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How To Calibrate iPhone Battery

How To Calibrate iPhone Battery

The iPhone features remarkable battery life, however, not every user experiences peak performance. It is essential to calibrate the lithium-ion battery periodically. This article details the process for maintaining your iPhone’s battery, which will ensure long-lasting battery life. This method also applies to the iPad and iPod Touch, as well as any other device with a lithium-ion battery.

Why Calibrate?

Battery calibration accomplishes two things: it conditions the battery and helps the software calculate the range of battery life. One should calibrate the battery once a month and after every major iOS upgrade. If you upgrade iOS and notice diminished battery life, try calibrating the battery before anything else.

Periodically draining and recharging the battery keeps the flow of ions moving in the battery. The material properties of lithium-ion batteries require constant usage to maintain peak performance. For this reason, Apple recommends discharging and recharging the battery once a month.

The amount of charge available in the battery is calculated by iOS. With every upgrade, new features are added, some of which affect battery life. Apple’s engineers often improve some aspects of battery life, while also introducing battery-intensive features, such as background updates. Allowing the battery to fully drain and recharge calibrates iOS to detect the full range of battery life. Some people are skeptical of this theory, and since few know the inner workings of iOS, it may sound superstitious. Research and experience have proven otherwise. I have no doubt that calibrating the battery after an iOS upgrade will improve battery life.

Amazing battery life on 4 year old iPhone 4
Here’s the battery usage stats for my over-four-year-old iPhone 4. As you can see, I am getting almost 18 days of standby time and 8 hours of usage. Although I do leave the device in airplane mode when not in use, the battery has held up very well. Calibration does work.

 

How To Calibrate the Battery

The first step is to drain the battery completely. This can be accomplished with normal use, but sometimes this may not be an option. After all, you don’t want to head off to work with 2% battery life left. Sometimes that 2% can last a few hours. It’s best to drain the battery when you can do without your device for several hours, perhaps before bedtime. To expedite battery drainage, turn on the flashlight, turn up the brightness, and play a video, preferably streaming over the Internet.

Once your device powers off due to insufficient battery charge, it’s best to leave it for some time. If possible, leave it overnight and don’t charge it until the following morning. This is not always an option, and if it’s too inconvenient, skip this step. Allowing the device to sit overnight will further drain the battery. You may notice that even when your iPhone runs out of juice and powers down, when you immediately plug it back in, you will see it at 2-3% charge. This is partly due to the fact that some battery life was remaining when it powered down. To keep your data safe, iOS has to power down before the battery is fully drained. Otherwise, it would shut off without being able to save its state to secondary storage.

Next, plug your iPhone into the charger. Keep it in the charger until it’s at least 100% charged. If possible, keep it in the charger longer. According to Apple, 100% means that you will get the expected battery life, but the device can charge beyond this. Keeping the device in the charger after it reaches 100% will ensure it is fully charged. Two additional hours should do it.

It is best to charge your iPhone when it is off. After you plug in the charger, your iPhone will automatically start up in a few minutes. When it is back online, simply hold down the sleep/wake button and slide your finger over the off switch. Your iPhone will charge faster when it is off. It will also generate less heat, which will extend overall battery life.

If you turn your iPhone off to charge, make sure to estimate how long it will take to charge beyond 100%. Five hours is a safe bet for an iPhone 6 or 6 Plus. My iPhone 6 will charge to 100% in three hours, but the extra two hours will ensure that it is fully charged — beyond 100%.

Now that your device is fully charged, you should reset it. This is done by holding down the sleep/wake button (on the top of the device) and home button, until the Apple logo appears. Your device will boot up and is now reset. Remove the charging cable when your device is up and running.

Step By Step Battery Calibration

The following process is what I consider to be the gold standard of iPhone battery calibration. For some, it might not be possible to follow all of these steps. If you are an on-call professional or hopelessly addicted to your iPhone, you might not be able to turn off your iPhone overnight or even for a few hours. At the bare minimum, you need to drain the battery until the device shuts off, charge your iPhone to 100%, and reset it by holding down the sleep/wake and home buttons until you see the Apple logo.

1. Use your iPhone until it shuts off automatically. If it is near 0% battery life and you want to drain it faster, turn on the flashlight, turn up screen brightness all the way and play a video, preferably streaming from the Internet.

2. Let your iPhone sit overnight to drain the battery further.

3. Plug your iPhone in and wait for it to power up. Make sure to use the charger supplied by Apple or one that runs at the same wattage and amperage.

4. Hold down the sleep/wake button and swipe “slide to power off”.

5. Let your iPhone charge for at least 5 hours. The charge progress indicator is not displayed while your iPhone is turned off.

6. With the charging cable still connected, press the sleep/wake button for about a second to start up your iPhone.

7. When the iPhone has booted up, hold down the sleep/wake and home buttons until you see the Apple logo.

8. When your iPhone is back online, remove the charging cable.

Make Your iPhone’s Battery Last Longer

A lot of people visit this site because their iPhone’s battery is shot. Calibration can help in some cases, but it is not a panacea. If calibration doesn’t improve your iPhone’s battery life, it may be time to replace the battery. Fortunately, you can prolong the lifespan of your new battery by following a few tips. For more information, please read “How To Extend iPhone Battery Lifespan”.

More Information

Many users are skeptical of this process and feel it is superstitious. I hope I have shed light on the reasons why you should calibrate your iPhone battery. If you doubt this article, take screenshots of your battery life (Settings > General > Usage) before and after conditioning the battery. I have found this process to work. Of course, your battery may drain at different rates depending on use. For more information and tips about lithium-ion batteries, please read this article. Also, make sure to check out “iOS 7 Battery Life Tips” for more information on how to preserve battery life with iOS 7.

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Comments

  3. I bought this iPhone 5s from a trusted seller and plugged it in. The Apple logo would show for about a second and went away. This repeated until it started charging. Then it would charge 4% every 10 seconds and the battery indicator is stuck at 100%

    Reply

  4. I’ve just replaced my iPhone 6s Plus battery as I want to sell it, but have a problem. I did the procedure for calibrating, but on the last step when I turn on the phone it was only at 45%.. I had left it on the 5W Apple charger for 5:30 h. Now the percentage increases when connected to my iMac.
    I started the whole calibration process because I’ve noticed the new battery drained very quickly (1% per 30-60 sec.) and this was after a restore. I will charge it now to 100% and see how it drains while on standby. If it’s too quickly I will buy a new battery, but can’t really decide from where. I live in Bulgaria and don’t want to wait 1-2-3 weeks for a delivery from abroad.
    I just hope I didn’t mess up something else during the installation of the battery 🙂

    Reply

  5. Wonderful wealth of information and I like how it continues! I have a week old iPhone X. Works beautifully. Would it make sense to calibrate it now or wait a couple of months? Thanks much.

    Reply

    • I would wait a few months. I find that the opportunity to calibrate usually presents itself. If my iPhone is close to 0% and I haven’t calibrated it in a few months, I do it.

      Reply

  6. It was interesting to learn about how calibration affects your battery. I learned a lot about why calibration is important. I wasn’t aware that it was something that needed to be taken care of once a month.

    Reply

  7. My wife and I just purchased those wireless chargers for the X. Really convenient but I do notice she takes every opportunity to rest the iPhone on the charger anytime she walks in the door. I’ve mentioned the 40-80% range with calibrating when the opportunity presents itself but she has a habit! Is the 40-80 advice still valid or was that from an earlier period? Thanks again for this wealth of information. I’ve been forwarding this page to friends/co-workers.

    Reply

    • Thank you for sharing this page. I really appreciate it. Also, sorry for the delay in responding to this comment. I have recently returned from winter vacation and I’m just getting back into the swing of things.

      You are correct about the 40% – 80% range. In fact, I wrote a whole article about the finer points of battery care — “How To Extend iPhone Battery Lifespan”. This is still valid for the iPhone X. In fact, I personally wouldn’t use a wireless charger, as they do create additional heat. But there is a tradeoff between battery lifespan and convenience. For example, if you only charge your iPhone to 80%, you will have fewer hours of use.

      I wouldn’t overthink it. Just get the battery replaced towards the end of the year, and you’ll get a few more years out of your device. I strongly recommend taking advantage of the $29 iPhone battery replacement program — even if you have an iPhone X.

      I am well aware of optimal battery care, however, I don’t really practice it. It’s just too inconvenient. I do calibrate the battery, but I also charge my iPhone to 100%. I let it run down below 40% all the time. Given the longevity of Apple devices, it will become obsolete before the battery dies. I still have my old iPhone 4 with the original battery, which still “just works”.

      Reply

  8. iPhone 6s. Original battery was getting tired and phone was horribly slow with new iOS update. Ordered and installed new battery, charged to 100%, phone restored to original speed and efficiency! Worked fantastic for a couple of weeks and I then found this article. I figured I would add some additional battery TLC by fully draining and calibrating it as per the above advice. Sadly it appears to have cooked my new battery and have found other articles that state fully draining a lithium ion battery is not only not necessary or recommended, it can be detrimental.
    My advice is to do some research before doing this procedure.

    Reply

    • I’ve been calibrating the battery on my iPhones for 7 years and have never damaged the battery in any way. In fact, I still use my old iPhone 4 every day as a kitchen timer and clock. I only charge it once in two weeks. I also have a three year old iPhone 6, with the original battery, that has been calibrated several times. The battery is in mint condition, and it is not slowed down due to a failing battery.

      Read through the comments and you will see many claims that this works. The whole reason I calibrate is because it was in my first iPhone’s manual. Although it is no longer in the manual, you can easily find that Apple Store geniuses recommend and follow this procedure.

      You have confused long term storage at 0% with running a phone down to 0%, waiting hours (not days or weeks) and charging it. Long term storage at 0% will damage the battery, but that’s not part of the calibration process. I have written about these issues in other articles. I have studied lithium ion batteries, particularly with regard to Apple devices, for years now. This cockamamie theory pops up every once in a while.

      There seems to be a lack of common sense in your comment. People run their iPhones down to 0% and charge them fully all the time. Some people do this every day. What you claim would suggest using the full range of one’s iPhone battery will ruin it. It would mean that simply running an iPhone down to 0% would ruin it. This is a misunderstanding with alarmist implications. It is simply not true.

      It seems to me that you had a defective battery installed. Either that, or you used a charger with too much power. There’s no way calibration will “cook” a battery. That is completely cockamamie. It is completely safe to run down an iPhone battery all the way and charge it. Just don’t leave it at 0% for weeks.

      Reply

    • OK. You ordered a battery online and replaced it yourself, and now you’re blaming the failing battery on this article. You probably should have had Apple install the correct replacement battery for $29. The battery you bought may be poor quality. It is well known that unofficial Apple replacement parts are often poor quality. You may have damaged the phone or battery with the DIY battery replacement.

      The lesson to be learned here is that people should get their devices serviced by Apple or an authorized service technician. I know for a fact that calibration does not ruin the battery. I also know for a fact that people often buy poor quality batteries and damage their phone with DIY repairs.

      Reply

  9. I can’t comment on calibration on iPhones as I’m not knowledgable of apples systems but given the amount of rubbish this author has spouted about overcharging past 100% I would be inclined to completely disregard anything he has to say, you can’t over charge lithium battery’s they can explode so they have cut off circuits built into the battery, and discharging a battery past 0% is also rubbish and potentially damaging lithium ion battery’s can be irreversible damaged if discharged past a certain point, my guess is apple shuts down phones to save data is correct but it’s also to save the battery from over discharging just my 50p

    Reply

    • I first learned about “overcharging” when I read an article featuring an interview with Apple SVP Michael Tchao. He admits that Apple devices charge beyond 100%. I have linked to this in my article, but you neglected to read it, and decided to add an ad hominem attack on my credibility. I don’t mind criticism, but I refuse to take this from such a moron.

      Your personal attack is ironic, because you attempt to undermine my credibility, yet you are too ignorant and lazy to read a linked article providing proof. Your inconsiderate and thoughtless comment only makes you look bad.

      Your writing is garbage. You can’t even formulate a proper sentence. Spell checking seems to be yet another technology you are unfamiliar with. I had to fix your spelling errors and profanity, but I left everything else as is. You should be embarrassed to post such poor quality trash. I rarely deal in ad hominem attacks, but you are a one-in-a-million moron. “Just my 50p”?!?! You are vastly overvaluing your opinion. You should be paying people to read or listen to your opinion, as it is of such low value.

      Beyond the Apple SVP, Dr. Ray Soneira at DisplayMate has tested this extensively, and most devices charge beyond 100%. This includes non-Apple devices. 100% just means that a microprocessor has determined that the battery will last the expected time. It is not a measure of lithium-ion concentration. That is much too difficult to measure. 100% is just an estimation provided by an algorithm. It is an abstraction.

      Was it too hard to search the web for this before posting? You don’t even need to look that hard. The link was right there.

      I never wrote anything about discharging a battery below 0%. I recommend draining the battery fully overnight or for a few hours. This only damages the battery if this is done over long term storage — months. I cover this in more detail in the linked article about extending iPhone battery life. Of course, you didn’t read that either. You seem more interested in clobbering us with the tiny bit of misinformation you have.

      “my guess is apple shuts down phones to save data”

      Wow, there is no limit to your moronic nature. Apple slows down some iPhones with failing batteries. This was all over the news. The conclusion you have come to underscores what a complete moron you are. Are you in a prison or institution? Are you not able to get news coverage? Or are you just a moron?

      “they have cut off circuits built into the battery”

      Incorrect once again. The power IC manages charging. There is nothing in the battery itself that regulates charging. I actually read the documentation for power ICs in Apple devices. I look at the iFixit teardown, find out what the part is and read the manufacturer’s documentation. We can’t all just make things up, like you do. Some of us actually research before writing.

      Reply

  10. I replaced my 4s battery a year ago and i still have the problem with the phone shutting down at approx. 44 percent of battery charge. I am not sure if it is just a calculation error or if I am being short changed. I have resorted the phone twice. That did not change a thing. This situation makes it difficult to fully discharge the battery if it is almost half charged as the phone will not turn on. About a month ago, I managed to get it fully discharged once, but it took 2 weeks. I tested it early at 15% and it ran done to 3%. I drained it again, the fully charged the phone. I may not have restarted it. But, once again it shut off at 44%. But, again, maybe its its okay as I still get a couple of days out of the first half as I keep it in airplane mode overnight and I don’t use it much.

    Reply

  11. I have an iPhone 4s as an extra phone. It has a fairly new battery. For a long time now, it has been turning off at 45-50% charge because of low battery. How would you run the battery done to 0 if the phone will not turn on?

    Reply

  12. Hi. My iPhone battery keeps jumping, it’ll jump from 99 percent to 76 within the minute or 2. Would this calibration work on my phone? My iPhone is new.

    Reply

    • You can try it, but I think something else is going on. When you buy a new iPhone, there are often background processes that drain the battery faster. I remember when I first got my iPhone 6, it was losing battery power like crazy. I calibrated it, and it helped, but something else was going on. Background processes were running to do all the optimizations and “housekeeping” required with a new device. These processes also run after major iOS updates.

      Calibration won’t hurt, but the problem may go away when the background processes stop.

      Reply

  13. Does anyone have any observations to make in relation to re-calibration and the Battery Health statistic in iOS 11.3?

    Reply

    • My 3+ year old iPhone 6 has 97% capacity after years of use. I calibrate it a few times a year. This would indicate that calibration definitely doesn’t hurt. It really surprised me that the battery is in great shape.

      It would be interesting to see if someone with a low capacity has it increase after calibration, but I wouldn’t expect this to happen. Calibration is partially about getting an accurate battery meter, so your phone doesn’t shut down unexpectedly before 0%. It’s not going to generate new lithium ions, but it could keep them from seizing.

      It may keep the capacity higher if it is done regularly. My iPhone 4 manual recommends calibration with the justification that partial charge cycles leave some ions stagnant — they stay in the same charged state. This causes ions to seize and diminishes battery lifespan. Calibration ensures that ions are discharged and then recharged. This should keep the capacity higher than for someone who charges their iPhone at, say, 50% battery level.

      Reply

    • when I re-calibrate it solves the problem of my iPhone 6 plus always restarting. But then if I let my battery go lower than 50% it suddenly starts again even if I recharge. Until I re-calibrate again and maintain a battery life above 50%. Tried replacing the battery at a local technician’s but it is still the same it just last a little longer before it gets below 50%. This seems to be a common problem after the iOS 11.3 update. I might just lose my loyalty to the apple brand -_- it really sucks!!

      Reply

      • I recently upgraded to iOS 11.3, and my iPhone is losing charge faster than normal. This is to be expected. After major updates, iOS typically runs some optimization tasks in the background. It seems to get back to normal after the subsequent charge cycle.

        With iOS 11.3, you can now check the health of your battery. Just tap on Settings > Battery.

        BTW, Apple will replace an iPhone 6 Plus battery for free. Just make sure to do this by December 2018. This was part of their apology for slowing down iPhones with failing batteries. If you don’t live near an Apple store, you can send it in. You will have to live without an iPhone for a few days. Make sure to forward calls.

        As a software developer, I think they made the right decision. People were upset about it, as if they’d rather have their phone shut down unexpectedly. No one I know wants that. It is the typical, mindless Apple-bashing that happens in Internet echo chambers. Thank (or blame) social media for that one.

        Reply

  14. Thank you for the time it took you to write such an informative article. I have 2 questions.

    1. In another article you alluded to the debate on daily charging and it’s effects on lifespan. You mentioned you typcially charge your own battery to 100%. I’m curious at what percent you go down to prior to charging. I generally wait until I’m under 5% and then charge to 100%.

    2. What is your opinion on leaving the battery in low power mode all the time? I typically do this and it helps the battery last longer, however I don’t know your take on if there is a downside to this for lifespan.

    Reply

    • It really depends on whether I need my iPhone all day or not. If my iPhone is at 70% in the morning and I am going out all day, I will charge it all the way. If I am staying home, I run it down as much as possible. That said, with all of the cyber attacks going on, my Internet service is fragile. Lately, I have been topping off my iPhone because sometimes I don’t have home Internet access for 12 hours. Yeah, I am a Comcast/Xfinity customer!

      Apple’s take is that incremental charging is fine and if you charge from say, 70% to 100%, it only counts as 30% of a charge cycle. You can expect about 300 to 500 charge cycles on an iPhone before the battery dips below 80% capacity.

      There’s actually a good case for incremental charging. When you charge an iPhone above 80%, it does a slower trickle charge. This is common with all lithium ion battery-powered devices, as the last 20% puts more stress on the battery, so it is done with less charge. Thus, charging it before it gets below 80% does a slower trickle charge.

      There is another notion that one shouldn’t let the battery go over 80% because of the stress issue. This is actually done in satellites, since it is so hard to get up there and replace the batteries. While it is true that charging above 80% shortens the battery’s lifespan, it also reduces the time you can use your iPhone.

      It’s all a balancing act. You have to choose between preserving battery lifespan and convenience.

      I noticed Apple updated their battery info page once again, removing even more information. They used to mention calibration. Now they don’t even mention the number of charge cycles. They’re sliding to the lowest common denominator because their competitors don’t mention these things, and if they do, people may perceive it as a flaw. It’s a true irony of the information age — a lot of times marketing experts like to keep things vague.

      If you want to keep your battery lasting longer, keeping it in low power mode all the time will help. I wouldn’t advise this, as it diminishes your iPhone experience. That said, I turn off all the automatic downloads and content refreshes. I do this more because it eats up network bandwidth, and as a Comcast/Xfinity customer, sometimes it slows down to 0.1 Mbps. Seriously. It is worse than 1993 CompuServe.

      Reply

  15. It IS true. Read everything thoroughly. If you follow the instructions as to how to turn it off exactly as stated on here, then it works perfectly. (I agree it won’t work if you just turn it off as per usual)….I used the above method followed precisely last night for the first time. Excellent! Bang on! Result!

    Reply

  16. Hello,

    Thank you so much for the detailed instructions and information about Apple batteries. Unfortunately, it hasn’t fixed my problem, but maybe you have another idea.

    I changed the battery of my iPhone 6S because the performance became low. The main problem for me was the fast drain overnight in standby mode (no Wi-Fi/cellular/bluetooth connection), I lost up to 70% during 7-8 hours. I tried some cheap eBay batteries, all of which were worse than my old genuine battery, or had different problems (bad connection, not chargeable, …). Now I tried a battery from ifixit.com, and in comparison to all batteries I had it is the best, but still loses several % overnight, up to 30% in 7-8 hours. The performance during the day is ok, I can use the phone up to 3-4h in different areas (often changing between Wi-Fi and cellular with good or weak signal). I did battery calibration, software reset, deactivated iCloud, and used the iPhone without restoring my backup. I always recognized the drain in standby mode.

    Maybe you have another idea? The iPhone works absolutely perfect, all parts are genuine except the battery. Of course I can try Apple’s battery service, but the next Genius Bar is too far away, and I don’t want to send my iPhone. And maybe Apple will decline the battery change because now a third party battery is installed?

    Cheers, Toni

    Reply

    • My advice is to find a certified Apple repair shop. Apple recommends some — https://support.apple.com/repair.

      Apple has pledged to repair all iPhone batteries (6/6 Plus or newer) for $29 until December 2018. It may be worth sending it in to Apple for that. They’ll use the right parts. You can always forward your calls to another number. But I do understand, living without an iPhone is not easy.

      One more thing you can try… My hunch is that, in standby mode, your phone is losing charge trying to maintain a connection to the cell tower. How good is your cellular reception at home? iPhones drain rapidly when they don’t have a good cellular connection.

      You can test this by putting your device in Airplane mode overnight. Keep in mind, you will not be able to receive calls. If you are on call in some important job (surgeon or something like that), make sure to forward your calls to another line. Otherwise, just put it in Airplane mode and have a good night’s rest. I think this will end the overnight battery drain.

      Reply

  17. Hi,

    thank you for your answer. Sorry for the misunderstanding, with “standby mode” I meant “airplane mode”. Anyway, at home I have a very good signal. Maybe you have another idea? Maybe it is a kind of software bug in iOS11?

    I will also try a genuine battery soon, then I will report my results to you.

    Cheers, Toni

    Reply

  18. Hello am Etta just wanted to inquire if it’s good to charge your iPhone on a laptop without an iTunes installed on that message

    Reply

    • Yes. In fact, I would avoid connecting to iTunes altogether and resist any impulse to install it. iTunes is simply horrible!

      Charging your iPhone with your laptop is also a smart move because it uses very little current — actually less than the original iPhone charger. It will take longer, but it will keep your iPhone’s battery in better shape. Slower charging is better for the battery.

      Reply

    • Yes. It also applies to virtually any device with a smart lithium ion battery. I have a vaporizer that I calibrate periodically too. It works on pretty much any modern, high tech, lithium-ion powered device.

      The new iPhones use the same lithium-ion technology and still need to be calibrated. I actually had a conversation with a Geek Squad geek about this at Best Buy a few days ago. They calibrate iPhone batteries, as do Apple Geniuses. In fact, they usually don’t even let users replace their battery if the “health” is above 80%. This is because any battery anomaly can usually be calibrated away. So to prevent unscrupulous maintenance techs from taking advantage of unsuspecting iPhone owners, Apple requires < 80% battery health for a replacement. They did waive this requirement for the $29 battery replacement offer (which expires at the end of December 2018!).

      Reply

  20. Thank you for this article! I am trying to recover my iPhone’s battery thru the process you have wrote. Hope this would help. 🙂

    Reply

  21. That was really nice to know about the calibration part. Actually we were looking for some more ways in which we can drain a battery at a very faster rate. Can you suggest any possible solution for that?
    One thing we got in mind is to make sure of gyroscope using an app but still we want few other things like such to drain at a very faster rate..
    Looking for suggestions.

    Thanks in Advance

    Reply

  23. I have an iPhone 8 plus since February this year. About a month ago or less my battery health was 93%, couple a days ago was 91%, yesterday was 90% and now is 89%. I don’t do anything with my new phone, I use it as usual. I don’t know if there is anything I can do to increase the battery health? I would be very thankful if someone can help me!

    Reply

    • I would recommend going for the $29 battery replacement deal before it expires at the end of December 2018. I just had my iPhone 6 serviced and it had 97% battery health. Now it is 100%. If they tell you it has to be under 80% to qualify for battery replacement, tell them that Apple has waived that requirement. I first took my iPhone to Best Buy and they told me Apple won’t allow them to replace the battery unless it is below 80%. That is usually true. I called Apple and they said they will replace the battery without question. They sent me a mailer box and the whole process took a few days. With shipping, it ended up being $37 or so.

      Calibration probably won’t affect the battery health statistic. I calibrated my iPhone and it stayed at 97%. Calibration fixes issues with battery metering and should also prolong battery life.

      I have a few ideas as to why your iPhone is losing battery health rapidly. My hunch is that the iPhone is getting warm. If you use a case, remove the case before charging. Apple mentions this on their site. Cases trap in heat, which affects battery health. Also, turn off your iPhone while charging. This will ensure that the battery doesn’t get too warm while charging. The iPhone runs its iCloud backup when it’s plugged in and turned on. This, combined with charging, can make your iPhone warm. Of course, you do want that iCloud sync to run. I typically do that once in a while, by turning on the iPhone after it has charged and leaving it plugged in. It does warm up the phone, so I’m to to fond of doing this, but it’s the only way to do an iCloud backup.

      Also, check if there are any apps that are using an unusual amount of battery power. You can find these statistics in Settings > Battery. It could be that some background process is running and using a lot of resources. I remember there was a bug in Google+ a few years ago, that caused the app to use a lot of battery power. My iPhone got really warm whenever I used Google+. Perhaps another app has a similar defect.

      Reply

  25. You are damaging the battery so your estimate will be accurate? You are just trying to justify wanting to fully charge it when you admit everyone says to keep it between 20-80%! Some batteries can’t be replaced so you will have to replace the phone in a few years, 1000 days of once a day charging like that and capacity will be so reduced it will lose 1% every few minutes. Do you get Apple kickbacks?

    Reply

  26. I just got an iPhone 6 for Christmas haven’t had it long my it new. My battery dain evey 15 to 20 I only can get a few 2 to 3 hour outta my iPhone haven’t had it a month yet

    Reply

  27. Thank you for the clear directions. I’m at a loss and could use some advice. I have an iPhone X that I acquired on 1/9/19, as my old X stopped working.

    It seems that something has gone awry since. My battery (the health reads 100%) drains rather quickly for the last month or so, since the last time the phone backed up, which was 1/25/19. I can’t seem to get it to back up for the life of me.

    The symptoms (I’m a RN) 🙂

    *Won’t back up (even manually in the cloud)

    *Very hot when its used/charging

    *Battery won’t charge past certain percentages like 82, 84, etc. even with a reboot, I can get the percentage up, once at 100%, but nonetheless, it drains within 3 hours and then charges very, very slowly.

    I’ve tried every possible remedy I can find online: soft resets, reset “all” settings, draining and calibrating the battery, signing out of the cloud…

    I see two restores in the back up section: 1/9/19 7.3 GB (this was done at the genius bar when I got the new phone) and 1/25/29 7.4 GB.

    I have tried backing up to iTunes (I use PC) and it won’t even allow me to do that!

    I fear losing all my photos, texts, etc. if I restore back to one of the backups as it was my son’s birthday and there are many photos, as well, I am in litigation and need to keep all my data.

    Is there anything you could think of that is causing my phone to act like a creep?

    Thank you, thank you, thank you for taking the time to read this!

    Reply

    • How are you backing up your iPhone? It should do the iCloud backup when you plug your iPhone in and leave it on. If this is getting interrupted, I would suspect a defective cable or some damage to the lightning port.

      A slow Internet connection can also prevent proper backups. Run Speedtest (www.speedtest.net) and make sure the upload speed is sufficient.

      What seems to be happening is that your iPhone is running some background process (backup?) and is caught in a loop. You may have to erase all content and settings and set it up again. Unfortunately, if you can’t back it up, you will lose documents and content, such as photos. You may be able to bounce those onto iCloud directly, without the backup. If you tap the heart button on a photo, it should sync it with iCloud. You can also use the Files app to bounce just about anything to iCloud. Then do the “erase all content and settings”. Then you will have a brand new, tabula rasa, iPhone X.

      Reply

    • I wouldn’t worry about it. It is most likely a coincidence. Once the battery starts getting below 100% “health”, you can expect further decreases in that statistic over time. I haven’t seen mine drop after calibration, so it is probably a coincidence.

      Reply

  30. My iphone 8 plus’ battery health was at 94% but suddenly dropped to 91% over a span of two days. I have no idea what caused it. Will this method help?

    Reply

  31. It’s taken weeks of searching the web to find a fix for my battery issues (suddenly plummets 30% in under 5 mins or shuts down at 6%) and then I found this page. And it has worked a treat. It’s been over a week since I followed your calibration advice and all battery issues have disappeared. Thank you.

    Reply

  32. Hi. Thanks for the article. I have couple of questions:

    1. After attending a call at around 1pm, my iPhone 6 showed 1% battery. It was around 20% before the call came. I spoke for 2 mins max. Now that 1% stays on the same even at 4:30pm. Only when I switch off to calibrate it, it does not restart because it now indicates me to attach charger. When I plug in the charger and then restart, it starts at 1%.

    What I wish to know is how do I synchronise battery % and actual battery left.

    2. I have always observed that while charging the iPhone, if I keep it charged for 10 mins more even after it has just reached 100%, the time taken for battery % to go to 99 from 100 takes little longer. This makes me feel that the phone is not fully charged when it indicates it has just reached 100%. You think that charging 10 mins more makes sense? Or am I harming the battery more?

    Thanks.

    Reply

    • Calibration resets your iPhone’s smart battery metering, according to Battery University. Of course, if your battery is in bad shape, the battery meter will be erratic. You can check battery health by tapping on Settings > Battery > Battery Health. Anything above 80% is OK.

      Your observation about 99 – 100% charging is correct. The iPhone allows for some overcharging. In fact, if you leave it plugged in after it’s at 100% it will charge fully, then stop charging, letting some charge deplete, and then start charging again. This prevents the battery from being overcharged.

      According to Apple, 100% gives you the expected run time. You can go beyond 100%, but the meter will only show 100%.

      Reply

      • Thanks for your reply.

        I just got my battery replaced 2 months ago. I keep a watch on the battery health. Currently, it is 100%.

        Regarding charging over 100%, I usually stop after 10 mins after it just goes to 100%. But if I forget to remove, does it impact the health of the battery? I have read several article with conflicting views stating overcharging for hours can deplete the health of the battery… Whereas some say it does not impact the battery…

        Also again talking about point no. 1 of my original post – after reading your article again – I am about to do the following to calibrate the battery…

        1. Let my iPhone 6 turn off completely by itself.

        2. Plug in the charger and let it charge 100% and beyond

        3. Remove the charger and press home and sleep button together to reset.

        4. Phone restarts automatically.

        Please tell if this is ok to do? Also how much extra time should I charge the iPhone for for this reset? Please note that I use iPad charger to charge my iPhone as it does not harm the phone but only charges it faster.

        Thanks again 🙂

        Reply

        • Sorry, for got to mention – I will have to keep my phone on when I charge to calibrate the battery as I cannot switch off for longer time…

          Reply

  33. Will this work in a surplus iPhone 5s? My bro in law bought an iPhone 5s in Japan. It’s working great except the battery life. It sucks. 100% won’t last for 1 hour use even if it’s just a normal browsing on the net.

    Reply

      • I just calibrated my battery using the steps below. I let the battery go out and let my phone sit there for two hours.When I plugged it in the charger, the battery icon showed up but the phone took about a minute or two to come back on, battery was at 2% when it came back on. I’m guessing when the phone didn’t come on right away after plugging it in to the charger that the battery was completely drained. Would you consider this to be an accurate assessment?

        Reply

        • Yes. What you see is normal. Your iPhone needs a certain amount of charge to start, in order to shut down properly if need be. If it started up just when it got enough juice, and the user yanked the cable, it wouldn’t shut down properly. This is by design. I usually see it in about that range.

          Reply

  35. When getting wrong percentage or you just replaced your battery (iPhone, iPad):
    – Put iPhone/iPad on charger
    – “Hard reset” your device (Home and Main button at the same time until it reboots)
    – Leave it on charger after restart until 100% charged + 1.5 hours

    This is called “calibrating the battery”. The “Hard reset” will reset your iPhone’s information about the (old) battery.

    It worked perfectly for my iPhone 5

    Reply

  36. I bought an iPhone 8 plus from a trusted source. It’s slightly used and is less than a week old. I just recently replaced the battery and the meter does not update when it is charging. It only indicates the last pecentage for many minutes.

    It only show an increse in percentage after you have restarted the phone. I tried factory settings but it’s the still same. I have yet to calibrate to see how it goes.

    Reply

  37. Hi. I bought an used iphone 6s which has the battery health of 99%. The thing is, the charge doesnt last longer. It keeps jumping from 100-75 in just 10-12 minutes. I switched off background process, location,wifi,bluetooth and just every other thing. Will this calibration help me?

    Reply

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