I'm using my MacBook Pro like a desktop sometimes. But for some reason, when I unplug the Power Supply, it is impossible. The MacBook Pro immediately shuts off. When I turn it on by hitting any key on the external keyboard, it wakes up for about 10 seconds but then goes to sleep again.
Sometimes I want to use my MacBook Pro without the Power plugged in to it, just to use the Battery a little bit. And also sometimes when someone else needs my Power Supply.
I couldn't find an option in the system preferences. Is there an trick how to get that work?