Apple yesterday debuted new Smart Battery Cases for the iPhone XS, XS Max, and XR, and review units are in the hands of members of the media and some lucky people who received early deliveries.

Many iPhone X users have been wondering if the ‌iPhone XS‌ Smart Battery Case will work with the older model given that the two devices are nearly identical in design, and the answer appears to be yes, though there is some uncertainty.

This morning, iMore's Rene Ritchie put an ‌iPhone‌ X running iOS 12.1.2 in an ‌iPhone XS‌ ‌Smart Battery Case‌ and received an error suggesting the ‌iPhone‌ X was not compatible with the case.

He updated the ‌iPhone‌ X to iOS 12.1.3, however, and was able to get the ‌iPhone‌ X to charge in the ‌iPhone XS‌ ‌Smart Battery Case‌. He also now says that the ‌iPhone‌ X will charge with the Battery Case if the incompatibility popup is dismissed.

Update: iOS 12.1.2 DID NOT work for me with iOS XS case. iOS 12.1.13 DOES work for me. ‌iPhone XS‌ Max case DOES charge X for @chriswelch on iOS 12.1.2. It DOES NOT for me, even on 12.1.13. So, um… 🤷‍♂️ More testing! https://t.co/H1kk031Z5d — Rene Ritchie (@reneritchie) January 16, 2019

Ok, here’s the 💯 correct info: You CAN use ‌iPhone XS‌ battery case with ‌iPhone‌ X. You may get that incompatibility pop up. But, if you dismiss it, it should charge fine. (Update iOS/reboot if not.) (Speaker/mics still won’t be aligned, if you care about acoustic performance.) pic.twitter.com/05IQyUctcQ — Rene Ritchie (@reneritchie) January 16, 2019

A MacRumors reader was also able to get the ‌iPhone‌ X to charge in an ‌iPhone XS‌ ‌Smart Battery Case‌, and Chris Welch of The Verge said in his testing, the ‌iPhone‌ X was able to charge an ‌iPhone‌ X running iOS 12.1.2 in an ‌iPhone XS‌ Max ‌Smart Battery Case‌.

Nothing but XS Max charges in my XS Max case, not even XS or XR. What version of iOS? — Rene Ritchie (@reneritchie) January 16, 2019

So it appears, based on this limited amount of testing, that the ‌iPhone‌ X is going to charge in an ‌iPhone XS‌ ‌Smart Battery Case‌, though there could be some compatibility issues on iOS 12.1.2. If the case doesn't charge the ‌iPhone‌ X, as Ritchie suggested, you can restart the ‌iPhone‌ or update to iOS 12.1.3 to get it working.

It is worth noting that while the ‌iPhone‌ X may charge in the ‌iPhone XS‌ Battery Case, the fit is imprecise. The speaker and microphone holes do not line up, and the camera cutout is a bit off.

Apple's Smart Battery Cases for the ‌iPhone XS‌, XS Max, (and presumably XR), feature 10.1Whr batteries that extend the life of each ‌iPhone‌.

The ‌iPhone XS‌ Max normally offers up to 25 hours talk time, 15 hours of internet use, and 15 hours of video playback, which is extended to 37 hours of talk time, 20 hours of internet, and 25 hours of video playback with the ‌Smart Battery Case‌.

The ‌iPhone XS‌ alone features up to 20 hours of talk time, 12 hours of internet use, and 14 hours of video playback, which is extended to 33 hours of talk time, 21 hours of internet use, and 25 hours of video playback with the ‌Smart Battery Case‌.

The iPhone XR features up to 25 hours of talk time, 15 hours of internet use, and 16 hours of video playback, which is extended to 39 hours of talk time, 22 hours of internet use, and 27 hours of video playback.

The Smart Battery Cases are priced at $129 and can be purchased from the Apple website.