5 Replies Latest reply: Dec 5, 2008 1:55 PM by DanH
saberchan Level 1 Level 1 (0 points)
battery capacity decreases as we repeat charging / using the phone.

but what if we use it while it is being charged? will it just use power from

the power source or charge+use up batter at the same time?

i hope it can just use draw power from the external power source and leave

the battery alone if it's full, then I can just use bluetooth and leave

the phone in the dock to not waste battery cycles.

N/A, Windows Vista
  • Malcolm Rayfield Level 7 Level 7 (28,075 points)
    The processor in the iPhone controls battery charging. It's not going to do anything that will damage the battery. It will not overcharge it if you leave it plugged in. If you use the phone while charging, the phone will use some of the power, so it will just charge more slowly.
  • NARDO422 Level 1 Level 1 (0 points)
    That doesn't quite answer the question though. If the iPhone is fully charged and plugged into an AC outlet, will it source power directly from the AC outlet or will the iPhone draw power from the battery which in turn will continually be recharged by the AC power source?
  • neuroanatomist Level 7 Level 7 (31,690 points)
    It will use power from the AC, not the battery, unless the power demands of the phone briefly exceed the power supplied by the AC adapter, in which case the phone would draw form the battery as well (that would happen briefly and rarely, if at all).
  • icebike Level 3 Level 3 (740 points)
    It will use power from the AC, not the battery,

    There are several posts lately suggesting that listening to the ipod (one of the lowest battery using feature of the phone) seems to prevent recharging under 2.2.
    Such as: http://discussions.apple.com/message.jspa?messageID=8496642#8574853

    Sometimes these posts are in other threads and you don't know for sure what is going on.

    I would agree that the wall charger, delivering a full amp, ought to be able to drive everything this phone can do. But there are reports that some users have problems with this under 2.2.
  • DanH Level 5 Level 5 (4,370 points)
    There are two issues here. A cycle is the EQUIVALENT of one complete use of the battery from fully charged to depleted. But it can take place over multiple uses and charges. There is no way to avoid using cycles (or portions of them) other than leaving the phone plugged in all the time. Which brings us to issue two:

    The worst thing you can do to your battery (other than letting it get very hot) is to leave it plugged in all the time. This is not because it will overcharge. As others have pointed out, the phone is smart enough to prevent overcharging. But li-ion polymer batteries like to get some "exercise" to say fresh. Apple recommends the equivalent of at least one cycle per month. If it's plugged in constantly, it will not get enough exercise and its capacity will diminish.