MBA - leave it plugged in or not?

Discussion in 'MacBook Air' started by Kg4zlb, May 19, 2015.

  1. Kg4zlb macrumors member

    Kg4zlb

    Joined:
    Dec 11, 2014
    Location:
    Cape Coral, FL
    #1
    I just purchased a new MBA; my first notebook/laptop in many years. I can't seem to find a definitive answer to my question so, is there any guidance about leaving it plugged in to the mains power when its off/sleeping/on ?

    From what I can determine, once the charging plug is green the battery is fully charged and it stops charging - is this true? Can I safely leave it in this state?

    Many thanks for any thoughts!

    David
     
  2. Butchie-T macrumors regular

    Joined:
    Oct 29, 2014
    Location:
    Colorado
    #2
    I have a MacBook Pro that is at home right now and plugged in. I have no problems with it at all, pretty sure you won't either.
     
  3. Kg4zlb thread starter macrumors member

    Kg4zlb

    Joined:
    Dec 11, 2014
    Location:
    Cape Coral, FL
    #3
    Many thanks - that does seem to be the general view and I am grateful for your reply!
     
  4. blesscheese macrumors 6502a

    blesscheese

    Joined:
    Apr 3, 2010
    Location:
    Central CA
    #4
    I'd use google to search the forums--this has been discussed before.

    My memory is that if you leave it plugged in, the power will slowly decrease, until about 96%, and then it will recharge. Leaving it in like this, and not running down the power will kill your battery.

    What you should do is unplug it every 5-7 days, use it until the battery runs down to about 10% or lower, and then plug it back in for another 5-7 days...lather rinse repeat.

    I've been doing this with my 2009 MBA, and I still get over 3 hours of battery life.
     
  5. motrek macrumors 68020

    Joined:
    Sep 14, 2012
    #5
    Yes, you are absolutely right. Plug the laptop in whenever it's convenient. This won't harm the battery. Actually the opposite. What wears a battery out is when you use it, i.e., run the computer on battery power and then charge it back up. So keep it plugged in and that minimizes wear.

    ----------

    Why do you think keeping the battery charged is bad for it?

    I leave my laptop plugged in almost all the time and its battery capacity is currently 102% of the factory rated capacity.
     
  6. bubulol macrumors 6502

    Joined:
    Mar 7, 2013
    #6
    My Macbook Air is all ll time plugged
    Do i need to unplug it time to time?
    My last charging is so far, maybe a month
     
  7. motrek macrumors 68020

    Joined:
    Sep 14, 2012
    #7
    Apple used to recommend that you discharge the battery and recharge it once per month but they stopped recommending that years ago.

    So maybe something changed with the batteries so they no longer benefit from that. Maybe it actually harms newer batteries.

    Or maybe people were misinterpreting Apple's advice and thought that if discharging it once per month was good, then doing it all the time would be better.

    So it's up to you to guess at Apple's motivations. All we know for sure is that batteries wear out when you discharge and recharge them, so you want to keep that to a minimum.

    If it makes some kind of sense to you to discharge/recharge the battery once per month then you're free to do that but we have very little information about why that might be beneficial.
     
  8. avemestr, May 19, 2015
    Last edited: May 19, 2015

    avemestr macrumors regular

    Joined:
    Aug 14, 2012
    #8
    motrek is right.

    It does not harm your batteri to keep it plugged in all the time.

    The worst thing you can do to the battery in your MBA is to let it become fully discharged. Instead charge it when you can. It's designed to quickly get to 80% and then slowly charge to 100%.

    As motrek mentions, Apple previously suggested letting your battery discharge completely once a month. They do not recommend that anymore. My only guess on why they would recommend this, was to calibrate the measurement of the condition of the battery.

    What DO matters is the number of charging cycles you go through. There's a reason that you can view the number of cycles in System Profiler. Apple defines a charging cycle this way:

    "You complete one charge cycle when you’ve used (discharged) an amount that equals 100% of your battery’s capacity — but not necessarily all from one charge. For instance, you might use 75% of your battery’s capacity one day, then recharge it fully overnight. If you use 25% the next day, you will have discharged a total of 100%, and the two days will add up to one charge cycle."

    So if you discharge your laptop entirely every day and re-charge it, you will have had 365 cycles in a year. If you keep it plugged in virtually all the time, you might end up at less than 20 cycles for a year.

    According to Apple:

    "With lithium-ion batteries, the capacity diminishes slightly with each complete charge cycle. Apple lithium-ion batteries are designed to hold at least 80% of their original capacity for a high number of charge cycles, which varies depending on the product."


    So, bottomline: Number of charging cycles matters. Keeping your laptop plugged in all the time reduces/eliminates the number of charging cycles, thus maintaining your battery in good shape.

    Sources:
    http://www.apple.com/batteries/
    http://www.apple.com/batteries/why-lithium-ion/


    Edit:
    Apple actually never said to completely discharge the battery once a month, but merely to "complete a charge cycle once a month": http://web.archive.org/web/20120917221543/http://www.apple.com/batteries/

    They have removed that recommendation. But if you want to, you can probably let your MBA get down to 50% once every two weeks. That way you'll do one cycle per month - without hurting the battery.
     
  9. Newtons Apple Suspended

    Newtons Apple

    Joined:
    Mar 12, 2014
    Location:
    Jacksonville, Florida
    #9
    WRONG!

    This is misinformation and is NOT what you should do.

    With today's batteries, cycles is what counts. The above will only shorten your battery life.
     
  10. blesscheese macrumors 6502a

    blesscheese

    Joined:
    Apr 3, 2010
    Location:
    Central CA
    #10
    Well, think for a minute...try...if I do what I've described in my post (leave it plugged in, then discharge it once a week), at the end of a year, I'll have 52 cycles on the battery...by Apple's own tech document, that means my 2009 MBA's battery will be good for 6 years.

    Current MBA's will be good for about 20 years (Apple says good for 1000 cycles), so, I'm betting you will replace your MB before the battery dies.

    What I have seen happen is, if you don't discharge your battery periodically, the battery monitor calibration goes bad, and starts reporting incorrect usage/time remaining info.

    Really, with the batteries being good for 1000 cycles, you could charge it up overnight, use it for about 2 days, and then charge it again overnight...doing only 180 or so charges per year, you would still need over 5 years to hit the 1000 cycle mark, so maybe worrying about battery life/plugging it in or not is a thing of the past.
     
  11. brdeveloper macrumors 68020

    brdeveloper

    Joined:
    Apr 21, 2010
    Location:
    Brasil
    #11
    You have to take care when your battery frequently reaches the 0-3% mark while it's not being used for a long time. This makes the battery unstable and may reduce its life span. If you reach 1% and a few minutes later you put it too charge it's not really harmful as when you just turn it off and keep it discharged for days (or months).

    My Late-2009 Macbook is around 450 cycles and I still can get nearly 4 hours when watching 480p movies in Netflix (Google Chrome, HTML5 mode, Yosemite).
     
  12. Boyd01 macrumors 68040

    Boyd01

    Joined:
    Feb 21, 2012
    Location:
    New Jersey Pine Barrens
    #12
    I just use my 2013 MBA as suits my needs and don't worry about it. If I'm travelling then it runs on battery most of the time. During the warm months, I use it on the porch on battery. This winter, it set on my desk and was rarely disconnected from an external screen, keyboard, audio interface, etc.

    Coming up on its second anniversary now and I don't see much if any drop in run time.

    Now my 2008 MBP ran mostly on wall power - you couldn't get much more than 3 hours on it when it was new! :p That had dropped to about 45 minutes run time by 2013. The battery went completely dead in 2014. That may have been a different battery technology than the MBA however.
     
  13. bubulol macrumors 6502

    Joined:
    Mar 7, 2013
    #13
    Can i leave my Macbook from long period (like 3 months)?
    I need to travel around the world, maybe not a good idea to pick my MBA with me, especially when i would cross mountains/jungles
    My idead its letting it plugged at home for 3 months
     
  14. dmitrivich macrumors member

    Joined:
    Dec 9, 2014
    #14
    This is what I do. That's what's so liberating - the long battery life. I average 12-14 hours. Even using it on battery most of the time, you're not really going to wear the battery out that quickly. I basically just charge mine when I'm sitting at the chair near the charger, or overnight when it's low or when I think of it. I never move my charger. I've had it for 7 months and there's 63 cycles on it. At that rate, I may or may not need or want to change the battery before the end of the computer's useful life (which I expect to be about 5 years, total). If I do, big deal, it's $120 (or something like that). Not worth my time to worry about; I'll just use the computer how I want to - just as I do my smartphone. Of course, I would leave it plugged in if using at a desk a lot, but I rarely do that.
     
  15. Newtons Apple Suspended

    Newtons Apple

    Joined:
    Mar 12, 2014
    Location:
    Jacksonville, Florida
    #15
    Same conversations about the battery no matter if it is the iPhone or MB. It is almost like a religion.

    Everyone needs to just do what they want if it makes them feel good about their battery. In the end it will not make a big difference.
     
  16. Samuelsan2001 macrumors 604

    Joined:
    Oct 24, 2013
    #16
    Nothing you do will make much difference to the life of your battery it will die in 4-5 years like all of them, lots of cycles will degrade it slightly faster but even cycles are far less important than age.

    You have bought a top of the range portable computer, just use it however you wish and enjoy the freedom you spent your hard earned money to achieve and get the battery replaced when it finally dies.
     
  17. motrek macrumors 68020

    Joined:
    Sep 14, 2012
    #17
    You can leave it plugged in for 3 months no problem at all.

    If unplugged, make sure it has some charge first. Maybe half or full charge.

    If you run the battery down and then leave it unplugged for a few months, it might never charge again.
     
  18. GGJstudios macrumors Westmere

    GGJstudios

    Joined:
    May 16, 2008
    #18
    Run on battery whenever you need to and plug it in whenever you can. You can plug or unplug any time you need to, regardless of the charged percentage, and you never need to completely drain your battery.
    Yes, it's true. Once fully charged, it stops charging and runs on AC power as long as it's plugged in. It cannot overcharge.
    Yes, for months at a time, if needed.

    The link below should answer most, if not all, of your battery/charging questions, including tips for maximizing battery performance. If you haven’t already done so, I highly recommend you take the time to read it.
    Not true at all.
    That is completely unnecessary.
     
  19. jdechko macrumors 68040

    Joined:
    Jul 1, 2004
    #19
    This pretty much describes exactly how I use my Air. I'm usually on it 3-5 hours per day during the work week, so I can almost make it through 2 full days. In practice, it's a lot like how I use my iPhone. Use it however I want and charge it at night or when I need it.

    Factoring in that it doesn't get used nearly as much on the weekends and the time using it while plugged in, I've somehow managed to put fewer than 200 load cycles on it in 22 months.
     
  20. Boyd01 macrumors 68040

    Boyd01

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    Feb 21, 2012
    Location:
    New Jersey Pine Barrens
    #20
    188 cycles in about 23 months here. :)
     
  21. DisplacedMic macrumors 65816

    Joined:
    May 1, 2009
    #21
    i just use my laptop. if i'm near a plug, i plug it in. if it starts to get low on charge, i plug it in. if i think about it at night, i plug it in. if i know i am going to be using it unplugged later, i plug it in.
    so far so good.
     

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