Got a tip for us?
Let us know
Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
iPhone 15 Pro Why use 80% max charge ?
- Thread starter Zapdoc
- Start date
- Sort by reaction score
this in theory should make your battery degrade slower, but only with the assumption that it will stay there most of the time anyway, which in practice doesn't really happen unless you are keeping it on a charger for days or weeks without ever carrying it with you and use it.
i find it actually a bit baffling that they started with this feature on the iPhone, where it in my opinion is making the least sense.
instead, it would have been more useful on Macbooks for people, who are using them mostly as desktop machines and have them plugged in most of the time
so if you are one of those people who are usually always staying at 80% charge and above, this feature is for you 🤓
i find it actually a bit baffling that they started with this feature on the iPhone, where it in my opinion is making the least sense.
instead, it would have been more useful on Macbooks for people, who are using them mostly as desktop machines and have them plugged in most of the time
so if you are one of those people who are usually always staying at 80% charge and above, this feature is for you 🤓
The idea is that if you keep a lithium polymer battery between around 20% and 80% it may degrade a bit slower than if you use the battery to its full capacity regularly. Batteries have the toughest time when being pushed to charge past about 80%, this is why charging speeds drop off significantly once the 80% mark is reached. That’s why if you use say a 20-watt charger to power your iPhone, it’ll pull the full 20-watts until 80% then slow steadily as it approaches full charge. Additionally, deep cycling is tough; dropping below around 20% regularly can contribute to battery degradation.
Teslas, as well as other EVs, only charge to 80% by default. This can and should only be overridden when maximum range is needed.
I wholeheartedly agree with the previous poster though that is is much less useful on iPhone, and would be a much more welcome feature on MacBooks, some of which are left plugged into AC mains for long periods of time.
Hope this helps.
Teslas, as well as other EVs, only charge to 80% by default. This can and should only be overridden when maximum range is needed.
I wholeheartedly agree with the previous poster though that is is much less useful on iPhone, and would be a much more welcome feature on MacBooks, some of which are left plugged into AC mains for long periods of time.
Hope this helps.
THIS is the best article I’ve seen on the subject (see 1st & last paragraph for TL;DR), plus other credible/corroborating data. 80% peak limiters are better than nothing, but an automated custom charge optimization (shortcut app + smartplug) would be far better. Does it work? Here’s my results after 4yrs (note: my usage pattern is unusually efficient w/ mostly wifi, lite apps, and tuned settings).
I personally wouldn’t bother plugging-in twice a day just to save battery, that’s too much of a PITA for me, and rather do a battery swap. But if I have some extra/free capacity, and the charge optimization is fully automated (ie, plug-in once/day and forget), then why not?
IMHO, phone batteries are sort of like car motors - they’re built to redline RPMs every single shift, but if you don’t require that peak power/capacity every time, then why not go easy on the motor/batt for longevity. If you lease/upgrade every 2-3yrs, then who cares. But for those that prefer to buy/keep longer, I’d say battery is THE trigger point that gets most folks to upgrade phones earlier then they’d prefer to - even with a relatively inexpensive batt swap option.
I personally wouldn’t bother plugging-in twice a day just to save battery, that’s too much of a PITA for me, and rather do a battery swap. But if I have some extra/free capacity, and the charge optimization is fully automated (ie, plug-in once/day and forget), then why not?
IMHO, phone batteries are sort of like car motors - they’re built to redline RPMs every single shift, but if you don’t require that peak power/capacity every time, then why not go easy on the motor/batt for longevity. If you lease/upgrade every 2-3yrs, then who cares. But for those that prefer to buy/keep longer, I’d say battery is THE trigger point that gets most folks to upgrade phones earlier then they’d prefer to - even with a relatively inexpensive batt swap option.
As others have already clarified this, I will just point out the following…
Alot of those concerned about this particular battery charging process are those wanting to maximize the resale or trade in value of their phone when they upgrade the following year. They want to be able to show that the battery says '100 percent' of health when they go to sell or trade.
Whether that's worth the OCD and anxiety about battery is a personal decision.
If a battery is charged to only 80%, it’s ultimate lifetime may exceed 4X or more years than a battery habitually charged to 100%.
If a battery is charged to 80% and discharged no lower than about 20%, the battery will probably outlive the useful life of the phone.
For one person, that may not seem like a big deal, but Apple has sold BILLIONS of devices that experienced premature battery wear simply by charging to 100%.
Billions and billions of batteries are in landfills throughout the world prematurely because of over charging.
That’s tons and tons and tons of batteries that didn’t need to be there.
If a battery is charged to 80% and discharged no lower than about 20%, the battery will probably outlive the useful life of the phone.
For one person, that may not seem like a big deal, but Apple has sold BILLIONS of devices that experienced premature battery wear simply by charging to 100%.
Billions and billions of batteries are in landfills throughout the world prematurely because of over charging.
That’s tons and tons and tons of batteries that didn’t need to be there.
It's for people who are more worried about selling their iPhone, than using their iPhone.
The battery is designed to reach 500 cycles if charged to 100%. Over a long period, you can increase cycles and reduce internal resistance of the battery by charging to 80%. Most people don’t need to use the enitre 17 Whr of energy stored in the battery each day, so there is no need to charge to 100%.
As I said in the other thread: Why is this exclusive to the iPhone 15s?
Feature rationing. Same reason why some camera features are limited to new iPhones even though they use the same A15 or A16 as past models.
I don’t know and it is infuriating. There is no reason why this can’t be included in iOS 17 supported devices.
Again, really would be helpful on MacBooks.
Likely the charging circuit needed to be changed to be able to talk to the OS. That’s likely why.
Charging circuit can already talk with iOS. iPhones with Lightning put charging on hold and stops at 80% if the device gets too warm. This is pure feature rationing.
If a Charging On Hold notification appears on your iPhone or iPad - Apple Support
If your iPhone or iPad is in a very hot or cold environment, it might not be able to charge. Find out what to do.
I fast charged my 14 PM to 100% every day or every other day since launch day and by the time I sold it a month ago, my battery health was at 100%. I'm not exactly sure how much of a difference it makes.
Same here, 99% after one year of continuous fast- and/or wireless charging to 100%...
The only reason I will use it is on a road trip when I’m plugged into CarPlay the whole time. Otherwise it’s a feature for the crazies that are obsessed with battery health.
Battery chemistry degrades more quickly the closer it is to 100% and 1%.
For people who charge the phone overnight, at their desk, and in their car, there isn’t a real reason to charge to 100% all the time.
Optimized charging attempts to allow for this by keeping the phone at 80% and only charging to 100% right before the user needs the phone, but not everyone has a steady schedule that repeats in a predictable pattern.
Manually setting the charging limit to 80% provides those who are always within reach of a charger a way of preserving the battery’s chemistry to extend its life. Since it’s just a toggle in settings, it’s easily disabled when traveling or away from charging sources for an extended period of time (provided there is advance notice).
Sure, however batteries in phones and laptops nowadays don't actually reach 100% or 1%, there is already an "invisible" margin because manufacturers know that a laptop could be left discharged at 0% for days or that some phones might be left on a wireless charge pad at 100% for a while. If these were the true values the amount of batteries failing early would be considerably higher.
Simpler versions of these rechargeable batteries that don't have these extra margins are for example high-power flashlights and any sort of drones/quadcopter/RC car hobby where you need to set such limits yourself and store them correctly. If you actually discharge those to 1% they'll actually be at risk of never charging again and the same goes for fully charging them and then not using them immediately.
The batteries in our iPhones are only rated for 500 cycles. Apple says at 500 cycles they "retain 80%" but at that point the battery life is already significantly shortened. So really the iPhone batteries aren't made to last more than around 1.5-2 years before battery life starts to drop noticeably and limiting charge to 80% won't change anything about that.
Hence why I find the 80% limiter absolutely useless for most iPhone users. It would be better to tell users up front that their battery will last for roughly 2 years no matter what and they should use it as they see fit and just expect at least one battery replacement over the device's lifetime after the first 2-3 years.
With other smartphones it can be really challenging to get the battery replaced in the first place, I remember that even some older phones where you could switch the battery yourself didn't make it easy because the manufacturers usually didn't sell their original batteries in stores (LG did for a while with their high-end G4 which I appreciated but at that time their phones were already garbage).
Apple charges a lot for the replacements but no other smartphone manufacturer has a store to drop off a phone so easily for the replacement. I once tried that with an Android (I mainly use Pixels now so I really love Android) and the manufacturer received my phone for the battery replacement, prompty lost it and I never got device or money back and it wasn't worth the headache (wasn't Google!). So where I am coming from I'd rather just pay Apple for a new battery and not worry about 80% or whatever.
I can see both sides of this, and have posted before with an analogy to camper vans - another forum I'm on people seem more interested in preserving their resale value over & above using the damn thing ...
I was annoyed previously by having damaged my iPhone 12 Pro with constant overnight wireless charging, but perspective and personal Use Case are all important. I think it's good that the option is there, and not everyone has to (or needs to) use it.
As an aside, my MacBook Pro 14" has been held at 80% charge all-day today - it mostly lives on my desk connected by USB-C to monitor, though tomorrow I'll be away on business for 24-hours and hammering it away from mains power.
I was annoyed previously by having damaged my iPhone 12 Pro with constant overnight wireless charging, but perspective and personal Use Case are all important. I think it's good that the option is there, and not everyone has to (or needs to) use it.
As an aside, my MacBook Pro 14" has been held at 80% charge all-day today - it mostly lives on my desk connected by USB-C to monitor, though tomorrow I'll be away on business for 24-hours and hammering it away from mains power.
Granted, but battery chemistry degrades faster the closer it is to 90% and 10%.
Some people only need to charge their phone to 100% when traveling, so they will use the optional setting to limit charging the rest of the time.
Even a few percentage points of additional battery health on an 18 month old phone will be appreciated when traveling, and the difference will be even greater on a 3 or 4 year old phone. The most used smartphone in the world is the iPhone 11, to give you an idea of the age of the average smartphone.
It’s an optional setting, so I personally don’t think it’s something to get too worked up about.
Since I’m at a desk most days with my phone near a charger almost all the time, I love this feature. I just wish there was a quick button to press to charge to 100% when needed.
I only use between 20-30% of my battery each day so I have mine set to charge to 80%. Not a big deal and might keep the 15 PM for several years.
Apple is giving us a choice! You do not have to use this feature, it is up to the user!
Choice is always good!
Apple is giving us a choice! You do not have to use this feature, it is up to the user!
Choice is always good!
Last edited:
With my 12 Pro Max that I got on launch day I tried to keep it between 20-80%. Of course, if I needed the extra juice then I'd charge it up more and let it drain more. It took about 11 months if I remember right for it to drop to 99% battery health. I traded it in when I got my 15 Pro Max and the battery health was at 88% after 34 months of usage. In the last year I stopped caring too much about keeping it between 20-80% so I was often letting it go to 100% and I'd always charge at 10-20%.
On my 15 Pro Max i set it to stop at 80%. In fact, I used to set a shortcut on my 12 PM to notify me when it charged to 80% so I could take it out. I'm happy that Apple has built this into iOS now.
Right now I don't need 100% charge. I've been keeping it at ~25-80% and that's more than enough to get me through the day. Over the weekend I didn't use my phone too much but I charged to 80% on Friday at about 4PM and then I charged it back up on Sunday afternoon at around 2PM. I last charged my phone 23 hours ago to 80% and I still have 54% charge and that's easily enough to last me the rest of the day.
Looking at my battery stats I'm only using about 20-40% of battery a day.
On my 15 Pro Max i set it to stop at 80%. In fact, I used to set a shortcut on my 12 PM to notify me when it charged to 80% so I could take it out. I'm happy that Apple has built this into iOS now.
Right now I don't need 100% charge. I've been keeping it at ~25-80% and that's more than enough to get me through the day. Over the weekend I didn't use my phone too much but I charged to 80% on Friday at about 4PM and then I charged it back up on Sunday afternoon at around 2PM. I last charged my phone 23 hours ago to 80% and I still have 54% charge and that's easily enough to last me the rest of the day.
Looking at my battery stats I'm only using about 20-40% of battery a day.
500 cycles > 80% is merely a li-ion standard for LCO chemistry that most consumer devices use, AND assumes the batt is charged to 100% every cycle. Credible/corroborating scientific battery research (I linked a few in a post above) show how cycle life can be greatly extended by avoiding high states of charge.
If a user requires over ~70% capacity (incl cushion) on a single plug-in per day, then there’s little spare capacity within which to conveniently manage a battery. So in that case, I’d also recommend batt swaps and phone upgrades, rather than the hassle of a 2nd plug-in per day, just to save the battery.
That said, there’re plenty of (if not most) folks that require less than 2/3rds batt/day (like me), and therefore can conveniently manage batts on a single plug-in/day. And with current automated options for charge optimization (ie, smartplug/shortcut, or this peak limiter), there’s really no need to worry, hassle, or tend the process anymore - ie, just plug-in once/day and forget about it.
Been doing this for over a decade, and my previous iPhone5 batt had no problem outlasting it’s iOS upgrades, and my current XR (on a smartplug/shortcut) is on the same track as well:
