Run off battery or PSU?

Discussion in 'MacBook Pro' started by Spikeywan, Jan 2, 2013.

  1. Spikeywan macrumors 6502

    Joined:
    Dec 11, 2012
    #1
    Most of the time, when using my rMBP I have access to mains electricity.

    Should I just run it off the power supply, or should I run it off the battery until it warns me to charge it, then only leave the power supply connected until the battery is fully charged again?

    Thanks.
     
  2. Spink10 macrumors 601

    Spink10

    Joined:
    Nov 3, 2011
    Location:
    Oklahoma
    #2
    With modern day battery technology it does not matter. GGJstudios will post a helpful post on batteries in a moment.
     
  3. GGJstudios macrumors Westmere

    GGJstudios

    Joined:
    May 16, 2008
    #3
    Run on battery whenever you need to and plug it in whenever you can. You can plug or unplug any time you need to, regardless of the charged percentage, and you never need to completely drain your battery. Just make sure you don't run on AC power exclusively, as your battery needs to be used regularly to stay healthy. The link below should answer most, if not all, of your battery/charging questions. If you haven't already done so, I highly recommend you take the time to read it.
     
  4. Spikeywan thread starter macrumors 6502

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    Dec 11, 2012
    #4
    Whoa! Can you tell me the numbers for next week's lottery, too! :D

    Thanks. I spotted an interesting point, which I would never have thought of... When hammering the machine, playing a game or similar, plugging the charger in will make it run faster.
     
  5. GGJstudios macrumors Westmere

    GGJstudios

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    May 16, 2008
    #5
    Where did you read that?
     
  6. KevinC867 macrumors 6502a

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    Jun 8, 2007
    Location:
    Saratoga, CA
    #6
    Lots of great info in your posts. However, I'm not sure I buy the idea that I keep hearing here that the battery must be used regularly to stay healthy. Apple points out that batteries are consumable items and charge cycles are the primary way they are "consumed".

    Note that Lithium batteries store very well - up to 10 years when stored at cool temperatures and moderate charge. They don't need to be continually cycled to stay healthy.

    Unfortunately, standard use is very different from the ideal storage conditions. Laptop batteries tend to be in a hot enclosure and and usually at full charge (even if they are often cycled).

    There's lots more great battery info here:
    http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries
    http://batteryuniversity.com/learn/article/how_to_store_batteries
     
  7. GGJstudios macrumors Westmere

    GGJstudios

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    May 16, 2008
    #7
    It has been proven countless times that running on AC power exclusively will shorten a battery's life. That's why Apple recommends running on battery power regularly.
    Storage is a completely different topic than using the battery. For storage, Apple recommends a 50% charge. See the Battery FAQ for details.
    The regular use recommendation still applies.
    Don't trust everything you read at batteryuniversity.com, as the information there is quite generic and may not specifically address the battery technology employed by Apple in its notebooks. A more reliable and trustworthy source is Apple itself, since they have a vested interest in making sure their batteries perform as advertised.
     
  8. mrsir2009 macrumors 604

    mrsir2009

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    Sep 17, 2009
    Location:
    Melbourne, Australia
    #8
    Isn't that only when you have energy saving features on that limit CPU power when the computer is running off battery?
     
  9. Spikeywan thread starter macrumors 6502

    Joined:
    Dec 11, 2012
    #9
    Here:

    AC POWER

    ...

    While you can't remove the new built-in batteries, this method of using both AC power and battery during periods of peak power demands is still applicable. This is why you may find your battery may temporarily stop charging or even drain somewhat, even though you have your AC adapter plugged in. This is working as designed and will only be used during periods of peak power demands.
     
  10. Mwam macrumors newbie

    Joined:
    Jan 3, 2013
    #10
    Having just recently received my rMPB would it be correct to assume that when I have access to an AC run it off that and then once in a while take it off the AC and run it on the battery?

    Running it primarily on AC and then switching to the battery wouldn't do the battery any harm in terms of longevity, correct?

    Thanks in advance.
     
  11. GGJstudios macrumors Westmere

    GGJstudios

    Joined:
    May 16, 2008
    #11
    That doesn't mean your computer will run faster. It just means it can draw power from both AC and battery during periods of high demand. Whether it's plugged in or on battery, it will run at the same speed.
    Read the 3rd post of this thread.
     
  12. Spikeywan thread starter macrumors 6502

    Joined:
    Dec 11, 2012
    #12
    Why would it need power from both the battery and the charger? The harder it works, the more power it uses, right?

    So if it only had battery power, or only had charger power, then surely it wouldn't have enough power to run at full tilt, therefore it would need to run at reduced power, which would equate to being a bit slower.
     
  13. GGJstudios macrumors Westmere

    GGJstudios

    Joined:
    May 16, 2008
    #13
    If it only had battery power available, it wouldn't slow down. It would simply drain the battery faster. If you removed the battery and only ran on AC power, it would throttle the CPU and run slower. That isn't going to happen on a Mac notebook with a non-removable battery.
     
  14. Spikeywan thread starter macrumors 6502

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    Dec 11, 2012
  15. Mrbobb macrumors 601

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    Aug 27, 2012
    #15
    At least with Wintel machines, it's typical for it to run on a "battery profile" when not on AC, which between several things, slows down the cpu clock a bit for obvious purpose. I dunno if this is true of Macs.
     
  16. GGJstudios macrumors Westmere

    GGJstudios

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    May 16, 2008
    #16
    No, it's not.
     

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