DC A/C Unit For Vehicles

  I would like to create a vehicle a/c system that, instead of using the energy from the vehicle's motor to turn the a/c pump, has an electric DC motor to turn the pump, reducing the drag on the engine and increasing fuel economy.
  The a/c compressor would get mounted near the fire wall along with the DC motor, then connect them and run power to the DC motor. Splice into the alternator for recharge of an auxillary battery, if needed, or get a high output alternator and battery, to resolve the need for a second battery.