Ubuntu drains battery while laptop is powered down

I have an HP Laptop 15s-eq1xxx with an AMD Athlon Silver and corresponding Raven integrated graphics. I've recently installed Ubuntu 22.04 as the only OS. I left the laptop 2 days ago completely powered off (not suspended or in hibernate) with around 65% of battery remaining. Today I find it only has with 11%.

I've had this issue also with Pop Os! 22.04 and Linux Mint 20.1, which were my previous attempts. With Windows installed as the only OS, the laptop's battery never drains even with the "fast boot" option enabled.

I checked system logs looking for unusual activity during the time it should have been powered off with ...

cat /var/log/syslog 

but the logs jump directly from Oct 27, 23:07 (when last used) to Oct 29, 12:11 (when I powered it on again).

Also checked the shutdown logs with ...

last -x | grep shutdown

to find that last power off was indeed from the time period previously said.

Laptop has no hardware issues, nor was left plugged in to the power supply. No USB devices connected were left connected, not even headphones.

I read in another post about "USB port with power off charging". The answer was "disabling power off charging and setting sleep state to Linux in the BIOS" but I don't know how to do any of these things.

I've also heard that HP is restrictive with what one can do at BIOS level (I've seen it myself when I was trying to manually add a boot option but no choice for that was given).

Any solutions or possible explanation to the issue apart from the above's paragraph answer? An explanation of why this is happening would be great, if possible, as well.

Same thing happend to me. The problem started after updating to 22.04 from 20.04. The upgradation was done by a popup from settings automatically. I think some settings has been changed by ubuntu before starting the update just to ensure not to shutdown during update or something like that.

My Lap is dual booted with Windows 11.

Copy pasting the explanation and resolution

I have tried this after booting to windows 11

Well It is because of bad Intel Management Engine Driver if yours is uprgarded to v11 something you don't need to downgrade, just go to device manager->System Devices-> Intel Management Interface->Properties->Power Management and uncheck Allow the computer to turn off this device to save power and try testing now hopefully it will work.

I have tried this yesterday and so far the issue seems to be solved