iPhone4s on charger discharges to 93%, then charges to 100% again?

Discussion in 'iPhone Tips, Help and Troubleshooting' started by grosssa, Oct 24, 2011.

  1. grosssa macrumors newbie

    Oct 24, 2011

    I observed the following behaviour of my (twice calibrated) iPhone 4S:

    - Charged it to 100% with flash status icon
    - At 100% it switched to cable status icon, and I left it in the charger
    - About half a day later it started to drop down from 100% (note: still in the charger)
    - Again about half a day later it reached 93% (note: still in the charger) and it charged itself automatically back to 100%

    Ok now my question:

    I know this behaviour of disconnecting itself from charger until about 95% from notebooks. My macbook and my Thinkpad do exactly this.

    Is this also the case with the iPhone 4S?

    Then, why is the iPhone 4S using 6-7% battery a day while its operation should be done by the charger power supply?

    And then IF the iPhone proceeds this way to prolong battery life, can I leave the phone in the charger as long as I want?

    Kind regards,
  2. puremike macrumors newbie

    Oct 25, 2011
    My 4S is doing the exact same thing. I left it plugged in over night and when I woke up in the morning it was at 93% I unplugged it and plugged it back in, and within 20 minutes was back to 100%.
  3. brian.from.fl macrumors newbie

    Oct 25, 2011
    Boca Raton, Florida
    My iPhone 4S is also doing exactly this when connected to a third-party USB charger (which we used because it charges 2 iPhones from one outlet, and worked fine with all the older iPhones).

    On a recommendation, I switched to using the charger block that came with the iPhone 4S. Now it charges to 100%, stays at 100%, is 100% in the morning just before I disconnect it, and is currently still showing 100% after a few texts (via iMessage) with light email viewing and browsing.

    So now the iPhone 4S with the charging block that came with it behaves just as the older 3GS with the third-party block, and also just as the iPhone 4 with that third-party block.

    Maybe something is different in the 4S that isn't as compatible with non-Apple charging blocks? I know that Li batteries can be very dangerous when overcharged / overheated, so my guess is that the 4S is trying to extend battery life as long as possible while ensuring that safety comes first, and it's erring on the side of safety when connected to a non-Apple charger.
  4. grosssa thread starter macrumors newbie

    Oct 24, 2011
    Well I use the charger that came with the iPhone 4S, connected to an original Apple dock ... ? I don't use third party chargers - with the exception of my car connector.

    I can't really understand why yours still is at 100% after night when mine drops on the original charger ... ?

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