My wife and I will be on a flight from Phoenix to Maui this fall and I want to continue to use my iPad on the duration of the flight. We will also be flying from another city to Phoenix to start the trip. I just have a very strong feeling my iPad will die before reaching the gorgeous island of Maui, and want to ask if there is any type of continual power source so my iPad won't die on the flights? I've seen some portable power supplies, but don't they just charge an iPad, after the iPad power has died? Is there something for continual power? Thanks in advance for any tips and suggestions.