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# Reserve Battery

Dell™ Latitude™ C640 Service Manual

### Removing the Reserve Battery

| NOTICE: The reserve battery provides power to the computer's RTC and NVRAM when the computer is turned off. Removing the battery causes the computer to lose the date and time information as well as all user-specified parameters in the BIOS. If possible, copy the information before you remove the reserve battery.

| NOTICE: Disconnect the computer and any attached devices from electrical outlets, and remove any installed batteries.

| NOTICE: To avoid ESD, ground yourself by using a wrist grounding strap or by touching an unpainted metal surface on the computer.

| NOTICE: Read "Preparing to Work Inside the Computer" before performing the following procedure.

1. Remove the hard drive.
2. Remove the keyboard.
3. Disconnect the reserve battery cable from the reserve battery connector on the system board.
4. Pry the reserve battery free from the EMI shield. The reserve battery is attached to the EMI shield with a piece of adhesive tape.
5. Remove any remnants of the adhesive tape from the EMI shield.

1 | reserve battery
2 | reserve battery tray
3 | reserve battery cable
4 | reserve battery connector on system board
5 | speaker cables
6 | opening for reserve battery cable

### Replacing the Reserve Battery

1. Connect the reserve battery cable to the reserve battery connector on the system board and then route the battery cable through the opening in the EMI shield to the battery tray.
2. Remove the backing from the adhesive on the bottom of the reserve battery, and press the battery into place in the battery tray.
3. Update the BIOS using a flash BIOS update floppy disk or CD. For instructions on how to flash the BIOS, see "Flashing the BIOS."

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