iPhone X Is fast charging bad for your phone?

Starfyre

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Original poster
Nov 7, 2010
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I just today got a USB C to Lightning cable and am experiencing the wonders of fast charging. I am convinced I can't go back to normal/slow charging anymore. My only concern is, are there issues with fast charge shortening battery life compared to normal/slow charging?
 

kritisharma

macrumors newbie
Aug 16, 2018
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India
I personally feel that fast charging does not affect the battery power, the factor which affects the battery life most is charging your phone from zero battery, you should try to keep the battery above 15–20% every day. If you are charging your mobile from near zero charges, it will have a negative effect on your battery life, reducing its lifespan as the battery is designed for a fixed number of cycles.
 

Banglazed

macrumors demi-god
Apr 17, 2017
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Cupertino, CA
Fast charging should only be used if you need a quick juice and you shouldn't charge it every time to 100% and like @kritisharma said to keep your charge above that range to avoid added stress on battery. Optimal range 15-85% What you should be worry about is keeping the device cool while charging! Fast charge and wireless charge can generate heat that can degrade the battery.
 

bopajuice

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Mar 22, 2016
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Dark side of the moon
Good question! I want to know too! Any experts out there?
Coming from the hobby world of radio controlled racing, I can say my experiences with fast charging lipo batteries at anything more than 1C can decrease the life of the battery. In other words, increasing amperage and voltage to charge the battery faster runs the risk of shortening the life of the battery. To be honest, not sure how that translates to phone batteries.

What do you gain with fast charging? The phone charges 5 to 10 minutes faster? Not sure if the tradeoff in battery life is worth it.
 
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Newtons Apple

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I just today got a USB C to Lightning cable and am experiencing the wonders of fast charging. I am convinced I can't go back to normal/slow charging anymore. My only concern is, are there issues with fast charge shortening battery life compared to normal/slow charging?
Why? What makes fast charging so great. Why not charge while sleeping at a normal rate?

You do sleep, don’t you?
 

Steve121178

macrumors 601
Apr 13, 2010
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Of course it's not bad. I have some news! Battery life degrades over time, no matter how you charge it. In fact a battery degrades over time even if you don't use it!

Just get on with your life and charge it however you see fit.
 

Newtons Apple

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Mar 12, 2014
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I've often wondered this myself. Sure, there might be a rare occurrence where you run the battery down and could use some juice fast. But seeing fast charging as a must have, I don't.
There is almost no way I could run my battery down in a day to the point I would need to charge before bed time. You would have to "live" on your phone . . . heck do these people work?
 
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Kendo

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Apr 4, 2011
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I personally think who cares, you're gonna sell your phone in a year anyway so don't sweat the small stuff.
 

thadoggfather

macrumors G4
Oct 1, 2007
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im pretty sure fast charge stops being 'fast charging' after 80% mark

I dont think it would, but I also don't think anyone can say-- we'll see long term

I use almost exclusively 29w chargers now, and Im personally not worried about it.

All but my X and 12.9 cant fast charge anyways, so it would charge @ 10 or 12w instead of 18
 

tonybarnaby

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Dec 3, 2017
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The reason fast chargers are blamed for battery capacity loss is the excess heat that is created. On android phones you can get apps that show a temperature monitor on the screen right next to the battery meter. Obviously there is nothing like this for iOS. On my previous android phones I would notice a difference in heat that was sometimes 10+ degrees hotter while fast charging. Wireless fast charging would easily send my phone over 90F. Battery capacity loss begins at 86F, according to sources I’ve read online. That’s impossible to stop, seeing as your hand is more than 86F.

If you do fast charge, I would definitely try to avoid using the phone while charging it. It most likely creates more heat than the default charger, but I don’t have a temp gun and there are no apps available to monitor it.
 

JPack

macrumors 601
Mar 27, 2017
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Fast charging iPad: maybe ok due to the larger surface area

Fast charging iPhone: probably not a good idea for battery health due to thermal density

Battery health is negatively affected by a number of things, but heat and extreme states of charge cause the most damage.
 

now i see it

macrumors 601
Jan 2, 2002
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Fast charging is definitely harder on the battery than slow charging. It's a compromise. Get both chargers. Use the 5 watt charger when you've got the time. Use the fast charger when you're in a rush.
 

thadoggfather

macrumors G4
Oct 1, 2007
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The theoretical logic of heat makes sense but is it actually proven / do the temp differences matter? My phone doesn’t feel too toasty fast charging
 
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SimonCowell123456

macrumors newbie
Jul 16, 2018
13
1
Ideally it does not. If it were why do you think manufacturers are shipping them with the phones.
But do you know what will reduce the battery life of your mobile?
Charging your phone from zero battery, you should try to keep the battery above 15–20% everyday. If you are charging your mobile from near zero charge, it will have a negative effect on your battery life, reducing its lifespan as the battery is designed for a fixed number of cycles.
This is valid for all the mobile phones and not only with the fast charging ones.
 

thadoggfather

macrumors G4
Oct 1, 2007
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Ideally it does not. If it were why do you think manufacturers are shipping them with the phones.
But do you know what will reduce the battery life of your mobile?
Charging your phone from zero battery, you should try to keep the battery above 15–20% everyday. If you are charging your mobile from near zero charge, it will have a negative effect on your battery life, reducing its lifespan as the battery is designed for a fixed number of cycles.
This is valid for all the mobile phones and not only with the fast charging ones.
I Almost never kill the battery life completely its rare, but I used to think doing it every once in a while helps keep it accurate and calibrated. I think I was wrong.

but that was far and few between so it probably had little to no impact.

What youre saying is what I've read as well as a general practice

And frequently letting battery die is probably not a great call, we all have those friends haha that ride on 1% every day
 

Starfyre

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Original poster
Nov 7, 2010
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Coming from the hobby world of radio controlled racing, I can say my experiences with fast charging lipo batteries at anything more than 1C can decrease the life of the battery. In other words, increasing amperage and voltage to charge the battery faster runs the risk of shortening the life of the battery. To be honest, not sure how that translates to phone batteries.

What do you gain with fast charging? The phone charges 5 to 10 minutes faster? Not sure if the tradeoff in battery life is worth it.
It's not just 5 to 10 minutes faster, it's noticably blazing fast... I'd stop it if I knew it would make the battery life shorten and degrade it faster though, thats why I asked. Silly for Apple to introduce a feature that kills/shortens your battery's lifespan.
 
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thadoggfather

macrumors G4
Oct 1, 2007
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either way Im living the 'dangerous' life.

fast charging 80-85% of the time I charge my X :cool:

I might very well keep this phone for a second year too

not really feel like paying crazy expensive prices this year for a really similar phone but well see
 
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joeblow7777

macrumors 603
Sep 7, 2010
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I personally think who cares, you're gonna sell your phone in a year anyway so don't sweat the small stuff.
LOL. Not everyone gets rid of a perfectly good phone every year. I know people still using an iPhone 5 or 5s. Lots of people believe in using something for as long as it still works, so they're interested in making it, battery included, last as long as possible.
 
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Kendo

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Apr 4, 2011
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Not everyone gets a new phone every year.
No, I won’t.
LOL. Not everyone gets rid of a perfectly good phone every year. I know people still using an iPhone 5 or 5s. Lots of people believe in using something for as long as it still works, so they're interested in making it, battery included, last as long as possible.
Sorry guys, I wasn't trying to come across as flashy or assume everyone buys a new model ever year. I myself buy a used model every year but always a generation behind to save money (I got the iPhone 7 used when the iPhone X came out). Basically the point I was trying to get at was that whether it is one year, two years (which is average), or three, I don't see the point in stressing ourselves out over something that will be replaced sooner rather than a decade later. Taking care of your phone is one thing, but to worry about fast charging killing the device, even if it did add additional wear and tear, I doubt it would be anything significant (otherwise Apple wouldn't go for it).
 

karmatourer

macrumors 65816
Oct 18, 2011
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In my house
I personally feel that fast charging does not affect the battery power, the factor which affects the battery life most is charging your phone from zero battery, you should try to keep the battery above 15–20% every day. If you are charging your mobile from near zero charges, it will have a negative effect on your battery life, reducing its lifespan as the battery is designed for a fixed number of cycles.
My 6S+ battery life is 89% and I nearly always charge my battery when it reaches 9-10%. YMMV.