Hi. I have recently bought a few powerbanks/portable chargers to be able to charge my iPhone 6 Plus on the go. The powerbanks I have bought are shake to turn on powerbanks with no power buttons, and they have automatic device detection, meaning they automatically turn on once the phone is connected into it with the USB/lightning cord. However, my iPhone 6 Plus does not start charging once connected. My old iPhone 4 does, on the same powerbanks. I've tried several different lightning to USB charge cords, all with the same result, and all 3 powerbanks I have do not charge the iPhone 6 Plus, but they charge the iPhone 4 and any Android phones. Is there something in the iPhone 6/6 Plus chipset that does not allow automatic charging from powerbanks? Or is it an issue with the phone itself?