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

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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?

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Anonymous 0 Comments

It mostly just depends on the charger, and how close the phones are to the charger.

The charger produces an alternating magnetic field. A simple oscillating circuit would produce a quite strong field with nothing to absorb its energy. So, in this simplified case, adding a phone to charge weakens the field. adding another phone weakens it further and the phones charge slower than of just one was present.

But in reality, the charger has a control circuit which decides how much power it puts down. When there’s no phone, it doesn’t put any power down, since it would just be wasting it. When a phone is added, it increases power to cope. When a second phone is added, it could increase even more. I’m not certain that engineers planned for that eventuality, though.

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