Battery question

Discussion in 'MacBook' started by polska9, Feb 22, 2009.

  1. polska9 macrumors member

    Feb 17, 2009
    can i leave my computer plugged in for extended periods of time when im photo editing or while that kill my battery? i read the battery FAQ but this was not covered there
  2. mcavjame macrumors 65816


    Mar 10, 2008
    phased to this universe
    I've have always been told that the battery needs to cycle a discharge in order to keep it's life. I powerbook I had for a few years was only ever plugged in. I had to use it for a presentation once without power and I only had about 20 minutes of battery life before it shut down. Wasn't a nice situation.
  3. polska9 thread starter macrumors member

    Feb 17, 2009
    my previous notebook was very similar in that it died after about 30 minutes and it was always plugged in too.
  4. aluminumapple macrumors regular

    Jan 7, 2009
    if you have applecare, use the battery as much as you want. if it gets to the point where it doesnt last very long goto apple get a new one. Brand new. Free.
  5. Skeletal-dæmon macrumors 6502

    Apr 27, 2008
    Replacing worn out batteries that could still be working with some careful management isn't really the purpose of Applecare.

    The battery will be perfectly fine with you using an intensive app, it will simply drain faster. Over time its health will deteriorate; but if you ensure that you completely discharge and then completely recharge the battery at least once a month (once a fortnight may be better if you're constantly running the battery down heavily) then you may be able to squeeze a far longer life from it.

    Think of this a another way, if you spend a little time looking after your batteries, less of them get dumped in landfill for some little b*****d to pick up and throw through your car window. I hate the Autoglass automated telephone system!
  6. jamse macrumors newbie

    Jan 21, 2009
    lithium rechargeable batteries dont have a battery memory, like nickel cadmium rechargeable batteries, but once they have been produced they begin to deteriorate because of a secondary reaction that goes on within the battery (this applies to all rechargeable batteries). when people tell you to "cycle a battery" every so often that does not extend your battery life. from research and what i have read, fully depleting your lithium ion battery will actually shorten its lifespan, and if you plan to use your laptop without a battery (i believe that if you use your macbook w/o a battery there is a cpu performance penalty, dont quote me on this) keeping it charged to 100% and storing will wear on your batteries life span, it should be left about 80-90% if you plan to store your battery. also, another way the battery wears down is that the cells do not draw power evenly, so each cell in your battery has a different individual charge % after use, when you plug your laptop in power is directed into all the cells, even the cells fully charged, this results in battery wear. batteries are suppose to last about a year maybe a little longer depending how you use it, so dont expect it to have anything close to a 3hr charge after +2 years. after a year most people will have about 300 cycles on their battery which equivates into about 15% loss in capacity, the more cycles that you go through decreases the battery length exponentially. (e.g. my old laptop before i bought my new macbook had about 1000 cycles in two years, due to the nature of my work and uni projects, this resulted in a battery life about 20mins from my original 8hr capacity)

    though the cool thing with the new aluminum macbooks, is that it has a sensor that detects the charge of each of the individuals cells, so it can charge smartly and evenly. it cuts the power to a fully charged cell, instead of bleeding power into that cell to charge another cell (which results in battery deterioration.)

    i hate posting stuff like this because people will still post about how "cycling" batteries will increase battery life, like how people will argue ddr3 has a performance advantage over ddr2, at the moment there is no performance increase, just higher price (this is based on ddr3 having same voltage, but higher frequency compared to corresponding ddr2 with lower frequencies i.e. ddr3 1333 vs ddr 800, they perform about the same). the fact is lithium ion batteries in my opinion have three advantages over nickel cadmium: they have no battery memory, weight, and charge capacity. of course there are more advantages, but those are my thoughts.

    *battery calibration does help your battery life, just not performing every week. just do when apple suggests to calibrate your battery

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