Other "Battery Health" is utterly useless

Discussion in 'iPhone' started by Oubadah, Dec 2, 2018.

  1. Oubadah, Dec 2, 2018
    Last edited: Dec 2, 2018

    Oubadah macrumors newbie

    Apr 2, 2017
    I have an iPhone SE which began to discharge rapidly and reboot with "unexpected shutdown, battery unable to deliver peak power" errors (and of course "performance management" was applied). All this, while Battery Health claimed that my battery was at 95% maximum capacity. Apple replaced the battery and the phone stopped rebooting, so the battery was clearly deficient. Why did Battery Health say that it had 95% maximum capacity?

    Recently my mother complained that her phone had rebooted with an error. I look in Battery Health, and what do you know:


    Crash and throttling despite Battery Health claiming that the battery is 97% healthy.

    To make matters worse, my phone (the one with the replacement battery), has dropped from 100% to 94% healthy in the <3 months since the battery was replaced. Why? The phone has barely been used in that time. I can't know whether they gave me a defective battery or if Battery Health just being useless again.

    So now I'm wondering whether to even recommend a battery replacement to my mother. It seems clear to me that Battery Health doesn't have a clue what is actually going on

    Oh, and one more thing I should note: on two other iPhones, I have observed the maximum capacity percentage sometimes increasing by as much as 3%. Doesn't exactly fill me with confidence.

    How did this feature get out of beta, and does the Maximum Capacity reading have any purpose other than giving second hand buyers a false sense of security?
  2. JPack macrumors 601


    Mar 27, 2017
    There are at least 3 measures of battery health.

    1. Capacity, the ability to store energy
    2. Internal resistance, the capability to deliver current, and
    3. Self-discharge, reflecting mechanical integrity and stress-related conditions

    Battery capacity at 95% (or 97% or 100%) only refers to the capacity to hold a charge.

    A battery's internal resistance or impedance also increases with age. The battery may hold the charge, but how quickly the battery can deliver the energy is another factor. A battery is degraded if it can't deliver peak output or if it's unable to hold sufficient capacity.
  3. now i see it, Dec 2, 2018
    Last edited: Dec 3, 2018

    now i see it macrumors 68040

    Jan 2, 2002
    Ignore it. It's not very accurate.
    CoconutBattery does the same thing. Up & down.
    Battery capacity % is derived from an algorithm. It can't be directly measured. There's "guesswork" involved attempting to quantify how much life has been sucked out of the battery. No one yet has devised a scheme that truly accurately displays real battery life. There's no way to really know what's going on inside the battery.

    You know when the battery is shot when it doesn't last very long and the phone sometimes crashes (especially when cold). Nobody needs a pretty graph or incorrect % of capacity rating to know how good or crappy their battery is.

    Plenty of people obsess on the battery capacity thing (myself included) but the best thing to do is try to ignore it and just use the phone (until it starts petering out quickly)
  4. BugeyeSTI macrumors 68030


    Aug 19, 2017
    I’d go one step further, the entire battery section has worthless information. The screen on time is way off and screen off time is always zero.. I prefered the way it was before...
  5. Oubadah thread starter macrumors newbie

    Apr 2, 2017
    That would mean two iPhone SE batteries shot in less than a year from purchase, which is making me think twice about buying another iPhone (was planning to upgrade to an XR).

    I guess I'll advise my mother to have her battery replaced.
  6. woodynorman macrumors 6502a

    Nov 26, 2011
    My mother in laws iPhone 6 has started acting weird. Dies from 100% in a few hours, but sometimes it will last all day. She also swears her calls are getting cut off after a minute or two, but I think she's ending the call with her cheek.

    The battery has never been replaced, but the battery health shows 100%. Theres no way its 100% after this many years.
  7. vertical smile macrumors 68040

    vertical smile

    Sep 23, 2014
    I have seen the same stuff lately, and I am at 100% capacity.

    I am not sure what is going on, but I might call Apple Support.
  8. BigMcGuire Contributor


    Jan 10, 2012
    My wife's 6s+ had the shutdown problem under 80% battery left under load. coconutBattery showed the battery randomly fluctuating between 40% capacity and 90% capacity. When my wife's phone restarted, it would boot up with 10% battery even if it shut down with 70% left. Her battery life was easily 1/5th my 6s+.

    We took the phone to apple and apple said her battery was "green" and nothing was wrong with it - when I saw the iPad showing the phone having 2 critical problems. So we paid the $79 to get the battery replaced and in so doing, they broke her phone (we got a replacement with AppleCare+).

    But it was really frustrating - eventually Apple announced the $29 battery replacements and we got $50 back from Apple.

    But yeah, that battery health thing is interesting. I use coconutBattery and take multiple readings a week and record them in excel and the coconutBattery app.

    Just fyi, though, battery capacity actually usually grows from 0 cycles to 100 cycles. Very normal. Isidor Buchmann's book shows this (author of https://batteryuniversity.com/). Wear is not linear at all for lithium ion batteries.

    There was definitely a bad batch of batteries that went out during the iPhone 6-7 days (including XE). Hence why Apple did their $29 thing. The batteries couldn't keep their design capacity output up, hence the reboot.
  9. whohasaquestion macrumors 6502a

    Sep 17, 2011
    The problem can be fixed by giving apple another $800 and get an XR.

    Cause let’s face it, you aint getting out of apple ecosystem. Are you?
  10. Newtons Apple, Dec 3, 2018
    Last edited: Dec 3, 2018

    Newtons Apple macrumors Core

    Newtons Apple

    Mar 12, 2014
    Jacksonville, Florida
    I lost faith in the battery health app when my X still showed 100% after a year of use.
  11. BLBL macrumors 6502a

    Apr 11, 2018
    It is possible that battery capacity was over 100% in the begin with. This could have been verified by using PC app, like Coconut Battery in Macbook, or iMazing in Windows PC's. Then maybe if there has not been overly high number of charging cycles and battery was way over 100% when new (and you happened to get a good battery in battery lottery), it might still be around 100% of the nominal capacity after one year of use.

    As mentioned here these capacity meters are more or less accurate in reality. I guess they work so that the estimate is based on the battery voltage when it is charged fully and if you did deplete it deep enough before charging it (once battery start to weaken voltage does not go so high anymore even it is fully charged. Just keep track of voltage numbers and you probably notice the same correlation between the capacity level and battery voltage as I did). It seems to me that running battery under certain level and then charging it fully (so that you keep it in charger for a little longer after display shows 100% battery) it triggers battery capacity number update. This also means that f you always keep topping up the battery when it is still say over 50%, you never trigged that "estimation run" and the capacity number never changes. This also works so that if you after long time let it run almost empty for the first time, you notice that battery capacity takes a huge just down, is just due to that. These all are my personal observations with various devices.
  12. DHeck macrumors newbie


    Jul 22, 2010
    Pgh, PA
    I agree the battery health "app" is horrible it said my 6S Plus was at 90%. I used coconut battery and it reflected it was at 73.2% with 936 cycle count. I ordered a battery kit from iFixit and did the swap myself (yes I know Apple is charging only $29 but I got kit on a cyber Monday deal, am going to upgrade soon anyway and my phone was exposed to water and didn't feel like hassling with the kids that work at my local Apple store). I had fun changing the battery myself, but had I not used coconut battery and relied on Apples built in battery "app", I would've thought it was something else causing the phone to drop from 100% to 50% in 30 minutes of regular use.
    before.JPG after.JPG
  13. dazz87 macrumors 65816


    Sep 24, 2007
    the health status is broken.......... People here really believe that their 1 yr old battery is still at 100%........ o_O
  14. Oubadah thread starter macrumors newbie

    Apr 2, 2017
    I barely have a toe in the Apple ecosystem. The thing that's more likely to keep me trapped in here is the guaranteed long term updates/security.
  15. Simacca macrumors 65816


    Jul 31, 2008
    UK, South East.
    My battery health was spot on compared to apple diagnostics when I went to swap out my 90% battery on my 8+.
  16. whohasaquestion macrumors 6502a

    Sep 17, 2011

    Well, that's interesting. How long do you plan to use your device anyway? Most people get rid of it by year 2.
  17. Jimmy James macrumors 601

    Jimmy James

    Oct 26, 2008
    A battery is a chemical reaction. The health rating is an algorithm. It doesn’t factor charge rate, amount of time plugged in, heat, or other factors. It’s a guess.
  18. skillwill macrumors 6502

    Feb 12, 2008
    It’s not really meant to be that useful, they just shoved it in there to stop people crying about the iPhone battery/device slowing down controversy.
  19. GrumpyMom macrumors 604


    Sep 11, 2014
    No, getting an XR isn’t going to help. Something is up with the last two updates of iOS.

    I’ve got an XR and an iPad mini 4 and something weird is going on. My battery has on my Xr been draining faster than it did when I first got it. It was a beast for weeks and now it’s not that impressive. Lol, sorry I know that’s not precise and this forum rightly asks for stats. But its all kind of sneaked up on me. I only noticed in passing that my phone was running out of charge completely by the end of the day. I am using it at the same rate as always and it used to have a lot of juice left. Now it’s drained at the end of the day.

    I’m also experiencing odd freezes and crashes on various apps. Just when trying to type this post, I got a text, went to answer it, came back here and I could not get a cursor to appear to continue my post. I had to swipe Safari closed and thank Mac Rumors for the day they implemented auto save on this forum so I did not have to retype everything.

    I’m having the same problems on my Mini 4. Come to think of it, same thing on my 8 Plus and I haven’t used that since mid October.

    So, something is going on and it’s not our batteries alone. iOS may be messing up our batteries. I saw that happen back when I got my iPhone 7 Plus. It worked great for a few weeks and then we got an iOS update and I ended up experiencing overheating and freezing and battery drainage for months until a more stable iOS update finally came out.

    Not everyone is seeing this. I was discussing this on another part of the forum and some of us are having app crashes. My husband with his XS Max is doing okay. Another forum member also has a Max doing fine.
  20. bushman4 macrumors 68020

    Mar 22, 2011
    its there to give you the opportunity to prevent Apple slowing your iPhone. Whether you call it useful or not is up to you
    Then again different features are useless to different people

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19 December 2, 2018