Started having this problem back in December 2020 after a windows update.
I've tried everything, clean installation, sending the battery to a technician, everything.
Since then, I've tried narrowing down the problem and I think Nvidia is the culprit.
I discovered this once when I was able to pass the login screen without having it drop to zero. For testing, I started a game, and suddenly the battery went to zero.
I disabled all Nvidia services from the device manager, but I'm still experiencing the problem.
The issue is NOT there when using Ubuntu.
As noted by someone on the previous page, they had success installing the Nvidia driver from the ASUS support page. Have you tried that driver?
No idea if this can help, but there was a suggestion at the link below to uninstall One Drive for the GL731GW battery drain issue if anybody wants to look into that. Thanks.
I've been looking into this issue for my GX502GW which exhibits a very similar problem to OP.
I think this problem might be affecting numerous other laptops in the ASUS lineup with Nvidia Optimus.
FYI - Before the below testing, my graphics mode is "Discrete" Graphics
My latest findings as per below has potentially narrowed down the issue and might provide a solution:
1) Reinstalled Windows
2) Installed only intel chipset drivers, nahimic driver and Asus Armoury Crate. Allowed Windows Update to handle the rest.
3) Downgraded BIOS from 312 to 306 using BIOS from Windows Update Catalog
4) After reproducing issue in Windows, shutdown the machine with the power cable plugged in and performed an EC reset
5) Re-configured BIOS to use SATA Mode: AHCI; Fast Boot: Disabled
6) Booted into Windows and observed that the system had automatically swapped back to Optimus mode for the graphics
Next I will fully charge the laptop again and drain to 68% to confirm if the issue has fully subsided. If successful, I will then swap back to "Discrete" Graphics and repeat the controlled test scenario.
What I am expecting:
The issue not to be present on Optimus mode
The issue will present itself in Discrete mode