iPad 8-9 hour battery backup is pretty decent and enough for most of the people, but if you want more the check out the external battery from QuickerTek. Its the same company behind the Solar Panel Charger for iPad.
The external battery will add another 20 hours to the iPad, which is humongous by any means. Now those long journey’s or 14hr flights wont be much boring after all. The battery also offers 2 usb ports, where you can plugin your iPhone and iPod touch. One stop solution for all battery vows.
The case is machined aluminum that has been anodized. With two USB ports you plug in to recharge the battery by using the Apple or any other USB charger. Which means no more lugging around an extra charger. The battery has 10 LED’s with a push button fuel gauge to display the external battery’s charge level. With two USB port’s you cano power or charge the iPhone, iTouch, and any 30 pin iPod simultaneously and it provides the correct internal circuity.
The battery costs $250 , which I agree is little more on the expensive side. But again its for super users, who are travelling a lot and need an extra pair of battery power for their gadgets. If interested, you can buy it from their official website