Air Battery Life - OS X Yosemite

Discussion in 'MacBook Air' started by loby, Oct 20, 2014.

  1. loby macrumors 6502a


    Jul 1, 2010
    First I have a MacBook Air i7 8gigs RAM 512gig SSD drive 2013 model,

    Has anyone noticed a difference in battery life with OS X Yosemite?

    I upgraded and noticed a little more draining than with Mavericks.

    Anyone else notice this?

    Thanks! :apple:
  2. shoehornhands macrumors regular

    Oct 9, 2014

    I upgraded to Yosemite on the Air in my sig. I haven't gotten the opportunity to test the actual battery life myself yet, but my estimated battery life on a full charge has actually gone up by a couple hours. I'm not sure if that's all that accurate though.
  3. kage207 macrumors 6502a

    Jul 23, 2008
    I see the same battery life in my 2012 MBA.

    Memory usage is a different story. I'm using so much more running less. :confused:
  4. motrek macrumors 68020

    Sep 14, 2012
    Memory usage is presented in a way that's difficult to understand in Activity Monitor. As long as the graph is showing green, you're fine.
  5. kage207 macrumors 6502a

    Jul 23, 2008
    I understand memory very well actually. I'm actually swapping when I used to not under the same load of work. I usually am running 7-12 tabs in Safari, Coda (or Xcode), iTunes (or Netflix), Mail, Messages, Calendar, Reminders.

    On top of this I run DropBox, Unclutter, Mint QuickView, Color Maker, and Google Drive. These are are all in the Menu Bar, I understand that these don't take up too much but 50MB each uncompressed still adds up. When they get compressed they maybe drop down to 30MB.

    I do begin to swap and the other day after 10 minutes of work, I had swapped about 150MB.

    I'm a Computer Science dude. I understand how it all works but I think iTunes and Netflix take much more memory as I used to do all this on Mavericks with about 1GB to spare (as long as I didn't use simulator in Xcode).
  6. motrek macrumors 68020

    Sep 14, 2012
    When you say you're swapping, do you mean that some memory is written out to disk (i.e., "Swap Used" is showing non-zero in Activity Monitor) or that your machine is thrashing the swap and thus performance is affected?

    I've noticed that starting with Mavericks, the OS is fairly aggressive about swapping out inactive pages to free up physical memory in case its needed. For example, right now I'm not running much stuff and I'm showing very low values for "memory used" and "app memory" and "memory pressure" but I still have 600+ MB swapped out, presumably because the OS thinks I'm not likely to need whatever's in that memory.
  7. kage207 macrumors 6502a

    Jul 23, 2008
    Yes, my "Swap Used" is nonzero. I had this fairly low on Mavericks usually if ever as I always had 1GB of free memory when I work (the apps above). The "Swap Used" was roughly about 15MB if it did.

    Now, I have about 16MB free and my "Swapped Used" is about 150MB when I start working in a very short period of time.

    Also note, my battery life hasn't been affected. I'm not too worried about this as I've always had great performance with it.

    Also, I hope the OP sees usage varies depending what you do. I don't do all the things I listed on my battery but when I'm plugged in. I'm a bit more reasonable when on battery.
  8. motrek macrumors 68020

    Sep 14, 2012
    Wouldn't worry about this at all unless performance is affected. As long as that "memory pressure" graph is green, you have free memory, or at least memory that Apple has deemed easily allocatable.

    If inactive pages are written to disk, i.e., swapped out, it shouldn't really make any difference to performance at all. Probably improves performance actually.
  9. watson10 macrumors member

    May 7, 2010
    I upgraded 2014 Air i5 8g RAM and battery life seems as good as before. In saying that battery testing always is so subjective to me that I only judge by what "seems" to be a decent battery life for me. And the new Air seems to have incredible battery life as has been stated countless time by others. :)
  10. kage207 macrumors 6502a

    Jul 23, 2008
    Ya, I just get nervous as it was after 10 minutes plus of usage for 150MB to be swapped. The only reason to be a bit nervous is the limited read / writes SSDs have that I don't want to burn through. I understand the technology behind it and there are plenty but I constantly work on my computer 12-16hrs a day really.
  11. motrek macrumors 68020

    Sep 14, 2012
    If you go to the Disk tab of Activity Monitor you can see how much data has been written to your SSD (well, any disk) since your computer was last rebooted. Then you can run 'uptime' in the terminal to see how long that was.

    If you divide, you can figure out how much data is written to your SSD per day.

    Personally I just checked and I seem to write about ~6 GB/day.

    If you figure that you can write to your SSD cells only 100k times (pessimistic number) then for a 128GB drive, you can write 12.8 million gigabytes to it before it dies, assuming perfect wear leveling and no write amplification.

    So for me, I need to worry about my SSD wearing out in about 5800 years.

    So I'm not that concerned if I swap out 150MB here or there. :)
  12. kage207 macrumors 6502a

    Jul 23, 2008
    Ah, good call.
  13. Leotno macrumors newbie

    Sep 30, 2010
    Actually, I think my battery life has gone down. Im at 80% right now and it says I have an estimated 2 hours left. I only have 2 tabs in safari and iTunes in the background.

    Does this sound normal to anyone? I just rebooted to see if there was anything in the background running and its still the same estimate.

    Its a Mid-2012 entry level 11-inch air.
  14. motrek macrumors 68020

    Sep 14, 2012
    Looking at the programs you have open is a fairly worthless way of telling how much your computer is doing. You have to go to Activity Monitor and see what's using up Energy, i.e., click on the Energy tab.

    If it doesn't look like any program is using a lot of CPU power or "Energy" then maybe you have something plugged into the USB port(s) that's sucking power?
  15. Leotno macrumors newbie

    Sep 30, 2010
    Ah, I see. I've attempted to include a screenshot, hopefully it works.
    I pulled it off the charger less than an hour ago from 100% and I'm already at 76% with minimal use.

    Attached Files:

  16. motrek macrumors 68020

    Sep 14, 2012
    Uff, that's pretty crap. And you haven't been using the laptop to charge/power anything like an external drive or your phone?

    I'd be reluctant to blame the operating system though BTW. Aside from making sure the computer goes into low-power modes at the right times, the operating system really has very little to do with how much power the computer uses. (Well, that, and Apple's indexing software sure does take a bunch of CPU/power if it needs to reindex something...)
  17. Leotno macrumors newbie

    Sep 30, 2010
    Okay, so I'm just not being sensitive about this. Phew. I figured my battery life was draining a little too quick.
    Nope, no usb or any devices plugged in.

    I've had OSX Yosemite installed since the public beta and even then the battery lasted about 5-6 hours on a charge. I'll continue to leave it be for the next few days and see if anything improves. If not, ill reinstall the OS and go from there.
  18. motrek macrumors 68020

    Sep 14, 2012
    Next question: is it cold where you're using the laptop, or is the laptop cold for some reason? Chemical reactions happen slower if it's colder, so the battery will seem to be running down faster when it actually isn't.

    Other than that, no idea what might be going on.

    Maybe download the Intel Power Gadget, which will show you if your CPU is using a lot of power (even though it doesn't seem like it should be based on Activity Monitor).

    Also probably worth downloading "Battery Health" which will show you how your current max charge capacity compares to the factory original state.
  19. Leotno macrumors newbie

    Sep 30, 2010
    Nope, everything is room temp and the computer is under normal operating temps.

    System Report states that battery is at 181 cycle counts and is in normal condition. I don't know how reliable iStat Pro is, but it rates the battery at 90% health.
  20. mangomind macrumors 6502a


    Mar 15, 2012
    Everything should work fine... like you, the only thing I can think of is a clean install. Maybe upgrading from a beta, there is a higher chance of system file corruption, than upgrading from a prime time release.
  21. blue2007 macrumors newbie

    Sep 10, 2012
    Mine is pretty terrible also. Upgraded to Yosemite (no clean install) and I'm getting 3-4 to 4 hrs.

    487 load cycles, 89% capacity, so it should still last more than 4 hrs. I tried to run with lots of tabs open in FF and Safari, then I only ran with 3 tabs in Safari and same thing. No flash. Did SMC and PRAM reset. Did a disk repair. etc...

    No improvement. Would hate to install everything from scratch and I wonder if that would even help.

    Any other thoughts?
  22. mangomind macrumors 6502a


    Mar 15, 2012
    If it was a software incompatibility / upgrade corruption issue, on your end, a clean install would help.

    Or the problem could be that Apple needs to issue Yosemite updates to fix various battery-draining bugs.

    In any case, a Yosemite bug fixe from Apple could solve both of these upgrade problems. I'm waiting a few months before updating any computers to Yosemite, or for that matter for updating any sort of device to a new OS in general. Apple needs to issue a couple bug fix releases in order to make the upgrade process smooth and hopefully trouble free.

    Your battery looks to be in excellent condition. Today I saw a 2012 macbook with 154 cycles and 77% capacity.
  23. blue2007 macrumors newbie

    Sep 10, 2012
    Yes, I have a July 2013 MBA, so the battery does seem to be okay. I would jus hate to reinstall all to find out it didn't help. I wish more people would report on a fresh install.
  24. motrek macrumors 68020

    Sep 14, 2012
    The power must be going somewhere. Run an app called Battery Health. It will give you an estimate of "mAh Usage (realtime)" that people can compare with their current laptops to see if its in-line with expectations.

    Also run Intel Power Gadget and see what your CPU is using.

    Also -- are you guys actually seeing these sub-par battery times or are you reporting the estimate that's displayed in the battery menu in the corner? Because who knows if that estimate is any good.
  25. Dweez macrumors 65816


    Jun 13, 2011
    Down by the river
    I've got the same MBA config as the initial poster, but haven't really noticed any difference in battery life. Caveat, I don't really pay attention to it as it the laptop works well for me and my use cases, plus spends the majority of its life on the charger.

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