Ideally, you want to get at least eight hours out of your tablet. The battery is a major contributor to the size and weight of your device. This means that manufacturers have to make a compromise. They lower the battery life in order to make a smaller device, or they install a more sophisticated battery and increase the price of your tablet. If you come across a thin and lightweight device that is economically priced then there is a high probability that battery life and power has been sacrificed.