Battery is one of the crucial part of a laptop and most of us have noticed that the battery life claims made by manufacturers generally not correct. Even though they mention 4-6 hours, you practically get only 3 hours. So it is always good to benchmark your laptop, so that you know how much the battery actually lasts. Battery Eater is a freeware tool which allows you to test your battery performance and benchmark it.
Once you install the tool, select the checkbox against Begin test when disconnecting AC and then remove the AC power. Battery Eater starts the test on your battery until the power is completely drained from battery.
Once the power drain is complete, it shuts down the PC, but plots a graph on the battery usage. From the options menu, you can select the different types of test available.
Battery Eater is a nice tool to benchmark your laptop power and the test says the result is the minimum of battery you will get on your PC.