Battery charger with low standby current

A method of sensing the presence of a battery connected to a battery charging system having a charging terminal for connection to a terminal of the battery, comprising the steps of:

• generating a reference voltage level;
• sensing the voltage level at the charging terminal;
• and
• comparing the voltage level at the charging terminal to the reference voltage.

A method of controlling a power control switch of a battery charging system having a charging terminal for connection to a terminal of the battery, comprising the steps of:

• generating a reference voltage level;
• sensing the voltage level at the charging terminal;
• comparing the voltage level at the charging terminal to the reference voltage;
• closing said power control switch if the reference voltage level exceeds the voltage level at the charging terminal;
• and
• opening said power control switch if the voltage level at the charging terminal exceeds the reference voltage level.

A method of controlling a power control switch of a battery charging system having a charging terminal for connection to a terminal of the battery and an input terminal for connection to a voltage supply reference terminal of a battery powered device housing the battery, the method comprising the steps of:

• closing the power control switch;
• sensing the voltage level at the charging terminal;
• comparing the voltage level at the charging terminal to a first predetermined threshold value;
• and
• opening said power control switch if the voltage level at the charging terminal exceeds the first predetermined threshold value or if the voltage appearing at the input terminal is low.

A method of controlling a power control switch of a battery charging system having a charging terminal for connection to a terminal of the battery and an input terminal for connection to a voltage supply reference terminal of a battery powered device housing the battery, the method comprising the steps of:

• opening the power control switch;
• sensing the voltage level at the charging terminal;
• comparing the voltage level at the charging terminal to a first predetermined threshold value;
• if the voltage level at the charging terminal does not exceed the first predetermined threshold value, comparing the voltage level at the charging terminal to a second predetermined threshold value;
• and
• if the voltage level at the charging terminal exceeds or is equal to the first predetermined threshold value, closing the power control switch.