(Technical) iPhone Charging Adaptors Power Output

[thebluecoat]

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

 

[aakshey]

You can check via Coconut battery. As per Coconut battery what you said above is false. 5W usually charges at 3-5W or less.

 

[Eau Rouge]

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.

 

[Lumpy05]

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.