GP's point is that although chargers are labeled with wattage, they can't output any combination of volts and currents as long as they multiply to the stated wa

GP's point is that although chargers are labeled with wattage, they can't output any combination of volts and currents as long as they multiply to the stated wattage. Can you take a normal 100W charger and ask it to output 100V and 1A? It can't. The Apple 29W charger supports two configurations only: 14.5V × 2A, or 5.2V × 2.4A The Apple 30W charger supports these four instead: 20V × 1.5A, 15V × 2A, 9V × 3A, 5V × 3A Do you see a problem here?