MagSafe adapters - power off when not in use??

Discussion in 'MacBook Pro' started by keeper, Sep 11, 2008.

  1. keeper macrumors 6502

    Apr 23, 2008
    Hi All

    Do MagSafe adapters power off when not required to charge the battery or do they use 85w all the time?

    UK power costs have shot up, so i now only use mine when required to reduce cost.

    Cheers Phil
  2. GGJstudios macrumors Westmere


    May 16, 2008
    Once the battery is fully charged, they stop charging.
  3. cubedweller macrumors 6502

    Nov 25, 2007
    I believe as long as the charger is plugged into the wall it will be drawing electricity whether the device is plugged in or turned on. I'm not too sure if the whole 85W is being pulled but it is generally advised that to reduce power consumption when you are not using electronics, unplug their plugs from the wall.
  4. wgr73 macrumors 6502a


    Oct 31, 2005
    New Mexico
    You are correct. It wont be drawing 85W, but it will be drawing minimal current, know as "Parasitic draw". Its nothing to worry about with something as small as an 85W power source.:cool:
  5. CaptainChunk macrumors 68020


    Apr 16, 2008
    Phoenix, AZ
    85W refers to its rated power output under maximum load. Except under extreme circumstances (max CPU utilization, all fans running, optical drive spinning at max speed), you won't see the adapter drawing all 85W.

    This is same in principle to the 1,000W supply in the Mac Pro. Imagine the power bill if that guy was continuously drawing 1kW....

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