Laptop dim battery power

Update: actually it turns out that it does dim, I just couldn't see it because I had set the plugged-in brightness to the same brightness as it dims to so there was no change. However, this was done through keyboard controls and I still want to find where I can set the level that it dims to (I want it as dim as possible when unplugged)... Could it be a driver update I am missing? Being a generic brand, Compal drivers aren't as easily located.

thanks, it was in the bios.

Best answer selected by wocketpatch.