battery life macbook pro early 2011 15"

I have only 55 charge cycles on this battery. it states "Normal", yet the battery only lasts about 40 minutes.

What is wrong? This is an Apple battery.

I just got the Logic board replaced. Running Mavericks. Was running 10.6.8 prior. Same issue prior.

With this low a charge cycle and System reporting Normal, what should a standard time life be. Used mostly for email reading / writing and some web.

Not heavy streaming.

Is there a battery charge sensor on this mac that could be faulty?