When we deal with fan speed and fan noise problems on MacBook Pros, we learned an intersting tip or information about power management on MacBook and MacBook Pros.
Here it is:
If the battery is removed from a MacBook or MacBook Pro, the computer will automatically reduce the processor speed. This prevents the computer from shutting down if it demands more power than the A/C adaptor alone can provide.
Important: It is strongly recommended that you do not use your MacBook or MacBook Pro while the battery is removed. Accidently bumping the A/C adaptor could disconnect power and shutdown the computer. Any information that was not saved on your computer would be lost