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Kendo

macrumors 68020
Original poster
Apr 4, 2011
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Using the parking lot analogy (you can find a parking space quickly when the lot is half full vs having a difficult time finding an empty spot when it is 95%) - I heard that charging a battery from 80-100% stresses the battery the same amount as when you charge 0-80%. In other words, that last 20% top off to 100 takes the same amount of time and energy as the first 80%.

So if you top off 20% twice (pretend two nights in a row) - you get a total of 40% charge. While going 0-80% two nights in a row is 160%.

Do you get "more for your money" simply charging from 0-80% thereby extending the life of the battery? I know official Apple paperworks says it is best to charge to 80%, but is this the actual reason?
 
I do only follow two or optional three easy steps about the iPhone lifecycle:

1. Avoid Heat
2. Never completely empty the battery. Stay above 10% if you can.
3. (optional) Try not to always fully charge it.


This is enough to stay healthy with your battery :)
 
The system is designed to rapid charge to 80% or so and then trickle charge it the rest of the way to 100%. The reason is that Lithium Ion batteries are volatile and nobody wants "My device exploded"/"My device burst into flames" stories.

If you could remove the "trickle" (filter), it would likely charge right to 100% just as fast as it did to 80%... but then you'd probably be one of the ones with a story about a spontaneous fire/burst.

Does it take the same amount of energy for the last 20%? I don't know. Logically, I would say it doesn't but there's room for anything when wild guessing.

Do you get more for your money charging to 80%? That's "eye of the beholder." There is some kind of use life logic in play that says not "topping off" will extend useful battery life. On the other hand, you may find yourself in situation where the other 20% would have made a meaningful difference and no way to recharge at such times.

My own approach is to buy the 80% idea most of the time. However, if I know I'm about the use the laptop for an extended period of time but do not know if I'll have access or opportunity to electricity, I'll go ahead and charge it the other 20%. By the end of such days, I'm down towards 0%-20% but also getting to wherever I'm traveling... and thus regaining easy access to a recharge. There, I'm back on the 80% train... until perhaps the return trip where I may go on up to 100% again for the travel day.

In short: selective "full" to fit situations where I don't know if I'll have access to a recharge but anticipate heavy use... otherwise playing along with the idea of 80% perhaps being better for general purpose use.

Is this the best possible way? Who knows? It's just the way I choose to go. If the battery wears out too much over time before it's time to replace the device, I'll pay the price to put in a new battery and restart the process.
 
I do only follow two or optional three easy steps about the iPhone lifecycle:

1. Avoid Heat
2. Never completely empty the battery. Stay above 10% if you can.
3. (optional) Try not to always fully charge it.


This is enough to stay healthy with your battery :)

Do you maybe know what can cause draining a batterie much faster when the device is turned off?

I have an iPhone 8 Plus that I only use every few days or once a week maybe. And when I turn it off with 90-100% after 2-3 days the batterie is completely empty. If I just let in on in Airplane mode it maybe loses just 1% per day.

IMG_0037.PNG
 
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Do you maybe know what can cause draining a batterie much faster when the device is turned off?

I have an iPhone 8 Plus that I only use every few days or once a week maybe. And when I turn it off with 90-100% after 2-3 days the batterie is completely empty. If I just let in on in Airplane mode it maybe loses just 1% per day.

View attachment 2478641

I think there is something just f***** with your iOS system. Easiest und safest way is factory reset iphone and set up as a new iPhone. :)
 
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I don't think the 0-80 vs 80-100 thing is so much about battery stress as it is about safety with charging Li+ batteries, in general. The first 80% can be charged safely more quickly with higher power. The final 20% has to be charged much more slowly to reduce the risk of fire.

Battery "stress" and shortening of lifespan occurs when you charge a battery too frequently. Ideally, you should let your phone's battery drain to about 10-20% before putting it on the charger for any amount of time to any percentage. But life doesn't necessarily work that way, and we don't always have practical access to charging during the day. So we have to manage by making sure it's charged up to at least what's needed. Add to that many of us have "battery anxiety" in which we start to panic if the battery indicator is anywhere below half, and yeah, the hyper-frequent charging reduces both the performance and lifespan of the battery over time.
 
Surely by now there have been scientific studies of this very question — even using the very same iPhones under different charging scenarios over months and reporting on changes in their battery health, ability to hold a charge, battery life — both on a single charge and over time, etc.

It'd be great if someone who already knows about them would post links and save us all the trouble of rummaging the Internet!

It'd be really useful to have experimental, rigorous findings and conclusions in addition to our usual MR anecdotal reports…
 
Ions reside on the anode side of the battery; when drawing power, the ions are attracted to the cathode side, releasing their electric charge to the terminal. Charging draws the ions back over to the anode where they acquire the electrons that they will later release. They mostly stack up neatly on the anode, but when you get to a higher charge level, they may tend to form chains ("dendrites") instead of gathering evenly around the anode. When the dendrites get too long, they can reach the cathode side and cause the battery to short out and possibly catch fire. The 80-100 trickle mode is designed to reduce the tendency for dendrites to form.
 
I have AC+ on my iPhone 13 PM. I just use the device and the batteries have come long way. I take my phone in to steam and sauna 4-5 times a week, often I charge to 100% as I travel and need as much battery. My launch day iPhone 13 PM stick is at 88% battery health. You would think my battery health would be far worse from exposure to heat or charging to 100% when traveling. Stop worrying about batteries.
 
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Surely by now there have been scientific studies of this very question — even using the very same iPhones under different charging scenarios over months and reporting on changes in their battery health, ability to hold a charge, battery life — both on a single charge and over time, etc.

It'd be great if someone who already knows about them would post links and save us all the trouble of rummaging the Internet!

It'd be really useful to have experimental, rigorous findings and conclusions in addition to our usual MR anecdotal reports…
There are none, except generic statements like x degrades the battery. In a way I stressed my batteries because I Travel and I also have AC+.
 
I bought an Apple pencil in 2017 and wanted to use it for the first time in 2024. The battery was completely dead. It maybe already arrived with an empty battery.

Two other rather cheap things I bought almost the same day and also turned on last year for the first time still worked fine I think the battery wasn't even empty after 7 years.

The 9.7" iPad Pro I bought from Amazon around the same time was used a few times in the first year and never again until 2024 too and the battery is also fine.

Same for a 4s that is mostly just lying around since many years. Battery still good, even if it was empty. And an older flip phone is also still working without the batterie getting empty fast.

The worst for a battery is just using it often and letting it empty for too long. But you never really know...
 
To me it is simply not worth all the effort to possibly extend the battery life of my phone maybe 6 months to a year? And at what cost? If I have to be careful not to overcharge it, I have to worry about if I have enough battery since I didn't fully charge it, etc. Is is really worth all that? Battery replacement is very cheap and will make your phone run like brand new for $89. Why not just use it hard, use the software designed to help you prolong it without any additional effort on your part, and replace it when you need to.

It's like trying to prolong the tires on your car... If I don't drive on the highway and take back roads, I could probably get an extra 5K miles out of them.. But at what cost? It now takes you twice as long to get anywhere and it is an inconvenience. And guess what you got 65K miles out of the tires instead of 60K, was it really worth it?
 
In short: selective "full" to fit situations where I don't know if I'll have access to a recharge but anticipate heavy use... otherwise playing along with the idea of 80% perhaps being better for general purpose use.
Same with me.

When I'm working from home or the office (where I readily have access to a charger), I'll charge my phone to 70-80%.

When I know I'm going to be away from a charger and use my phone for long period (ie working outside taking loads of photo or hotspotting, working overseas etc etc) I'll charge up my phone to 100%.

But at what cost? It now takes you twice as long to get anywhere and it is an inconvenience. And guess what you got 65K miles out of the tires instead of 60K, was it really worth it?
Guess the cost depends on the person and what they value?

Me personally? Starting from the iphone 15 (IIRC), you have a battery setting option to limit the charge % from 80% to 100%. It's trivial to adjust this setting to suit your needs (ie see my example above)...

But I appreciate some people just want their phones 100% charged every time it's removed from the charger. If that's what they want, all good by me...
 
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Besides enabling Optimized Battery Charging feature that's available on most Apple devices, I would not waste time thinking about battery health:

The kind of "battery babying" required to keep the battery within certain percentages is far too much work and effort in relation to the possible(not guaranteed) positive outcomes you could see from it.

You'd be prioritizing the devices battery health over your user experience, using it less often than you want to, putting it more or less often on the charger than you want to, etc.

But what you really need to hear is that you cannot avoid wearing down your battery in any meaningful way unless you actively make an effort to use your iPhone so little that the amount of charge cycles per day is drastically lessened.

Consider all of this in relation to what AppleCare+ or an out of warranty battery replacement costs for your iPhone and it simply doesn't add up.

We all have different values and budgets, I know. But for me, at some $89-$119 for an out-of-warranty battery replacement, I will happily pay away this worry and just use the iPhone and charge it when I need it to stay turned on for longer instead of charging it in a way that prioritizes the battery's needs.

I'm not always near an outlet, or have my charger on me, but life sometimes has us running out the door when we had other plans.

Living life and making sure there's enough "juice" on my devices when I need them is enough in itself. I'm not willing going to add an additional element of prioritizing my iPhone's battery life, not at those prices for a battery replacement.

Your iPhone's battery, and iPhone at large is not perfect and you can't keep it from changing, wearing down and needing repairs or replacing, partially or completely.
 
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I don't bother about it either but I also use my MacBook Air 30w charger on my 15pro as well. not sure if that kills it more but I do like how quick it charges!
 
I do only follow two or optional three easy steps about the iPhone lifecycle:

1. Avoid Heat
2. Never completely empty the battery. Stay above 10% if you can.
3. (optional) Try not to always fully charge it.


This is enough to stay healthy with your battery :)


So much this. I'd also add - fast discharge incurs a lot of wear too.

HEAT kills batteries a lot. So many people micromanage their charge level to 20-80 percent, but heat is a big killer.

Add heat plus heavy battery load and it is even worse.
 
HEAT kills batteries a lot. So many people micromanage their charge level to 20-80 percent, but heat is a big killer...

If you believe the credible/corroborating battery research, time spent at high state of charge is more harmful then high heat. Eg, 100% charge at room temp will degrade the battery faster than 75% charge at 60c/140f.

51964534629_ab2818b315_o.jpg


Also, is it ‘micro-managing’ if all I do is plug-in once/day at bedtime time and let a shortcut automation/smartplug handle my charge just before I wake? Here’s my 5.5yo XR on original battery. (Note: I have a usually efficient usage pattern of mostly lite apps, wifi, and efficiency-tuned settings.)

54280027787_7ec43d9de3_o.jpg
 
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I have no idea. I don't give that much consideration to battery life.

I use my phone and charge when needed to 100% It's that simple just like it should be.
Exact same. I have never once considered what’s best for the battery and never once had to deal with what I felt was a short shelf life of one.

I read something on here once, someone asked if charging this way or that was bad for the battery, and this person responded “being a battery is bad for the battery” lol

It’s gonna degrade no matter what you do. Use your phone. Charge it when you need to. Change the battery if it gets too low.
 
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Do you maybe know what can cause draining a batterie much faster when the device is turned off?

I have an iPhone 8 Plus that I only use every few days or once a week maybe. And when I turn it off with 90-100% after 2-3 days the batterie is completely empty. If I just let in on in Airplane mode it maybe loses just 1% per day.

View attachment 2478641
Doesn't make much sense because if it was battery internal self discharge it would do it in airplane mode too.
Try this, iPhone, Settings, [tap your name], Find My, Tap on Find My iPhone and turn OFF Find my network and Send my Location, then repeat your 2 day powered off test.
Find my network is tyenonly process to run after powering off.
 
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