Prolong battery life???

Discussion in 'MacBook Air' started by still in school, Mar 13, 2009.

  1. still in school macrumors 6502

    Feb 21, 2009
    I want to prolong the battery life as long as possible. If I am sitting at my desk with an available ac outlet and my battery is already full. Is it better to run off the ac adapter? Is it harmful?
  2. Macjames macrumors 6502a

    Dec 12, 2007
    Yorkshire, England
    To prolong the battery life you need to let it drain completely once a month, as far as i am aware running it constantly from the ac is not good for the battery.

    EDIT: Heres a link to the Apple advice
  3. SeanU macrumors member

    Feb 2, 2009
    Apple is pretty good...

    I wish Apple gave you more control over charging thresholds. Li-ion batteries do not like to be fully discharged. The only reason Apple (and others) recommend a full discharge is so that their battery meter is more accurate.

    Mac's won't charge the battery if it is just a few ticks under 100% which is a good thing. Apple considers a charging cycle to be a full 0 - 100% battery charge... so if your battery drops to 50%, you plug in and charge to 100%, that is 1/2 a cycle.

    The 2 best pieces of advice I have gotten about maintaining batter life are
    1) When the battery drops to 30% plug it in and charge.
    2) When storing the laptop for extended periods, do not charge it fully. Leave it at 50 or 60%.

    Other than that, just use your laptop the way you want to. These batteries lose capacity over time, as well as charge cycles. It will need to be replaced someday.

  4. SeaneyC macrumors member

    Jan 27, 2009
    There is no way in a modern device to fully discharge a Li-Ion or Li-Polymer battery, the circuitry between the battery and device prevents this no matter how hard you try.....

    Which is why they recommend doing a full discharge every so often.
  5. still in school thread starter macrumors 6502

    Feb 21, 2009
    well since macs won't let you charge a tick over 100%, and if i keep the ac adapter in, wouldn't that mean i'll be using pure a/c line and avoiding use of battery at all?
  6. Zedsdead185 macrumors 6502

    Sep 14, 2006
    Hmmm, i would probably suggest unpugging it when you need. I remember being in the same boat as you just over 12 months ago with my new at the time macbook pro. Well, most of the time i use it plugged in, occasionally unplugged, and i think i may have ruined the battery. I've just calibrated my battery again today and coconut battery is telling me the max capacity it can now hold is only 36% of what it used to be :(
  7. still in school thread starter macrumors 6502

    Feb 21, 2009
    wow, thanks for your input!
  8. manhattanboy macrumors 6502a


    Jan 25, 2007
    In ur GF's bed, Oh no he didn't!
    great post, thanks
  9. dubhe macrumors 65816


    May 1, 2007
    Norwich, UK
    I bet if you cycle it a few times you'll be back above 50%.

    Batteries are funny things, and as one of the earlier poster said, cycling the battery is more about the chip inside telling you an accurate story than the battery actually having more capacity.

    Batteries these days are designed to be used a little, then recharged. That is what we should be doing. Once every couple of months, do a cycle, but more to keep a tab on what the chip is telling you. I think the phrase 'condition' is incorrect.
  10. GeekAtBirth macrumors member


    Mar 21, 2009
    Is it okay if I just cycle it all the time?
  11. imax2k2 macrumors regular

    Feb 25, 2009
    I just downloaded Coconut battery and I have the full capacity now on 95%, and thats after 2 months of usage, and it shows I have had about 69 cycles, I usually make it go down to 20-30% and recharge somtimes as low as ~4-5%, is this not how I should be using it? Also is it normal to have dipped 5% in 2 months.

  12. McGilli macrumors 6502

    Nov 11, 2008
    I think that applies more to devices that don't eat a lot of battery when they are powered off.

    With all other devices that is what I do - but with the MBA - since even when shut down mine uses about 4% battery per day - I prefer to have it topped up when being stored for a long time (usually around 10 days) - otherwise when i turn it on I would be down to like %10-20% battery .... and then looking at a good 7 to 8 hours to charge! (for mine anyways)

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