Extending Runtime Battery Life
The Macbook Pro 15-inch laptop battery is supposed to last from eight to nine hours on a single charge. However, several variables can cause this number to be significantly shorter. One of the most prevalent variables affecting battery life is the brightness of your Macbook's LED display. Logically, the brighter the screen, the faster the battery will drain. For example, the difference between viewing your Macbook at full brightness and lowest brightness can be a few hours.
In addition to the screen brightness, the backlit keyboard on your Macbook Pro 15-inch can also drain your battery. If you're not in a dark room that requires the backlit keyboard, turn the keyboard lights completely off.
Another major drain on your battery life is wireless communication. If your airport and bluetooth are on, your battery tends to drain at a faster rate. If you must have the airport on to access the Internet, turn off the bluetooth by clicking the bluetooth icon on the upper-left corner of your Mac and selecting "Turn Bluetooth Off."
Running multiple applications at one time can decrease your battery life for several reasons. First, running too many applications can cause your Macbook's CPU to overheat. Overheating causes the battery to drain at a faster rate. Second, running multiple applications can drain your battery due to your Macbook's paging scheme. That is, applications that aren't currently in use will place a burden on your Macbook's hard drive. Hard drive usage can cause the battery to drain faster.