Macbook pro Mid-2009 battery question.

Discussion in 'MacBook Pro' started by desmondjy, Sep 17, 2010.

  1. desmondjy macrumors newbie

    Sep 28, 2009
    Saw this question on the apple website regarding battery,

    "Does it harm the battery or reduce battery life, to use the AC adaptor for extended periods while the battery is fully charged?"

    Someone answered,

    "I would have to disagree with the others who say that it hurts your battery & reduces battery life by keeping your AC adapter plugged in with a full battery.

    I have done extensive research and asked many apple employees and have always come to the same conclusion. They all say to keep your laptop plugged into an power supply whenever possible. Only use your battery if you have to, in those times when you are not near a power supply.

    Every time you use your batteries power you are adding to the amount of cycles your battery can cycle. If you continually charge your battery to 100% and then take it off the AC Power, and use it all the way down to 0% or even 50% you are taking away from the batteries lifespan. And eventually your battery will not be able to hold a full charge, and eventually will not hold a charge at all, and you will have to buy a new one!

    Use your AC Power as much as you can, but remember to calibrate your battery at least once a month to maintain proper battery health."

    I would just like to know whether this is true. Because i have been recharging every time, even when i'm at home. I'm afraid that keeping the AC adaptor on at all times will harm and reduce the battery life.
  2. cluthz macrumors 68040


    Jun 15, 2004
    Not using the battery will indeed ruin it.

    A friend of mine is working at the IT department on an university and they have over 1000 laptops, the ones that have used the battery least, are the ones that have bad batteries first.

    My 2007 MBP had over 600 charge cycles when I replaced the battery, it still had 60% capacity left. My MacBook Pro i5 already have 170 cycles it still have 100% battery health (actually 99% now, but it goes up and down from charge to charge).
  3. tpg macrumors regular

    Mar 19, 2010
    From the apple website:

    "Exercise Your Machine
    Lithium-ion polymer batteries need to be used for maximum performance. If you don’t use your device often, be sure to complete a charge cycle at least once a month."


    I'm not sure about complete charge/discharge vs continual topping up though. Likewise, I have heard recommendations for each practice, although I guess it will depend on the precise design of the battery & charging circuitry.
  4. AlphaDogg macrumors 68040


    May 20, 2010
    Boulder, CO
    What I do is: When I am at home, I set my MBP up with my external screen, power adapter, backup drive, keyboard, and magic mouse. When at school, I use my MBP from 100% to around 50%. Then I charge up when I get back home.

    All I can recommend is: when at home, keep it plugged in. When you are not at home, do not be afraid to drain the battery. If you do not take it with you away from your house, be sure to drain it at least once per month (according to Apple), but I recommend once per week.

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