Battery draining 20% overnight while turned off

[roxy1712]

I have a 15" Envy, bought in 2016 that's been mostly reliable. Lately I've noticed that if I leave it turned off and unplugged from the charger, the battery drains significantly overnight. I'm shutting it down entirely - not putting into sleep mode - and I've turned off fast boot. All USB devices are unplugged, I've run a BIOS check/update, ran battery tests, all to no avail. It used to only discharge around maybe 5-10% overnight, but last night it went from 100% to 80% in about 18 hours.

I did upgrade the memory earlier this year, but otherwise nothing else has been done to the machine.

Any other suggestions?

[WAWood]

@roxy1712 

Just to be clear, Fast Boot is different from Fast Startup -- although they accomplish pretty much the same thing.  The first is a BIOS/UEFI option; the second is a Windows option.

You should read the following about disabling Fast Startup to see if that helps:

Fast Startup is supposed to dramatically speed up the booting process, but in some PCs, it actually slows it down or causes it to hang. It's also a new form of hibernation known as hybrid sleep -- and this causes battery drain to maintain the state of the PC while turned off. In some rare cases, it can also cause a laptop to overheat because the processor is still running and still generating heat, as this has been reported when the laptop was turned off and put inside a case.

Disabling Fast Startup might fix booting and shutdown problems.

There are two ways to disable FastStartup in Win10: (1) through the Control Panel, and (2) through an elevated command prompt.

Control Panel - Open Control Panel --> Power Options.
Select "Choose what the power buttons do"
Select "Change settings that are currently unavailable"
At the bottom of the Window, under Shutdown settings, uncheck the box regarding fast startup

Elevated command prompt - run the following command:
REG ADD "HKLM\SYSTEM\CurrentControlSet\Control\Session Manager\Power" /V HiberbootEnabled /T REG_dWORD /D 0 /F

In both cases, reboot Windows.

NOW, Fast Startup is disabled.

See if that helps.

[roxy1712]

Thanks WAWood. I should have clarified, FastStartup is currently set to "off." It certainly takes much longer to boot!

[roxy1712]

Replying again, because I'm not only still having this issue, but I found that if I leave it in "Sleep" mode for 12+ hours unplugged, it drains NO battery. Meanwhile, if I turn it off and leave it unplugged, I'm STILL seeing 20-50% battery drain. Clearly there's something wrong here....