They couldn't possibly fly...they're too heavy.
Seriously, though, we wondered the same thing, and talked with our carrier several times with all the battery data on hand and got answers that ranged from a solid yes to a solid no. With that (no way we want to run into "solid no guy"), we contacted the folks from our supplier, found out how they ship, and shipped 2nd day to the hotel where we're staying. I hope they know who's coming (FIRST) so they aren't concerned when odd things start showing up on their doorstep!