Why doesn't the iPhone 3GS smart charge?

Discussion in 'iPhone' started by WilliamG, Jun 27, 2009.

  1. WilliamG macrumors G3

    Mar 29, 2008
    My MacBook Pros won't start charging until they fall below 95% charge.

    If you unplug the iPhone 3GS, and then plug it in after it hits 99%, it starts charging again! I've woken up in the morning and looked at my phone and the battery has hit 99% and is charging again...

    Anyone else find this behavior odd?
  2. rKunda macrumors 65816


    Jul 14, 2008
    A little. Though most people likely don't have their phones plugged in on their desks all day, like some people do with laptops. Maybe it wasn't considered necessary?
  3. WilliamG thread starter macrumors G3

    Mar 29, 2008
    It just can't be good for the phone. I'm pretty sure the iPhone 2G and 3G both smart charged. The problem is that if you leave the 3GS plugged in overnight, it charges to 100%, stops charging, and then will drop to 99% an hour later (or whenever that is), and then charges again to 100%. So there's a lot of "bit" charging going on here... Can't be good for the battery...
  4. DotComCTO macrumors 6502

    Aug 17, 2006
    I've never seen that happen - even with my 2G iPhone. Maybe I'm not observant enough, but both of my iPhones (2G and 3GS) go to 100% and stay there...at least that's how it seems to me!



  5. Johnathan macrumors member

    Sep 12, 2008

    You don't know what it's actually doing, you only know what the phone is reporting that it's doing.
  6. hchavarria macrumors 6502

    Oct 8, 2008
    My iPhone says 100% when it's plugged in but when I unplug it's at 98% and draing real fast.
  7. WilliamG thread starter macrumors G3

    Mar 29, 2008
  8. doubleatheman macrumors 6502a


    May 27, 2009
    My kill a watt meter reports a constant 1 watt drain even after the iPhone is fully charged, could be a trickle charge, or the power required to keep the phone in standby, or the inneficency in the charging process.

    The iPhone itself requires 5-6 watts of power when at full speed charge, then goes to 3 watts at 80% charge, and the. 2-1 watt for the rest.
  9. OneMike macrumors 603


    Oct 19, 2005
    I've started keeping my phone plugged in while at work and have never noticed this. This was with 2g. From what I see was always reported as fully charged. Will confirm tomorrow with 3gs

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