It would technically be faster to recharge it from the rover/aircraft at astrape since you don't have to travel to santorini and and back but yeah charging directly from santorini shouldn't take more time than from the rover
You can't recharge the rover at Astrape because of the incompatible power systems. It seems difficult to get to Astrape with the rover and enough spare fuel + power to totally recharge the block; it's such a power-hungry process that I'm not sure a full load of fuel cells is enough.
I hadn't considered trying to partially repair the aircraft to use its power systems, though; does that work?