According to the ThinkPad X1 Carbon (Type 20A7, 20A8) documentation, the part number for the CMOS battery is '''04X0443'''.
As far as replacing the battery, Lenovo has bite-sized tutorials that cover every step of the process. As you disassemble the computer, remember to keep all the parts organized so that reassembly will easier!
Here is how to remove the base cover of the device:
According to the ThinkPad X1 Carbon (Type 20A7, 20A8) documentation, the part number for the CMOS battery is '''04X0443'''.
As far as replacing the battery, Lenovo has bite-sized tutorials that cover every step of the process. As you disassemble the computer, remember to keep all the parts organized so that reassembly will easier!
Here is how to remove the base cover of the device:
[https://download.lenovo.com/lts/RTPW1240/FOF/RTPW1240-NewX1Carbon_REM_FRU_02_BaseCover.mp4|https://download.lenovo.com/lts/RTPW1240/FOF/RTPW1240-NewX1Carbon_REM_FRU_02_BaseCover.mp4]
Here is how to remove the system board to get to the CMOS battery:
[https://download.lenovo.com/lts/RTPW1240/FOF/RTPW1240-NewX1Carbon_REM_FRU_12_SystemBoard.mp4|https://download.lenovo.com/lts/RTPW1240/FOF/RTPW1240-NewX1Carbon_REM_FRU_12_SystemBoard.mp4]
Here is how to remove the CMOS battery:
[https://download.lenovo.com/lts/RTPW1240/FOF/RTPW1240-NewX1Carbon_REM_FRU_13_CoinCellBattery.mp4|https://download.lenovo.com/lts/RTPW1240/FOF/RTPW1240-NewX1Carbon_REM_FRU_13_CoinCellBattery.mp4]
Here is how to relace the CMOS battery:
[https://download.lenovo.com/lts/RTPW1240/FOF/RTPW1240-NewX1Carbon_Rep_FRU_13_CoinCellBattery.mp4|https://download.lenovo.com/lts/RTPW1240/FOF/RTPW1240-NewX1Carbon_Rep_FRU_13_CoinCellBattery.mp4]
To reassemble the computer, just perform all the disassembly steps in reverse.