:2)

        by Bumbul ( 7920730 )

        Yes, absolutely it matters.

        For maximum battery life you should always slow charge.

        Then again, if the battery lasts the expected lifetime of the phone otherwise, the effort put into optimizing battery life is kind of wasted? I mean, if it results in ANY inconvenience to your daily routines, then then the net effect is negative.

        I had my previous phone, a Samsung Galaxy S10 for 4 years - I put it in the charger (a big Lenovo laptop charger with USB-C, by the way) EVERY night, and took it out in the morning. Was topped at 100% for hours, plugged in, during the night. No problems with the ba

        • if the battery lasts the expected lifetime of the phone otherwise, the effort put into optimizing battery life is kind of wasted? I mean, if it results in ANY inconvenience

          I expect my phone to be useful as long as the battery lasts, because it speaks modern protocols and does everything I want it to do. Therefore your comment does not actually make any sense to me. Perhaps you are buying devices which are expected to be worthless after a short period because you are wealthy, but I am not so I do not.

          • Re: (Score:2)

            by Bumbul ( 7920730 )

            if the battery lasts the expected lifetime of the phone otherwise, the effort put into optimizing battery life is kind of wasted? I mean, if it results in ANY inconvenience

            I expect my phone to be useful as long as the battery lasts, because it speaks modern protocols and does everything I want it to do. Therefore your comment does not actually make any sense to me. Perhaps you are buying devices which are expected to be worthless after a short period because you are wealthy, but I am not so I do not.

            Got your point, but I might still add that the phone was fully useful at the time I replaced it - the reason for switching was that I dropped it and the screen broke. Thought I might as well upgrade at that point instead of spending money to repair it - having had full 4 years out it already. My desktop computer is now around 14 years old (runs Linux Mint just fine), so no, I'm not spending money that wastefully...

      • Thanks, great info. Here's a good site with some charts and data https://mpoweruk.com/life.htm [mpoweruk.com]
    • There's something to be said for not charging "too fast" as it will mean the battery/phone getting hotter whilst that happens. Pixels have a feature where it'll learn your nightly habits and aim to be 100% charged something like 30 minutes before you'll wake up, trickle charging the whole time.

  • Electricity (Score:4, Funny)

    by TheNameOfNick ( 7286618 ) on Sunday June 30, 2024 @03:29PM (#64590479)

    Don't fill it up with gasoline. Won't work.

    • Don't fill it up with gasoline. Won't work.

      Hopefully most people are aware that smartphones use two-stroke diesel engines.

      • Just the other day, I saw a guy lying under my phone trying to steal it's catalytic converter!

      • converted my phone to Top Fuel for faster reboots after updates, it's running 90 percent nitromethane and 10 percent methanol.

  • PC Charging is the Best Way (Score:3)

    by Ichijo ( 607641 ) on Sunday June 30, 2024 @03:56PM (#64590527) Journal
    Pulsed Current [slashdot.org] charging is best, but your phone probably doesn't have that option yet.

    • Re: (Score:2)

      by AmiMoJo ( 196126 )

      The main issue with pulsed current is that it can cause the voltage to get quite high. The phone must be designed to cope with that, which generally means an extra regulator, which will decrease overall efficiency i.e. battery life.

      It's less of an issue for EVs because they already deal with fairly large voltage ranges due to having so many cells in series.

  • Not sure about Galaxy but many modern batteries report 100% charge when the actual battery charge is at 85-95%, stoping you from charging all the cells to the maximum and shortening the battery life in the long run. Some battery firmware also keeps track of charged cells and rotates them to load-balance the lifespan of the entire battery unit. Like I said, I'm not sure about Galaxy in particular. Do your research and see what you find but there's a good chance you don't need to worry about charge levels bec

    • >"Not sure about Galaxy but many modern batteries report 100% charge when the actual battery charge is at 85-95%"

      My previous/old Samsung devices would, indeed, report the fake "100%" when the battery charger limit was set on. Kinda confusing. But the newer ones accurately say "85%" (or now "80%") along with a message saying it stopped charging automatically. That is far better.

      Now, there might be an additional 5% in reserve, hidden and not accounted for, that one can never use on either side. That, I

  • gives you poor service when they "flagged you as a low-profit customer."

  • Partial charging is the way... (Score:5, Interesting)

    by OneOfMany07 ( 4921667 ) on Sunday June 30, 2024 @04:12PM (#64590577)

    https://play.google.com/store/... [google.com]

    I've used this for a while, but I don't know how perfect it is without root (my latest Samsung was never rooted, and includes a built in option too). It attempts to estimate how much wear and tear you're causing your battery by the charging an discharging (too much of either isn't great). And what health your battery is in by comparing rated battery maximums and what the phone thinks is happening during charging/discharging (that part takes time as it watches your use).

    As I've read it, the last bit of charging does the most damage. Meaning if you don't typically run out of charge then it is best to lower the stop point like you originally did. No, 95% then 100% then... isn't a good thing to my knowledge. That app suggested 80% and claimed it'd double your battery's longevity (or some such huge sounding difference).

    This isn't specific to preventing the pillow effect, but less wear on the battery should make it last longer (hold a higher maximal charge later in your ownership) and I'd hope prevent the pillow effect too. My understanding is the pillow effect is from puncturing the membrane separating the positive and negative layers, and/or out-gassing. That things like charging quickly (makes more heat, and causes more wear) and to a high level can cause out-gassing. Seems altitude/pressure changes mattered too (remember the Samsung battery issues after flights from a few years ago?).

    • Everything I've read on maximizing battery life suggests never charging above 80%, and never discharging below 40%, which sounds kinda wild since it means only ever really having 40% of your total capacity available. But, I guess if you want the absolute maximum lifetime out of a battery, that's about it.

      • >"Everything I've read on maximizing battery life suggests never charging above 80%, and never discharging below 40%, which sounds kinda wild since it means only ever really having 40% of your total capacity available"

        But for many, many use cases, having 40% is way more than is needed. So if your normal routine can be that 40%, why not? My normal use between charging is rarely more than 20 to 30%. You can always modify that and get 100% when you need to. It is nice having choices :) And I am far fr

      • Maybe similar to how databases can only use 40% of their space since they need a gazillion bytes free to delete a table.

    • Re: (Score:2)

      by AmiMoJo ( 196126 )

      I use Battery Charge Notifier which doesn't need root. It's free and as the name suggests, notifies you when the battery reaches a certain %. You have to manually take it off charge, but no root needed.

      You can also get WiFi USB switches on AliExpress that let you limit charging to a certain %.

      I recommend getting a 1A or lower charger, Using a computer USB port that is limited to 0.75A (USB3) or 0.5A (USB2) works well too. Reason being that you want a nice slow charge that doesn't produce too much heat. Rapi

  • I have never had troubles with batteries until recent Pixel phones, two of which have had swollen batteries. With newer phones charging faster there is often more heat. So in some cases it may be less about what level to charge at but rather how fast it is charging and how efficiently.

    On risk not talked about much is Qi charging. If the coils are not well lined up you can get a lot of waste heat which is a risk for swollen batteries. Personally I have added a Magfit phone case to improve Qi coil alig

    • >"With newer phones charging faster there is often more heat. So in some cases it may be less about what level to charge at but rather how fast it is charging and how efficiently."

      Probably both. I am NEVER in a rush to charge, so I intentionally use lower-rated chargers with my phones and tablets. I *also* use the 80% charge setting. That might not be applicable to everyone, of course :)

      >"On risk not talked about much is Qi charging. If the coils are not well lined up you can get a lot of waste hea

  • Here is a presentation by Jeff Dahn regarding maximizing Li-Ion battery life. Although the audience is EV owners there are some things applicable for phones.

    https://www.youtube.com/watch?... [youtube.com]

    Basically prevent deep discharge cycles for Li-Ion batteries by using them between 45-75%. Try to keep the battery cool. Don't store a battery at high state of charge, especially in high ambient temperatures--store at 30%.

    Hopefully with newer "single-crystal positive electrode material" batteries there shouldn't be any i

  • Don't worry about it too much, if you just use the middle thats better but the battery is like the cheapest thing to replace. On cheaper samsungs you just need a fingernail and a small screwdriver that comes with the set anyway to replace and it'll hold up for 5 years if it doesn't have a flaw in the battery. And if you bought a 1000 bucks samsung use it to the full to get the moneys worth.

  • See Battery University (Score:4, Informative)

    by gaiageek ( 1070870 ) on Sunday June 30, 2024 @05:11PM (#64590673)
    If you want to get into the nitty gritty: How to Prolong Lithium-based Batteries [batteryuniversity.com]

    My conclusions from reading that site years ago (the page has been updated so my info could be out-of-date):
    1. 1. In daily use, avoid going above 80% charge and below 40% (the latter also guarantees you have a reserve in an emergency)
    2. 2. Slow charging is better, i.e. use a slow (1A) charger for your daily at-home charger (put the newer, faster charger in your carry-on bag)
    3. 3. Avoid heat (killer of batteries)

    • I don't charge my phone every day, but use the Adaptive Charging feature on my Pixel 5a with a daily 7am alarm and a 5V/1A charger on a timer that switches it on at Midnight and off at 7:30am -- that way I don't have to worry about when I plug the phone into, or disconnect it from, the charger. The battery never seems to get that warm during charging -- on those occasions I've been up all night and have checked. :-) I use the higher capacity Google charger, that came with the phone, when I travel and am

    • The problem with a site like that is it talks about cell charge. Phones don't report cell charge because the engineers who designed the phones know a thing about prolonging lithium batteries as well. 100% charge on your screen does not necessarily correlate to 100% charge on your battery cells. What is it really? No one knows other than the company who designed that specific phone.

      FWIW I have my phone virtually permanently on charge at 100%. I've had it doing this for 4 years now. There's no sign of battery

    • Re: (Score:2)

      by AmiMoJo ( 196126 )

      Reducing battery use at night also helps. I use Tasker to put the phone in airplane mode and extreme power saving mode from 00:15 to 07:00. That turns off all transmitting radios and stops most background apps running for nearly 7 hours a day. No point wasting energy when I'm asleep.

  • My phone is now entering its 6th year (Huawei P20 Pro). It is only charged via USB cable connected to my desktop PC. It still holds more than enough charge for a full day of use. Usually, I tend to connect it before I go to sleep, and disconnect when I wake. So it gets continuously charged till 100%. Never had any issue.

    Before that I was "rocking" a Windows phone. One made by Nokia, not Microsoft. Charging happened the same way as my current phone. Lasted 4 years, but lack of software made me get rid of it.

  • 80/20 (Score:3)

    by markdavis ( 642305 ) on Sunday June 30, 2024 @05:42PM (#64590719)

    >"Unfortunately... After a recent upgrade, now my Galaxy has three options for the battery where it had two. The 85% option is still there, but it has been lowered to 80%."

    I also noticed that and was a bit annoyed. Why is it that they can't just let you set whatever percent you want?

    Anyway, I have been doing that with my phones and tablets (both Samsung/Android) for a long time now and batteries hold up very well. Charge generally to around 80-85% and discharge to no more than 50% (unless really necessary). And my phone sits on a charger most of the time (when I am home), so this helps to prevent it sitting for long periods at 100% or accidentally being left uncharged and allowed to run really low. I do think, generally, the 80/20 rule is a good one (although it usually ends up much closer to 80/50 for my normal use).

    I recently started doing this on my Linux laptop (Lenovo X13 AMD Gen 2) as well. It has the ability with "tlp": https://linrunner.de/tlp/usage... [linrunner.de] All I had to do was install the package and edit /etc/tlp.conf and uncommented the two battery thresholds and it works to keep the battery charged no more than X amount (and can be easily asked to charge to full with a single command if I think I need full capacity for some reason). It, too, is left on the charger most of its life (whenever it isn't being used, and it isn't used much because I like my desktops, I use a laptop only when portability is needed, which is rare).

    >"The other old option says something about using AI to control the battery charging, but I don't trust it"

    I don't trust it either. There is no good explanation how it works, and I like knowing exactly what is happening and I can predict what state it will be in at any time and have full control.

    • Re: (Score:2)

      by AmiMoJo ( 196126 )

      The "AI" thing is just that it learns what time you normally get up, so if you put it on charge overnight it will pause at 80%, and then go to 100% just in time for you to get out of bed. That way it spends less time at 100%. Some phones also charge at a slower rate overnight, to reduce heat.

      Personally I don't use it, I just charge to 80% in the morning after I get up.

  • Isn't swelling a defect? (Score:3)

    by ThosLives ( 686517 ) on Sunday June 30, 2024 @06:08PM (#64590789) Journal

    I haven't heard of battery swelling in, oh, quite some time. If you've got a swelling battery, isn't that either sign of a manufacturing defect or some kind of special cause?

    If every phone you have had exhibits swelling - that suggests it's something you're doing systematically to the phone/battery; the probability of having a manufacturing defect that doesn't impact every instance of the models you have but hitting you individually multiple times is statistically unlikely and points to something in your environment / use case.

  • Apple just makes sure that you can't install a new app or a new version of an app long before the battery runs out.
    Therefore iPhone users never experience these battery problems because they already had to move on to their next iPhone.

  • I feel this was probably a legitimate thing to worry about 10 years ago, but batteries and phones have improved across the board so much that it feels kind of pointless to care this much. I've always just...plugged my phones in whenever they were low, not worrying about if it's a fast charger, or if it's already at 90%, or anything else, and it's been fine! My current phone, a cheap Motorola that I've just plugged into fast charging and relied on the default settings to manage that, has been going strong fo

  • My Samsung S10 which runs perfectly had a battery that went bad. You know what I did? I got a inexpensive battery replacement kit open the phone up and put a new battery in it! Who cares about this question of the optimal way to charge a damn battery when they're so cheap and you can just replace them? I don't care I'm not thinking about it one bit and I'm no longer going to think about it ever again after reading this article.

  • I have a motorola RAZR HD (model XT925) that I bought in 2013.

    I would charge it up to 100% at every opportunity, even multiple times a day and rarely let it get below 40-50% for the first few months, with an occasional "deep dive" to the point where it would switch itself off. Only switch on wi-fi or mobile data or bluetooth or GPS when required.

    It was principally a work phone, so 90% of its use was phone calls and SMS. A little web browsing, occasional videos, zero social media, and zero games. Very little

  • Who the fuck is regularly experiencing battery swelling on any modern mobile phone?

  • 99.99% of the world don't give a shit about how they charge their batteries and batteries don't swell. We've got several phones in the house. One constantly discharged. One used for "gaming" (Pokemon go) which gets hammered. One spends a large portion of its life sitting on charge at 100%.

    Swelling is something I remember from over a decade ago. Maybe the longtime Slashdot user doesn't need a technical solution as much as they need Jesus to stop spiting them and afflicting them with a problem no one else has

  • Just replace the battery or device when the battery swells.

  • Charge slowly if time permits. Avoid deep discharge if possible. Don't charge to 100% given the option. Don't discharge to 0% given the option. I've built consumer electronics devices that intentionally don't charge the battery to 100% of cell capacity and intentionally power down before the cell capacity reaches 0. The user-facing battery indicator showed 0% and 100% relative to usable capacity, not relative to the cell capacity. This something like doubles the longevity of the cell, but I don't know how

  • I think for most people 80% is way more than they really need. Some people have a psychological urge to keep it at or near capacity, as if the zombie apocalypse could happen at any minute and you might really need that extra battery so your phone can be a flashlight I guess?

    The 80% cap is my favorite Galaxy feature. I've been surprised at how little anxiety I get by seeing the number drop. It's not uncommon for me to look down and see it at 30-40%, and I just plug it in for a while and go about my busines

  • There were many, and I felt obliged to look over the entire discussion since it could be said that it was ultimately my fault. Sure would be nice if the moderation was more helpful in finding the best bits, eh?

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