Abstract: An on-line battery monitoring system for monitoring a plurality of battery cells identifies and computes individual cell and battery bank operating parameters. The system comprises a controller for designating a given battery cell to be monitored, a multiplexer responsive to designation by the controller for selecting a given battery cell to be monitored or for selecting a battery pack to be monitored, an analog board for receiving electrical signals from a given battery cell for providing an output representing measurement of a parameter (voltage, temperature, and the like) of the given battery cell, a voltage sensor circuit for sensing voltage appearing across positive and negative terminals of the battery pack, and a control board responsive to address information for selectively initiating a load test, battery bank charging, or common-mode voltage measurement.