Just this Morning I noticed that my truck will.

Just this morning I noticed that my truck will start to die once it hits 3000 rpms. When I say die, this means that the guage cluster will start to dim, the battery light will come on, and the battery guage will go almost all the way down.
I didn't start it at all yesterday and didn't have a problem starting it this morning when going to work, I just noticed it while driving.
It is a 5 speed, so when I would hit 3000 rpm and the lights started to dim I would just shift up and everything would return to normal.
I'm hoping that it just needs a new battery and not an alternator or fuel pump, or anything like that.