If someone puts two phones on a wireless charger, where does the energy to charge the second phone come from?

Question

I understand that the current in the wireless charger causes a current to be induced in the first phone via magnetic fields. However, if I place a second phone on the wireless charger at the same time, what happens? Does the second phone steal some of the energy that would have gone to the first phone? Does it cause the wireless charger to somehow pull in more power from the outlet? Would the first phone now charge at a slower rate compared to before? Or does it merely productively use some of the energy that would have been lost due to heat or something else?

In: 1

Answer 1

Depends on the charger and the phones. If the whole charger can charge at 20W, and you put two phones capable of charging at 10W each, then they both charge at their maximum.

It’s the same as if you had a two-port 20W USB charger and charged two phones off it it. Add up the phone charging wattages, and if they’re more than the charger then neither will charge at full speed.