If smartwatches have one problem, it is their restricted battery capacities. The company Togvu has announced its "battery case" that may solve this problem for Apple Watch users. It is a strap for these devices that integrates wireless charging and a 600mAh battery.
https://www.notebookcheck.net/Batfree-the-first-charging-strap-for-the-Apple-Watch.414572.0.html