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MrInquestador

macrumors regular
Original poster
Nov 14, 2015
229
52
https://www.zdnet.com/article/iphon...r-out-the-battery-faster-than-cable-charging/

In the comment section someone posted his opinion as an Engineer:

"The things about wireless charging that do affect battery life? Excess heat, and excess top off cycles. Charging a battery produces heat, and inductive charging adds it's own heat to the process. Lithium cells don't like excess heat, and it shortens their lifespan. The excess top off cycles are a result of wireless charging being convenient: "Hey, here's a pad! Why not top off?"... even if it's for the 10th time that day. So what's the problem with that? Normal battery voltage for these cells is 3.7 volts. Topping it off pushes it up to 4.25 volts for most Androids, 4.28 volts for iPhones. Keeping the battery voltage that high all the time reduces the battery lifespan. Leaving the phone on the charging pad (or plugged in) overnight also causes the phone to cycle though charge/drain/charge cycles through the night. It will not damage the battery, but the cycling does flow more power through the cell, and that does affect battery life span. It's ok once in a while, but it's not something you want to do EVERY night."
 

New_Mac_Smell

macrumors 68000
Oct 17, 2016
1,931
1,552
Shanghai
I'm not sure I understand this bit.

"The issue is that when the iPhone is being charged using a cable, the phone is being powered by the cord (there is some load on the battery, but it's minimal), but when using wireless charging, the battery is what's powering the iPhone, with the wireless charger only being used to top up the battery. This means that by switching from a cable to a wireless charger, my battery isn't getting a break, and in turn, this is making me go through recharge cycles at an even faster rate."

In both situations, power is being transferred through the charging circuit to the battery. If you plug it in, or wirelessly charge it, it's the same. It's not directly charging the battery in either situation, it's powering the phone and transferring power to the battery.

I think the comment you linked referred to the possibility that people are constantly charging their phone to 100% as opposed to letting it run down during the day, not that wireless charging directly damages anything.

Technically, there is a slightly higher degradation due to the heat - however this is only noticeable using a cheap pad. In most situations, the difference is highly negligible and not something to be concerned about. As always, the battery will degrade and will need replacing, there are a few things you can do to limit this and increase the lifespan, but for the vast majority of people it's better to just use and enjoy. Gaining 2 months out of 3 years is not worth it if you have to set up timers and everything, also consider when you're likely to replace the device.

The real concern with wireless charging is efficiency and adoption. I think off the top of my head they are about 70% efficient, meaning 30% of the energy is being lost during wireless charging. If you extrapolate this by the adoption of wireless charging devices, that's a whole heap of wasted energy!
 

acorntoy

macrumors 68020
May 25, 2010
2,029
2,267
Wireless charging and fast charging produce more heat, which damage the battery. you cannot get around this. It's simply not possible at this time, on a $1000 iPhone or a $100,000 tesla (although wireless wouldn't apply there), you can't avoid it.

The main issue is heat, wireless charging is inefficient compared to wired charging at the same wattage (why many 5w wireless chargers REQUIRE a 10W power brick) , and that inefficiency is turned into heat that is directly aimed and pressed against your battery.

Will it destroy your battery? Unlikely. But batteries are more a "lottery" than panels ever were, every battery is a little different, will wear differently, have a different lifespan. You can set a goal, but some will get a little under that and some will get a little over. The question is, with the chance of already having a semi weak battery that may degrade faster, do we wish to push them hard all the time to get a fast charge or wireless one, or do we reserve those for when they are truly necessary to the situation?
 
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C DM

macrumors Sandy Bridge
Oct 17, 2011
51,392
19,460
https://www.zdnet.com/article/iphon...r-out-the-battery-faster-than-cable-charging/

In the comment section someone posted his opinion as an Engineer:

"The things about wireless charging that do affect battery life? Excess heat, and excess top off cycles. Charging a battery produces heat, and inductive charging adds it's own heat to the process. Lithium cells don't like excess heat, and it shortens their lifespan. The excess top off cycles are a result of wireless charging being convenient: "Hey, here's a pad! Why not top off?"... even if it's for the 10th time that day. So what's the problem with that? Normal battery voltage for these cells is 3.7 volts. Topping it off pushes it up to 4.25 volts for most Androids, 4.28 volts for iPhones. Keeping the battery voltage that high all the time reduces the battery lifespan. Leaving the phone on the charging pad (or plugged in) overnight also causes the phone to cycle though charge/drain/charge cycles through the night. It will not damage the battery, but the cycling does flow more power through the cell, and that does affect battery life span. It's ok once in a while, but it's not something you want to do EVERY night."
https://forums.macrumors.com/thread...rms-battery-more-than-cable-charging.2109794/

https://forums.macrumors.com/threads/wired-vs-wireless-charging-what’s-better-for-battery.2146307/

https://forums.macrumors.com/threads/wireless-charging-effects.2144109/
 

Banglazed

macrumors 601
Apr 17, 2017
4,931
9,094
Cupertino, CA
I’ll keep it short. Watch your device while it is charging for heat. Keep battery level 15-85% to prevent stress on battery when it runs low or max charge. Don’t fully charge the device every time it runs low because you will add more full cycle to the battery. Don’t leave plug in.

I will only plug my device in to charge once a day and charge up to 80-89%. Wireless charging do generate a little more heat since it absorb energy through the coil.
 
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doboy

macrumors 68040
Jul 6, 2007
3,768
2,940
I specifically purchased Qi charger with a built-in fan to help with possible heat issues.
 

Renho

macrumors 68030
Sep 15, 2014
2,797
1,413
SR, CA
I had my X for a year. 90% of charging was done wirelessly overnight or when sitting at my desk or watching TV etc. The battery was constantly being topped up. Battery health still showing as 100%.

But I bet it takes longer and the phone gets hot when you charge. Without a case on.
 

Newtons Apple

Suspended
Mar 12, 2014
22,757
15,254
Jacksonville, Florida
But I bet it takes longer and the phone gets hot when you charge. Without a case on.

I have picked up my X and MAX while wireless charging and it is, at the most, slightly warm or not warm at all.

My X ended it’s year with 100% battery life and I expect the MAX to be the same.
[doublepost=1540889152][/doublepost]
I’ll keep it short. Watch your device while it is charging for heat. Keep battery level 15-85% to prevent stress on battery when it runs low or max charge. Don’t fully charge the device every time it runs low because you will add more full cycle to the battery. Don’t leave plug in.

I will only plug my device in to charge once a day and charge up to 80-89%. Wireless charging do generate a little more heat since it absorb energy through the coil.

I do not have time the “babysit” my iPhone. Most of your comments are just wrong. Nothing you can do to prevent cycles except to just turn it off and not use you phone or keep it plugged in 24/7..
 
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seezar

macrumors 6502a
Jan 18, 2018
567
582
I’ll keep it short. Watch your device while it is charging for heat. Keep battery level 15-85% to prevent stress on battery when it runs low or max charge. Don’t fully charge the device every time it runs low because you will add more full cycle to the battery. Don’t leave plug in.

I will only plug my device in to charge once a day and charge up to 80-89%. Wireless charging do generate a little more heat since it absorb energy through the coil.

You cannot avoid charging cycle wear just by not charging it past 89%. That's not how charging cycles work.
 

acorntoy

macrumors 68020
May 25, 2010
2,029
2,267
I had my X for a year. 90% of charging was done wirelessly overnight or when sitting at my desk or watching TV etc. The battery was constantly being topped up. Battery health still showing as 100%.

And my dads iPhone 6 that was bough 3.5 years ago has 89% health at 516 cycles. It is throttled, because despite the capacity health the voltage properties of them will still wear down.

Looking at the capacity will tell you how much charge you might still be able to get, but it’s only part of the battery health equation.
 

bhayes444

macrumors 6502a
Jul 13, 2013
772
292
My iPhone X had 100% capacity from launch until early September this year, and is currently sitting at 97%. I used to only use a wireless charger, but over the last couple months have been fast charging it on occasion. The wireless charger only made it slightly warm. In fact the phone gets warmer during iCloud backups while being charged than just by charging. Still has not died on me during the day so I’m pleased with the battery performance.
 

SidBoggle

macrumors regular
Sep 30, 2007
165
97
Bucks, UK
But I bet it takes longer and the phone gets hot when you charge. Without a case on.

Well yes it takes longer but the point is I changed my charging habits. Whatever room I am in I just put my phone on a charging mat so when I am home I am always near full battery. The X battery still works perfectly and I have not noticed any hit on the battery life when I am out for a full day. The phone gets a little bit warm when charging but nothing more.
 

now i see it

macrumors G4
Jan 2, 2002
10,895
23,086
you cannot avoid charging cycle wear just by not charging it past 89%. That's not how charging cycles work.

Wrong.

Battery life span is directly proportional to the amount of discharge before each charge AND the peak voltage reached before terminating the charge, with higher voltages degrading the battery much faster. A li-ion battery always charged to 100% will degrade much faster than one only always charged to 80%.
 

deeddawg

macrumors G5
Jun 14, 2010
12,260
6,412
US
Good grief.

It's a technological tool, not a priceless family heirloom you're going to pass down to your grandchildren.

Just use the phone.

If the battery should degrade to a point where it becomes problem before it's time to get a new phone, spend the $69 to replace the battery.

FWIW: my 26 month old iphone7 has lived nearly all its life in a Qi charging case, so that's roughly two years of fairly heavy daily usage. Charging pad at my desk, charging pad in my car's phone holder, charging pad at home for overnights. Never gave a thought to babying the battery. Currently at 93% battery health.
 
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AppleB

macrumors 65816
Oct 18, 2011
1,149
1,366
One of the reasons I upgraded from my 7P to a Max was to take advantage of wireless charging.

So I’m going to use that feature. I’ll be trading in my Max next year so I’m not worried about the battery.
 

seezar

macrumors 6502a
Jan 18, 2018
567
582
Wrong.

Battery life span is directly proportional to the amount of discharge before each charge AND the peak voltage reached before terminating the charge, with higher voltages degrading the battery much faster. A li-ion battery always charged to 100% will degrade much faster than one only always charged to 80%.

So if that's technically true, is it worth the trade-off that you've now basically lost 20% battery capacity right from the start?
 
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Jimmy James

macrumors 603
Oct 26, 2008
5,488
4,067
Magicland
You cannot avoid charging cycle wear just by not charging it past 89%. That's not how charging cycles work.

Correct, but it will reduce wear. Topping off way above the nominal voltage increases wear.

Does it matter enough for most people to need to care? No. But if you are interested in achieving the absolute maximum lifespan it will help a bit.
 

12vElectronics

macrumors 68040
Jul 19, 2013
3,947
1,246
California
I'm consistently charging my iPhone 7+. No issues what so ever. And like said before, most people will get a new device between 1-3 years. You'll be fine.
 

itsmemuffins

macrumors 68040
Jun 23, 2010
3,187
1,346
My year old iPhone X is wirelessly charged 99.9% of the time. Sit on the charger overnight. Battery health is at 100%
 
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