i always just take my external battery out and toss it in the bin next to my laptop when I go thru security. Never had a problem. In fact, the only time I ever *did* have a problem was when I forgot to take it out...the xray machine could only see a big dense brick with circuitry in it, which the TSA people did NOT like.

But now that I think about it, I guess I've never had occasion to pass thru international security with my external battery, oddly enough.