I've noticed today that my MBP 15" late 2014 maximum battery capacity is fluctuating somewhat.

These two screenshots were taken just seconds apart http://imgur.com/a/jqyZs

Should I be worried? Should I "recalibrate" the batteries?


2 Answers 2


The system management controller is responsible for reading battery voltages and reporting it to the operating system. You could reset that one time to see if it made a difference. When the output voltage of the battery shifts like that, it's a sign of failure within the battery.

Getting the machine serviced would be the way to fix that if it's not the SMC.

  • Hey, thanks for the answer. Only this weekend I've found the time to try out resetting SMC - or I hope that I reseted SMC properly (left Option-Shift-Control and Power - there was no feedback when I was pressing this sequence). I did not "recalibrate" the batteries since many sources say that it's not needed. Now System Report shows steady 8403 mAh, which is about 150 mAh lower then year ago when I bough the Mac. I read the warranty - only when the battery goes below 80% design capacity is eligible for repair, which is 6752 mAh in my case. So I cannot do a thing other then keep my eye open.
    – Rade_303
    Commented Nov 1, 2015 at 20:40
  • Well, it seems that I the battery max capacity started fluctuating again. It again behaves like in the screenshots I left earlier. Until it drops significantly there is nothing I can do...
    – Rade_303
    Commented Nov 1, 2015 at 22:58
  • 1
    @RockyMM I would document the fluctuations in FCC with time stamped image captures and seek service. This fluctuation should be covered under warranty and isn't related to normal depletion. IMO of course :)
    – bmike
    Commented Nov 2, 2015 at 14:36
  • I'll try on the weekend.
    – Rade_303
    Commented Nov 3, 2015 at 10:36

I’ve never heard of this issue, but I think it would be a good idea to calibrate the battery. If you haven’t calibrated it in a while, that very well could be the solution. This is because lithium-ion batteries have micro-controllers which measure the amount of remaining charge and use that information to tell the computer the percentage of remaining battery power, but the micro-controllers aren’t flawless. To get an accurate reading, the battery needs to be fully discharged and recharged. Only using a portion of the battery and recharging can, over time, confuse the micro-controller.

  • Can you provide any sort of reference that a 2014 Macintosh requires any sort of calibration whatsoever for the battery. Maybe 15 years ago when Apple just reused for more crude battery designs made by other vendors was this a viable option. apple.com/batteries/maximizing-performance/#macbook documents that absolutely no user calibration steps are required since the system is self-calibrates continuously.
    – bmike
    Commented Oct 27, 2015 at 14:56
  • I did a bit of research, and it looks like you might be right about 2014 MacBooks not needing battery calibration. However, my MacBook Pro is from 2011 and I’ve had to re-calibrate the battery at least twice in the few years I’ve had it.
    – Jblagden
    Commented Oct 28, 2015 at 15:43
  • Excellent. Do you perhaps have the 13 Inch model with the CD drive? It's the oldest battery tech Apple has shipped by a long, long margin. Not as bad as when batteries were user swappable, but barely into the modern controller chips that handle each cell smartly.
    – bmike
    Commented Oct 28, 2015 at 18:20
  • Yeah, I do. The nice thing about it that I can upgrade to a solid state drive if I want to, and I can also upgrade the RAM and the wireless card. I can even remove the optical drive and put a hard drive in its place.
    – Jblagden
    Commented Oct 29, 2015 at 16:54

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