Question about charging volts amps etc

Discussion in 'iPhone' started by jkaz, Feb 23, 2012.

  1. jkaz macrumors 6502

    Feb 3, 2004
    Upper Mid West

    Just got a new charging unit and it has two USB ports.

    One is labeled 5V/1A and the other is 5V/2A

    It advertises as 5V/1A for the iPhone and 5V/2A for charging iPads.

    A few friends have said that charging the iPhone in either port will have no problems at all.

    Anyone care to chime in?

  2. Steve28 macrumors regular

    Jun 14, 2011
    That is correct. You can use either for the iPhone. You can use either for the iPad as well, but it will just take longer for the iPad to charge if you use the 1A plug. The iPad can use up to 2A to charge, while the iPhone uses up to 1A. Plugging in to a lower amp plug only means it will take longer.
  3. takeshi74 macrumors 601

    Feb 9, 2011
    ^ This. iPhone will draw only what it needs and this is covered in countless prior threads.
  4. ichabodkky macrumors member

    Nov 25, 2008
    In a way, your friend is correct. BUT......

    Both the iPhone and the iPad have Lithium-Polymer (Li-Po) batteries in them. They are great batteries because they can be shaped into pretty much any space required, but they are VERY dangerous to charge if not done properly. That being said, the difference between the 1 Amp and 2 Amp is the speed of the charge. 1 amp will charge the iPad, but very slowly, and probably won't top off the entire charge. Hence, the 2 amp port. 2 amp will charge the iPhone faster than the 1 amp, BUT (and this is important), it's a rapid charge, which is not great for the battery over time. Using the 2 amp port on the iPhone will give you more power in a shorter time, but I wouldn't use it exclusively. It will do more harm to your battery over time, ruining any battery life long term. I've learned A LOT about batteries and charging them over the last couple of months as I've started flying RC airplanes. Ni-CD, Ni-MH, Li-po...... all have their pluses and minuses, and specific uses.

    I'd use your charging station as suggested, 1 amp for phone, 2 amp for pad.
  5. cynics macrumors G4

    Jan 8, 2012
    Should those of us that have been using a 2amp charger for YEARS be worried? Lol
  6. jkaz thread starter macrumors 6502

    Feb 3, 2004
    Upper Mid West
    hey guys, thanks for all the responses, but as takeshi74 said, this information has been covered in countless prior threads.

    Adding useful information to this thread only serves to perpetuate people's non-use of the search function.

    if you are interested in researching this issue further, here are a few links to message board posts regarding the topic:

    I've asked the mods to delete this thread.

  7. -Garry- macrumors 6502a


    Oct 23, 2005
    Manchester, UK
    I've tried charging my iPad with a 5W charger (5v, 1A) and with many of them it will only charge when not in use. When using it (while charging) it will simply say "Not Charging" in the top right-hand corner. It does, however, charge when it is asleep.
  8. TJ61 macrumors 6502a

    Nov 16, 2011
    This is not true. The iPhone limits the charging current in this case.


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