Go to support.dell.com. Search on "Recalibrate Battery"

You will get two responses. The first is:

<< Start Dell Support >>
1. Batteries do not have to be fully discharged periodically like the older
notebook batteries did.

No. The new lithium-ion batteries do not acquire a false memory of the
charge level and do not have to be fully discharged periodically like the
older notebook batteries did.

You may need to recalibrate the battery from time to time. Recalibrating the
battery maintains the accuracy of the main-battery indicator on the status
display panel, the charge gauge on the main battery, and the battery status
icon. The following message prompts you when it is time to recalibrate the
battery:

"You must recalibrate the battery to maintain the accuracy of the battery
status indicators."

NOTE: You do not have to recalibrate the battery immediately. However, the
longer you delay, the less accurate the battery status indicators become.
The message appears each time you boot the computer until you have
recalibrated the main battery.

To recalibrate the main battery, attach the AC adapter to the computer and
leave the computer on. You may continue working while the recalibration
process goes on. Or, it may be more convenient to let the battery
recalibrate overnight. During recalibration, the computer completely
discharges the main battery. The main-battery activity indicator in the
status display panel blinks and the bars on the battery status indicator
change to show the changes in the battery's charge level. When recalibration
is completed, the main-battery activity indicator stops blinking and the AC
adapter recharges the battery.

If you are not getting the life that you have been from the battery, you can
download and run the "BATRECAL" utility from the Dell website at:

http://www.dell.com.

This will force a recalibration.
<< End Dell Support>>