How to Change an Internal PC Battery

Written by thomas west
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How to Change an Internal PC Battery
Replace your internal PC battery by removing the case. (computer image by Andrey Rakhmatullin from

Your PC, or personal computer, has an internal battery that keeps time when your computer is switched off. The internal battery is sometimes called a CMOS, or Complementary Metal Oxide Semiconductor. If your computer is not keeping the correct time after you boot it up, it is probably time to change your battery. You should be able to obtain a replacement battery at a computer store. You can have your internal battery changed out in just a few minutes.

Skill level:


  1. 1

    Purchase a new battery for your computer. Write down the model and serial number, which are located on the rear panel of the PC tower, as this will insure you get the correct battery.

  2. 2

    Turn your computer off and unplug the power cord from the wall. Wait at least 30 minutes before proceeding to allow the CMOS to discharge.

  3. 3

    Make a note of the location of the mouse, monitor, keyboard and speaker wiring that is plugged into the back of your computer. Unplug all devices from the computer and set them aside.

  4. 4

    Remove the screws from the PC tower outer cover by backing them out with a Phillips-head screwdriver in a counterclockwise direction. Slide the cover off to reveal the inner chassis of the PC. The covers on some computers are not attached with screws and can be removed by merely sliding them off. Check your computer's user guide for instructions.

  5. 5

    Locate the battery on your computer's motherboard. Determine how the battery is connected before attempting to remove it. Some batteries fit into the slot and can be pried out with your finger; however, some batteries are held in by a clamp that you need to move to one side.

  6. 6

    Remove the wiring connector from the battery if it is so equipped. Remove the old battery and put the new battery into place as quickly as possible to avoid loosing any settings. Push the new connector into place and move the clamp back into position.

  7. 7

    Slide the PC tower cover onto the chassis and replace the screws, if necessary. Plug in your keyboard, mouse, monitor, speakers and any other devices you disconnected. Plug the computer in and turn it on.

Tips and warnings

  • Locate the battery on your motherboard by using the new battery for comparison purposes.
  • If your CMOS is already dead, you are losing your settings (such as date and time) every time you turn off the computer. However, if your battery still has some juice left, you can avoid losing your settings by swapping the old battery for the new one quickly. Back up your computer using the instructions in your PC user manual just to be sure.
  • If you have an older PC that has its CMOS soldered into place, have a computer shop replace your battery. If you are not familiar with using a soldering gun, you could damage the motherboard.

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