Samsung says that you can’t wireless power share with the Galaxy Watch 7 and Galaxy Watch Ultra because a new sensor design changed the shape of the back glass of each watch.

The support site confirms that the Galaxy Watch 7 and Watch Ultra do not support reverse wireless charging using your phone. This is due to a revamped health and physical activity monitoring sensor.

In addition to removing support for reverse wireless charging, Samsung also warns against slower charging on the Galaxy Watch 7 and Ultra if you use older chargers.

Like the wireless charging support for the Galaxy Watch 7 and Galaxy Watch Ultra, Samsung’s wireless power sharing mode is not supported due to the new sensor design used.

The site compared wireless charging for all three models—the base, Plus, and Ultra S22s and S23—and came away with the conclusion that "all three new members of the Galaxy S23 series charge ...

From the table, it might appear that charging the Galaxy Watch 4 Classic’s tiny battery sucks up nearly all the power from Galaxy S22 Ultra’s 5,000 mAh battery.