Every product here is independently selected by Mashable journalists. If you buy something featured, we may earn an affiliate commission which helps support our work.
As of December 2017, an "older model" iPhone includes the 6, 6S, SE, and 7, though it's possible newer models like the iPhone 8 and iPhone X may see similar issues once they've been in customers' hands long enough for their batteries to degrade.
Yes, Apple could have been more forthcoming about this before millions of people updated their phones. But, to be clear, this probably isn't some nefarious Apple plot to get you to buy a new phone. It's an engineering decision made to ensure that older phones with weaker batteries don't shut down when the phone is in heavy use and drawing lots of current.
This wouldn't be as much of an issue, of course, if users could easily replace the old batteries in their phones. But they cannot: It's an intricate 25-step process that involves specialized tools and a suction cup, according to IFIXIT.
This leaves you with three realistic options:
1. If your iPhone is still under either the standard one-year or two-year AppleCare+ warranties and you believe the battery is defective, Apple will replace your battery if Apple determines it's defective, which isn't a given. According to Apple, if you mail the phone to Apple this process will take 7-9 days, and if you make an appointment and take it to either an Apple Store or an Apple Authorized Service Provider, this process will take up to 7 days. However, Apple does note, "If you bring your iPhone to an Apple Store or an Apple Authorized Service Provider, we'll try to fix it during your appointment."
2. If your iPhone is out of warranty, Apple offers a battery replacement service for $79 (plus shipping and tax), and you'll be without your phone for the same amount of time. You can also make an appointment, like above, and bring the phone in.
3. Take it to a third party, as in a local repair shop that fixes iPhones (and isn't an official Apple partner), and they can replace the battery for you for a fee. That fee will include both the battery and the labor, so it'll likely be more than what Apple charges, but it has two key advantages:
It will almost certainly be quicker than the official process in options No. 1 and 2, and...
Whether or not you choose to replace the battery it is up to you, not Apple.
Keep in mind Apple could potentially void your warranty if you have work done on your phone by an unauthorized party. (Apple will not void your warranty for the very common screen replacement, though, for whatever that's worth.)
Source : https://mashable.com/2017/12/22/how-to-replace-your-iphone-battery/704