Charging isn't needed or even very helpful. It's a million times easier, cheaper, and more efficient to just drop a few cheap drones in areas your target might go, then have someone monitoring remotely activate them at the appropriate time.
The range of even an inefficient quadcopter drone being what it is, if your target is somewhere in San Diego then "in the area" of your target includes bits of Mexico.
(For competently designed fixed-wing drones, Canada is "in the area" of San Diego).
Ok, I guess I will drop it in some unimportant ditch 20 miles away at 1am on a nondescript stolen bicycle. That cost me about 1% of the cost of this hypothetical recharging hunter-killer terminator.
