Abstract: A monitoring circuit for a Li-Ion battery pack charging apparatus is disclosed. The monitoring circuit modifies charging time for a Li-Ion battery pack inserted in the charging apparatus to compensate for temperature effects on the charging current input to the battery pack. In one embodiment of the monitoring circuit, a comparator is utilized to compare a voltage across the battery pack, V.sub.charge, to a set point voltage value, V.sub.sp. The set point voltage value, V.sub.sp, is taken off a temperature sensor circuit comprising a voltage divider circuit. The voltage divider circuit includes at least one thermistor in a ground connected leg of the divider. In a second embodiment of the monitoring circuit of the present invention, a differential amplifier is coupled to opposite ends of a low resistance sensor resistor. The sensor resistor is coupled between charging circuitry and the Li-Ion battery pack to be charged. The voltage differential across the resistor, V.sub.