iPhone 15 battery health at 88% after 6 months

If you're charging your phone up to 100% each time you charge, that's probably the cause. Ideally, you'll want to charge your battery up to 80%, and stop there. There's a setting to do just that.

From Settings, go to Battery -> Charging. Then, consider these settings.

Optimized Battery Charging - This will control when your charge goes to 100% based on your activity. Holding that 100% charge puts a lot of strain on the lithium battery, so you'll want to reach 100% only when necessary.

Charge Limit - This is better, because it will prevent you from going passed a specified percentage. 80% is a sweet spot. I'm up to over 160 charges, and still have 100% battery health on the iPhone 16.

Charging it up to 100% repeatedly will be a fast way to reduce the life of any lithium battery. Even laptops now have a feature to limit charges to 80% by default.

Hope it helps! Your next iPhone battery will last much longer at 100% if you limit max charges.

What you are describing isn’t that far off the ordinary as far as battery capacity to cycles. The number of cycles is a bit high (my 16 bought June of last year is at 106 cycles). You might also consider that battery wear is NOT linear and it could take longer than you think to get to 80% where you would need to consider replacing it.

This links to the first page of the battery section of the user guide: https://support.apple.com/guide/iphone/charge-the-battery-iph63eecc618/ios

Read through this and the subsequent pages.

I will say that other than turning on optimized charging, I simply charge my phone overnight unless it is near full at bedtime. No other precautions. I always charge to 100%.

Larwri wrote:

If you're charging your phone up to 100% each time you charge, that's probably the cause. Ideally, you'll want to charge your battery up to 80%, and stop there. There's a setting to do just that.

From Settings, go to Battery -> Charging. Then, consider these settings.

Optimized Battery Charging - This will control when your charge goes to 100% based on your activity. Holding that 100% charge puts a lot of strain on the lithium battery, so you'll want to reach 100% only when necessary.

Charge Limit - This is better, because it will prevent you from going passed a specified percentage. 80% is a sweet spot. I'm up to over 160 charges, and still have 100% battery health on the iPhone 16.

Charging it up to 100% repeatedly will be a fast way to reduce the life of any lithium battery. Even laptops now have a feature to limit charges to 80% by default.

Hope it helps! Your next iPhone battery will last much longer at 100% if you limit max charges.

I don't agree with you on the charging to 100%. Most senior member of this forum see the Charge Limit as more gimmick than useful. To start the day with 80% battery, typically pushed people to have to charge more often, not less often. What most of us do here, after years of experience is put our phones on to charge when we go to bed, leaving them on Charge ALL night, EVERY night, with Optimized Battery Charging enabled. We wake to a phone fully charged to 100%, which for most people, will last all day.

Lawrence Finch, one of the most respected forum members here, wrote this VERY informative article on charging --> When to charge your iPhone or iPad - Apple Community

I follow his advice as do most of us who have been on this forum for years.

Please don't take the few words out of context, which you believe supports your position. He said and these are quotes from his article:

The Best Practice, however, is to charge the device overnight, every night. As it stops automatically at 100% you can't overcharge it doing this. You thus start the day with a fully charged device. And, if you configure the device for automatic backup using iTunes or iCloud, the phone will back up every night when it has a WiFi connection and is asleep.

With iOS 13 and later iOS devices now have an Optimized Charging option. With this enabled, if you charge overnight an iPhone will stop charging at 80%, then resume charging in time to reach 100% in time to meet your normal usage pattern. During the nighttime pause the phone will use mains power instead of battery power, allowing the battery to “rest”, and thus reducing the need to charge the battery quite as often; over the long term this will extend the useful life of the battery. The figure below shows how Optimized Charging works; notice that it started charging when put on a wireless charger around 9:30 PM, stopped charging at 80% a short while later, then resumed charging at 6 AM to reach 100% around 7 AM.

Followed by:

With iPhone 15 series and later Apple added a feature that limits charging to 80%, based on the assumption that leaving a Lithium ion battery at 100% for long periods of time will cause some degradation. While this is meaningful in your EV car, which may remain parked for days at a time, or your laptop that you leave plugged in for days or weeks, it will make little if any difference for an iPhone that is used constantly, and, if Optimized Charging is enabled, will only be at 100% for an hour a day or so. (Newer MacBooks also automatically limit a usually plugged-in device to 80%).

Sorry, but comparing two phones, which are not used identically at all times means nothing.

If the OP has any questions about how I use my personal phone, I'm happy to share my own experiences.

I'm sure what I say won't mean much to you, since we probably don't use our phones identically. And that's fair.

I prefer science. And a respected scientist conducted a scientific study. He took 12 iPhones, all used exact the same amount of time, doing the exact same things. Six of them used the Charge Limit to 80%. Six of them used Optimized Battery Charge, charged to 100%. There was no degradation of Battery health on the phones charged to 100%. None. His conclusion was that the Charge Limit provided no tangible benefit. None.

I'm not a scientist. But, of course I prefer science as well. That said, I'm sure you would agree with me on the following points (since, you did link to Lawrence Finch's write up, which also supports these points).

1: Charging a phone to 100% increases chemical wear.

2: More time spent on a full charge ages the battery faster.

These points are also raised and supported in thousands of studies relating to lithium ion batteries. I realize that my 2 phones are no adequate sample size for a scientific study, but 12 might not be sufficient either.

So, maybe the OP could share how they use their phone? I think that's a fair question. I'll tell you how I use my work and personal phones so you could have better context.

Work Phone (100% Health): Overnight charge, limited to an 80% charge Used immediately upon waking up, and throughout the day, I get down to about 70-75%. I have 352 apps installed on this phone.

Personal Phone (84% Health): Overnight charge, charges fully to its 100% capacity. Mostly used after work, but by the time my work day ends, it's at 80-85% of its charge capacity. I might make one call during work. This phone has 22 apps installed.

I'm not saying you're wrong. But I will tell you that my experiences differ from the post you've cited. And, I've had a repeated experience for my last 3 series.

I skipped the 17 series, and when I get the 18 series, I plan on changing my charging habits, because I also find it odd that my personal phone would get down to 84% battery health (like the OP).

I appreciate your perspective, and am here to learn. Thank you.

lobsterghost1 wrote:

He's clearly making the point that Optimized Battery Charging is the better option over Charge Limit

For anyone with a predictable, fixed schedule, yes. Optimized Battery Charging is probably the better option.

But if you're working with an unpredictable work schedule, and you're constantly charging up to 100%, and letting your battery hold onto that charge for long periods before you get to use your phone, you're doing increased damage over time. Therefore, Charge Limit is the better option for some of us.

lobsterghost1 wrote: because at 100% an iPhone is not going to remain at the level, likely for more than hour. Thus not injurious to the batteries health overall.

This supports my point. Thank you.

The more time a battery spends at a high charge, the more chemical stress you're causing. This is why, if you start using your device immediately after it hits 100%, it's going to consume power quicker, alleviating the chemical stress. Or is physics wrong?

Also, I'm very curious what video you're referring to when you said a respected scientist conducted a scientific study on this topic. Do you have a link you could share? I found dozens of studies that allege and prove the counter argument, but I'm not so arrogant that I won't look more into it, to hopefully get a better perspective and understanding. I'd love to check out what you're referring to.

lobsterghost1 wrote: I don't agree with you on the charging to 100%. Most senior member of this forum see the Charge Limit as more gimmick than useful. To start the day with 80% battery, typically pushed people to have to charge more often, not less often. What most of us do here, after years of experience is put our phones on to charge when we go to bed, leaving them on Charge ALL night, EVERY night, with Optimized Battery Charging enabled. We wake to a phone fully charged to 100%, which for most people, will last all day. Lawrence Finch, one of the most respected forum members here, wrote this VERY informative article on charging --> When to charge your iPhone or iPad - Apple Community I follow his advice as do most of us who have been on this forum for years.

I have a work phone, and a personal phone. I charge my work phone to 80%, and my personal phone to 100%. I charge my phones every night before bed, and I wake up to an 80% charge on my work phone, and a 100% charge on my personal phone.

• Work Phone - 100% Battery Health
• Personal Phone - 84% Battery Health

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This is based on my own, repeated experiences with the iPhone 14, 15, and 16 series.

Larwri wrote:

lobsterghost1 wrote:

I don't agree with you on the charging to 100%. Most senior member of this forum see the Charge Limit as more gimmick than useful. To start the day with 80% battery, typically pushed people to have to charge more often, not less often. What most of us do here, after years of experience is put our phones on to charge when we go to bed, leaving them on Charge ALL night, EVERY night, with Optimized Battery Charging enabled. We wake to a phone fully charged to 100%, which for most people, will last all day.

Lawrence Finch, one of the most respected forum members here, wrote this VERY informative article on charging --> When to charge your iPhone or iPad - Apple Community

I follow his advice as do most of us who have been on this forum for years.

•

I have a work phone, and a personal phone. I charge my work phone to 80%, and my personal phone to 100%. I charge my phones every night before bed, and I wake up to an 80% charge on my work phone, and a 100% charge on my personal phone.

Work Phone - 100% Battery Health

• Personal Phone - 84% Battery Health

https://discussions.apple.com/content/attachment/413f4460-bfb7-40af-a7af-822e9ec04ddb

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https://discussions.apple.com/content/attachment/bc82d077-78ae-4d18-85fd-462156d1e5d0

This is based on my own, repeated experiences with the iPhone 14, 15, and 16 series.

Sorry, but comparing two phones, which are not used identically at all times means nothing. And by your own admission, neither of them have been through the same number of charge cycles.

I prefer science. A respected scientist conducted a scientific study. He took 12 iPhones, all used exact the same amount of time, doing the exact same things for six months exactly. Six of them used the Charge Limit set to 80%. Six of them used Optimized Battery Charge, charged to 100%. There was no degradation of Battery health on the phones charged to 100%. None. He scientifically demonstrated that using the Charge Limit provided no tangible benefit. None. Except the phones set to 80%, did have to charge more often, so theoretically, he surmised their health would ultimately diminish faster.

Sometimes science based on verifiable facts can be amazing!

Larwri wrote:

Work phone - 164 cycles

Personal phone - 249 cycles (usually gets a top-up mid-day)

So, yeah, that would explain the discrepancy and why you have chewed up as much battery capacity as you have. You are obviously using a great deal of power on that phone. And you may need to replace the battery sooner than later. No big deal. It’s an expendable commodity. That’s the way it goes.

Larwri wrote:

So, what's being taken out of context? And, what are we disagreeing on?

He's clearly making the point that Optimized Battery Charging is the better option over Charge Limit, because at 100% an iPhone is not going to remain at 100% for more than hour. Thus not injurious to the batteries health overall.

We can agree to disagree. And you should by all means do what you think is best for your devices. I will continue to charge my phone to 100% using Optimized Battery Charging as I believe that overall, it is the best option for me. And most of the senior members who post here every day, week after week, month over year, agree with this point.

Unfortunately, your report is meaningless unless both phones are identical, are exactly the same age with exactly the same apps installed and you have used both phones for exactly the same amount of time. Is that the case?

Bob Timmons wrote:

Unfortunately, your report is meaningless unless both phones are identical, are exactly the same age with exactly the same apps installed and you have used both phones for exactly the same amount of time. Is that the case?

Fair point. I responded to lobsterghost1 who raised the same point, so I gave more context there. I won't re-post since I think it should be easy to find.

I'm not disagreeing with you, and I appreciate you raising these points. I know that they're important to consider. Thanks.

Larwri wrote:

lobsterghost1 wrote:

He's clearly making the point that Optimized Battery Charging is the better option over Charge Limit

For anyone with a predictable, fixed schedule, yes. Optimized Battery Charging is probably the better option.

But if you're working with an unpredictable work schedule, and you're constantly charging up to 100%, and letting your battery hold onto that charge for long periods before you get to use your phone, you're doing increased damage over time. Therefore, Charge Limit is the better option for some of us.

lobsterghost1 wrote:

because at 100% an iPhone is not going to remain at the level, likely for more than hour. Thus not injurious to the batteries health overall.

This supports my point. Thank you.

The more time a battery spends at a high charge, the more chemical stress you're causing. This is why, if you start using your device immediately after it hits 100%, it's going to consume power quicker, alleviating the chemical stress. Or is physics wrong?

Also, I'm very curious what video you're referring to when you said a respected scientist conducted a scientific study on this topic. Do you have a link you could share? I found dozens of studies that allege and prove the counter argument, but I'm not so arrogant that I won't look more into it, to hopefully get a better perspective and understanding. I'd love to check out what you're referring to.

I'm not sure I supported you point, but if you think I did, that's fine.

As to the scientific study, I subscribe to a lot of scientific journals and it was about a year ago and I did't keep a copy of it. Sorry.

lobsterghost1 wrote: I'm not sure I supported you point, but if you think I did, that's fine.

In that case, I'm glad we've been quoting each other! 😊

Larwri wrote: As to the scientific study, I subscribe to a lot of scientific journals and it was about a year ago and I did't keep a copy of it. Sorry.

No worries.

Thanks for the engagement. I hope to learn a lot from you and others on the forum.

And how many cycles do you have on it?