ElusiveNinja

Q: Question about charging the battery for a long time

I may have asked this question before but I'm going to ask it now just to make sure I fully understand. What happens if I charge my macbook pro everytime I use it, and then discharge it to about 50% once a week, will charging the battery alot decrease the battery life? As in normal the battery will last say about 8 hours, will charging the battery alot decrease it to less than 8 hours?

MacBook Pro with Retina display, OS X El Capitan (10.11.5)

Posted on May 27, 2016 11:56 PM

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Q: Question about charging the battery for a long time

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  • by dominic23,

    dominic23 dominic23 May 28, 2016 3:21 AM in response to ElusiveNinja
    Level 8 (41,651 points)
    Mac OS X
    May 28, 2016 3:21 AM in response to ElusiveNinja

    ElusiveNinja wrote:

     

    IWhat happens if I charge my macbook pro everytime I use it, and then discharge it to about 50% once a week, will charging the battery alot decrease the battery life?

    Number of cycle counts will have an effect on battery life.

     

    ElusiveNinja wrote:

     

    in normal the battery will last say about 8 hours, will charging the battery alot decrease it to less than 8 hours?

       

    As the battery ages, full charge capacity will decrease and "say about 8 hours" will not be the case.

     

     

     

    • Cycle count: Batteries are expected to function for a certain number of cycles. This number represents the sum of total and partial discharge cycles throughout the life of the battery. You can see the cycle count limit for your computer by reviewing Determining battery cycle count for Mac notebooks.

     

    • Consumed / depleted: Consumable parts are those that deplete over time as their internal components are used. Batteries, due to their chemical components, are considered consumables, and slowly over time they lose their ability to hold a charge. If the cycle count on a battery exceeds its expected limit, the battery is considered consumed.

     

     

  • by ElusiveNinja,

    ElusiveNinja ElusiveNinja May 28, 2016 3:56 AM in response to dominic23
    Level 1 (4 points)
    Mac OS X
    May 28, 2016 3:56 AM in response to dominic23

    But won't always charging decrease the number of cycles used? So won't the full capacity actually take a looong time before the "8 hour life" decreases?

  • by dominic23,

    dominic23 dominic23 May 28, 2016 5:11 AM in response to ElusiveNinja
    Level 8 (41,651 points)
    Mac OS X
    May 28, 2016 5:11 AM in response to ElusiveNinja

    Running the computer on battery reduces charge level, releases the stress and prolong the battery life.

    You can keep it always plugged in, but at least twice a month run the Mac using the battery

    so that battery charge level drops to 50%, thus completing a Battery cycle, the so called “exercise the battery” factor.

     

    There are three factors involved.

     

    Battery cycle count.

    Age of the battery

    The stress the battery goes through.

     

    We cannot take the Cycle count as the  sole  battery health determining factor.

  • by danielfromrandolph,

    danielfromrandolph danielfromrandolph May 28, 2016 9:04 PM in response to dominic23
    Level 1 (57 points)
    iPad
    May 28, 2016 9:04 PM in response to dominic23

    Let the battery run down on occasion, then recharged to full charge

  • by steve359,

    steve359 steve359 May 28, 2016 9:31 PM in response to danielfromrandolph
    Level 6 (14,032 points)
    May 28, 2016 9:31 PM in response to danielfromrandolph

    DO NOT run it dead.  That reduces battery life.  Down to 30% is sufficient ... you should be able to find a few minutes here and there to add a few more mAh to keep it 30% or above.

  • by ElusiveNinja,

    ElusiveNinja ElusiveNinja Jun 3, 2016 12:48 AM in response to dominic23
    Level 1 (4 points)
    Mac OS X
    Jun 3, 2016 12:48 AM in response to dominic23

    This just came up in my mind, so is there no point to conserving cycle counts because eventually the battery is going to age? And even if the battery is old with a low cycle count it'll still need replacing?

  • by dominic23,

    dominic23 dominic23 Jun 3, 2016 6:05 AM in response to ElusiveNinja
    Level 8 (41,651 points)
    Mac OS X
    Jun 3, 2016 6:05 AM in response to ElusiveNinja

    ElusiveNinja wrote:

     

    so is there no point to conserving cycle counts because eventually the battery is going to age? And even if the battery is old with a low cycle count it'll still need replacing?

     

    Yes. That is correct.

  • by Allan Jones,

    Allan Jones Allan Jones Jun 3, 2016 7:29 AM in response to ElusiveNinja
    Level 8 (35,141 points)
    iPad
    Jun 3, 2016 7:29 AM in response to ElusiveNinja

    To support Dominic's point, I've been here a long time and I've seen too many posts with this approximate working:

     

    "I don't understand why my battery failed! I never use the comuter on battery!"

     

    Apple has dumbed down most of their good tech articles on battery performance but the old verions talked about the battery needing to be used--"keeping the electrons flowing". Like a human muscle, if not used a battery will attrophy and die.

  • by Courcoul,

    Courcoul Jun 3, 2016 7:43 AM in response to ElusiveNinja
    Level 6 (14,193 points)
    Jun 3, 2016 7:43 AM in response to ElusiveNinja

    The Li-Ion battery chemistry used nowadays is inherently unstable. The system will degrade whether it is used or not. From what we've gathered observing Apple's demeanor on these matters, they are betting on an average life of ~4 years, giving them a margin from having to replace for free within the 3-year warranty+AppleCare period. My old Late-2011 MBP's battery started circling the drain going into its 5th. year and had to be replaced on my dime. I dread the day when the Retina does the same. So:

    • Use it, enjoy it, take advantage of it while it lasts. Gonna lose it whatever you do.
    • Avoid deep/total discharges, especially as it gets older.
    • Keep it as cool as feasible, both in use as well as in storage. Heat kills all batteries.
    • More info: http://batteryuniversity.com/