Why does battery percentage say 23% when it just died?

Discussion in 'iPhone Tips, Help and Troubleshooting' started by sam011989, Sep 30, 2009.

  1. sam011989 macrumors regular

    Jun 17, 2009
    Tucson, AZ
    Ok, I've had my iPhone since it came out which has only been a couple months.

    It's already starting to be inaccurate with the battery percentage information.

    For example, It'll say 34% remaining, and after I plug it in for about a minute to sync with iTunes it jumps up to 65% remaining. No way it charged that much in just a couple minutes.

    And just now, I had all the antennas on, streaming music over the internet, using MobileMe to track it's location, everything I could to kill the battery. It finally died after the batter percentage read 0%. I plugged it back in, and it IMMEDIATELY says 23% remaining. Again, no way it "really" charged that much. I know this is typical for batteries, but this usually starts to happen after 1-2 years of continuously being on and ALWAYS being plugged in.

    I have the 3GS so it's only a couple months old, I charge once a day when it gets to about 30% remaining, and turn on airplane mode at night (I need it for alarm). I do turn it off for a few minutes every couple days too.

    Anyone else having this same issue with the battery, considering they're basically brand new? And are there any thoughts as to how to get the battery information more accurate?

  2. Rodimus Prime macrumors G4

    Rodimus Prime

    Oct 9, 2006
    You need to remember how the battery meter is read by the phone. It bases everything off votage coming out of the phone. So when you put a huge demand on it cause the votage to drop and intern the metter to read low. The phone detected it got to 0% (or below its threshold) so it turned itself off. Well wiht the reduced demand on the battery when you first plug it in it is going to detect more votage in there and boost the metter/

    Because of this it will give false reading right after plug. Also battery do not charge linearly but more of a logarithmically. This means the closer it gets to a full charge the slower it is gaining more charge.
  3. -aggie- macrumors P6


    Jun 19, 2009
    Where bunnies are welcome.
    The battery needs to be calibrated every month or so (let die and charge fully).
  4. intrepid00 macrumors 6502

    Sep 28, 2008
    It's the meter that needs to be calibrated. You don't calibrate Lio-Poly. Running it down all the way just wears it out faster. That's why they say once a month or so. So as not to wear it down faster then it needs to be.
  5. firewood macrumors 604

    Jul 29, 2003
    Silicon Valley
    It's not a problem with the battery, unless you don't get enough hours of actual usage. It's the meter that's inaccurate. Try a calibration cycle or two.

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