Xalos, I couldn't tell from your post whether you know this or not, but the apple products calculate tha percentage from the activities you are currently doing. If you have two app downloads, three music downloads, have all eight tabs open on the Internet in the background, and play angry birds, the percentage will drop significantly while you are doing those activities. Once all the processes cool down, the percentage will go back up. There are a few apps out there that show you how long your battery would last while performing certain functions, such as watching a video or listening to music. The typical iPhone with nothing in the background can play a 3.5 hour video before it runs dead.
For the OP, here are some suggestions for increasing battery life:
Turn brightness down to below half. It might look dark, but you will get used to it.
Double click the home button and delete al of the app history tiles. Keeping this unnecessary data runs down the battery.
Put a lock timer on the device, somewhere around three to five minutes.
Put a lock on your device. You'd be surprised to know how many times your phone could unlock from random movements and jeers.
If you have an iPhone, 3G kills your battery and most likely your data plan. Keep wifi turned on at all times.
Plug your device in when you are sitting down for a long time.
