Linked by Thom Holwerda on Wed 20th Dec 2017 17:36 UTC

A Reddit post from last week has sparked a discussion regarding iPhone performance as a function of battery age. While we expect battery capacity to decrease as batteries age, we expect processor performance to stay the same. However, users with older iPhones with lower-than-expected Geekbench 4 scores have reported that replacing the battery increases their score (as well as the performance of the phone). What's going on here? How many phones are experiencing decreased Geekbench 4 score?

To answer these questions I've plotted the kernel density of Geekbench 4 single-core scores for the iPhone 6s and the iPhone 7 running different versions of iOS. Scores obtained in low-power mode are not included in the distribution.

Evidence seems to be mounting that Apple is decreasing the clock speed of iPhones with decreased battery capacity to maintain the advertised battery life.

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Known issue
by quatermass on Wed 20th Dec 2017 22:03 UTC
Member since:

Not surprised.
When smart phone batteries get a tad old, say after 18 months, a sharp increase of performance by the device will cause the battery (which may claim it's at 25%) to shut down.

The reason for this is the old problem of crystals developing inside the battery which reduce the capacity of the battery. So the battery monitor is basically no longer accurate. The battery voltage dips slightly and the phone thinks it's about to run out of juice.

Happens in ALL phones.

Get a new battery...

Reply Score: -1

RE: Known issue
by Alfman on Wed 20th Dec 2017 22:19 in reply to "Known issue"
Alfman Member since:


Happens in ALL phones.

There's a high risk of being wrong when you make absolutist blanket assertions like that. But nevertheless it's worth testing on my phone. I will try to get back to you on whether the charge has any effect on performance, as outlined in my earlier post.

Get a new battery...

Unfortunately this is part of the problem, manufacturers would have us throw our phones away instead ;)

Reply Parent Score: 4

RE[2]: Known issue
by Alfman on Thu 21st Dec 2017 04:33 in reply to "RE: Known issue"
Alfman Member since:

I will try to get back to you on whether the charge has any effect on performance, as outlined in my earlier post.

Well guys, here I was taking measurements, but it seems that I've been banned from geekbench for performing too many benchmarks. Apparently the geekbench app internally doesn't let you view your results directly, instead results must be processed by a geekbench server first. Not that I'd care except that they blocked access to my data. This is what pisses me off about not having apps that run locally and forcing us to be dependent on 3rd party servers, they're not dependable. To Geekbench: designing local apps this way is totally lame.

Anyways, the following graph is an incomplete snapshot of what I was able to get, I actually ran the tests down to about 30%, but those results are missing from my benchmark history. I was also going to test on a full charge. Unfortunately without those tests it's inconclusive as is.

Note: libreoffice insisted on sorting the battery % in ascending order even though the data was collected in descending order.

I'll try checking if I'm unblocked tomorrow. If anyone else attempts to perform a test, don't attempt to go for as many data points as I did - having this level of detail is useless if you cannot finish!

Edited 2017-12-21 04:46 UTC

Reply Parent Score: 3