How to Replace a Compaq Presario CMOS Laptop Batteries

The CMOS laptop batteries in your Compaq Presario computer helps your PC keep the correct date and time. If the battery fails, you may experience problems with your computer because many features rely on the system keeping time. When the battery is low, you should see an error message when you start your computer. This battery is similar to a watch battery. The CMOS battery is a small, silver, circular battery, very similar to a watch battery. Note the position of the battery (the direction of the positive and negative sides). On some Presario models, the battery is positioned vertically--this requires lifting straight up. 6 Match up the new CMOS battery with the old CMOS battery. A common battery is CR2032--however, this may vary between Presario models. 7 Install the new CMOS battery into the slot exactly as the previous one was.