Why is Charging iPad via iTunes/MBP so Slow Compared To Wall Outlet?

Discussion in 'iPad' started by HappyDude20, Apr 7, 2010.

  1. HappyDude20 macrumors 68020

    HappyDude20

    Joined:
    Jul 13, 2008
    Location:
    Los Angeles, Ca
    #1
    I've tried charging the iPad both ways; through the wall and when connected to my Macbook Pro and when its connect to my MBP its very slow to charge. Last night it was at 40% charge and forty minutes later it was barely at 42%.

    Of course when hooked up to the wall its a different story...

    ...but what gives?

    Side note: How long does it take for the iPad to charge completely? Or even to 80% like all previous iPods?
     
  2. miles01110 macrumors Core

    miles01110

    Joined:
    Jul 24, 2006
    Location:
    The Ivory Tower (I'm not coming down)
    #2
    Because USB ports don't have the same power rating as the wall adapter.
     
  3. HappyDude20 thread starter macrumors 68020

    HappyDude20

    Joined:
    Jul 13, 2008
    Location:
    Los Angeles, Ca
    #3
    Ah, makes sense.

    Dammit, guess I gotta keep waiting for that dock/keyboard to come out.
     
  4. ugp macrumors 65816

    ugp

    Joined:
    Jan 7, 2008
    Location:
    Inverness, Florida
    #4
    My iMac will charge the iPad with screen on but the charge time is slow. I plugged it in for the first time to the wall last night and it charged up pretty fast. I love that fact that I can go all day using this on the web and watching movies without having to recharge it during the day.
     
  5. diabolic macrumors 68000

    Joined:
    Jun 13, 2007
    Location:
    Austin, Texas
    #5
    The users guide tells you to plug it into the wall to charge, and USB to sync.

    The charge time is directly related to the extra-long battery life.
     
  6. indy1979 macrumors newbie

    Joined:
    Apr 8, 2008
    #6
    Charge time is directly related to the output power of what it's plugged in to.

    2.5 Watt USB port = super long charge time
    10 Watt wall adapter = super quick charge time
     
  7. diabolic macrumors 68000

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    Jun 13, 2007
    Location:
    Austin, Texas
    #7
    It isn't that quick.
     
  8. shujin macrumors member

    Joined:
    Jul 22, 2006
    #8
    No it's not that quick but it is four times faster.
     
  9. tomneff macrumors newbie

    Joined:
    Apr 16, 2010
    #9
    The classic Mac USB port puts out 0.5 amps of 5V power per the original USB spec. Late model MacBooks like the Air can increase their power output if they sense a device (like the SuperDrive) that wants it. The ultracompact "cube" USB wall charger for iPhone 3G puts out 1.0A of 5V. The 10W power adapter sold for the iPad puts out 2.1A of 5.1V power. The result is that they all charge the iPad, but at different rates. For a fast charge at the airport, you will want to bring your 10W adapter. If you're mostly tetherable to wall or computer power in an office environment, you can use anything.
     
  10. /dev/toaster macrumors 68020

    /dev/toaster

    Joined:
    Feb 23, 2006
    Location:
    San Francisco, CA
    #10
    Has anyone tried chargine it using the iphone adapter ? Is it safe ?
     
  11. Consultant macrumors G5

    Consultant

    Joined:
    Jun 27, 2007
    #11
    I use my iPhone charger. Probably doesn't have as much power as the iPad wall charger.
     
  12. andyblila macrumors 65816

    andyblila

    Joined:
    Jul 8, 2008
    Location:
    On My iPhone, or my iPad?
    #12
    iPhone charger is 5W, and the iPad's is 10W.
     
  13. Chundles macrumors G4

    Chundles

    Joined:
    Jul 4, 2005
    #13
    iPad 10W Power Adapter = 2.1A
    USB 2.0 port = 500mA (some new Macs can ramp it up to 1A but none of them will output the full 2.1A that the wall charger does)

    Hence, the wall charger will charge the iPad ~4x faster than a USB port AND it can be in use the whole time.
     
  14. danpass macrumors 68020

    danpass

    Joined:
    Jun 27, 2009
    Location:
    Miami, FL
    #14
    Thanks.

    Since I haven't seen otherwise …… the current iPhone USB cord can be used in the ipad for charging*? It'll sync as well?





    *My car Belkin dual charger puts out 1A when only one device is plugged in and it accepts the iPhone cable (in addition to any other USB cable)
     
  15. hsotnicam8002 macrumors 6502

    hsotnicam8002

    Joined:
    Mar 13, 2008
    Location:
    United Kingdom
    #15
    I used my iPad yesterday until the battery was so low that it shut off. This is the first time I have done that in the 7 weeks I have had it. I have been getting excellent usage times (10+ hours) and previously have mainly charged it from a USB hub connected to my iMac whilst working on the computer. I haven't really noticed how long it takes to top up the charge, but it must be within 4 hours. The battery indicator always show 100% after that period of time.

    Here is the issue. After it shut off, I plugged it in to my wall charger. After 2 hours there was still no charge indicated. I unplugged and tried to restart it, thinking that a reset might show there was actually some charge. But there was still no charge shown. In fact the iPad immediately shut down. I tried plugging into my USB hub, in case my wall charger was faulty. The same issue remained. There was an battery icon in the centre of the screen but nothing seems to have changed after another half hour. I reset the device several times then left it on the wall charger again. Now, after about 4 hours there is 55% battery life indicated.

    Anyone know what's going on? 4 hours to charge to 55% seems very slow, especially on the wall charger. Has my iPad lost it's magic? Should I contact my local wizard?
     

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