Just a quick update on this. Unfortunately, other things have prevented me from experimenting with the shutdown.exe command over the last few weeks, but I did experience the same drastic power loss as originally posted. In fact, twice this week. The first on the morning of the 17th, where it dropped from 16% overnight to 1%, as shown here:
That sort of confirms what I had been experiencing previously. This morning however was much worse. The laptop was shut down with 37% battery charge, and when powered on, I got the message about charging the battery. Despite shutting down the same way as always, it somehow lost 36% of charge. The only other item I had thought that 'might' have an impact was if there were Windows updates involved. Specifically, when you go to shut down and it gives the various options. When this happens, I always choose to install the updates and restart, and then shut it down again, even those times I'm tired and just want to go to bed. From memory, I've only had one instance of that since my original post, and that was in the middle of the afternoon, so it definitely got done there and then.
This is the result from this mornings startup:
Windows shutdown shortcut created and placed in prominent space on the desktop, so will try and use that every time from now on.
