How to disable battery charging? From the pmset man page:


  POWER SOURCE ARGUMENTS
  
  -g with a 'batt' or 'ps' argument will show the state of all attached power sources.
  
  […] Certain Apple battery calibration tools may temporarily disable
  battery charging, even though your Apple portable is plugged into AC
  power.
  
  Such tools will never surprise you with this behavior; you will know
  it's happening. This state will be reflected in an additional line of
  output to 'batt' or 'ps' readings, including the pid of the app
  inducing this behavior.

     'ChargeInhibit':    1432



So, does any piece of publicly available software exist to force the battery not to charge?
If you use a small piece of tape to block the middle (signal) pin on your MagSafe charger, your Mac will not charge because it can't identify the charger.