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Be cautious of wireless chargers and their impact on your phone’s battery

pdx_m3s

Active Member
May 18, 2019
1,371
1,242
Portland, OR
Wireless chargers are convenient (albeit slow), but be aware of the risks (to your phone battery).

The reason they are slower compared to corded charging is due to their overall inefficiency. All of that wasted power is converted to heat and dumped pretty much directly into your phone Li-ion battery. They WILL degrade your phones battery faster, especially during summer. Don’t just take it from me, research the issue on your own.

My iPhone 8 (less than 1 year old) degraded 5%, from 97% to 92%, over the course of a couple months using a wireless charger. I noticed the phone was getting warm and finally put 2 and 2 together. Degradation stopped as soon as I switched back to corded charging.
 

TyH2009

Member
Apr 12, 2019
522
601
St. Louis
I have an iPhone XS Max, had it a little over a year, almost strictly charge wirelessly for about the last 6 months, Jeda in my Model 3 since April and a wireless stand at my desk at work, and I’m still at 100% battery health.
 

pdx_m3s

Active Member
May 18, 2019
1,371
1,242
Portland, OR
I am also at 100% health on my year old iPhone Xr been charged mostly on home and auto wireless.
I have an iPhone XS Max, had it a little over a year, almost strictly charge wirelessly for about the last 6 months, Jeda in my Model 3 since April and a wireless stand at my desk at work, and I’m still at 100% battery health.

Even the most tortured phones won’t show any degradation on the first 6-8 months. There is a buffer in the “100%” battery health metric provided in iOS.
 

DopeGhoti

Active Member
Aug 28, 2019
1,242
1,429
Phoenix, AZ
My phone is aware of this, and if the internal temperature gets too high, it disables wireless charging to prevent damage. I found this out because in my previous car, the Qi charging mount was in direct line of sight with the windscreen, and therefore Sol. On a hot afternoon, I would be unable to charge wirelessly. I doubt this will be an issue with the Model 3, because the phone will be tucked away out of the sun, in a car that is always at a comfortable temperature before I get to it.

The thing that worries me is leaving my phone (and therefore my car key) in the car, as I'm currently used to it being in my pocket when I egress the car. But I suppose it'll be easier to notice that I've not got my phone on my person than a car key, so I have that going for me at least.
 

earthwormjim

Member
Jun 25, 2019
171
179
California
A good summary of wireless phone charging, phone Li-ion batteries, and impact of elevated heat.
Wireless charging can mess up your phone's battery - Futurity

A 3C rise in phone temperature is nothing. You cause a greater rise having the phone screen on, or just using the phone or holding it. Are you going to tell people not to hold their phones too?

The degradation that comes from wireless charging is not so much the inefficiency losses, its the fact that your phone is still running entirely off of the battery while charging. Using a wired charger, the phone can run off of the cable itself. In a car though, how much extra battery use time are we really talking about? Maybe an hour for the average driver, per day? Pretty insignificant, and no worse than just not charging at all.

Where wireless charging can really lead to a significant difference is when using it to charge your phone overnight. Your phone's battery never gets that 8 hour break it normally would with a wired charge cable.
 

pdx_m3s

Active Member
May 18, 2019
1,371
1,242
Portland, OR
A 3C rise in phone temperature is nothing. You cause a greater rise having the phone screen on, or just using the phone or holding it. Are you going to tell people not to hold their phones too?

The degradation that comes from wireless charging is not so much the inefficiency losses, its the fact that your phone is still running entirely off of the battery while charging. Using a wired charger, the phone can run off of the cable itself. In a car though, how much extra battery use time are we really talking about? Maybe an hour for the average driver, per day? Pretty insignificant, and no worse than just not charging at all.

Where wireless charging can really lead to a significant difference is when using it to charge your phone overnight. Your phone's battery never gets that 8 hour break it normally would with a wired charge cable.

For me, it was far more than a 3C rise.
 

earthwormjim

Member
Jun 25, 2019
171
179
California
For me, it was far more than a 3C rise.



Versus a wired charger? Then perhaps you were never aligning your phone with the coil.

I cannot feel any temperature difference with my wireless charger at home, versus using a wired charger. Same with the charger in my car.

Perhaps you are comparing with no charger at all? In that case, yes a wireless or wired charger causes a significant temperature rise.

3C is what the study you linked said for an aligned charger. So that's not valid now?
 
Last edited:

Eno Deb

Active Member
Aug 17, 2018
2,624
3,367
SF Bay Area
For me, it was far more than a 3C rise.
This depends on the charging power, and to a lesser extent on good coil alignment. Chargers connected to the car's front USB ports generally charge at 5W and will not produce much heat. The OEM Tesla Qi charger also has oversized coils to improve alignment for phones of different sizes. My iPhone 8 gets barely warm on the charger.
 

DopeGhoti

Active Member
Aug 28, 2019
1,242
1,429
Phoenix, AZ
Technically this applies wired or wireless. If the phone temp is too hot, all charging is disabled.
Depending on the phone, it may have sufficient granularity to individually disable induction charging independently of traditional charging. Ofttimes, I would, when seeing it not charge wirelessly, go ahead and plug in the USB-C cable and it would be happy as a (n unusually warm) clam.
 

KenC

Active Member
Sep 4, 2018
3,753
3,487
Maine
I use a mix of wired and wireless charging. Wireless during day, and wired overnight. I find the wired charging warms up my iPhone X more than wireless.

My 2yr old iPhone X shows 98% on battery health, but when I run the CoconutBattery app, it shows 2690mAh out of a design capacity of 2716mAh, so 99%. Cycle count is 240.
 

KenC

Active Member
Sep 4, 2018
3,753
3,487
Maine
Wireless chargers are convenient (albeit slow), but be aware of the risks (to your phone battery).

The reason they are slower compared to corded charging is due to their overall inefficiency. All of that wasted power is converted to heat and dumped pretty much directly into your phone Li-ion battery. They WILL degrade your phones battery faster, especially during summer. Don’t just take it from me, research the issue on your own.

My iPhone 8 (less than 1 year old) degraded 5%, from 97% to 92%, over the course of a couple months using a wireless charger. I noticed the phone was getting warm and finally put 2 and 2 together. Degradation stopped as soon as I switched back to corded charging.
What's your cycle count, and did you look at your data from the CoconutBattery app?
 

boriszima

Member
Jul 12, 2018
678
335
Los Angeles
interesting information. I posted this somewhere, my iphone went down to 89% less than a year usage. I mostly use wired charging and only when driving use wireless pad. I think new feature on iphone to charge to 80%or something will improve degradation going forward.
 

jkoya

NA2 NSX
Nov 21, 2018
3,626
1,569
Northern CA
My iPhone X is 22 months old and charged exclusively with an Anker Wireless charger (bought the Taptes wireless charger for the Model 3, but haven't put my phone on the charger, other than to test it) and my battery health is 99%.

Never thought about the harm wireless chargers could do, so thanks for the education and insight...
 

ewoodrick

Well-Known Member
Apr 13, 2018
5,285
4,270
Buford, GA
Wireless chargers are convenient (albeit slow), but be aware of the risks (to your phone battery).

The reason they are slower compared to corded charging is due to their overall inefficiency. All of that wasted power is converted to heat and dumped pretty much directly into your phone Li-ion battery. They WILL degrade your phones battery faster, especially during summer. Don’t just take it from me, research the issue on your own.

My iPhone 8 (less than 1 year old) degraded 5%, from 97% to 92%, over the course of a couple months using a wireless charger. I noticed the phone was getting warm and finally put 2 and 2 together. Degradation stopped as soon as I switched back to corded charging.
I'm going to have to disagree with this. For the power that makes it to the phone, efficiency is pretty high, very little energy is converted to heat in the phone.

The loss is in the charging portion. That's what gets warm and while some of its heat is sent to the phone, a lot is sent to the surface that it is setting on.
 

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