Charging speed

[Fille84]

I have started to charge my iPhone 6 using my Macbook pro with USB 3.0. From what I understand it should charge faster with the iPhone switched off but for me it charges slower when its turned off which is pretty strange. When off it charges 5% in 10 minutes while its on it charges 10% in 10 minutes. So its pretty much half the speed when switched off. Anyone know why this happens? It doesn't make any sense...

 

[Bigeric23]

I have never had that happen.

 

[Fille84]

Yeah...I get a feeling that it only gives an output of 500mA when the iPhone is off and 1.5A or something when its on.