There's already a crazy scheme to extend the Apple Watch battery
As with any new Apple product, there will soon be a robust third-party accessory market filled with cases, bands, and inexplicable gadgets built for the Apple Watch, many of which won’t do what they claim or will be simply awful. The wipowerband lands somewhere between the last two options. Wipowerband says its high-density polymer case that straps on to your Apple Watch can nearly double the battery life of your new favorite wearable, a fact seemingly not backed up by any actual tests with an actual Apple Watch, but by “estimates.”
This is not to mention the fact that Apple would likely need to approve any device that uses the MagSafe charger on the back of the Apple Watch, and wipowerband’s “Inductive tight couple” technology might…
Source:: The Verge