Keep in mind with Andriod, it really matters what apps you have installed. There are some that will just suck the battery right down. It's trial and error finding which apps are battery friendly and which ones aren't
There's a bowling game Amazon gave away that just one hour of play pretty much brings me into red on my phone. I uninstalled it.
I only charge my phone every other day but when I got it was everyday till I learned that some apps aren't worth it. Mantano and Cool Reader do not do much draining for me. Youtube and TuneinRadio Pro both drain pretty quickly.
Andriod Market by google is a huge battery hog. I wont miss it on the Fire!