What is healthier for the battery (17" UMBP)

Discussion in 'MacBook Pro' started by mcfields, May 13, 2009.

  1. mcfields macrumors newbie

    May 4, 2009
    Keeping it plugged in all the time, or unplugging it whenever it is fully charged? Of course when I'm on the go I'll unplug it, but 90% of the time I'm just at my desk with it.
  2. Jongewehr macrumors 6502

    May 1, 2009

    if im correct , leaving it plugged in is fine, it will NOT over charge it, it just uses the AC to run,

    you should drain your battery once a month.
    to keep everything moving

    expacilly if u dont use the battery that much
  3. MPHL macrumors regular


    Apr 7, 2008
    I'm better sure it really decreases your battery life keeping it always plugged in. If your going to keep it plugged in then you should remove your battery from the unit.
  4. u49aa2 macrumors 6502a


    Nov 3, 2008
    Between Heaven and Hell

    This is a myth! you don't need to take the battery out (you will slow the CPU and with UMBP you can't take the battery out anyway). Actually keeping the mac plugged will prolong the battery life as it goes through less life cycles.

    You don't even need to drain the battery once a month, this is also another myth. You just need to recalibrate your battery every few months (which will include draining the battery).
  5. NATO macrumors 68000


    Feb 14, 2005
    Northern Ireland
    Sorry, but that isn't quite right I'm afraid.

    Having the laptop plugged in all the time WILL harm the battery as it's held at full charge over a long period of time, which Li-Ion batteries don't like. Li-ion batteries really like to be used, regular charges and discharges (but not drained completely) help keep the cells maintained leading to less capacity loss over time.

    In addition, Li-ion batteries are sensitive to temperature and in my experience people who have their laptops plugged in 24/7 tend to have them switched on longer (compared to those using the battery who tend to shut down or sleep their computers more). This means the battery is exposed to higher temperatures for longer, again leading to a loss of capacity over time.

    My advice is that there's nothing wrong with having the laptop plugged in for periods of time, but I would regularly allow the battery to drop down to around 10-20% minimum before recharging. This will keep the battery at it's best.

    There's any amounts of advice online about how to treat Li-ion laptop batteries which back up what I've said. The logic is that having it plugged in 24/7 means less battery recharge cycles, but that doesn't take into account the fact Li-ion batteries don't like being at 100% for long periods of time! :)

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