This document pertains to HP and Compaq Notebook PCs with Windows Vista.

Calibrating the battery

Calibrating the battery means recharging the battery to its maximum capacity and resetting the battery gauge to accurately display the level of charge.

The Windows battery meter in the system tray might not accurately display the charge level of the battery. The battery's maximum charge level changes over time; making the battery gauge or meter inaccurate. If the battery gauge becomes inaccurate, use one of the methods below to calibrate the battery.

Calibrate the battery while the computer is in use

A calibration cycle requires that the battery be completely charged and then completely discharged. During the calibration cycle, the power management properties must be disabled to allow the battery to completely discharge.

Follow the steps below to calibrate the battery power meter readings.

1. Connect the power cord and allow the battery to charge to 99% - 100% of capacity.
2. Disconnect the power cord from the computer.
3. Click Start , type power options in the Search field, and then select Power Options from the list.
4. On the Select a power plan window, click Create a power plan in the left sidebar.
   Figure 1: Select a power plan

   Selecting Create a power plan
5. On the Create a power plan window, click in the Plan name field, type Calibrator , and then press Enter or click Next .
   Figure 2: Create a power plan

   Plan name - Calibrator
6. On the Change settings for the plan: Calibrator window, select Never for all topics in the On battery column.
   Then click Create to accept the values and force the battery to discharge.
   Figure 3: Change settings for calibration

   On battery - selecting Never
7. Allow the battery to discharge completely until the computer shuts down.

   NOTE:

   The battery power meter is now calibrated, and the battery level readings should be accurate.

8. Connect the power cord and press the power button to start the computer.
9. After calibration, return to the Select a power plan dialog box (Step 4) and select your default power plan setting.

Calibrate the battery while the computer is not in use

A calibration cycle requires that the battery be completely charged and then completely discharged. The calibration might take one to five hours, depending on the age of the battery and the computer's configuration.

Follow the steps below to calibrate the battery power meter readings.

1. Shut down the computer.
2. Connect the power cord and charge the computer until the battery charge light is green, indicating that the battery is completely charged.
   On some models the battery light glows white, and on other models the light turns off when fully charged.
3. Press the power button to start the computer.
4. Press F8 repeatedly when the HP logo appears.
5. When the Windows Advanced Boot Options menu displays, use the Up and Down arrow keys to select Safe Mode and then press Enter .
6. When the Windows Advanced Startup Menu displays, click Startup in Safe Mode .
7. Disconnect the power cord from the computer.
8. Allow the battery to discharge completely until the computer shuts down.

The battery is now calibrated, and the battery level reading on the power meter should be accurate when the computer starts again.