Fastest safe charge rate for LiPo's is 1 hour.

With A123 batteries you can get this down to 15 minutes.

So with LiPo's you may need 2 or 3 packs to keep you flying constantly.

This assumes that after you fly, you'll shoot the breeze for a little while before flying again, between flights.

Since I can get 30+ minutes on my SuperSportster EP, two packs suffice to keep it flying all day, however I typically bring out enough packs for 2 or 3 hours of non-stop flight.