Battery life display not showing under power icon

Hello I just got my 700m.

My question is, how long is the max battery life of the 700m using the 4-cell battery.  And for some reason i notice that under the little battery icon on the taskbar, it only list the % of the battery left, but it never lists the time in hrs/minutes of how much time is left.

Please help me how to fix this or reason why it does this?  thanks