A couple hours MAX is all you'll get out of the standard 2/3A rechargable reciever packs. 4-ish hours MAX from the larger AA rechargable packs & normal voltage for all nimh rechargable batts is 1.2V per cell not 1.5 like alkaline batts.Lipo is a different story with different concerns. You might want to stick with nimh for a while till your ready to deal with the other things that go along with lipo.
Just going out & running till your batts die is not the way this hobby works. Expect to charge every day before you take the car out.That is the habbit that all RC racers use. 9lbs car @ 35mph & batts die = more problems than you want to deal with.