Owners of Apple's MacBooks have the ability to hot swap their batteries without using a power adapter.

Imagine that you're a blogger and you've worked all day in the local park blogging about squirrel mating rituals and the various trees, when suddenly your MacBook warns you that you have less than 30 minutes of power left in your battery. If you want to continue working before the MacBook eventually falls asleep on its own, follow these easy steps.

1. Save and close: Save any open files in open applications. To be extra cautious, close the files you just saved. It is okay to leave the applications themselves running, and you could even leave the files open, but just in case, to prevent loss or damage to the open data file, we recommend that you close the file(s) before proceeding.

2. Sleep, that's where I'm a viking: If your Macbook is not asleep, tuck it in by pressing ctrl+eject and selecting Sleep, or tapping the power button and selecting Sleep, or closing the MacBook's lid. Keep an eye on the sleep indicator light at the front of your MacBook.

When this light pulsates, it's safe to pull the battery

When you first put your MacBook to sleep, the LED light at the front of your machine glows solid. During that time, the MacBook is writing your machine's RAM contents to the hard dive. Once the LED begins to pulsate, it's safe to proceed to the next step.

Note: At this point your MacBook is in Safe Sleep mode. Mac OS X has saved the contents of the RAM (Random Access Memory) to the computer's hard drive. When you remove the battery, the sleep light will go out and the computer will power off. This is normal, do not panic.

3. Swap that battery: Remove the drained battery and replace it with the fresh battery.

4. It's alive!: Open the lid and tap the power button to wake the MacBook up. The Macbook will start up from Safe Sleep mode, the screen will initially be gray and then will show you your desktop with a gray tint and a progress bar.

Once the progress bar finishes, you're ready to rock.

Once the progress bar is finished your system resumes where it left off when you put it to sleep. This means any open applications, etc. will be open as you left them. Your MacBook is now wide awake and ready to go!

Note: We recommend practicing this how-to a few times. If you press the power button too long you'll restart the MacBook.