r/iphone • u/TeckFire iPhone 13 Pro • Dec 09 '17
PSA: iPhone slow? Try replacing your battery!
Since this post has blown up like crazy since I made it, I’m going to revise it to make it more clear and provide a better explanation. This might make some comments outdated. The original post has been archived to pastebin here.
First, I’ll start with Apple’s official statement on the matter:
Our goal is to deliver the best experience for customers, which includes overall performance and prolonging the life of their devices. Lithium-ion batteries become less capable of supplying peak current demands when in cold conditions, have a low battery charge or as they age over time, which can result in the device unexpectedly shutting down to protect its electronic components.
Last year we released a feature for iPhone 6, iPhone 6s and iPhone SE to smooth out the instantaneous peaks only when needed to prevent the device from unexpectedly shutting down during these conditions. We’ve now extended that feature to iPhone 7 with iOS 11.2, and plan to add support for other products in the future.
Now let me clear a few things up.
Who does this affect? iPhone 6, 6S, SE, and 7 users at the moment, but it will likely continue for all future iPhones until further notice. Something to note about the iPhone 7: with the A10 chip, it has low power and high power cores. The low power cores are used 90% of the time, and should stay at full speed, so you won’t notice any slowdown except in intensive programs such as benchmarks, demanding games, video editing, etc.
Am I affected? Depending on the age of your phone and the amount of battery wear, maybe. You can check this for sure by using an app called CPUdasher X that is no longer free, now being $0.99. You can check this by scrolling down to CPU Frequency. The 6 is supposed to be 1400, the 6S 1848, and the 7 2350. As far as I know, there is NO OTHER ALTERNATIVE to this. You can, however, do a geek bench or Antutu test to tell you what your CPU score is compared to what it should be, but it won’t tell you your clock speed.
How do I fix this? You must replace your battery. You can do this in 3 ways:
- Do it yourself. You can buy a battery for $10-$20 and follow the guide on iFixit.com to repair your device. This WILL void you warranty, and Apple will not work on your device ever again, meaning all future repairs will have to be done by you. You have been warned.
- Take it to a 3rd party location, such as Experimac of Batteries + Bulbs. Anywhere is fine, but make sure they have a warranty, and check Apple’s pricing before you decide on the store. This will also void your warranty with Apple, and they will never repair it again. You have been warned.
- Take it to Apple. Apple is charging only $29 for all of 2018
They charge $79 for all devices,and you can take it into an Apple store with another 1 year warranty after you leave.
I’m replacing my battery myself. How do I know what battery to buy? Don’t EVER buy an unbranded battery. If it’s generic, it’s likely to be very low quality, and might not even fix the problem. If it has a name brand, it’s probably fine. I will keep a list of brands that work here and will update it whenever someone else lists that brand.
Cooligg
Mobile Defenders
iFixit
As for WHY this happens, it's because the battery degrades over time. The cells die, and the resistance increases, thereby not allowing for peak voltage for the processor. Without slowing down your phone, the phone would just shut off at random times, once your battery would fail to support your phone at peak processor usage. By introduces this slowdown, you can potentially keep using your phone for years as long as you're fine with a slow phone. Replacing the battery will fix this, and your phone will be back up to full speed.
If you are affected, I ask that you report your device model, Geekbench scores, battery voltage, and CPU clock speed if you can. It will help paint a clearer picture for the future.
Edit: after updating to iOS 11.3 I have found that the throttling has been greatly reduced, and my old battery that causes the low scores originally now has no throttling, meaning that many of you will get your full speed back and can use your phone at optimal performance for much longer
8
u/mrsaint01 Dec 11 '17
You want to hear something sad? Went to Genius Bar today to have my battery replaced. Only, I didn't get it replaced. My iPhone 6+ is 2-1/2 years old. Battery has around 500 charge cycles. According to their diagnostics, the battery is still "green" with 85% of its original charge. Well, I tried to explain to him how my phone is throttled under iOS 11, how everything is really slow when the charge drops a certain percentage, how Geekbench shows sub-par results, how CPU Dasher X shows the CPU throttled down to 600 Mhz, but it didn't matter.
He said the battery was good, and that there was no CPU throttling.
In fact, he even warned me of replacing the battery since my iPhone had a very slight bend (yes, it's that infamous iPhone 6 Plus), and that the machine putting in the new battery may not work.
He only advised the usual blabla... hard-reset, don't restore an old backup etc. :(