iphone 12 pro max battery health degrading

"There's no reliable trend that can be drawn here."

OK, but I've read many replies here stating that a trend of 1% less per month is normal: therefore, my trend couldn't be considered totally normal, since my battery has lost 11% of its full capacity in 9 months (9% in three months, from the end of June to the end of September).

I always close any unused app and I keep both power saving and optimized charging enabled, as well as disabling localization for any app that does not strictly need it to work.

Your battery is fine. If it falls below 80 percent, it's time for a new one.

Health is an estimate and the algorithm changes based on any of a number of factors. But, a loss of 11 percent of health in 9 months isn't exceptional in any way.

For what it's worth, my 12 Pro Max 256's battery is at 100% after a year of use. Never charged it wirelessly, because of heat degrading the battery, and rarely to 100%. Daily battery drain is some 40-50%, on average.

Ok so i don't know if this has anything to do with my battery capacity, but here goes.

my battery has been charging really slowly recently (keep in mind I only charge 40% every day, from 60%-100%). it's taking a little over 2 hours to be exact, and i really don't know why. however, yesterday and the day before, it charged noticeably faster, even while i used it the entire time. it took only about 1 hour and 40 mins. my capacity hasn't dropped for over a month, so i really wonder if it's accurate now. today, it went back to charging super slowly even when i was NOT using it. i've had my iphone 12 for more than a year, so maybe that explains it, but why did it charge so "normally" for the last two days even when i never restarted or did anything to my phone? i have been using the exact same charger, brick, and wall plug. what is going on, exactly?

crystal_star wrote:

Ok so i don't know if this has anything to do with my battery capacity, but here goes.

my battery has been charging really slowly recently (keep in mind I only charge 40% every day, from 60%-100%). it's taking a little over 2 hours to be exact, and i really don't know why. however, yesterday and the day before, it charged noticeably faster, even while i used it the entire time. it took only about 1 hour and 40 mins. my capacity hasn't dropped for over a month, so i really wonder if it's accurate now. today, it went back to charging super slowly even when i was NOT using it. i've had my iphone 12 for more than a year, so maybe that explains it, but why did it charge so "normally" for the last two days even when i never restarted or did anything to my phone? i have been using the exact same charger, brick, and wall plug. what is going on, exactly?

Some background…

Batteries are considered consumable or wear items. All batteries will inexorably and inevitably degrade, and all will fail. When (and not if) the battery fails, the battery can be replaced, if that happens before the iPhone is replaced. Individual batteries will vary, too. Some arrive with more capacity. Some other batteries are exposed to environmental heat, and degrade mire quickly. Details and usage all vary.

Battery charge and battery capacity are also digital estimates of what is an analog device. Batteries can have temperature sensors and voltage sensors connected, but there’s no charging sensor nor any capacity sensor. The charge and capacity values shown are estimates, and are derived indirectly from other available data over time. With a petroleum-powered vehicle fuel gage, you can have a physical float sensor or an electronic depth sensor measuring how full the fuel tank is, and you know the tank capacity. Batteries lack that tank sensor, and the original maximum capacity of individual batteries can vary based on materials differences within individual batteries.

For charging…

iPhone will charge to about 80% and then wait until somewhat before your normal usage starts, and will then fully charge the battery.

That is, iPhone will quickly charge to ~80% (depending on the available wattage at the charger, the battery temperature, and probably some other factors) and then charging will pause, and then fully charge.

This scheme all to avoid trying to hold the battery at fully charged for longer than is necessary, as this tends to degrade the battery more quickly than does a partial charge and then a quick sprint to fully-charged.

You can see this charging pattern behavior on the charge graph, too.

This is what is mentioned in the text of the screen shot shown at the top of this webpage.

It is common to charge the battery during the user’s downtime and particularly the user’s during sleep, and the optimized battery charging tries to learn your charging (sleep) schedule.

As for shifting behaviors, with iOS 15.1 Apple also implemented “Battery algorithms updated on iPhone 12 models to better estimate battery capacity over time”, so there can or will be some changes around the battery capacity display from previous iOS versions.

When your battery capacity drops below 80% and you find yourself needing to add an additional charge cycle into your normal usage, get your battery replaced. Otherwise, use your iPhone for what you bought it for. Which probably wasn’t as a battery gage.

thanks, of course I will replace it, but that probably won't be for another 2 years when i get a new phone anyways. so there's really no specific way to make my battery charge faster, right? because if it can charge faster even while using it, that's mildly suspicious.

and yes, for the last two days before yesterday, my phone did charge quickly from 60%-80%, in about 40 minutes. it charged to 90% only about 15 minutes after it was 80% (I have on a shortcut that sends me a notification every time my battery reaches 70, 80, 90, and 100, so i know the time differences between two percentages). but yesterday, it took about 15 minutes longer even when i wasn't using it, so i don't think the part about charging quickly to 80% applied. it became more normal towards the end (by that i obviously mean faster), so it was really the beginning that threw it off. but still, there's really no one specific way to judge, correct?

iPhones capable of fast charging (essentially, the 7 and later), if used with a high enough power energy source, will fast charge to 80%, then slow down to avoid overcharging. It can take another 2 hours to go from 80% to 100% with any iPhone, but an iPhone 11 or later with the right charger will go from zero to 50% in 30 minutes, and to 80% in another 15 minutes. In addition, if you fast charge it will pause completely at 80% to allow the phone to cool down, sometimes for an hour or more.

But you should be charging overnight, every night, with Optimized Charging enabled. If you do that it doesn’t matter how long it takes. And also enable automatic backups, so when your phone gets thrown under a bus, you will not lose much data.

crystal_star wrote:

and yes, for the last two days before yesterday, my phone did charge quickly from 60%-80%, in about 40 minutes. it charged to 90% only about 15 minutes after it was 80% (I have on a shortcut that sends me a notification every time my battery reaches 70, 80, 90, and 100, so i know the time differences between two percentages). but yesterday, it took about 15 minutes longer even when i wasn't using it, so i don't think the part about charging quickly to 80% applied. it became more normal towards the end (by that i obviously mean faster), so it was really the beginning that threw it off. but still, there's really no one specific way to judge, correct?

Apple has sought to avoid the need for the user to need to manage the battery; to automate battery maintenance.

Your iPhone is working normally, including the charging behavior.

A completely charged battery is good when you need it, but sitting at a full charge is not best for lithium ion battery longevity.

What you are seemingly expecting to happen here—a direct and immediate run to a full charge—and are clearly puzzled by—slower charging past 80%—are part of the charging algorithm’s efforts to preserve battery capacity.

Enable optimized charging, charge your iPhone on a regular schedule, and (as was mentioned in Lawrence Finch’s reply above) have regular and preferably scheduled backups of your data.

If you’re interested in lithium ion battery technologies in general, there are lots of references around the net. Here’s one:

https://batteryuniversity.com/article/bu-808-how-to-prolong-lithium-based-batteries

yeah i don't know what i've been doing wrong, and i hope it's not the battery because the capacity is still the same, but my phone randomly restarted in the middle of a song i was listening to today, and i can't think of anything else other than the battery. again, the capacity is still above 90%. i tried doing some research, and all the articles i read mentioned a defective battery so i really wonder what happened? I hope not, and I don't want to keep reading, so what other factors are there besides defective battery and not enough storage? I am running on the latest version of iOS, by the way.

crystal_star wrote:

yeah i don't know what i've been doing wrong, and i hope it's not the battery because the capacity is still the same, but my phone randomly restarted in the middle of a song i was listening to today, and i can't think of anything else other than the battery. again, the capacity is still above 90%. i tried doing some research, and all the articles i read mentioned a defective battery so i really wonder what happened? I hope not, and I don't want to keep reading, so what other factors are there besides defective battery and not enough storage? I am running on the latest version of iOS, by the way.

iOS itself can crash, as can apps.

These crashes can be due to app flaws, due to OS flaws, and due to hardware flaws, and due to flaky network connections.

Add-on VPNs and add-on security products can cause network connections to be flaky.

Not enough storage, and the resulting storage corruptions that can then arise from insufficient storage.

Yes, batteries can cause crashes, so can a whole lot of other problems. If the iPhone crashes persist, contact Apple Support.

ps: Apple effectively has two “current” versions right now: 14.8.1 just arrived and 15.1 has been available for a bit.

There’s more that can go wrong with batteries than loss of capacity. One is increasing internal resistance, and the symptom of that is sudden unexpected shutdowns. Apple can test the battery remotely, so you can contact them to do that with the Get Support link at the top of this page.

Yes, will do. Does the capacity show anything related to that? And also, one strange thing that happened today, and I’m really worried about it because it’s the second bad sign with my phone that’s happened this week.

So I have on a shortcut that sends me a notification right when my battery hits 60% so that I can plug it in. I plugged in it no more than 10 seconds after i got that notification, but right when the plug connected to the phone, the battery percent dropped down to 59%. I got extremely suspicious because that has NEVER happened before, unless of course I waited for at least a minute and used more battery when it was at 60%. But NO, i didn’t open any apps after i plugged it in, so why did it drop from 60 to 59 in FIVE SECONDS?! Does this have something to do with what you mentioned? My battery has been acting normal the entire day.

crystal_star wrote:

Yes, will do. Does the capacity show anything related to that? And also, one strange thing that happened today, and I’m really worried about it because it’s the second bad sign with my phone that’s happened this week.

We can’t run diagnostics, and—should this iPhone warrant a battery swap or other repairs—we can’t schedule any of that.

Check with Apple Support.

crystal_star wrote:

Yes, will do. Does the capacity show anything related to that? And also, one strange thing that happened today, and I’m really worried about it because it’s the second bad sign with my phone that’s happened this week.

so why did it drop from 60 to 59 in FIVE SECONDS?!

Because it wasn’t at 60%, it was at 59.5%, which rounds to 60%, and it dropped 0.1% to 59.4%, which rounds to 59%. And when you plugged it in the phone first had to negotiate the correct charging voltage and current with the power source, which both uses energy and takes a couple of seconds.

But why are you charging at 60%? That makes no logical or technical sense. You should be ignoring the battery and just enjoy using the phone unless it drops to 20%, which the phone will warn you about; that’s when you should consider charging it soon (not even immediately). And stop obsessing over the battery. You have a smartphone, not a $1,000 battery monitor.