Benchmark confirms: aging batteries are the main reason for slowing iPhones

Just last week, a Reddit thread uncovered a surprising iPhone behavior: as more and more users report slow iPhone performance, battery life seems to be the unexpected culprit. It's expected for a battery to lose capacity over time and battery life to decrease, but it is totally unexpected for this to affect the processor performance.

However, this is indeed happening: users report that changing to a new battery on their old iPhone, increases the processor performance and brings it back to normal. There are hard facts to prove this: popular CPU performance benchmark Geekbench shows that iPhones with older batteries score lower and swapping to a new battery improves the score back to normal.

This is about as close as it gets to the "planned senescence" that people accuse Apple of, but while all of this has been speculation, now we have some fact-based evidence. Geekbench founder John Poole thought it was time to investigate and see if all this is indeed true.

To check performance degradation claims, Poole plotted the kernel density of Geekbench 4 single-core scores using different versions of iOS to see if there is a difference. It's worth mentioning here that Apple is throttling CPU performance in this new way after many users complained their iPhones would unexpectedly shut down even when they have plenty of battery power left. Apple tried offering some users free battery replacements, but issues persisted even with the new batteries. That's when it has decided to throttle CPU performance with an iOS software update.

Reddit user kadupse explains this the following way:

In the charts above, you can see that on iOS 10.2.0, all Geekbench scores gravitate around the 2,500 mark. Then suddenly, after the iOS 10.2.1 update, you can see that results are all over the place: the majority (those with healthy batteries) still are around the 2,500 mark, but there are many throttled devices scoring much lower. With iOS 11.2.0 the issue only worsens with more and more iPhone 6s deviecs affected by lower CPU performance.

iPhone 7 is also affected

The newer iPhone 7 seemed to be immune to those issues until recent iOS 11 developments. Here are the benchmark scores of iPhone 7 running iOS 10.2, iOS 10.2.1 and iOS 11.1.2.

As you can see clearly, all iPhone 7 Geekbench scores gravitate around the 3,500 mark, meaning that there are no artificially throttled devices. Keep in mind that Apple also throttles CPU performance in Low Power Mode, but this is expected behavior and no iPhones used in low power mode were included in this test.

But something interesting - and rather disappointing - happens with iPhone 7 devices after the iOS 11.2 update.

Here, we can suddenly see many iPhones (allegedly ones that already have aging batteries) throttled to much lower frequencies, in a similar way to the iPhone 6s.

What this means simply is that many users that have an aging iPhone battery (obviously, even 1-year old iPhones count as aging), will see a noticeably drop in performance without any notification that it is related to an older battery whatsoever. This is unexpected and will catch off-guard all but the most technical of users who happen to stumble upon articles like the one you are reading. As John Poole of Geekbench rightly points, many users will simply think: "my iPhone is getting slow, I need to replace it", rather than figure out it is in need of a battery replacement.

source: Geekbench, Reddit

Related phones

iPhone 6s
  • Display 4.7" 750 x 1334 pixels
  • Camera 12 MP / 5 MP front
  • Processor Apple A9 APL0898, Dual-core, 1840 MHz
  • Storage 128GB
  • Battery 1715 mAh(14h 3G talk time)
iPhone 7
  • Display 4.7" 750 x 1334 pixels
  • Camera 12 MP / 7 MP front
  • Processor Apple A10 Fusion, Quad-core, 2340 MHz
  • Storage 256GB
  • Battery 1960 mAh(14h 3G talk time)



1. theunspoken

Posts: 310; Member since: Jul 06, 2017

squeeze the money out of customers pocket till the end

2. Dr.SamX

Posts: 245; Member since: Jan 19, 2015

This can't be true! It is Apple we are talking about after all.

15. piyath

Posts: 2445; Member since: Mar 23, 2012

It is true and done only for consumer's convenience but not to force them buy a new iPhone. But after all Apple should've done this in a more transparent way which doesn't effect the performance at all. They should fix their battery problems rather than doing such ugly things.

20. theunspoken

Posts: 310; Member since: Jul 06, 2017

"It is true and done only for consumer's convenience but not to force them buy a new iPhone" I cant stop laughing hahahahahahhaha you are so blindfolded, someone should bring you back to reality. how come degrading battery is for consumers convenience, what does a consumer gain from it, more increase in his spendings? there is a limit to being an apple fan

3. AVVA1

Posts: 228; Member since: Aug 01, 2017

Glad to know! however kinda unfair that even 1 year old iphone shows degradation in performance already. It would be nice if they'd somehow start on the 2nd year of the phone rather than sooner

6. worldpeace

Posts: 3135; Member since: Apr 15, 2016

For years Sheeple used to say: "Apple use slow charging because it could prevent battery wear"

27. bucknassty

Posts: 1395; Member since: Mar 24, 2017

they suddenly forget this now

28. MrShazam

Posts: 987; Member since: Jun 22, 2017

Haha, so true, wonder what asinine excuse they'll come up with this time to bend over for their herd master yet again...

4. Whitedot

Posts: 893; Member since: Sep 26, 2017

Grammar spelling PA "off-gurad" .

5. uzbek-mobile-man

Posts: 118; Member since: Sep 27, 2014

Original iPhone SE (2016) with 16 GB and iPhone SE (2017) with 32GB are good enough, even though they are not best. Both of them do not have OIS (optical image stabilization) for photos and videos. But, their battery life is pretty good. I hope, iPhone SE (2018) with 4.0" or 4.7" display will have stronger battery and, of course, this 2018 version of iPhone SE will have both OIS (optical image stabilization) and EIS/DIS (electronic/digital image stabilization), like Google`s Pixel 2/2XL.

7. cnour

Posts: 2305; Member since: Sep 11, 2014

Replacing battery, replacing the processor, replacing RAM, of course will make your phone faster. So nothing new in these news.

13. Peacetoall unregistered

for 500$ yeah sure

29. Macready

Posts: 1830; Member since: Dec 08, 2014

Huh. Android phones do not become slower with older batteries that lose capacity abd conversely do not gain speed with new batteries. Basically the root problem is that Apple calibrated the CPU with a too tightly set voltage range, outside which the phone can't function, thus not counting for a large chunk of batteries falling outside that range even with mild aging. To add insult to injury they don't communicate this issue and worse, they do not tell customers that their "fix" is a throttle that can result in less than half the original performance. Yikes is the kindest reaction I can come up with.

36. tedkord

Posts: 17511; Member since: Jun 17, 2009

Proving one again you are a tech illiterate.

8. TheNeighbor

Posts: 370; Member since: Nov 15, 2013

This is what you get for sealed batteries. I could just change it without wasting time and more money going to a service center. I could even change it to an even higher capacity Zerolemon battery.

11. Wiencon

Posts: 2278; Member since: Aug 06, 2014

It is a fact that after 2 major updates Apple deliberately slows down the performance on iPhones, I have been iPhone user for 6 years and it is the case with every iPhone. iOS7 killed iP4, 8 and 9 killed 4S, 10 killed iP5, 11 killed 5S and 6 I use SE now and I'm staying on iOS10, maybe I will get 11 but there is no way I will update to 12 because it will slow my phone for no reason and I'm sure about it And I often changed batteries in my iPhones, guess what, it didn't change performance at all

16. piyath

Posts: 2445; Member since: Mar 23, 2012

I have a iPhone 5 running on iOS 10, it still runs super fast and gives me the same Geekbench scores as before. This battery problem only affects a small number of people.

19. Peacetoall unregistered

"This battery problem only affects a small number of people. " and so did the note 7 but apple fanboys and apple paid prostitutes make it the biggest deal out of it.

30. darkkjedii

Posts: 31763; Member since: Feb 05, 2011

I can't believe you continue to argue with those two dude. SMDH. They're getting from you exactly what they want.

25. Victor.H

Posts: 1104; Member since: May 27, 2011

Obviously, the charts show that a huge percentage of devices are affected. Admittedly, devices running on versions before 10.2.1 are not affected, but I would guess those are in the minority rather than majority.

33. Macready

Posts: 1830; Member since: Dec 08, 2014

Based on the statistics provided, it actually affects a significant percentage of users.

37. canitmakephonecalls

Posts: 1; Member since: Dec 21, 2017

good news is since a9 in 6s is only marginally faster than teh a8x in air2, air2 is gonna be teh longest lasting ios device of teh decade! chant with me, air2 masterace! btfo ipad5! who needs a brighter screen and way better battery life! as mungdahl in chowder once victoryskreetched, NO ANIMATION..i mean..NO LAMINATION! seriously though...i cant wait to see air2 refurbished/ebay prices inevitably get higher than ip5, its wht jesus would want. had a ipad3 with ios7.0, by far teh biggest perf killer was hving too many bookmarks in safari, open new tab=15sec wait. as for android being immune, my s4mini turned to turd real fast, constantly running outta ram even though jacksqut was running, reset and its fast again, basically too much samsung bloatware. ive had 1 10w apple ios charger and 1 30pin/lightning die on me, my ip3 became a cracked windshield 1day outoftehblue, and my air2 has hairline scratches...maybe i shoulda got teh thiner and lighter s2 9.7 instead, its too bad s3 went back to being thicker and fatter, AND TEH WHOLE WORLD KNOWS IM FAT AND IM PROUD SO R/FATHEYPEEPLESITSAUDREY TELL ME ONCE AGAIN, whos fat safari has teh crapiest url bar keyword search ive ever seen or though was possible, u litteraly need to typle the bookmark name exactly as it was for it to appear as a result, change the order of the words and ure fubar moto xoom had the most luxuriously thic glass ive ever seen, like i wish my budget ips monitor had tht instead of its cheap plastic screen, now give me some honey ivy! not u poison, ima talking abt johny, i got tht new upgrade in colleenatwood college

14. PhoenixFirebird

Posts: 128; Member since: Oct 10, 2016

I just couldn’t believe of it. My belief in Apple is destroyed. I never thought it’d really happen.

21. RossoRider

Posts: 5; Member since: Dec 19, 2017

As a consequence - more e-waste will be generated and more revenue $$$$$ to the company Apple.

26. TheOracle1

Posts: 2340; Member since: May 04, 2015

Two of my devices were upgraded to Nougat earlier this year and performance actually improved in one case. One is a two year old Lenovo tablet with an "old" battery and it's zipping along nicely. So yeah, I'm calling bs on this one. Apple are doing it deliberately.

31. Subie

Posts: 2442; Member since: Aug 01, 2015

If even more concrete evidence comes out I wonder if we'll see a class action lawsuit in the near future.

32. TechVoid

Posts: 13; Member since: Feb 18, 2014

Android phones also slow down over time as you use them more ESPECIALLY Samsung, my Galaxy S7 ran like a beast for almost a year and now over a year and a half later and multiple factory resets its a slow mess and the battery life is absolute crap.Also iPhones in general age a lot better in terms of speed over years compared unless you get something like a nexus/pixel which is much closer.

35. TheOracle1

Posts: 2340; Member since: May 04, 2015

My two year old Xiaomi Redmi Note 3 Pro is just as fast today so it's likely a Samsung issue and not android. Miui also has a very aggressive app killer switched on by default. My 4 year old Asus Padfone which is still on Kitkat is working perfectly too. Your blanket statement doesn't hold water.

34. ebilcake

Posts: 1231; Member since: Jul 16, 2016

Another reason not to buy an iPhone, not that I needed another reason.

* Some comments have been hidden, because they don't meet the discussions rules.

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