BatteryBar is a simple application that lets you keep track of your laptop's battery life.
BatteryBar will show you the battery's capacity, percentage, duration, the AC power supply, and battery drain. This gives you a better idea of how much long your battery will last and details your battery's physical condition.
As you use your battery, BatteryBar will show you a bar that precisely indicates how much battery you have left. Here you'll also be able to see your battery charge expressed in time remaining.