RE: battery charging
I don't mean to hijack the thread either, but to answer your question, 4.4v is usually considered to be a "totally discharged" state. You never want to fly to that point. Follow your instructor's guidance. If that's the guidance you elect to follow, set your discharger to stop at 1.2 volts per cell (4.8v). You will then know exactly how much time you have to fly.