If 10 hours of the iPad off-line work are not enough for you, then HyperMac is exactly for you. It can be connected as to the iPad as to all Apple laptops. By dint of this wonderful device time of the iPad operation increases to 100 hours, time of laptop operation increases to 36 hours.
The accumulator comes in four variants with different powers, sizes and weights. HyperMac price is rather high – $200-500. In my opinion, it is irrationally to spend such sums of money for devices like this as power cords still exist, and there are numerous alternative power supplies, and note, they are at reasonable prices. However, you can choose anything you want and we are watching the video with the device announcement: