rMBP alwayus plugged in - OK for battery?

Discussion in 'MacBook Pro' started by EricT43, Jul 14, 2013.

  1. EricT43 macrumors regular

    Joined:
    Oct 5, 2011
    #1
    Most of the time that I use my rMBP, it is attached to my ATD and plugged into power. Will it harm my battery to use it like this, or should I unplug it occasionally to cycle the battery a bit?
     
  2. Ih8reno macrumors 65816

    Ih8reno

    Joined:
    Aug 10, 2012
    #2
    From what I understand you have to cycle the battery once in a while and recalibrate it once a month.
     
  3. Yahooligan macrumors 6502a

    Yahooligan

    Joined:
    Aug 7, 2011
    Location:
    Illinois
    #3
    No need to recalibrate it, it is good to exercise it once a month or so but that said I leave mine plugged in and connected to my ATD the vast majority of time and my battery health is still just fine a little over a year later.
     
  4. priitv8 macrumors 68020

    Joined:
    Jan 13, 2011
    Location:
    Estonia
    #4
    From my own experience with cMBP battery - if you don't use it on battery at all, the battery's maximum charge capacity will gradually diminish to the point where OS X starts to demand battery replacement.
     
  5. Ifti macrumors 68000

    Joined:
    Dec 14, 2010
    Location:
    UK
    #5
    Use the battery one every few weeks just to keep the cells flowing around nicely.
     
  6. opinio macrumors 65816

    Joined:
    Mar 23, 2013
    #6
    Yes that's fine. I have left my MacBooks plugged in for a few years and my batteries are in excellent shape. The mac switches to battery power when it is approx 95-100% so you actually use less battery.
     
  7. nickandre21 macrumors 6502a

    Joined:
    Jun 21, 2012
    #7
    its usually better to use the batteries atleast once in a while, My white macbook was used on power supply continuously which hampered its life. Either ways a battery has to go someday so its totally upon you.
    I charge my retina macbook and then use it of the battery when its low again i find an outlet and charge back. Im constantly out of home hence my 12 days old macbook has a load cycle count of 33, gives me a good battery life of 6 hours if im writting some scripts or listening to music and 2-3 hours when working on fcp or logic pro.
     
  8. EricT43 thread starter macrumors regular

    Joined:
    Oct 5, 2011
    #8
    Thanks for all the feedback, folks. I suppose I will just unplug the power and let it run dry once in a while to keep it healthy.

    Opinio, I don't quite understand what you said here, can you explain?
     
  9. opinio macrumors 65816

    Joined:
    Mar 23, 2013
    #9
    I can't remember the exact figures behind it but Macs and iOS devices when they hit 100% on the charge will use the charger to run the device and do not feed of the battery. The charger will not 're-charge' until the battery capacity drops below a certain level, which I recall is about 95% (could be 96 or so as well).

    That is why when you keep the MacBook plugged in and it hits 100%, the battery actually still decharges back to about 95% then it recharges again. There have beena few posts ont he forum about why does my battery decharge while plugged in. Thatis the reason. Basically the Macbook is running off the charger (not battery) during that period, but the battery is decharging due to a trickle being used.

    So if you leave a Macbook plugged in permanently, it will go from 100% to about 95 (slowly due to a trickle being used) and back to 100% quickly (charging) etc etc. During the decharging period from 100 to 95 it is runnign off the charger, not battery.

    All this means you are using the charger for the majority of the time to run the MacBook and the battery is going from 100 to 95 on a slow unused decharge and back to 100 on a full charge. Also you are limiting the full charge/decharge cycles on the battery which it what ultimately wears down the battery.

    I have seen a few posts on this so I am sure someone else has the exact percentages that trigger the charge.

    I do the full decharge/recharge thing every few months just to remind the Mac of the full capacity of the battery. I find the Caffeine app works really well for this because it forces the Mac to stay on.
     
  10. Yahooligan macrumors 6502a

    Yahooligan

    Joined:
    Aug 7, 2011
    Location:
    Illinois
    #10
    Interestingly, coconutBattery shows that it does do a slow discharge of the battery after it reaches 100% but this seems to be temporary. Seems my battery is doing just fine being connected to power 90+% of the time. :)

    Earlier today it was this...

    [​IMG]

    And it had been at 97% for some days, but then it jumped down to 95% and the charger kicked on. After reaching 100% with the trickle charge it now shows this...

    [​IMG]

    And eventually the battery usage will go back to 0.0 Watt.
     

    Attached Files:

  11. sholzer macrumors regular

    Joined:
    Jun 21, 2013
    #11
    FWIW, I have pretty much never left my computer on the charger for more than charging over night. I have over 1200 cycles on the battery and istat says my battery's health is at 87% (6032 mAh out of designed 6900 on coconut battery) and I still get 5 or so hours of browsing/word processing to a charge.
     

Share This Page