It’s a well known fact that the new iPad takes significantly longer to charge than the iPad 2. You can chalk that problem up to the fact that the new iPad has approximately 70% more battery in the same form factor than the iPad 2, requiring almost twice as long to charge. Consequently, the iPad has gone from being something you could charge up in just a few hours to a tablet that needs all night to charge to 100%.
But you shouldn’t stop charging your iPad at 100%. No sirree bob. If you want the most battery life from your new iPad, you should keep the device plugged in for at least an hour after it reports full. Why? The iPad battery gauge lies.