In addition to pairing with your phone through Bluetooth, the machine has a USB port to charge during particularly gloomy weeks.
The design does require some careful planning to work properly. You need to space your crops loosely so that the robot can kill weeds in between, and you'll want to avoid any steep inclines so Tertill doesn't stuck. There will have to be some kind of basic barrier to prevent the vehicle from wandering away, too. You may also have to rethink how you kill weeds. While you're probably used to pulling weeds out by the roots, Franklin is counting on its bot repeatedly cutting down weeds until they wither and die.
Franklin is launching a Kickstarter crowdfunding campaign for Tertill on June 13th, with a price around $300. That's not a trivial figure, but the company is betting that the convenience will pay for itself. It might have a point. There's a chance you'll need to double-check Tertill's work (it might not catch weeds very close to your crops), but the time you save could be better spent on the rest of your gardening... or just relaxing on the back porch. And it's even a bit eco-friendly, since it reduces the pressure to use herbicides.