The CMOS battery stores settings while your laptop is off.
A BIOS battery is a backup battery that keeps the BIOS settings saved even when your Dell laptop is completely powered off. Since the BIOS holds the boot menu options, it's imperative that it remain working. Replace a dead BIOS battery immediately to ensure your laptop will boot properly. Replacing the battery has a side effect of wiping out your BIOS settings, however, so the factory default options need to be restored as well.
Instructions
1. Shut down your Dell laptop's operating system and unplug its AC adapter cable, if it is currently attached. Shut the display screen lid and turn the Dell upside-down to access the bottom half of the case.
2. Find the plastic release latch for your Dell's battery pack, which is located near either the top or bottom edge, just above or below the battery. Push the latch down and move it over to the side to pop the battery upwards. Lift out the Dell's battery and set it aside.
3. Turn your Dell back over so the top half is visible, and open the display screen lid all the way so the entire laptop is laying flat. Locate the plastic indicator light strip, which is the entire plastic piece positioned between the keyboard and screen.
4. Wedge the flat end of a flat-head screwdriver underneath the right-hand edge of the plastic indicator strip. Push the screwdriver inward and lift it up slightly so the strip pops off the Dell laptop.
5. Lift off the strip and place it aside so the keyboard's screws are visible. Remove the two screws at the top of the keyboard with a Phillips screwdriver.
6. Grip the top end of the Dell's keyboard and flip it towards you, so the keyboard is facing down on the laptop's palm rest area. Disconnect the thin cable connecting the bottom of the keyboard to the rectangular port on the Dell's motherboard.
7. Remove the keyboard from the laptop. Locate the circle-shaped battery near the top of the motherboard. The battery also has a short cable connected to its side.
8. Unplug the cable and pull the BIOS battery off the motherboard. Set your new BIOS battery into the Dell laptop and connect the cable. With some models the cable is run through a short plastic channel, and you need to thread the cable through the channel before plugging it in.
9. Replace the Dell's keyboard and its screws. Push the indicator strip back onto the laptop and pop the battery pack into the port on the bottom of the laptop.
10. Turn on your laptop. Tap "F2" as the Dell logo loads on the screen. With certain Dell models, you must press either "Fn" and "F1" at the same time, or press the "Delete" key instead.
11. Navigate through the BIOS menu with the right arrow key until you reach the "Exit" menu. Navigate down to the "Load Factory Defaults" entry and press "Enter" twice. Choose the "Save and Exit" option and press "Enter" twice.
Tags: your Dell, your laptop, battery pack, BIOS battery, BIOS battery, BIOS settings, cable through