Why does it stay on 100% for so long?

Discussion in 'iPhone' started by Jayson A, Dec 4, 2016.

  1. Jayson A macrumors 68000

    Sep 16, 2014
    Why does my iPhone 7 Plus stay on 100% for so long?

    Seems like I can get 45-50 minutes of use before it switches to 99%, but the rest of the battery depletes faster.

  2. NovemberWhiskey macrumors 68030


    May 18, 2009
  3. macfacts macrumors 68030


    Oct 7, 2012
    Short answer: iOS does a bad job of estimating.

    Long answer:

    Let's say you have a x/y graph of a straight line. If someone gives you a Y value, it is easy to find the X value.

    Now look at the line of a graph of voltage/time graph of any battery, it doesn't have a straight line near the 0℅ and 100℅ points of the graph.

    With the example graph I gave, if the phone reads the battery as between 3.9 and 3.7V, it might think zero time has past and estimates it has 100℅ still.

    This is same reason on the other side of the graph, if the phone reads between 3.5V or lower, it is harder to estimate the lime left.

    Example graph of a battery.

    Attached Files:

  4. imagineadam macrumors 65816

    Jan 19, 2011
    Is this your first iPhone? I've had a 4, 5, 6, and now a 7 and they have all done this on every iOS version I've ever seen.

    My theory is that apple wants you to think you have more battery than you really do towards the beginning of a full charge and eventually things speed up and catch up to accurate as the battery drains.

    What is new in iOS 10 though is that the battery indicator doesn't start visually depleting till it hits 95% now. Used to be 98% pre iOS 10 and you'd see a sliver gone. Just another illusion to make you think you have more battery than you do.
  5. Aditya_S macrumors 6502

    Jan 25, 2016
    I read an article a long time and somebody explained it was done on purpose to make you think you have good battery life.
  6. pat500000 macrumors G3


    Jun 3, 2015
    What's wrong with 100 percent?
  7. Stevessvt macrumors 6502

    Jul 2, 2010
    Besides being inaccurate?
  8. se1000 macrumors 6502


    Sep 24, 2014
    LA, CA
  9. pat500000 macrumors G3


    Jun 3, 2015
    Op could use a battery life app.
  10. Stevessvt macrumors 6502

    Jul 2, 2010
    Won't it just report whatever the system is telling it? Same as the battery % is showing?
  11. pat500000 macrumors G3


    Jun 3, 2015
    I don't think so. I used a battery app and it gave me different result than the actual iPhone battery percentage.
  12. Brookzy macrumors 601


    May 30, 2010
    Could it also be exacerbated by a tendency for new batteries to exceed their rated capacity? E.g. if at full charge the battery is 103% its rated capacity, the battery status will read 100% until you lose 4 percentage points.
  13. Mlrollin91 macrumors G5


    Nov 20, 2008
    Ventura County
    iOS reports anything between 95-100% as 100%. Once iOS drops to 94% the battery indicator starts drop in a linear fashion.

    Actual vs. Reporting
    95-100% = 100%
    47.5 = 50%
    24.25% = 25%

    For the record, macOS does this as well. Its been this way for years and years now.
  14. Taisiya macrumors regular

    Nov 16, 2015
    I just got the 7 and noticed the 100% battery "issue" as well. After a full charge, I unplug the phone and use it to play YouTube video. It can play videos for almost 20 minutes before dropping to 99%. That's really weird.

    It's kind of the reverse problem with my car since it was new. When the yellow low-fuel warning light comes on, it still has at least 50 miles of range remaining.(or almost 70 miles if cruising at freeway speed)
  15. C DM macrumors Westmere

    Oct 17, 2011
    Battery estimates based on voltage are not linear and have smaller fluctuations at the extremes.
  16. rugmankc, Dec 4, 2016
    Last edited: Dec 4, 2016

    rugmankc macrumors 68000


    Sep 24, 2014
    All my phones have done that. But, not that long at 100%

    That said, wouldn't worry about it.
  17. T5BRICK macrumors G3


    Aug 3, 2006
    The percentage is an estimate and inaccurate.

    Just turn it off and don't worry about it.
  18. C DM macrumors Westmere

    Oct 17, 2011
    They are certainly estimated and thus won't be perfect generally but they are usually not inaccurate in the sense of not being useful. The battery meter that's there with or without the percentage is still based on the same estimates.
  19. Dj64Mk7 macrumors 65816

    Sep 15, 2013
    I always have battery percentage turned off, because I have better things to worry about than one little estimate. After all, iOS prompts me to turn on Low Power Mode when the battery gets low. Computers are smarter than humans a bunch of the time.
  20. Koudspeel macrumors regular


    Apr 8, 2013
    It's done with purpose. It has to to with the human psychology. No one likes to see 99% a minute after they unplugged their phone. It stays on 100% for a while even though the battery isn't 100% fully charged anymore. After a while it'll go down to 99% and counts down faster than it stayed on 100%. It's all to ease the human mind.
  21. WashupDawg macrumors regular

    May 26, 2010
    Apple programmed this "feature" on purpose. Before iOS10, when CoconutBattery still worked, you could monitor this closely. My 6S usually dropped from 100 to 99% when it was at 93% actual charge.
  22. C DM macrumors Westmere

    Oct 17, 2011
    No one likes to see it go faster and lower when it's below 100% either. If it was done for those types of purposes it sure doesn't help ease the human mind once it's dropping faster, and really makes it worse in that sense.
    --- Post Merged, Dec 5, 2016 ---
    Ah, so Apple did that with other phones and devices that run Android and other operating systems too? Well, that totally explains it.
  23. WashupDawg macrumors regular

    May 26, 2010
    Apple probably didn't invent it :)
  24. C DM, Dec 5, 2016
    Last edited: Dec 5, 2016

    C DM macrumors Westmere

    Oct 17, 2011
    Ah, an even more widespread/complex conspiracy theory when a more limited/simpler one doesn't quite hold up. At least that really gives it all more credit as a conspiracy theory. ;)

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