MBA cant drive monitor with out AC power?

Discussion in 'MacBook Air' started by alpha752, Mar 16, 2011.

  1. macrumors newbie

    Feb 25, 2011
    I have a 2010 13" Ultimate. I connect it via HDMI to my 21" Acer monitor and it works fine. Today I noticed that the AC power was disconnected, and it wouldnt connect to my monitor. It was wierd, because if I opened the lid, it would connect and power the external in dual monitor mode, but it would not drive the external monitor as a single screen (I do have resolution set to 1080p. Once I plugged in the Magsafe, it started up the monitor no problem.

    Is this a known thing? I didnt think driving a slightly bigger screen would cause an issue like that, I figured it would drain the battery faster.

    Its usually not a problem to leave the MBA plugged in when docked to the monitor, but I happened to need the plug for something else this time. Is this how it should be or what?
  2. macrumors 601


    Feb 6, 2010
    On the fence
    That's normal. Apple notebooks will not use "clamshell" mode without being plugged in. They will dual screen fine, however. No idea why it's that way.
  3. hfg
    macrumors 68030


    Dec 1, 2006
    Cedar Rapids, IA. USA
    Here is the Apple support document on clamshell mode:

    If you are using a Bluetooth keyboard and mouse on a Bluetooth enabled Apple portable:

    Make sure the computer is plugged in to an outlet using the AC power adapter.
  4. thread starter macrumors newbie

    Feb 25, 2011

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