Other Case study: iPhone batteries degrade at least 2% per year no matter what?

[sarpler]

I have a spare iPhone which I got new in November. I only use it as a backup so as a test I've turned every possible feature off (including wifi and cell data) and let it sit on a desk with "low power mode" always enabled. The battery easily lasts ten days but I charge it once every weekend anyway. I've been following the 80/20 rule: I always try and unplug it before it hits 90% and it's never been below 20%. I've charged this thing less than 40 times in its life.

I noticed the other day that the battery health is already at 99%. Extrapolating at this rate that means it's losing about 2% per year. Considering that the battery usage is as low as it's physically possible to go without turning the phone off completely, does this mean that losing 2% health per year is the physical minimum for iPhone batteries?

 

[mrochester]

Battery health degrades all the time whether the device is being used or not.

 

[Juicy Box]

I wouldn't worry too much about it, as I am pretty sure that the battery health data characteristics are just estimates.

I got an SE replacement back in Sept 2019, and had 100% with the new battery. Using it how I normally use it, which also includes never putting it in Low Power Mode, I was able to maintain 100% capacity until about a month ago when it dropped to 99%. I just check it now, and it is at 98%.

If I drained the battery and charged it back up until full, I wouldn't be surprised if the capacity would show as 99% or 100% again.

I noticed the other day that the battery health is already at 99%. Extrapolating at this rate that means it's losing about 2% per year.

Again, these are just estimates, and not really enough data to say that batteries lose 2% per year. For example, if we used your experience and compare it to my experience, it appears that never putting a phone in low power mode and not following the 80/20 rule when charging would actually extend your battery capacity life.

I am not saying that is true, but comparing our two iPhone usage and experience shows that your iPhone battery is wearing faster than mine.

 

[Puonti]

For comparison, I've had my Xs Max for about 21 months now. It's been used actively every day, given a bit of extra juice when needed and charged to 100% every night (with Optimized Battery Charging enabled since iOS 13). It has occasionally dipped under 20% charge, but to my knowledge never under 10%.

Its battery health is currently at 94%, which is great considering how much use I get out of it.

 

[daniel_m]

I got a brand new sealed iPhone XS a few weeks ago. It's probably been in storage for months. I only put 10 cycles on it and looking now, the battery health is at 98%.

 

[Juicy Box]

I got a brand new sealed iPhone XS a few weeks ago. It's probably been in storage for months. I only put 10 cycles on it and looking now, the battery health is at 98%.

Yeah, I think it is just estimates, because I had the exact opposite experience with an iPhone SE.

Two-ish years ago, iPhone SE models started to pop up on Apple's clearance page. I decided to purchase one as a spare, as I liked the size and model, and if something happened to my SE or my wife's SE, I could just easily swap it with the new clearance one.

After I purchased the clearance SE, it just sat in the unopened box for at least 8 months.

I was a little worried about letting the battery sit unused for the time that I had it, and I had no idea how long the SE was sitting on a shelf somewhere prior to going clearance. But, I never got around to opening it and to let the electrons flow.

Maybe about 8 months after purchase, I decided to let me wife start using the clearance SE since her SE's battery capacity dropped to about 82%.

Out of the box, the SE had 100% battery capacity and it stayed that was for at least a month. My wife uses her phone much more than I do and charges it everyday, so now almost a year later, it is at 88%. BTW, this is also with the optimize charging turned on.

So, I think it is just estimates and not anything exact. For the OP, even it is dropping 1% every six months, I don't think it is anything to be concerned about. At that rate, it would be 10 years before the capacity drops to the level that Apple recommends replacing the battery.

 

[Apple_Robert]

Just use and enjoy your phone. If the battery fails or gets to 80% or less while under the standard Apple Care, Apple will replace it. Otherwise, it is very affordable to have Apple replace the battery after a year plus. As such, it doesn’t make much sense spending time focusing on an issue that has already been addressed by Apple.

 

[now i see it]

You can't extrapolate battery longetivity by timing the loss of one percentage point. Li-ion batteries don't age linearly.
The best thing for a li-ion battery during storage is for it to be at 40% SOC. About 3.6V. That is the sweet spot. As the voltage increases, so does the stress on the battery.