I just received my Inspiron 6000 a week ago.  I ordered the 9 cell battery which is supposed to last up to 5.5 hours.   I have my computer totally dimmed all the way, and yet the most I can get out of the battery is 3 hours

 

Did I get the wrong battery (the 6 cell) or is this a normal thing with laptops?

 

I am a first time laptop user.

 

Thanks!