Research proves that on Android Mobials the free apps "Drain" the battery down pretty quickly. The reason for this is because there are lots of adverts on free apps, that is how the free apps make money but it is costing the app user 75% of battery used to power the application just on the adverts, however much battery life is used. A way to save your battery is unfortunately to buy the paid apps with no adverts but personally I would prefere to just get all the free apps rather than buying all my apps for money but it will run your battery low quite quickly if you don't but you could always just buy a portable phone charger or a car charger. It is always good to know these things so I just thought i would tell you just incase you were interested.
Please comment and ask questions and I will try and get back to you as soon as possible.
By George :)