Battery pack charger

A battery pack charger detects whether a terminal of the charger is disconnected from a first node between cells of a battery pack docked in the charger. The charger comprises a first resistor connected to the terminal, a second resistor connected in series with the first resistor, and a switch connected to a positive supply terminal of the battery pack, wherein the switch is connected in series with the first and second resistors. A threshold determination module of the charger measures a voltage at a second node between the first and second resistors and determines that the terminal of the charger is disconnected from the first node between the cells of the battery pack when the switch is closed and the voltage is greater than a threshold voltage.