MacBook Pro with latest ops installed.
Battery charged to 100%
I shut down the MacBook, unplug it and put it in my travel case
Next day, the MacBook cannot boot up because the battery is completely drained.
WHY?
What causes the MacBook to drain when it’s shutdown?
MacBook Pro 13″, macOS 12.6
Several things to consider.
First is the exact model of this laptop. Apple has made so many changes with recent models that the exact model can be very critical here since every year there is some new major change to the previous year.
When you boot the laptop and log into a macOS user account, is the battery charge low? You cannot go by the information presented on the login screen as it may not be accurate or even updated.
Are you just seeing the black screen with battery icon (red)? If so, this does not necessarily indicate a drained battery as I have seen this occur on numerous laptops with our organization even when the battery has a sufficient charge on it. I believe this just indicates some sort of Logic Board issue where it loses contact with the battery (or thinks it loses contact). If the battery has significant charge when you log in and this only happens once in while I would not be concerned, but if it is a regular occurrence, then it likely indicates some sort of hardware issue. If the battery has a very low charge when logging in, then you may have a hardware issue.
Keep in mind the 2016+ Apple USB-C laptops can power on by opening the lid/display, touching any key on the keyboard (2018+), or by connecting (sometimes even disconnecting) the power adapter (possibly even other devices/cables). With some later models, Apple changed the sensor mechanism used to detect a closed lid/display....this new mechanism requires calibration so it is possible it could go out of calibration or even fail since it is more complex than the older traditional method. Maybe the display is pressing on a key while in your travel case.
If you confirm the battery charge is very low when you first log in, then it may be as others have suggested, perhaps the laptop was not fully powered off when put into the travel case. Just because you select "Shutdown" does not mean it actually finishes the process. I have seen software prevent the full shutdown of a Mac. I personally like to press the Caps Lock key so its LED is lit so when this LED goes dark I'm certain the laptop has powered off since there are no other power LED indicators anymore.
You can try running the Apple Diagnostics to see if any hardware issues are detected. Unfortunately the only useful diagnostic result is one which results in a failure code.
You are going to have to be very observant to try to solve this mystery. Unfortunately this may be a very difficult task.
Several things to consider.
First is the exact model of this laptop. Apple has made so many changes with recent models that the exact model can be very critical here since every year there is some new major change to the previous year.
When you boot the laptop and log into a macOS user account, is the battery charge low? You cannot go by the information presented on the login screen as it may not be accurate or even updated.
Are you just seeing the black screen with battery icon (red)? If so, this does not necessarily indicate a drained battery as I have seen this occur on numerous laptops with our organization even when the battery has a sufficient charge on it. I believe this just indicates some sort of Logic Board issue where it loses contact with the battery (or thinks it loses contact). If the battery has significant charge when you log in and this only happens once in while I would not be concerned, but if it is a regular occurrence, then it likely indicates some sort of hardware issue. If the battery has a very low charge when logging in, then you may have a hardware issue.
Keep in mind the 2016+ Apple USB-C laptops can power on by opening the lid/display, touching any key on the keyboard (2018+), or by connecting (sometimes even disconnecting) the power adapter (possibly even other devices/cables). With some later models, Apple changed the sensor mechanism used to detect a closed lid/display....this new mechanism requires calibration so it is possible it could go out of calibration or even fail since it is more complex than the older traditional method. Maybe the display is pressing on a key while in your travel case.
If you confirm the battery charge is very low when you first log in, then it may be as others have suggested, perhaps the laptop was not fully powered off when put into the travel case. Just because you select "Shutdown" does not mean it actually finishes the process. I have seen software prevent the full shutdown of a Mac. I personally like to press the Caps Lock key so its LED is lit so when this LED goes dark I'm certain the laptop has powered off since there are no other power LED indicators anymore.
You can try running the Apple Diagnostics to see if any hardware issues are detected. Unfortunately the only useful diagnostic result is one which results in a failure code.
You are going to have to be very observant to try to solve this mystery. Unfortunately this may be a very difficult task.
If the Mac is shut down—not sleeping—I'd suspect malfunctioning hardware. Check with Apple Support.
DO make sure that the Macbook is FULLY shutdown - using “Apple -> Shutdown” - BEFORE closing the lid.
If your model doesn’t have a touchbar, turning “on” Caps Lock before shutdown can provide a good visual indication of full power-off.
Why MUST the MacBook Pro be continuously plugged in to prevent the battery from draining completely when it’s shutdown
