If you’ve noticed that your $199 Smart Battery Case is struggling to charge your iPhone, or you can’t really charge the case itself that well (or at all), then you’ve got a defective product on your hands. Apple is aware of these issues and is ready with replacements, and you only have to jump through a single hoop to get one.
First, let’s talk eligibility. Apple’s replacement program is only good for the Smart Battery Case on the iPhone XS, iPhone XS Max, and iPhone XR. And affected cases were manufactured at some point between January and October of 2019. Apple isn’t, however, replacing every case that was sold between this time period. You’ll have to bring yours to one of Apple’s authorised service providers or an Apple retail store for inspection. If Apple agrees that your case is defective, it will be replaced for free.
While you should probably stop using any Smart Battery Case that isn’t charging (itself or your iPhone), Apple notes that the case itself won’t damage your much-more-expensive iPhone. The issues with the case aren’t a “safety issue,” which I believe is Apple speak for “It won’t blow up.” That said, if you get a replacement case, you’re keeping your original case’s warranty. You don’t get any kind of extension or reset with an Apple replacement.
To get started with your replacement, simply make an appointment at an Apple retail store or visit another authorised service provider.