From what you've said you're running one battery, correct? That does make a difference, but, most quals are 5 min. (at least where I race) I can easily get both quals in IF they do 3 quals, I can also get the 3rd qual in on one charge.

I would definitely have a full pack for the main, but, all those chargers are going to cut down on the life of your battery.

Having 2 batteries (of like or similar specs) would be a good invesment IMHO. Personally, I take 4 batteries just 'coz I like to play with different ones. And playing is what I'm all about with my RCs.