Adjusting Laptop Display Brightness Based on Power Source Question

[cyberSTACK]

I am having a problem with my Dell Inspiron 6000 laptop. When I am running on batteries the display is quite dim, however, when I plug it into the wall, the display becomes brighter and much easier to look at.

I understand this is most likely a battery saving measure, however, does anyone know how to make the display the same brightness when it is running on batteries or plugged in?

Thanks!