Skip to main content

Remove the CMOS battery

Use this information to remove the CMOS battery.

About this task

The following tips describe information that you must consider when removing the CMOS battery.
  • Lenovo has designed this product with your safety in mind. The lithium CMOS battery must be handled correctly to avoid possible danger. If you replace the CMOS battery, you must adhere to local ordinances or regulations for battery disposal.
  • If you replace the original lithium battery with a heavy-metal battery or a battery with heavy-metal components, be aware of the following environmental consideration. Batteries and accumulators that contain heavy metals must not be disposed of with normal domestic waste. They will be taken back free of charge by the manufacturer, distributor, or representative, to be recycled or disposed of in a proper manner.
  • To order replacement batteries, call your support center or business partner. For Lenovo support telephone numbers, see Support Phone List for your region support details.

After you replace the CMOS battery, you must reconfigure the server and reset the system date and time.

When replacing the lithium battery, use only Lenovo specified part number or an equivalent type of battery recommended by the manufacturer. If your system has a module containing a lithium battery, replace it only with the same module type made by the same manufacturer. The battery contains lithium and can explode if not properly used, handled, or disposed of.

Do not:
  • Throw or immerse into water
  • Heat to more than 100°C (212°F)
  • Repair or disassemble

Dispose of the battery as required by local ordinances or regulations.

disconnect all power
The power-control button on the device and the power switch on the power supply do not turn off the electrical current supplied to the device. The device also might have more than one power cord. To remove all electrical current from the device, ensure that all power cords are disconnected from the power source.
  • Read Installation Guidelines and Safety inspection checklist to ensure that you work safely.

  • Power off the server and peripheral devices and disconnect the power cords and all external cables. See Power off the server.

  • Prevent exposure to static electricity, which might lead to system halt and loss of data, by keeping static-sensitive components in their static-protective packages until installation, and handling these devices with an electrostatic-discharge wrist strap or other grounding system.


  1. Remove the top cover. See Remove the top cover.
  2. Remove any parts and disconnect any cables that might impede your access to the CMOS battery.
  3. Locate the CMOS battery. See System-board-assembly connectors.
  4. Open the battery clip as shown and carefully take the CMOS battery out of the socket.
    • Failing to remove the CMOS battery properly might damage the socket on the processor board. Any damage to the socket might require replacing the processor board.

    • Do not tilt or push the CMOS battery by using excessive force.

    Figure 1. The positive and negative end on the CMOS battery socket
    The positive and negative ends of the CMOS battery

    Before you remove or install the CMOS battery from or into the socket, differentiate between the positive and negative ends. Use the illustration above for guidance.

    Figure 2. CMOS battery removal

    1. Pry the CMOS battery from the socket with a flat-blade screwdriver.

    2. Remove the CMOS battery.

After you finish

  1. Install a new one. See Install the CMOS battery.

  2. If you are instructed to return the component or optional device, follow all packaging instructions, and use any packaging materials for shipping that are supplied to you.

  3. Dispose of the CMOS battery as required by local ordinances or regulations.

Demo video

Watch the procedure on YouTube