I just searched about “battery drain after shut down”. Here are some info.
$ sudo shutdown -H -P +0
-H = halt
-P = power off
+0 = now
The syntax of shutdown changed with systemd. Some things still us OLD methods $(shutdown -h now), which doesn’t always do the things on NEW hardware.
There could also be extras like usb ports ON, wake on lan, and such which DO have UEFI options. Although buried in some cases, you have to disable / enable and such various options to “expose” those options. I had to delete windows keys just to have the secure boot disable save between boots on my hp 15 machines. ba053nr / bw053od
As a work around you might press and hold the power button 5+ seconds after shutting down to hardware shutdown. Although not the best practice when it comes to spinning rust drives.
Remove the battery for several hours and check if it will drain out. If the battery still charged, it should be healthy.
One possible trouble maker could be any USB port or other device that still powered while the system is shut down.
Extra powered USBs are feature for some laptops. Usually these ports are yellow colored. Port as this could be troublemaker especially if something is plugged in this port. In most cases this feature could be disabled via the BIOS settings.
Recently I’ve discovered that the new batteries should be charged to 100%. Unfortunately I can’t find the source of this statement but this solve my problem with my new battery jump drain from ~35% to 5%.
I don’t understand this well. But it might be a clue.
This is for Windows. But there might be a clue.