Since successfully upgrading from Windows 7 to Windows 10 a while back I have noticed that the laptop's battery drains to about 0% charge following a Shut down faster than before the upgrade. The laptop and battery are a few years old, so part of the accelerated draining could be the battery age, but this was a significant difference immediately following the upgrade.
What would happen: Battery fully charged, laptop shut down, laptop disconnected from charger and sitting unused for 2-3 days, attempt startup, get message at startup that battery charge is low. After connecting charger and successful start up, battery shows charging with current charge of almost 0%. Battery successfully gets to full charge when connected to charger.
By the way, I'm talking Shut down, not hibernate or sleep.
After ignoring this behavior for a while, I did a few searches and tried the following with success.
I went in to Power Options > Choose what the power buttons do > Change settings that are currently unavailable, and under Shutdown settings I unchecked the the box for "Turn on fast startup (recommended)" option.
I just started the laptop after sitting disconnected from charger for 10 days, and turning "Fast Startup" off appears to have addressed the battery draining issue. Battery was at about a 60% charge and laptop started up fine without connecting charger.
This was the only configuration change I made for weeks prior to this cycle. Windows 10 had all current updates applied, including November update (Threshold 2).
I hope this helps anyone having a similar issue.