The new iPhone XS battery case works with the iPhone X, but don’t expect perfection
The iPhone XS looks almost exactly like the iPhone X, and that similarity is leading many people to wonder if they can use Apple’s spiffy new battery cases with the older handset. The answer appears to be a shaky yes, although enough doubt remains that I’m hesitant to recommend taking the $129 plunge.
Apple’s official landing page doesn’t explicitly say that the new case doesn’t work with the older phone. It only lists the iPhone XS under Compatibility.