It‘s claimed that iPad‘s battery life can support "up to 10 hours of surfing the web on Wi-Fi, watching video, or listening to music". Here are some useful but not happy tips to help you use your iPad a lot longer without having to plug in all the time.
1- Turn off all apps and functions you don‘t use. A lot of functions are turned on by default, so go to your settings and turn off everything you don‘t really use.
2- Live streaming and downloads Live streaming videos like youtube and download stuff from sites will significantly drain your battery power. Wait until you can get to a place where you can plug in to do those
3- Screen Brightness Turn down your screen brightness and lights. To do so go to Settings > Brightness & Wallpapers > Then drag the slide to the left.
4- Stay away from games Don‘t play games if you know you‘re going to use your iPad battery power for something else more important.That‘s a battery killer.
5- Emails and Social Networks You can check that facebook & twitter page later on your desktop or laptop. Oh, the emails. Do you have to check that now?
6- Disable Wi-Fi and Bluetooth But, no game, no Youtube, no Facebook, no Twitter, no email, why I use iPad?
"iPad Tips and Tricks : Extend iPad Battery Life "
Reference : top-ipad-video-converter.com