(Technical) iPhone Charging Adaptors Power Output

Discussion in 'iPhone Accessories' started by thebluecoat, Jun 5, 2018.

  1. thebluecoat macrumors newbie

    Sep 9, 2011
    Hello All,

    Just recently switched to iPhone 8 Plus from Galaxy S9 Plus. I’ve read that it’s possible to fast charge the newest iPhones. I came across an article that pointed out charging speeds with 5 watt, 12 watt, 29 watt, 69 watt adaptors. 5 and 12 Watts are possible via lightning, higher wattages require USB C to Lightning cable that supports Power Delivery.

    I picked up the 12 watt iPad Adaptor and out of curiosity , picked up @ BestBuy (Insignia WiFi Smart Plug with Power Meter) for a visual aid in trying out various charging adaptors.

    What I’ve noticed is that all of my Apple Charging Adaptors output more Watts than advertised.

    5 watt adaptor charges @ ~9 watts
    10 watt (old iPad) adaptor charges ~14
    12 watt iPad Adaptor charges ~22 !!!
    Samsung Fast Charge Adaptor ~11Watts

    My question is : How are all of these adaptors able to output more Watts to the phone than what is rated ? It sucks I can’t really see the charging current via software on iOS . Anybody have any insight on how to interpret these results ? Is it just simply more Watts and there’s loss by the time it gets to the phone ? Or should I consider a USB based power meter to read AFTER the Adaptor rather than before ? Thanks
  2. aakshey macrumors 65816


    Jun 13, 2016
    You can check via Coconut battery. As per Coconut battery what you said above is false. 5W usually charges at 3-5W or less.
  3. Eau Rouge macrumors regular

    Sep 21, 2013
    You're measuring the power out of the wall, on the AC side. You need an inline meter between the brick and your phone to measure the DC output into the phone.
  4. Lumpy05 macrumors regular

    Mar 16, 2010
    Bloomington, IN
    Like others have said your AC to DC brick is not 100% efficient so a rough assumption would be 50% efficient and then your measurements make sense. Keep in mind there are losses through the charge connection including the wire to the phone itself, i.e. a 10ft lightning cable will have more loss than a 3ft cable.

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