When you begin receiving errors that your system doesn’t match the configuration, or you getting a warning in the BIOS that your battery is dead, you most likely need to replace your CMOS battery. The CMOS battery provides the motherboard just enough power to retain the CMOS settings for your laptop. If this battery dies, your machine will likely still function, but some of the stored parameters such as time and date will not be correct and any BIOS settings that are stored in CMOS would be lost also each time the computer is powered down.
Replacing the CMOS battery is not usually difficult, but the procedure can vary greatly depending on the laptop’s model. The easiest way to find specific instructions is to do an internet search for the term “service manual” and your laptop’s manufacturer and model. Often, you can find a PDF version of the service manual for your specific laptop, which will give you detailed instructions for repairs and upgrades.
Most CMOS batteries are located under the keyboard, which can require removing the keyboard. Other common locations are under the touchpad, behind the battery, and some are accessible from the bottom of the machine via a small plastic cover. While it is difficult to give detailed instructions for the multitude of laptop models on the market, here are a few guidelines for replacing the laptop CMOS battery.
- Wear an anti-static wrist strap when disassembling any laptop. This reduces the risk of damage from static electricity.
- Remove the battery completely and disconnect all power cables to avoid the risk of electric shock or damage to the laptop or notebook.
- Remove the Keyboard or associated cover to expose the CMOS Battery and remove. Carefully keep track of all screws removed. Group and label them to avoid confusion when reassembling.
- When prying ribbon cables or plastic parts apart, be gentle to avoid damaging sensitive components.
With some preparation and planning, replacing the CMOS battery should be possible for most users. If you cannot find a suitable service manual or you don’t feel confident in your abilities, it is a good idea to take it to a repair center.