A charger appliance configured to determine a no-load, disconnected state from an electronic device having a rechargeable battery, and configured to determine a connected state of the charger with an electronic device in which recharging power may be supplied through the charger to the electronic device. Automatic connection and disconnection of a mains power supply is made depending on the detected state of the charger to avoid wasteful energy consumption in a no-load state. State detection may be determined by monitoring a voltage on one or more signal lines associated with the electronic device.