Battery drains despite being shut down
With a fully charged battery, I completely shut down my MacPro. When I turn it on, the battery is often less than 50%
MacBook Pro 13″, macOS 10.12
Are you sure the laptop actually completely powered off? Sometimes it can take a computer time to power completely off since the OS can stall during the shutdown process, or maybe an OS update was being installed before the final shutdown.
Before selecting "Shutdown", press the Caps Lock key so its LED lights up. When the laptop completely powers off, then the Caps Lock LED should go out.
Also, keep in mind with some Macs opening the display will power on the laptop. Also with some Macs pressing any key or even the Trackpad can power the laptop on. Maybe this is occurring when you think the laptop lid is closed and powered off.
Edit: Do you have any external devices attached to the laptop? Maybe one of them is still getting power from the laptop. Try disconnecting all external devices to see if that makes any difference.
What is the exact model of your Mac? You can get this information by clicking the Apple menu and selecting "About This Mac".
