Although an external gage is a very convenient way to assess power status, another handy method lies right in your software. The power meter found in both Windows and the Mac OS. This method's biggest downer? You can use it only when your system is on.
The power meter in Windows looks like a tiny battery, and it sits in the lower right corner of your screen in the system tray. Simply run your pointer over this image, and the percentage of remaining power appears. This icon turns into a power plug when your system is plugged in. Run the pointer over the plug to monitor how quickly your laptop is recharging.