Charger for a battery pack, charging system and method of charging

A charging system comprising:

• a battery pack comprising:
• a battery input line;
• an electrochemical cell electrically connected to the battery input line;
• a blocking device disposed in the battery input line and configured to permit current flow from the battery input line to the electrochemical cell;
• and
• a battery sense line electrically connected to the battery input line at a location between the electrochemical cells and the blocking device;
• and
• a charger configured to be selectively coupled to the battery pack, the charger comprising:
• a charger integrated circuit having an input configured to receive power, an output configured to provide a charging voltage, and a sense input configured to receive a sensed voltage used to regulate the charging voltage;
• a charger output line configured to be electrically connected to the battery input line upon coupling of the battery pack to the charger;
• a charger sense line configured to be electrically connected to the battery sense line upon coupling of the battery pack to the charger;
• and
• a switching circuit configured to selectively place the sense input in a first state and a second state, wherein, in the first state, the sense input is electrically isolated from the charger sense line, wherein, in the second state, the sense input is electrically coupled to the battery sense line through the charger sense line upon sensing of the battery pack by the charger, and wherein the charger integrated circuit is configured to regulate the charging voltage based on the sensed voltage, the sensed voltage being based on a voltage drop across the at least one blocking device.

A method of charging a battery pack with a charger having a charger integrated circuit, the method comprising:

• selectively placing a sense input of the charger integrated circuit in a first state in which the sense input is electrically isolated from a charger sense line when the battery pack is not sensed by the charger;
• sensing the battery pack as coupled to the charger;
• in response to sensing the battery pack, selectively placing the sense input in a second state in which the sense input is electrically coupled to a battery sense line of the battery pack through the charger sense line;
• and
• regulating, by the charger integrated circuit, a charging voltage provided at a charger output line based on a voltage at the sense input.