CMOS batteries on all computers only have a certain lifespan and must be replaced after a time. Luckily, the CMOS battery on Acer laptop computers is quite easy to access and replace. The hardest part of the process is disassembling the computer.
Disconnect the power cord from the laptop and remove the main battery.
Open the laptop computer's screen and extend it as far back as it will go. Be careful not to stress the screen and cause any damage, but press it hard if needed.
Press a flat head screwdriver under the front of the plastic bar lining the back of the laptop's keyboard. Pry the bar up slightly and hold it with one hand.
Pry up the other side of the bar with the flat head screwdriver and fully pull out the bar. Keep its ribbon cord connected and set the bar on the laptop's screen.
Remove the two Phillips screws securing the computer's keyboard. Slide the keyboard up and out to remove it. Again, do not remove its ribbon cord, and set the keyboard over the laptop's touch pad.
Remove the four screws securing the cover plate over the motherboard and remove the plate as well.
Locate the CMOS battery at the bottom-right corner of the motherboard.
Remove the battery by prying it up gently with the flat head screwdriver. Then, replace the battery with a new one of the same specifications.
Replace all the parts in the laptop in the reverse order that you removed them.
While you have the laptop computer open, blow out some of the dust inside. This will help prevent cooling problems in the future.
Always be careful of static electricity when working on computers. Just the slightest shock can ruin components.