What is this button cell for and why is it present in only one of my laptops?

[MorayM]

This question is more curiosity than anything else!

I was swapping the keyboard from my 11th gen laptop to my 13th gen laptop and noticed this on the motherboard. The 11th gen has a button cell on the board, and the 13th has the holder for the cell but nothing in it. I assume it’s a CMOS battery for UEFI/internal timekeeping, but why is it not needed in the later model?

[MJ1]

Welcome to the forum.

They changed the circuity to allow it to use the main laptop battery.

An RTC/CMOS battery holder or plug remains because it’s useful to those who put the mainboard to use where they don’t have a main battery.

[MorayM]

Fascinating, thank you!