David Weiss

Q: How long will a MacBook Pro sleep, when draining the battery for calibration?

I've heard it's a good idea to completely drain a battery every once in a while, to improve its longevity and the accuracy of the battery's "life meter." I normally wait until it goes to sleep, and then start it up again and go my merry way.

 

But today I thought I'd wait until it was really truly totally drained, or when it stops sleeping. But about how long might that be? Thanks!

Posted on Jun 16, 2016 11:44 AM

Close

Q: How long will a MacBook Pro sleep, when draining the battery for calibration?

  • All replies
  • Helpful answers

  • by Carolyn Samit,

    Carolyn Samit Carolyn Samit Jun 16, 2016 11:45 AM in response to David Weiss
    Level 10 (122,048 points)
    Apple Music
    Jun 16, 2016 11:45 AM in response to David Weiss

    Better to not allow the battery discharge completely. Perhaps down to 25% then charge.

  • by Esquared,

    Esquared Esquared Jun 16, 2016 12:12 PM in response to David Weiss
    Level 6 (8,415 points)
    Mac OS X
    Jun 16, 2016 12:12 PM in response to David Weiss

    Is that a MacBook Pro with a removable battery or not? If the latter, do not calibrate:

    https://support.apple.com/HT201575

  • by Grant Bennet-Alder,

    Grant Bennet-Alder Grant Bennet-Alder Jun 16, 2016 12:13 PM in response to David Weiss
    Level 9 (60,926 points)
    Desktops
    Jun 16, 2016 12:13 PM in response to David Weiss

    I've heard it's a good idea to completely drain a battery every once in a while, to improve its longevity and the accuracy of the battery's "life meter."

     

    You heard WRONG.

     

    Lithium batteries are not subject to the Nickel-Cadmium battery "memory effect". Deep discharge will shorten their life substantially, and provides no benefits whatsoever.

  • by Courcoul,

    Courcoul Jun 16, 2016 12:27 PM in response to David Weiss
    Level 6 (14,193 points)
    Jun 16, 2016 12:27 PM in response to David Weiss

    That was awhile back, modern batteries (or rather, their charging circuits) do not need "calibration". What's more, older batteries may get damaged beyond usability if they are drained too much.

     

    See here:

    About Mac notebook batteries - Apple Support

  • by David Weiss,

    David Weiss David Weiss Jun 16, 2016 1:22 PM in response to David Weiss
    Level 1 (29 points)
    Notebooks
    Jun 16, 2016 1:22 PM in response to David Weiss

    Thanks everyone! I should have specified, this is for an older 2.2GHz model from '07 or '08, and I'm using a Newer Technology replacement battery. This is what Newer says on its website about "conditioning," or what they call "exercising":

     

    - "Exercise" your primary and spare battery once a month. You will actually get a shorter lifetime out of a battery if you use it infrequently as a "backup" battery. To exercise your battery, run your computer on battery power until it shuts down or until you get a low battery warning. Then use your notebook as an acceptable method to charge/recharge your battery.

     

    So I'll just follow their advice and drain to sleep every now and then, and then just plug-in and recharge from there. 

  • by Esquared,

    Esquared Esquared Jun 16, 2016 1:25 PM in response to David Weiss
    Level 6 (8,415 points)
    Mac OS X
    Jun 16, 2016 1:25 PM in response to David Weiss

    Ah, yes. Those you have to calibrate (as in Step 2). And running it empty can take quite a while.

  • by Michael Black,

    Michael Black Michael Black Jun 16, 2016 2:42 PM in response to David Weiss
    Level 7 (24,457 points)
    Jun 16, 2016 2:42 PM in response to David Weiss

    You don't need to do that very often.  The drain to sleep and recharge process does nothing other than calibrate the battery meter/indicator.  Doing it a lot will just age your battery faster than is necessary.  You "exercise" your battery by just regular use - every partial discharge/charge is "exercising" your battery - that is, Lithium cells do last longest with moderate regular use.  They die most rapidly if left wholly idle for long periods, or subject to regular or frequent deep discharges.

     

    Ideally though, since you don't want to drain the battery any more than necessary to calibrate the meter, you really should plug it in when it shuts down due to low battery.  Leaving it sitting for a long period will further deplete the battery, beyond the point that the battery's own SMART circuitry is indicating the minimum safe charge state (which is why it shut it down in the first place as it is very bad to 100% deplete a lithium cell).

  • by jndupuis1,

    jndupuis1 jndupuis1 Jun 16, 2016 2:46 PM in response to David Weiss
    Level 2 (470 points)
    Jun 16, 2016 2:46 PM in response to David Weiss

    I agree with Michael Black!

    Something to consider:

    Just use both batteries under Normal Use conditions swapping out on a schedule such as every 90 or 180 days. You don't want your spare to have a long shelf life and expire, so just alternate the two. You will get max use out of both and extended use by swapping. Three or four times a year. It is a suggestion - you decide what's right for you.

     

    Cheers!!