What If Charger Is Plugged Into Supply But Not Connected To A Device?

In a situation where the charger is connected to a socket without any device plugged in, the charger will draw a minimal current from the mains and the regulator will maintain a steady supply of 5 V. Since the charger is not connected to the laptop (the load), it will result in a waste of electricity, but wastage amount is trivial. Many modern chargers come with a sleep mode, which turns the charger off if it remains disconnected for a long time.

However, if the charger remains connected to the main power source and is not connected to any load for days on end, the electricity wastage extrapolated over weeks and months, and years may be considerable. In short, its best to switch off the main power source or remove the charger from the wall once youve disconnected your device from its charging adapter.