Everyone has that "good charger" in the house, the one that seems to get your phone from 4% to 100% in record time. But it's a bit of a mystery, isn't it? Why does one charger work great while another doesn't seem to budge at all? It has to do with whether that charger supports USB Type C Power Delivery (PD) and, of course, the supply's output current ability and the length and quality of the cable used. All things that an electrical engineer could work out with a multimeter and some notepaper - but who has time for that!