Hello together, I hope you had nice holidays. On the tour to the dear relatives I had connected my iPhone to the said USB interface under the armrest (front slot) and could then watch how the iPhone’s battery emptied, although the display of the phone jumped to green (= charge). My questions: 1) is the power of this interface too low to charge a smartphone? 2) What is the small slot below the USB port (see photo) meant for? Would there possibly have to light an LED to confirm the function? Thanks in advance, and comes well into the new year.