Charging – Does a Charger Consume Power After Device is Disconnected?


Quite similar to this one. If I'm not mistaken any impulse mobile device charger is still consuming power, when plugged into socket, but when cable is disconnected from charged device. Correct?

Does the same rule goes for power sockets equipped with USB ports for charging mobile devices (link to Polish seller):

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I was wondering, if this kind of construction means that my socket(s) will be continously draining power, 24 hours a day, no matter if anything is connected to it or not? Or do these have some kind of power-off "switch" (meaning stops draining power when everything is disconnected)?

Best Answer

Yes, the charger will use some standby current (unless there's a switch), but the current can vary widely depending on the charger.

I measured a dozen chargers a while ago and found the standby power usage varied from 19 milliwatts to 375 milliwatts depending on the charger. This works out to about 2 to 47 cents a year at average US power costs.

The switching power supply chip in the charger may be designed to minimize power when the charger isn't in use, for instance by skipping cycles when the load is low.