Battery Question

Discussion in 'MacBook Pro' started by NavySEAL6, Jan 26, 2009.

  1. NavySEAL6 macrumors 6502a

    Dec 13, 2006
    Ok, so I've had my macbook pro for a while. My first battery was defective, and im now on my second. Ive had the battery for about a year, it has seen 52 cycles, and im at 83% health. I read on the apple website that the battery should get to 80% health after 300 cycles. Naturally, I bring my computer to the apple store to get my battery replaced. The manager gives me a whole big spiel about how it doesnt matter how much you use the battery, its the duration of time you use it. Basically, he told me my battery was in good condition for a year, despite the low number of charge cycles. I got tired of arguing, and he offered me a half price battery so I took it. Did I get hustled or is he right?

    Also now that I have a new battery I want to take care of it as good as possible so what should I do with it in terms of usage? (I know about calibrating and blah blah). Is it harmful to the battery life to keep the computer plugged in and on running 24/7? Do I need to use the battery to keep it in good health? A little help please
  2. adamk77 macrumors 6502

    Jan 6, 2008
    I'd just use it normally without much thought. Just keep it plugged in when you are near an outlet. Every once or twice a month, run it off the battery until it drains down to 50% and then plug it back in.

    I believe these batteries have chips on them that puts it into trickle charge mode when it's almost fully charged. So you don't have to worry too much about overcharging them.

    My normal computing habits are such that I do this without effort or thinking about it. I plug it in when I'm near an outlet. And a few times a month, I decide I have to work from odd locations around the house and feel too lazy to lug around the charger so I end up running it off of the battery.

    I wouldn't worry too much about it and suffer from the paralysis from analysis syndrome :)
  3. NavySEAL6 thread starter macrumors 6502a

    Dec 13, 2006
    Even still, apple promises 80% retention up to 300 cycles. Theoretically, if the computer was plugged in 100% of the time can this be bad for the battery?
  4. SFStateStudent macrumors 604


    Aug 28, 2007
    San Francisco California, USA
    That's a good question. I've tried to plugin every chance I get b/c I had my MB in 2007 die on me, so I'm gun-shy when it comes to using my battery...:eek:

    Presently have a new MBP, with a replacement new battery "0" cycles (received Friday, January 23, '09.
  5. adamk77 macrumors 6502

    Jan 6, 2008
    Actually if you know you won't be running it off of the battery, it's best to take out the battery all together. But I believe when you do that, your machine runs off of only one processor. There's a thread about this.

    That's why the chip is on the battery. Once it reaches almost full charge, it goes into trickle charge mode. Meaning, it takes a very long time to charge that remaining few percent. So you can't really overcharge your batteries. I would think that if you constant ran it off your battery and then recharged, you would be using up your full-cycles more frequently.

    However, I have heard others suggest that once or twice a month, do run it off the battery. But for the most part, you can keep it plugged in.
  6. NavySEAL6 thread starter macrumors 6502a

    Dec 13, 2006
    Ok, well now I'm putting my new battery in. I'm assuming i should let it fully charge first before I unplug it, but is there anything else i should do like leave it plugged in a while, calibrate immediately etc
  7. adamk77 macrumors 6502

    Jan 6, 2008
    You don't have to condition lithium ion batteries.

    Just don't let it drain all the way down.

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