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  1. #1


    Member Since
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    Can MacBook Pro overcharge?
    Hello,

    Just a little question. When the charger shows the MacBook has charged to its full, does it continue charging and weakening the battery if I donīt take off the charger? Wondering if I can let the computer charge over the night without weakening the battery.

    I hope you understand the question and help me.

    Thanks.

  2. #2


    Member Since
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    According to what I read the school of thought is that you should keep the computer on power whenever you can. I personally dont leave it on over night unless it needs too charge because it's justa my own quirk lol. But from what I gather what kills the battery is the number of charge cycles that you put it through( from 100-0%). And it seems to be true being that my laptop is 4 years old and I stil, get several hours charge out of my battery doing normal internet and email functions.. Hope this helps

  3. #3

    That's Angel's Avatar
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    I'm actually hoping for more opinions on this, too. I'm in the habit of unplugging once I hit 100% to prevent overcharging. People who have older models than mine (late 2011) tell me to keep it off the charger often. But on heavy use days, I'm draining down to about 8%, recharging to 100%, and draining back down to 40% before I stop working.

    Right now I'm at 65%. Not too sure what the best course of action for me should be.

  4. #4

    _Stormin's Avatar
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    As I understand, new laptops have batteries and charging systems that do not allow them to overcharge.

  5. #5

    bobtomay's Avatar
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    There is no reason to unplug the charging cable whatsoever just because it hit 100%. If you're sitting next to the plug - plug it in.
    There are no compelling reasons to unplug it "just because".

    There are no "opinions" needed related to "overcharging". It will not overcharge.
    I cannot be held responsible for the things that come out of my mouth.
    In the Windows world, most everything folks don't understand is called a virus.

  6. #6

    pigoo3's Avatar
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    Quote Originally Posted by _Stormin View Post
    As I understand, new laptops have batteries and charging systems that do not allow them to overcharge.
    Older laptops have been this way for years & years & years...I'm talking since the 1990's. Nobody wants a laptop that can over-charge the battery!

    - Nick
    - Too many "beachballs", read this: Beachballs
    - Computer seems slower than it used to? Read this for some slow computer tips: Speedup
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  7. #7

    That's Angel's Avatar
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    Quote Originally Posted by bobtomay View Post
    There is no reason to unplug the charging cable whatsoever just because it hit 100%. If you're sitting next to the plug - plug it in.
    There are no compelling reasons to unplug it "just because".

    There are no "opinions" needed related to "overcharging". It will not overcharge.
    What's your compelling reason not to unplug at 100%?

    I asked for more opinions because the people I've interacted with are split on the concept. Some Mac owners, even people who own newer models from 2010 to present, have recommended unplugging. You, on the other hand, seem certain that it's not necessary. I want to know what's changed. Overcharging is something people have guarded against from cell phones to portable DVD players.

    So yes, a discussion on the pros and cons, and the possibility for a link to something that I may have missed with regard to overcharging, is pretty compelling to me.

  8. #8


    Member Since
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    Virtually every laptop made after 2000-2001 has technology built in to prevent overcharging of the battery. There is no reason to unplug the laptop just to prevent something that has already been addressed. The main culprit to diminishing battery life is the number of charge/discharge cycles, not leaving it plugged in at 100%. Not sure what you are looking for as a "compelling" reason not to unplug the laptop at 100%, but extending the life of the battery is a pretty compelling reason for me personally.
    -------------------------------------------------
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    2.6 GHz Core i7 | 16GB | 1TB SSD | OS X Mavericks 10.9.3

  9. #9

    pigoo3's Avatar
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    Quote Originally Posted by That's Angel View Post
    What's your compelling reason not to unplug at 100%?
    I've answered this question what seems a "bazillion" times! There is no need to unplug a laptop when the battery hits 100% charge (assuming someone is sitting next to a power outlet).

    Unplugging the laptop will only (if next to a power outlet) cause unnecessary battery "charge cycles" to accumulate. Older Macintosh laptop batteries (the user removable/replaceable type) had a battery lifespan of 300 charge cycles. The newer Macintosh laptops with the non-user replaceable/removable batteries have a battery lifespan of 1000 charge cycles.

    What is necessary for a laptop that is plugged in most of the time (like my laptop)...is every 2-3 weeks unplug the battery for 1-2 hours...to let the battery drain partially. This allows the battery electrons to flow in the opposite direction (discharge) versus the other direction (charging). For optimal battery life...the battery electrons need to flow in both directions (at least occasionally).

    I have a 2007 MacBook Pro that I've had for about 2.5 years. The battery was basically brand new when I got the computer (new to me). The battery currently has 29 total charge cycles on it (that's NOTHING for a 2.5 year-old battery). My laptop is plugged in about 99.5% of the time...and is pretty much only unplugged when I discharge the battery for a couple hours every 2-3 weeks to allow the elecrons to flow in the opposite direction.

    And most importantly...my 2.5 year-old battery with a total cycle count of 29...still gets 4-5 hours total runtime when running on the battery (just what an almost brand new battery is supposed to get).

    If someone feels that unplugging the laptop when the battery is charged to 100% (when using it next to a power outlet)...then using it on battery power till it gets low...then plugging it in again...I wish you lots of luck.

    By following this procedure (depending on how much the laptop is used)...the battery cycle count will go thru the roof...and don't be surprised if in 6-12 months the battery needs to be replaced (due to high battery cycle count)...and running the laptop on the battery unnecesarily in situations when a power outlet is conveiniently located nearby.

    Of course then a new Mac-Forums thread will be started asking..."Why has my battery worn out so quickly...I have only had it for less than a year?"

    - Nick
    - Too many "beachballs", read this: Beachballs
    - Computer seems slower than it used to? Read this for some slow computer tips: Speedup
    - Almost full hard drive? Some solutions. Out of Space
    - Apple Battery Info. Battery

  10. #10

    BrianLachoreVPI's Avatar
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    There's really not much to discuss as has already been pointed out. Under no circumstances could Apple release a laptop with a charging circuit that could overcharge. These batteries do not react well to that - they go boom and/or start a fire. You can rest assured that you're not going to overcharge - that goes for just about everything these days.

  11. #11

    Doug b's Avatar
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    Well, here's a different "opinion": It's not so much about "over charging" to the point of where a battery would explode.. because that wouldn't happen under any ordinary circumstances.

    You can however, shorten the overall life of your battery if you keep it plugged in all the time. Pigoo I feel, has been fairly fortunate, if it is indeed true that he's still getting about 4-5 hours worth of battery life when it's not plugged in. Though I'm sure he's really good about discharging the battery every so often, which is very important.

    While it's true that today's battery technology is "better" than it used to be (don't ask me to quantify that in terms of relevance to years/time), it's still not perfect, and "memory effect" is still a very real thing. What Pigoo said is true... the cells in these batteries need and want to be in a state of recycled motion most of the time.

    If you were to leave the battery charging 24/7 for a few years, I can absolutely guarantee that as soon as you run the MBP on the battery alone, it would die in a matter of minutes. Literally. This then should prompt us to figure out when, and how often it is good to run off of battery and when to charge.

    I suppose that if one was to run off of battery alone for each session at their computer, and only charged until it was topped up again, then ran it down again, the argument could be made that you'd only be able to get so many charge cycles out of the battery before it died. So then, a healthy compromise should be made.

    I personally wouldn't leave my battery plugged in all of the time for months at a time, or even just a month. The key here is to "condition" your battery. And by condition, I do actually mean "get it accustomed to" something. Even if getting accustomed to, happens to mean making sure that it charges and runs on battery power alone, at random times.

    Maybe that should mean leaving it plugged in for a few days, and then unplug it and run it down a bit, or more than a bit. Then maybe the next time leave it plugged in for a week, and then let it drain down almost all the way then recharge etc.. .

    My point is, that it is NOT true that leaving it plugged in constantly will do no harm to the overall life and longevity of the battery. Apple stores leave their machines plugged in constantly, but they can afford to, because they don't have to replace the batteries. They simply replace the machines when a new one comes out!

    Ironic timing, this thread. I had a friend come over the other day, and I helped her upgrade to Lion. Her battery read 78% when we turned it on, and within about 20 minutes or less, the MBP died. No warning, nothing.. just died. It wouldn't turn back on until I plugged it in.

    Funny thing is that it recharged to 100% in less than half an hour. I unplugged it again just to see what was happening, and the battery was draining like water down a plughole. I asked her what kind of battery life she usually got, and her reply was that she had no idea because she has not unplugged it in the 2+ years she has owned it! Well that's just great...

    And this is definitely not the only time I've seen this happen, trust me on that.

    I think that one easy solution might be to shut the machine off when you go to sleep, and unplug it. There are obviously other ways to go about it... but I can not recommend keeping it plugged in all the time. And to keep it all "pc", I'll follow up with an "IMO".

    Doug

  12. #12

    pigoo3's Avatar
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    Quote Originally Posted by Doug b View Post
    ...Pigoo I feel, has been fairly fortunate, if it is indeed true that he's still getting about 4-5 hours worth of battery life when it's not plugged in. Though I'm sure he's really good about discharging the battery every so often, which is very important.
    Definitely what I've been doing for at least the past 2.5 years...and of course I don't just follow this procedure because some "crazy-wild" thought entered my mind...it's based on various expert info I've been exposed to over the years...for example this Apple document:

    Apple - Batteries - Notebooks

    Which states in the "Standard Maintenance" section:

    "For proper maintenance of a lithium-based battery, it’s important to keep the electrons in it moving occasionally. Apple does not recommend leaving your portable plugged in all the time. An ideal use would be a commuter who uses her notebook on the train, then plugs it in at the office to charge. This keeps the battery juices flowing. If on the other hand, you use a desktop computer at work, and save a notebook for infrequent travel, Apple recommends charging and discharging its battery at least once per month."

    I don't follow this 100% to the letter (my laptop is plugged in pretty darn close to 100% of the time)...but I do follow the "spirit" of the message...which is to:

    - keep the electrons flowing in both directions (charge & discharge)
    - I do this at least occasionally (every 2-3 weeks)
    - I do a partial discharge every few weeks (usually 100% down to 80-85%)...versus possibly a full discharge (which the Apple article mentions...but is not totally clear about if it's supposed to be a full or partial monthly discharge)

    I've had great luck/success following this procedure so far...so if it ain't broke...don't fix it!

    - Nick
    - Too many "beachballs", read this: Beachballs
    - Computer seems slower than it used to? Read this for some slow computer tips: Speedup
    - Almost full hard drive? Some solutions. Out of Space
    - Apple Battery Info. Battery

  13. #13

    rabbitjetta's Avatar
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    I leave my macs plugged in at all times when i am at home and then on batteries when i am traveling.

  14. #14


    Member Since
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    I hear what people are saying, and I have read Apple's advice on battery life. But hang on a minute, these machines are portables! By definition you should be able to run from the battery most of the time.
    I use mine like that. I think I have about 100 battery cycles in about 18 months. I think that means that I should get somewhere near 15 years out of the battery assuming the drain was linear. I can't see me still using this machine in 15 years time.

  15. #15

    pigoo3's Avatar
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    Quote Originally Posted by neilf View Post
    I hear what people are saying, and I have read Apple's advice on battery life. But hang on a minute, these machines are portables! By definition you should be able to run from the battery most of the time.
    You're absolutely right....but laptops/notebooks have become so popular & powerful...that they are desktop replacements for many people...and are only occasionally used for their portability features.

    Also, the question isn't so much about being able to run a laptop off the battery 100% of the time...it's about can a MacBook Pro overcharge (thread title)...and should the laptop be unplugged when the battery reaches 100% charge.

    Quote Originally Posted by neilf View Post
    I think I have about 100 battery cycles in about 18 months. I think that means that I should get somewhere near 15 years out of the battery assuming the drain was linear. I can't see me still using this machine in 15 years time.
    I'm thinking you may not be using your laptop quite as much as some/many people. If you:

    - use your laptop on battery power 100% of the time
    - if you currently have 100 battery cycles in 18 months
    - that you have a Mac laptop with the newer 1000 cycle battery
    - and you get approx. 8 hours of runtime on a single charge (which may actually be a bit optimistic)

    Then doing the math...this works out to be:

    - 18 months = 547.5 days
    - 100 battery cycles x 8 hours/cycle = 800 hours of total use

    Thus 800 hours / 547.5 days = 1.46 hours of computer use/day. I can see this being a realistic number for a busy person (work, house, kids, wife, etc.). But I think that many of us on Mac-Forums are MUCH more heavy users of our computers.

    As far as the 15 year estimate (based on the usage patterns mentioned above & assuming linear degradation of the battery)...well...it does sound good in theory...but I think in real life there are slow chemical changes in the battery that would make getting 15 years of use out of a battery difficult.

    But on the other hand...I have an Apple "Clamshell" iBook from 2000 (12 years old now)...and it's battery is still working (get about 1.5-2.0 hours on a full charge)...but I have no idea if it is the original battery.

    - Nick
    - Too many "beachballs", read this: Beachballs
    - Computer seems slower than it used to? Read this for some slow computer tips: Speedup
    - Almost full hard drive? Some solutions. Out of Space
    - Apple Battery Info. Battery

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