Why did my MacBook Air get faster with new battery?

Discussion in 'MacBook Air' started by booyahbooyah, Jan 7, 2015.

  1. booyahbooyah, Jan 7, 2015
    Last edited: Jan 7, 2015

    booyahbooyah macrumors regular

    Sep 11, 2011
    I've been running my MBA (11", mid-2011, Yosemite) with a dead battery for about a month (i.e. always connected to power). I just swapped out the battery with one I got at a value-price off of Amazon.

    The MacBook is now running twice as fast.

  2. filmbuff macrumors 6502a


    Jan 5, 2011
    Because the CPU is throttled when battery voltage is unacceptably low (or the battery is removed)
  3. booyahbooyah thread starter macrumors regular

    Sep 11, 2011
    Interesting. Any good reason idea why?
  4. stefanski macrumors member


    Apr 11, 2004
    From a no longer existing Apple support document...

    Apple essentially down-clocks the CPU to prevent the system from shutting down if it happens to demand greater power than the AC adapter alone can provide:

    "If the battery is removed, the computer will automatically reduce the processor speed. This prevents the computer from shutting down if it demands more power than the A/C adapter alone can provide."

    If you google it you will find plenty of reports as far back as 2008. It also happens with my MBP from 2009 which I ran for a long time without battery after it blew up. Now, after installing a new battery, it runs noticeably quicker.
  5. Newtons Apple macrumors P6

    Newtons Apple

    Mar 12, 2014
    Jacksonville, Florida
    That was a good reason and the truth.:rolleyes:
  6. John marts macrumors member

    Sep 20, 2014
    I've noticed my computer is a little sluggish at under 10% battery. I guess this is for the same reason?
  7. satinsilverem2 macrumors 6502a


    Nov 12, 2013
    Richmond, VA
    I ran my 2011 Macbook Pro without a battery for around 2 months and noticed a severe cut in processing power. I think OS X automatically down clocks to half speed or to 1GHz depending on model. From what I was seeing my 2.7GHz i7 wouldn't go above 1GHz.
  8. motrek macrumors 68020

    Sep 14, 2012
    You can search for "Intel Power Gadget" and install that and it will tell you what frequency your CPU is running at, plus how much power it's drawing and what its temperature is, FYI.

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