Left MBA fully discharged overnight bad for battery?

Discussion in 'MacBook Air' started by asenna, Nov 15, 2012.

  1. macrumors newbie

    Oct 30, 2012
    I left my MBA fully discharged overnight, is that bad for the battery? I know lithium batteries don't like being discharged.
  2. macrumors 6502a

    Jan 5, 2011
    No, because it wasn't "fully discharged", it was just below the voltage required to run the computer. There is a chip dedicated to keeping your battery from actually discharging or overcharging.
  3. macrumors 68020


    Jan 11, 2002
    Bay Area, Ca.
    Try not to do that again. I killed both my PowerBook G4's battery and my MacBook's battery by running out of juice and then forgetting to charge them for a day or so. When I got around to trying to charge them, the computer wouldn't recognize the battery.

    The same dang thing happened to my bro's MacBook battery too!

    Basically, there has to be enough power for the battery's control unit to work, and if it manages to get too low (like, you run the computer down to the point that it won't even turn on AT ALL), then after some time there won't even be enough power for the control unit, and unless the control unit has power, it won't let the battery charge.
  4. thread starter macrumors newbie

    Oct 30, 2012
    Perhaps the older batteries were more susceptible to this? There was a change in battery technology/performance when they moved up from 300 cycles to 1000 cycles of guaranteed capacity. What year was your brothers macbook?

    And cheers to a Bay Area member. Its wet out there today drive safe :D
  5. 2IS
    macrumors 68030

    Jan 9, 2011
    The man speaks the truth. There's essentially a "cut off switch" with laptops, once the voltage drops below a certain level, it will simply stop providing power to the machine.
  6. macrumors 6502a

    Aug 22, 2005
    I doubt it causes harm; Apple actually instruct you to do it for older MacBooks to calibrate the battery/time remaining thing, but say it's not necessary for newer models. They don't say it's harmful.

  7. macrumors 604

    Jul 29, 2003
    Silicon Valley
    The battery controller doesn't actually let the battery fully discharge. It will shut the MBA down before a dangerously low level. A consumer product Li-Ion battery is designed for several 100 to over a 1000 full discharge/charge cycles before losing half their capacity (and many many more partial cycles), so at most you will lose a fraction of a percent of your battery capacity.
  8. macrumors Westmere


    May 16, 2008
    I wouldn't do it on a regular basis, but one time isn't going to hurt anything.

    The link below should answer most, if not all, of your battery/charging questions. If you haven't already done so, I highly recommend you take the time to read it.

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