*Read guide note* How to rebuild a laptop CMOS battery

If your laptop has a dead CMOS battery and the OEM no longer sells new CMOS batteries (and aftermarket ones are hard to find), it is possible to take the dead battery apart and replace the cell so your laptop holds the CMOS contents again.

IMPORTANT: DUE TO THE ASSOCIATED DANGER IF THINGS GO WRONG, THIS IS ONLY RECOMMENDED FOR OLDER NOTEBOOKS WHERE THERE ARE FEW OR NO THIRD PARTY COMMERCIALLY AVAILABLE REPLACEMENTS. If a pre-built replacement can be purchased, this is (generally) better as the cost is similar to this procedure. It is also somewhat error-prone and can create the same issue as a dead battery if the tape fails.

Guide notes:

• The cell does not need to be covered 100%. Due to the risk of an explosion, you MUST cover every visible area at least to the point it is "protected". Liquid electrical tape is used to do this since it can be removed cleanly if something goes wrong and provides a better seal without the risks introduced by using heatshrink and a butane flame.
• Laptop disassembly is not covered. Every laptop is different, so yours probably varies from the one this was pulled from. Check iFixit or the manufacturer's website for instructions. NOTE: SOME TOSHIBA LAPTOPS SOLDER THIS TO THE MOTHERBOARD.
• This guide ONLY applies to coin cell rebuilds. Do not use this guide for other batteries.
• When adding tape to the cell, be very careful not to create a direct short. To avoid this, place the tabs slightly higher than the factory and cut the tape sort but will also hold reliably.