If the batteries are removable and can only be charged outside the drone, then I can see the argument for not counting them as part of the empty plane (since th

If the batteries are removable and can only be charged outside the drone, then I can see the argument for not counting them as part of the empty plane (since they are something you put in to fly, analogous to aviation fuel). But I don't think that argument would fly once the batteries have a structural purpose.