MacBook air 2015 question

Discussion in 'MacBook Air' started by Airboy1466, Mar 23, 2015.

  1. Airboy1466 macrumors regular

    Airboy1466

    Joined:
    Feb 23, 2015
    #1
    So I got a free replacement 2015 MacBook air for my 2014 and I'm noticing huge battery life difference

    2014 4gb ram 120gb SSD core i5 (22 charge cycles)

    2015 8gb ram 256 GB core i7 ( 5 charge cycles)

    I used to get around 10-12 hours on my 2014 I usually get around 8-9 hours on the core i7 with similar usage is this because of the larger processor?
     
  2. GGJstudios macrumors Westmere

    GGJstudios

    Joined:
    May 16, 2008
    #2
    No, the processor model has little to do with battery life. There are many factors that impact your battery life, including workload and settings like screen brightness. See the BATTERY LIFE FROM A CHARGE section of the following link for details, including tips on how to maximize your battery life.
    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.
     
  3. qcmacmini macrumors 6502

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    Location:
    The Netherlands
    #3
    I have to disagree. It is a factor. However, you are correct in saying that usage patterns dictate more than processor model.

    With exactly identical usage, the i5 will give you longer battery life.
     
  4. GGJstudios macrumors Westmere

    GGJstudios

    Joined:
    May 16, 2008
    #4
    It doesn't matter what model the processor is. What matters is the workload you put on the processor. A processor with no workload won't drain the battery at all. It's the work you give the processor that determines battery life. You could argue that one processor may be more power efficient in handling the same workload, but the difference would be so negligible as to be unnoticeable.
     
  5. qcmacmini macrumors 6502

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    #5

    That only works for near idle workloads.

    It's even more an issue now that the base clock has risen in the i7.

    Once you ramp up the workload the i5 will take a bit longer to complete the task but will use less power doing so. The Anandtech review proves this for the MacBook Air.
     
  6. motrek macrumors 68020

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    Sep 14, 2012
    #6
    Processor families do make a difference though. Ivy Bridge to Haswell was a big jump in power efficiency and Broadwell is another 30% improvement over Haswell.

    Agree that an i5 vs. i7 at the same clock speed and same processor family won't see a difference.

    i7 will probably consume more power if it's running at a higher clock speed.
     
  7. qcmacmini macrumors 6502

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    #7

    This so called 30% improvement is yet to be seen in real life though. Apple still claim the same battery life for the Broadwell Airs.
     
  8. Y So Jelly macrumors regular

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    Sep 14, 2013
    #8
    Broadwell has been a big disappointment.. battery gains are marginal at best, from all brands. If I was thinking about buying a new laptop, I would try and hold out for Skylake.
     
  9. motrek macrumors 68020

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    Sep 14, 2012
    #9
    That's because their battery life specifications are for when the processor is nearly idle (web surfing) and even with Haswell, the processor was not using much power compared to the other components.

    If I'm doing something processor intensive with my 2014 MBA the battery life might decrease to maybe 3-4 hours, or even less. I'm sure it would run hours longer with Broadwell.

    ----------

    So Broadwell wasn't a big improvement but Skylake will be...?
     
  10. qcmacmini macrumors 6502

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    Oct 26, 2014
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    #10
    This is the bit that's yet to be seen, I haven't heard of anyone getting insane battery life out of Broadwell compared to Haswell, including the many other brands of laptop out there now available with Broadwell.

    Ivy Bridge to Haswell was a big jump in real terms.
     
  11. motrek macrumors 68020

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    Sep 14, 2012
    #11
    How many people run processor intensive stuff for hours at a time on battery power though?

    If somebody has a Broadwell Mac then we could test this fairly easily using the Intel Power Gadget.
     
  12. AWgamer macrumors newbie

    Joined:
    Aug 11, 2010
    #12
    My 2015 MBA i5 is getting great battery life but I'm not doing anything too processor intensive either.
     
  13. Airboy1466 thread starter macrumors regular

    Airboy1466

    Joined:
    Feb 23, 2015
    #13
    Well I later discovered my mac has a defective battery
     
  14. jdechko macrumors 68040

    Joined:
    Jul 1, 2004
    #14
    Also don't forget that on a new Mac, spotlight takes up quite a bit of power while running the initial index. And running backups/ online backups while on battery power will consume the battery quickly as there are a lot of continuous network operations.
     
  15. bnmcj1 macrumors 6502

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    Apr 13, 2014
    #15
    8 GB ram causes lower battery life. That is why I have a 2015 MBA 1.6 i5 with 4 GB ram. 12-14 hours battery life. Had 8 GB mid 2012 MBA before, but would rather have battery than more ram now.
     
  16. AWgamer macrumors newbie

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    Aug 11, 2010
    #16
    I went through and shut off anything I don't use. Spent a good hour in preferences trying make sure nothing was clicked on that was wasting resources.
     
  17. GGJstudios macrumors Westmere

    GGJstudios

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    May 16, 2008
    #17
    That is false, and the reverse is true in many cases. The amount of RAM installed does not play a significant role in battery usage, but as long as it's actually being used, more RAM would lower battery consumption. If you have insufficient RAM, page outs occur. At that point, your system is writing and reading from the drive, which consumes far more energy than accessing RAM. The amount of RAM installed isn't a major factor in determining battery life. Screen brightness and other settings, along with the actual workload being processed, are the primary factors in determining power demands on a battery.

    See post #2 for more details.
     
  18. SmOgER macrumors 6502a

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    Jun 2, 2014
    #18
    When you think about it... Leaving aside the finances,
    2013 and Haswell 2013 MBAs was the perfect time for buying them, and soon it will be the perfect time for selling them and getting 2016 skylake MBA (more than probably a slightly redesigned version as well).
     
  19. bnmcj1 macrumors 6502

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    Apr 13, 2014
    #19
    I know that, but many people does not have those high requirements for hardware specs that they think. I did a lot of graphics work on my mid 2012 MBA connected to a thunderbolt and there I needed 8 GB ram.

    Many people experience 2 hours less battery when they install a lot of ram. It is also my own experience.

    More ram requires more power and that is also why iPhone and iPad have low RAM amount.
     
  20. GGJstudios macrumors Westmere

    GGJstudios

    Joined:
    May 16, 2008
    #20
    As already stated, the extra power needed for additional RAM is negligible and wouldn't be noticed in real-world usage. Installing extra RAM alone will not significantly impact battery life. If people were getting 2 hours less, there were other factors at work besides the extra RAM.
     
  21. bnmcj1 macrumors 6502

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    Apr 13, 2014
    #21
    How did you discover that?
     
  22. motrek macrumors 68020

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    Sep 14, 2012
    #22
    Indeed, I can't find out exactly how many watts those chips require but common sense indicates that LPDDR3 uses negligible power. It's not uncommon for Android phones to have 2-4GB of the stuff and they can last a day on a tiny phone battery that's also being used to power the rest of the phone.
     
  23. bnmcj1 macrumors 6502

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    Apr 13, 2014
    #23
    Well. My experience is that 8 GB ram is taking some battery. Also had several other MacBooks, which always got less battery life right after memory upgrades. Therefore, I do not care about theoretical standpoints. My MBA 2015 is now showing 10:27 hours with 73% left. When I opened it up from idle and did nothing, it showed 19:28 hours with just the screen on. I am 100% sure this would not be the case with 8 GB memory.
     
  24. motrek macrumors 68020

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    Sep 14, 2012
    #24
    Those estimates of remaining battery life are just that, estimates, based on power consumption over the last minute or so. They can vary widely for a million different reasons. Trying to divine why it's showing different numbers is almost pointless on a machine you own; speculating about the estimates that might be shown by a machine you don't have experience with is even more pointless.
     
  25. GGJstudios macrumors Westmere

    GGJstudios

    Joined:
    May 16, 2008
    #25
    The time remaining indicator is based on minute-to-minute power demands of your MBA, which change constantly. It is not a reliable indicator of battery life. There are dozens of processes running, in addition to screen brightness, Wi-Fi, Bluetooth and other settings, all of which can affect battery life far more than the amount of RAM you have installed.
     

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