The problem with battery packs is that batteries age. It's not like returning a propane tank and getting a full one. If you just bought your car and you go to refuel and they swap your once used battery pack with one that's seen ten thousand charge cycles you aren't getting a fair deal.
I totally get where you're going with this, but propane tanks also age. One time I swapped the tank, and when I got around to replacing it less than a year later it was past it's certification time and they wouldn't take it unless I paid to get it recertified someplace else.
Much less of an issue than getting a bad battery though.
Why do you care if your interest in the battery pack is that it lasts 200 - 300 miles? The only way this model would work is if maintenance/replacement of the batteries is the charging network's problem.
