Prevent battery drain during suspend mode on Linux

will return "s2idle" and "deep" values, value surrounded by square brackets will show which mode is currently activated.

Probably when you observer battery drain during suspend, you will see "s2idle" highlighted.

To change it do deep sleep mode use command:

To make change permanent add the following to your kernel cmdline in your bootloader, edit /etc/default/grub file and put mem_sleep_default=deep parameter at the end of line containing GRUB_CMDLINE_LINUX string.

Next thing is to rebuild GRUB2 config file.
For BIOS computers:

For UEFI computers:

After reboot again verify using:

For more information about System Sleep States please visit https://docs.kernel.org/admin-guide/pm/sleep-states.html