A battery pack monitoring apparatus is provided. The apparatus includes a voltage measurement system configured to couple to opposed ends of each of a plurality of blocks of a battery pack and to measure voltages thereof, the blocks being coupled in series by interconnects each having an interconnect resistance. The voltage measurement system is configured to derive an internal resistance of each of the plurality of blocks based upon the voltages of the opposed ends of each of the plurality of blocks and based upon a measurement of current of the battery pack and derive the interconnect resistance of each of the interconnects based upon the voltages of the opposed ends of each of the plurality of blocks and based upon the measurement of current.