Apple said the new battery case is not compatible with the iPhone X, but some people have tried it. On Thursday, foreign media iMore’s ReneRitchie put the iPhone X running iOS 12.1.2 in the smart battery case of iPhone XS, and then iPhone X Case received an error message indicating that the phone and iPhone XS Case is not compatible.
However, after upgrading his iPhone X to iOS 12.1.3, he found that the iPhone XS smart battery case can charge iPhone X. He also said that if you ignore the error message, the iPhone XS Case can also charge the iPhone X. If not, it can be implemented after rebooting the device or upgrading the iOS system.