iPhone 6(S)/Plus Trying to understand iPhone random shutdown

[icymountain]

My iPhone (6s) just started to do random shutdowns, although the batter is reported as "supporting peak performance capability" by the OS, and with 97% maximum capacity. The battery is about 15 month old (I had it replaced by Apple).
It has now happened twice in ten days; each time, the battery was at about 30% to 40% and the phone shut down just when I started a call. After I plug it in and restart it, it would show a very low level less than 10%, although it was much higher right before shutdown.
In the same time, I cannot say the battery life is poor. As I am used to with this phone, I have been consistently getting from 2.5 to 4 days or battery life.

I just checked with cononutBattery with the phone plugged to my laptop, and the numbers seem much less nice than what iOS reports: 83% health, with 124 cycles.

What to make of all this ? It does not seem to make sense the battery would have to be replaced after less than a year and a half (the initial battery worked for more than 4 years...). I know it is an old model, but I cannot say the features of the new models really make me want to upgrade, and even if I did I would first like to understand what is happening here.
Any idea ?

 

[BugeyeSTI]

What does coconut battery show when the battery was made? It could be the battery has been sitting in a warehouse for awhile before Apple installed it in your device

 

[turbochgd]

My iPhone (6s) just started to do random shutdowns, although the batter is reported as "supporting peak performance capability" by the OS, and with 97% maximum capacity. The battery is about 15 month old (I had it replaced by Apple).
It has now happened twice in ten days; each time, the battery was at about 30% to 40% and the phone shut down just when I started a call. After I plug it in and restart it, it would show a very low level less than 10%, although it was much higher right before shutdown.
In the same time, I cannot say the battery life is poor. As I am used to with this phone, I have been consistently getting from 2.5 to 4 days or battery life.

I just checked with cononutBattery with the phone plugged to my laptop, and the numbers seem much less nice than what iOS reports: 83% health, with 124 cycles.

What to make of all this ? It does not seem to make sense the battery would have to be replaced after less than a year and a half (the initial battery worked for more than 4 years...). I know it is an old model, but I cannot say the features of the new models really make me want to upgrade, and even if I did I would first like to understand what is happening here.
Any idea ?

If I remember correctly I had a similar experience years ago and I think what I did was let it run down completely and then doing a full charge to 100% to recalibrate the battery meter. I believe that worked to fix the issue.

 

[icymountain]

Thanks for the replies!

What does coconut battery show when the battery was made? It could be the battery has been sitting in a warehouse for awhile before Apple installed it in your device

It does not give me the age of the battery itself, only that of the phone. So I cannot check this for sure, but that is a possibility indeed, although I would expect Apple not to play that game.

If I remember correctly I had a similar experience years ago and I think what I did was let it run down completely and then doing a full charge to 100% to recalibrate the battery meter. I believe that worked to fix the issue.

That is a possibility too. After the failure, I did a recharge to 100%. I will try to make a full cycle again next time in the hope that this will address potential calibration issues.

 

[bodonnell202]

I used a 6s for 3 years (bought new when it first came out) and this doesn't surprise me in the slightest. I actually had my battery replaced twice while I had it. With both the original and 2nd battery by the time the battery was a little over a year old the phone would be unreliable and shut down when the change got down in the 30-40% range (I sold the phone shortly after it was on its 3rd battery). Apple tried to rectify it with software, but Apple didn't put a big enough margin in the output of the 6s batteries to account for ageing.

I'm actually more shocked that you managed to get 4 years without issues on the original battery.

 

[icymountain]

I did not imagine that point could come that soon in the life of the battery.
For now, I will try to do regular calibration cycles and see. If this happens again, I guess that will mean another battery or... another phone.

 

[Andeddu]

I did not imagine that point could come that soon in the life of the battery.
For now, I will try to do regular calibration cycles and see. If this happens again, I guess that will mean another battery or... another phone.

The 6S is a great phone but it is close to the end of its life. Rather than a battery replacement, I reckon you should look at getting a new phone.

 

[FeliApple]

The 6S is a great phone but it is close to the end of its life. Rather than a battery replacement, I reckon you should look at getting a new phone.

Agreed. Unfortunately, iOS 15 has rendered the 6s useless as a main phone.

OP, if you like it, I think you could give it one more try. If it happens again to that degree, unfortunately you'd have to upgrade...

 

[MacCheetah3]

What @turbochgd said. Here’s a nice and simple video explanation:

How often? Probably at least every few months but there’s no absolute guideline. I do uninterrupted full charge cycles almost every time — in part due to OCPD/OCD.

 

[icymountain]

Agreed. Unfortunately, iOS 15 has rendered the 6s useless as a main phone.

OP, if you like it, I think you could give it one more try. If it happens again to that degree, unfortunately you'd have to upgrade...

Indeed, this is the plan. (I do like it: perfect size, useful jack...).

What @turbochgd said. Here’s a nice and simple video explanation:

How often? Probably at least every few months but there’s no absolute guideline. I do uninterrupted full charge cycles almost every time — in part due to OCPD/OCD.

Thanks, useful video. I thought recalibration was over a single cycle, but they recommend a few full cycles. As of late, I often recharged when it showed 30 or 40% as that was more convenient, but probably not so good for calibration. We will see.

 

[FeliApple]

Indeed, this is the plan. (I do like it: perfect size, useful jack...).

You said that battery life was good enough for you, and if you like the phone, it is perfectly usable even now.

My 6s is my favourite phone ever. It is 6.5-years-old, it has the original battery, and I plan to keep using it.

Like you said, you like the device, so if it works for you, you can keep using it with no issues at all!

 

[BugeyeSTI]

Why you shouldn’t calibrate the battery in your iPhone, iPad, or iPod

Calibrating the battery in your iPhone, iPad, or iPod sounds like a good idea until you learn more about how lithium-ion batteries work.

appletoolbox.com

 

[guesswho183]

I've got three 6s and one with the same symptoms. Phone actually stays too long in box, battery discharged and battery capacity from cycle 1 one was 97%. Phone usually turn off ~ 20% battery and that is very frustrating but lesson learned - from that point I'm only buying phones manufactured recently with fresh battery.
In your case it 100% problem with battery.

 

[MacCheetah3]

Why you shouldn’t calibrate the battery in your iPhone, iPad, or iPod

Calibrating the battery in your iPhone, iPad, or iPod sounds like a good idea until you learn more about how lithium-ion batteries work.

appletoolbox.com

Unfortunately, these are clickbait articles.

“Extreme charge level” refers to either 100% or 0% charge. When a lithium-ion battery spends too long at 100% charge, it reduces the maximum capacity of that battery.

While true, the fact they ignore, overlook, or intentionally leave out is the proper (re)calibration process doesn’t expose the battery to the extremes for long. In fact, it can be short.

Speaking of contradictions, the article author, shortly following the above quoted statement, goes on to explain Apple doesn’t allow/tries to prevent these extremes anyway:

Apple designs its software to include a buffer around the battery. So, when your device says the battery’s at 100% charge, it isn’t really. It stops charging before it gets that far.

Similarly, when your iPhone, iPad, or iPod turns off because the battery died, there’s actually still a bit of charge left in it. That’s how it displays a low power icon when you try turning it back on.

========================

I am not great at analogies but let’s try one anyway.

You have a silo which has no bottom, standing on the ground. Over time, the weight of the walls and erosion cause the silo to slowly sink. As the walls slide deeper in the ground, the capacity decreases. Assuming you know the original height of the silo, at any time, you could measure from ground level to the top (i.e., current height) and calculate the new capacity. However, what if you didn’t have the ability to (re)measure? Sure, you could “eye it up,” compare using a visual perspective recollection. Of course, that would be far less accurate.

Battery (re)calibration — indeed misleading as it’s really battery charge meter calibration — is like remeasuring the silo height.

=========================

Ultimately, the present battery charge and battery health percentages are best guesstimates. I did find an article that appears to contain accurate info about the many parameters/characteristics/values of Li-ion batteries:

Battery Fuel Gauges: Accurately Measuring Charge Level | Analog Devices

Battery fuel gauges determine the amount of charge remaining in a secondary battery, and how much longer (under specific operating conditions) the battery can continue providing power. Such indication

www.analog.com

Last but not least, tools such as coconutBattery are fine. However, they only report the battery statistics/values as of that moment (i.e., second). With that said, for best results err estimate, use coconutBattery when your iDevice/Mac reports fully charged.

 

[BugeyeSTI]

Unfortunately, these are clickbait articles.


While true, the fact they ignore, overlook, or intentionally leave out is the proper (re)calibration process doesn’t expose the battery to the extremes for long. In fact, it can be short.

Speaking of contradictions, the article author, shortly following the above quoted statement, goes on to explain Apple doesn’t allow/tries to prevent these extremes anyway:



========================

I am not great at analogies but let’s try one anyway.

You have a silo which has no bottom, standing on the ground. Over time, the weight of the walls and erosion cause the silo to slowly sink. As the walls slide deeper in the ground, the capacity decreases. Assuming you know the original height of the silo, at any time, you could measure from ground level to the top (i.e., current height) and calculate the new capacity. However, what if you didn’t have the ability to (re)measure? Sure, you could “eye it up,” compare using a visual perspective recollection. Of course, that would be far less accurate.

Battery (re)calibration — indeed misleading as it’s really battery charge meter calibration — is like remeasuring the silo height.

=========================

Ultimately, the present battery charge and battery health percentages are best guesstimates. I did find an article that appears to contain accurate info about the many parameters/characteristics/values of Li-ion batteries:

Battery Fuel Gauges: Accurately Measuring Charge Level | Analog Devices

Battery fuel gauges determine the amount of charge remaining in a secondary battery, and how much longer (under specific operating conditions) the battery can continue providing power. Such indication

www.analog.com

Last but not least, tools such as coconutBattery are fine. However, they only report the battery statistics/values as of that moment (i.e., second). With that said, for best results err estimate, use coconutBattery when your iDevice/Mac reports fully charged.

I respectfully disagree with your opinion.

 

[ian87w]

The 6s was plagued with battery problems that Apple had a service program for it. Due to the tiny battery and possibly old inventories for replacement, it wouldn’t be a surprise that even a recent replacement from Apple can present problems within a year or so. Unfortunately, Apple already ended that service program.

If the shutdowns bother you, I would suggest upgrading soon as there is probably nothing you can do about it other than trying another battery replacement and hoping to get a fresher newer battery. My advice is to just upgrade to the 2022 iPhone SE.