Using iPad Charger to charge iPhone 4

Discussion in 'iPhone Accessories' started by aelalfy, Aug 3, 2010.

  1. aelalfy macrumors 6502a

    May 2, 2010
    Berlin, Germany
    Hi All,

    Is it ok to use my iPad charger to charge iPhone 4? I don't see an issue because the iPhone requires less watts than the iPad charger offers.

    Let me know please,
  2. redbotsoftware macrumors regular

    Jun 2, 2009
    I have used all the chargers interchangeably. iPod Touch, iPhone and iPad. It seems to work just fine.
  3. kepner macrumors 6502

    Sep 7, 2003
  4. aelalfy thread starter macrumors 6502a

    May 2, 2010
    Berlin, Germany
    I don't think charging an iPad using an iPhone/iPod charger is a good idea. The iPad requires more watts than the iPhone. For example my gf tries to charger her macbook with my macbook air charger and the charger really heats up. because my charger is a 45W, hers is 60W or so.

    I don't think thats a good idea, see above.

  5. greylee macrumors member

    Aug 2, 2010
    look at the charger. there will be specifications on it. look at the 'output' . I think for small gadgets like ipod and iphone they are the same. but Im not sure about ipad. but look at the ipad charger, see what is its output specs.

    the iphone charger output spec is 5V 1A.
  6. Poochi macrumors 6502a


    Jul 30, 2010
    It is safe.

    iPhone 5V 1Amp
    iPad 5V 2Amp

    When you connect iPad charger to iPhone, iPhone will only draw 1 Amp, so no harm.

    When you connect iPhone charger to iPad, I will charge half as fast.
  7. greylee macrumors member

    Aug 2, 2010
    errr.. I don't think so. if the output current is 2 Ampere, you should not use it on a 1 Ampere machine. the electric current is out of limit. it's simple physics
  8. Shawnstra macrumors regular

    Oct 12, 2008
    The iPad charger is rated 5V, 10W, while the iPhone is rated 5V, 5W. That simply means it's the maximum amount of power it can provide across it.

    Since both are 5V, they provide the same amount of so called energy. It is when you have a higher voltage that fries your electronics. The current is dependent on the device, which in the case of the iPhone draws a smaller current due to lower resistance.

    10W is just the maximum power that can be drawn. As such, the charger will not operate at maximum power. The charger may be less efficient, but it will cause no harm to your device.
  9. Condex macrumors newbie

    Jan 13, 2011
    Uing IPAD Charger for IPHON 4

    HI, just had a very strange thing happen.

    not withstanding all the comments about it should be OK, and I would agree with most of them, I am an Avionic Engineer and would NOT have thought it would be a problem.


    Half an hour ago I had plugged by IPHONE into the wall outlet with my IPAD charger.

    I tried to use my IPHONE4 whilst still charging and the sreen touch sesitivity was all screwed up. Thiought I was low on memory so cleared, stiil same , so switch off and try again. I could not get the slider to slid properly so I could not switch off!!! So I pulled the charger lead out not realy excpecting that top do anything but I would be able to see if my case (OTTER) was screwin the screen. and as soon as it was disconected all was OK.

    Reconnected it and it was all screwed up again.

    I dont know why but it did not like it. It must be something to do with the power being applied or being available and not being limited by the phone !!! crazy I know but what else. Only other thing comes to mind is that is it can draw more current to charge than it would with its own charger then it my be producing high electro magnetic fields that could be affecting the capacitve screen. OK he is off his head now I hear......... but what is causing it????? it is the charger all is well with the IPHONE4 charger connected????

    Though I had seen some strange things during Aircraft trouble shooting but this one is strange.. well done Apple!!!!

    Any thoughts

  10. ComputersaysNo macrumors 6502


    Apr 15, 2010
    I have the same issue when using a cheap dealextreme charger and my iphone 3G. The screen becomes unresponsive or opening different apps than what i pressed.

    My guess is that the output of the charger is not completely noise free compared to USB-power, resulting in weird behaviour, as it does not happen when connected to my computer.
  11. drummingcraig macrumors 6502a


    Sep 19, 2007
    "Armpit of the South"
    I picked up a 12v "cigarette lighter" charger recently which as two USB outlets on it. One is designed for the iPad (providing the higher amperage) and the other is designed for "regular" devices such as iPods/iPhones. At any rate, I have charged my iPhone using both and it works just fine.
  12. motofabio macrumors newbie


    Feb 18, 2011
    Actually, that is correct. Ampere is an expression of a device's watt draw and the voltage output supplied. The iPad charger and iPhone charger output the the same voltage, but the iPad charger simply allows a higher powered device to draw the necessary wattage. Hence, plugging your iPhone into the iPad charger is perfectly safe - and I do it all the time with no screen craziness issues.

    Electrical Engineering is confusing for most people and is anything but "simple physics".
  13. Sodner macrumors 68020


    Jan 12, 2011
    Pittsburgh, PA
    I've used my iPad charger on my iPhone a lot and never had an issue.
  14. AuroraProject macrumors 65816


    Feb 19, 2008
    Right there
    Wirelessly posted (iPhone 4: Mozilla/5.0 (iPhone; U; CPU iPhone OS 4_2_1 like Mac OS X; en-us) AppleWebKit/533.17.9 (KHTML, like Gecko) Version/5.0.2 Mobile/8C148 Safari/6533.18.5)

    I use a 2.1 amp car charger with my iPhone, no issues at all, charges it as fast as the a/c version does too!
  15. jpetticrew macrumors 6502a


    May 13, 2009
    If you look at the box that the iPad charger comes in at the Apple store, it cleraly says on the back, for use with iPad, iPhone, and iPod Touch.
  16. Badfoot macrumors 6502

    Sep 27, 2009
    London, UK
    You could use a charger rated at 1,000,000 amps, as long as the output voltage is the same. The device will regulate the charging current according to the battery capacity fitted.
  17. oakie macrumors 6502


    Oct 16, 2008
    you have very little grasp on how electrons flow. because of that, you shouldnt chime in on the subject until you're familiar with it.
  18. TEHi macrumors regular

    Jan 6, 2011
    I tired numerous times to charge my iphone with ipad charger. It does charge faster, but the phone heats up more than normal. Given the battery capacity is 1400mah, you should not charge it with a current flow greater than 1C, or 1.4a, to prevent battery damage.
  19. Badfoot macrumors 6502

    Sep 27, 2009
    London, UK
    Yes but this current is regulated in the iPhone charge circuit, not in the power unit.The power unit just needs to be able to deliver at least this amount.
  20. ridax macrumors newbie


    Jan 31, 2011
    If both chargers are according to Apple standard, you can use an iPad charger to charge the iPhone and an iPhone charger to charge an iPad. When an iPad charger is connected to an iPhone, the iPhone will just not use more than half the capacity of the iPad charger and when the iPad is connected to the iPhone-charger the iPad will not draw more than the iPhone charger can hande (1A) and thus charge at half rate compared to the iPad charger.

    There will be no harm in either of these cases.
  21. sithbrach macrumors newbie

    Jun 18, 2011
    What physics tells us.

    Ohm's Law:'s_Law

    That tells us what the 5v x 1 or 2A translates to. It would indicate that twice the wattage is coming out of the iPad charger (W=V*A) and twice the current (I=V/R).

    As I understand it, the block acts as a transformer:

    So, it takes the 120V*15A=1800W power from the outlet and converts that power so that it will be transmitted at a much lower rate, giving the device less of that wattage.

    I'm not sure if the earlier post by someone was trying to say that the iPhone has a particular resistor of it's own and so any different level and rate of power would simply dissipate, but wouldn't that still be stressful on that resistor?

    I think, in the end, one would be better off spending the couple of bucks for an iPhone charger.

    If there was absolutely no difference, then why would they make different chargers with different values? There would only be a need for stronger chargers for larger, more powerful devices, but the inverse (using that more powerful charger for a smaller, less powerful device) wouldn't make any sense.

    Just use the corresponding charger.
  22. nonukez macrumors newbie

    Jun 28, 2011
    What Apple tells us

    On Apple's website: Apple iPad 10W USB Power Adapter - compatible with iPhone 4, iPad, iPad 2.
    Should be perfectly fine
  23. Rocko1 macrumors 68020


    Nov 3, 2011
    Is there a circuit for this that does not allow overcharging so to speak?
  24. RegularJoe macrumors newbie

    Apr 6, 2012
    I'm reading through too many threads and find too many different response. I am an electrical engineer and would like to offer a simple answer:

    It is okay to use iPad charger to charge iPhone. Any charger with the same output voltage is also fine. The output current is what you should be less concerned about because it can vary up to max depending on the device being charge (i.e. the load).

    For example, charging iPad with iPhone charger would take longer because the charger would give out 1amp max.

    Charging iPhone with iPad charger would take the same amount of time since the iPhone only draw 1amp from the charger even though it is capable of providing 2amp.

    On a different notes, most electronics is rated about 5% variance in voltage; therefore, a slightly higher or lower voltage of the charger should be okay.

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