[eisen]

Maybe I'm crazy but if it is a physical battery swap then this brings memories of history class. Horses were swapped along the silk road to extend distance in shorter range of time. Same goes for horses as do batteries I guess. They get the job well on more available energy but take for ever to regain to keep going. 2c of thought

[sliverstorm]

I really doubt horses were fungible. I don't know the actual details, but I would expect when you swapped horses, you got off a company horse and got on another company horse.