Previous 1 2 Next 18 Replies Latest reply: Feb 22, 2015 7:07 AM by LexSchellings
The Teserak Level 1 Level 1 (0 points)

Dear Jedi Master Mac Users: I love my new MacBook Pro! Is it better to let it drain completely or should I just charge it every night.  It is OK to leave it charging over a weekend I am away?

MacBook Pro with Retina display, iOS 7.0.4
  • PlotinusVeritas Level 6 Level 6 (14,705 points)

    Is it better to let it drain completely


    Never do that on purpose, ever.  



    OK to leave it charging over a weekend I am away?


    Dont do that on purpose either




    Keep it plugged in when near a socket so you keep the charging cycles down on your LiPo (lithium polymer) cells / battery, but not plugged in all the time. When not being used for several hours, turn it off.


    "Apple does not recommend leaving your portable plugged in all the time."


    General rule to remember of Lithium batteries is:

    Never drain them LOW  & dont always/often store them HIGH


    While cycle count is commonly seen to be the “miles” on your Lithium Ion pack cell in your Macbook, which they are, this distinction is not a fine line at all, and it is a big misconception to “count charge cycles”


    *A person who has, for example, 300 charge cycles on their battery and is recharging at say 50-60% remaining of a 100% charge has better battery usage and care than another person who has 300 charge cycles at say 15% remaining on a 100% charge. 


    DoD (depth of discharge) is far more important on the wear and tear on your Macbook battery than any mere charge cycle count.  *There is no set “mile” or wear from a charge cycle in general OR in specific.    As such, contrary to popular conception, counting cycles is not conclusive whatsoever, rather the amount of deep DoD on an averaged scale of its use and charging conditions.

                              (as a very rough analogy would be 20,000 hard miles put on a car vs. 80,000 good miles being something similar)

    *Contrary to some myths out there, there is protection circuitry in your Macbook and therefore you cannot overcharge it when plugged in and already fully charged


    *However if you don’t plan on using it for a few hours, turn it OFF (plugged in or otherwise) ..*You don’t want your Macbook both always plugged in AND in sleep mode       (When portable devices are charging and in the on or sleep position, the current that is drawn through the device is called the parasitic load and will alter the dynamics of charge cycle. Battery manufacturers advise against parasitic loading because it induces mini-cycles.)


    Keeping batteries connected to a charger ensures that periodic "top-ups" do very minor but continuous damage to individual cells, hence Apples recommendation above:   “Apple does not recommend leaving your portable plugged in all the time”, …this is because “Li-ion degrades fastest at high state-of-charge”.

                        This is also the same reason new Apple notebooks are packaged with 50% charges and not 100%.


    LiPo (lithium polymer, same as in your Macbook) batteries do not need conditioning. However...


    A lot of battery experts call the use of Lithium cells the "80% Rule" ...meaning use 80% of the charge or so, then recharge them for longer overall life.


    Never let your Macbook go into shutdown and safe mode from loss of power, you can corrupt files that way, and the batteries do not like it.


    The only quantified abuse seen to Lithium cells are instances when often the cells are repeatedly drained very low…. key word being "often"

    Contrary to what some might say, Lithium batteries have an "ideal" break in period. First ten cycles or so, don't discharge down past 40% of the battery's capacity. Same way you don’t take a new car out and speed and rev the engine hard first 100 or so miles.


    Proper treatment is still important. Just because LiPo batteries don’t need conditioning in general, does NOT mean they dont have an ideal use / recharge environment. Anything can be abused even if it doesn’t need conditioning.



    From Apple on batteries:


    Storing your MacBook

    If you are going to store your MacBook away for an extended period of time, keep it in a cool location (room temperature roughly 22° C or about 72° F). Make certain you have at least a 50% charge on the internal battery of your Macbook if you plan on storing it away for a few months; recharge your battery to 50% or so every six months roughly if being stored away. If you live in a humid environment, keep your Macbook stored in its zippered case to prevent infiltration of humidity on the internals of your Macbook which could lead to corrosion.



    Your battery is subject to chemical aging even if not in use. A Lithium battery is aging as soon as its made, regardless.


    In a perfect (although impractical) situation, your lithium battery is best idealized swinging back and forth between 20 and 85% SOC (state of charge) roughly.


    Further still how you discharge the battery is far more important than how it is either charged or stored short term, and more important long term that cycle counts.


    Ultimately counting charge cycles is of little importance.  Abuse in discharging (foremost), charging, and storing the battery and how it affects battery chemistry is important and not the ‘odometer’ reading, or cycle counts on the battery. 


    Everything boils down to battery chemistry long term, and not an arbitrary number, or cycle count.


    Keep your macbook plugged in when near a socket since in the near end of long-term life, this is beneficial to the battery.







    More information than needed for that "in case you wanted to know" feeling:


    Gaming: In cases of heavy and frequent use in gaming it is recommended, if possible, to keep your Mac plugged in since these frequent fast and deep discharges of the battery are not ideal for battery longevity.

    If you were to always keep your macbook battery floating between 20% and 80% charge roughly, then you’d have no other considerations to make about your battery and its care,… except for long-term storage.


    Natural changes of capacity in lithium batteries happens when they undergo cathode degradation at roughly 20% per year where Ion exchange becomes less efficient. Mostly low draining (deep DOD) and to a much lesser degree high standing charge rates accelerate this process. Unnatural capacity for lithium battery charges changes, and chemistry changes in a lithium battery when often pushed or pulled to extremes


    In a lithium battery, deep discharges alter the chemistry of the anode to take up lithium ions and slowly damages the batteries capacity for the cathode to transport lithium ions to the anode when charging, thereby reducing max charge levels in mAh. In short, radical swings of power to lithium cells disrupts the chemical ecosystem of the battery to hold charges correctly which likewise impedes the perfect transfer of lithium ions both in charging and discharging.  In charging your lithium battery, lithium ions are “pushed uphill” (hard) to the anode, and discharged “downhill” (easy) to the cathode when on battery power. Deep discharges, damages this “upward” electrolyte chemistry for the battery to maintain a healthy charge and discharge balance relative to its age and cycles.


    Optimally, in terms of a healthy lithium battery and its condition, it is most happy at 50% between extremes, which is why low-power-drain processors such as the Haswell are ideal on lithium battery health since a partially charged battery with a low-drain processor has, in general, much more usage in hours

    Battery calibration, battery memory, battery overcharging, battery training, …all these concepts are mostly holdovers from much older battery technology, and on older Apple portable Macbooks ranging from early nicads, NiMh and otherwise; and these practices do not apply to your lithium battery and its smart controllers.

    Calibrating the battery on older Apple portable Macbooks with removable batteries.


    There is no calibration of current Apple portable Macbooks with built-in batteries.


    There is no battery calibration with current Apple portable Macbooks with built-in batteries. Lithium batteries have essentially a 0-‘memory’, and all such calibration involve the estimations fed to the system controller on the SOC (state of charge) of the battery over long periods of time as the battery degrades. The software based battery controller knows the battery's characteristics, or SOC and adjusts itself. This is why there is both no need and purpose to periodically deeply drain your macbook battery, since it doesn’t affect the characteristics of the battery, and further still deep discharges are something you should not do on purpose to any lithium battery.


    From BASF: How Lithium Batteries work


    How its made, Lithium batteries

  • alex94598 Level 2 Level 2 (170 points)

    There are no real guidelines for it except


    Let your battery fully drain at least once per month


    If you are not going use your laptop for a couple months, then leave it at around a 50% charge


    Don't leave your computer plugged in all the time when you are using it. It's ok every now and then just don't do it for weeks at a time.


    You have a great computer, enjoy it and try not to worry about the battery. You have a 1 year warranty if anything happens

  • LowLuster Level 6 Level 6 (12,050 points)

    The advice above about letting the battery Drain Fully is completely incorrect, Wrong, Do NOT do That.


    Draining a Li battery to 0% does harm to it. Don't let it get down to below 20-15% before you reconnect the system to the AC charger.


    As for the other post Way to much information, hard to read because of the formatting and fonts and not needed unless you are thinking about a career in the battery industry.



    Short answer, Recharge the battery when it get to 15% or slightly above. Leave it connected to the AC when AC is handy. Leaving it connected to the AC will not damage or degrade the battery. The battery will not overcharge.

  • alex94598 Level 2 Level 2 (170 points)

    LowLuster, it really seems like you have no idea what you are talking about.


    I got all my info from here. Apple's site



    Under standard mainteance it clearly says


    Apple recommends charging and discharging its battery at least once per month


    Which in other terms it clearly means fully charging the battery and fully discharging it.

  • LowLuster Level 6 Level 6 (12,050 points)

    Before you start with the insults why not READ the link you posted. Where does it say to Drain the battery completely and or Fully?

    Then read this.



    Specifically this part.


    Portables with built-in batteries

    Current Apple portable computer batteries are pre-calibrated and do not require the calibration procedure outlined in this article. These computers use batteries that should be replaced only by an Apple Authorized Service Provider.


    And I said to let the battery get to around 15-20% before recharging.




    Then turn that insult around and direct it at yourself.


    Live and learn.


    Bye Bye.

  • LexSchellings Level 5 Level 5 (6,570 points)

    INDEED, Read this

    and all is clear.

    your question about leaving it on the charger over the weekend: no problem at all, it will not overcharge. Even when the the MBP is switched off completely.

    Do not let it on the charger "forever".

    Do not store it for a long time on the charger, but store it when switched off completely with the battery about 50%.

  • PlotinusVeritas Level 6 Level 6 (14,705 points)

    Let your battery fully drain at least once per month



    Wrong, you NEVER do that on purpose, .....ever




    Apple recommends charging and discharging its battery at least once per month

    Which in other terms it clearly means fully charging the battery and fully discharging it.


    Wrong again, discharge in that instance refers to taking it off power and DISCHARGING it from 100% charge down to 20% or so.


    Dont give out counterproductive and incorrect advice please.


    All low discharges are to be avoided, especially on a frequent basis, they will, no if or buts, corrupt battery chemistry and cause premature capacitance failure.

  • LexSchellings Level 5 Level 5 (6,570 points)

    Alex, you are not correct with your statements here: you should not let your battery fully drain at least once per month. That used to be the idea 5-10 years ago (and was meant to reset the battery electronic measurement, not the battery it self). With the modern Li-ion batteries this works counterproductive, it "damages" the battery. The electronics do not need to reset anymore, and if you still would like to do that, you should do a SMC reset.


  • masterwizard155 Level 1 Level 1 (0 points)

    after reading everything i am completly lost, one post say something and the other say another thing, i let my MBP discharge to 20% and charge it, is it ok to do that ? should i do that only if i am away and not at home ?

    Because in a typical day i can recharge my computer 3 times at least...


    Thanks in advance for the tips


    I have a MBP late 2013

  • LexSchellings Level 5 Level 5 (6,570 points)

    Just use your MBP. When you use it connected to the wall outlet, no problem, Once in a while (5-10 days) use it disconnected and let it run on the battery until remaining charge is around 50%, but not lower than 20%, then connect the charger again. You may do that every day or once in two weeks, whatever you like. Letting it go down untill it switches off, is killing the battery when you do that often.

  • masterwizard155 Level 1 Level 1 (0 points)

    thank you for your answer !

  • LexSchellings Level 5 Level 5 (6,570 points)

    you're welcome

  • adsl_keeki Level 1 Level 1 (0 points)

    The best way to extend li-ion battery life (or in another word slow the battery degradation) are by 1) reducing its cycle life, and 2) not charging your battery to 100% and store it (i.e. 4.2V per cell), and 3) not fully discharge it down to like empty (lower than 2.7V). In ordinary laptop with battery removing ability, you would discharge the laptop battery to about 10-15% (3.4-3.5V no load) and remove it for storage and use the laptop solely on AC-DC adapter. When you are on the road, you have no choice but to use the laptop like your iPhone (charge it to full overnight and discharge it when you have no access to power outlet). All laptop including macbook pro has battery management protection built-in, so charging it full to 100% or discharging it all the way to 0% will not be dangerous, but it will accelerate the battery degradation, especially if you charge the battery to 100% and keep it there. To maximum usage runtime, Apple probably set the maximum charge to 4.2V or very near to that.


    Solution: for my macbook pro with magsafe2, I use a thin tape to block the middle connection to prevent the battery from charging and keep the charging percentage around 5-50% (macbook will stop the charge, and draw power from the ac adapter to power the laptop). By doing that, I should be able to slow the battery degradation rate to about 5 times slower compared to a person who kept the battery always fully charged. I would not be worry about battery life if you are on the road. If you always have power access like me, you should opt for the tape method. People with manufacturer capability, like me, can actually machine and assemble an removable extender device that blocks the middle connection and stop the charge when the laptop is plugged-in.

  • LexSchellings Level 5 Level 5 (6,570 points)


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