Abstract: A retrofit system for converting a hybrid vehicle to a plug-in hybrid comprises a battery for storing a charge sufficient to provide a vehicle with an electric-only driving range in excess of 5 miles, a battery management system for monitoring battery parameters indicative of the state of battery charge to produce a signal indicative thereof; and a control unit responsive the battery management system to report an inflated state of battery charge to the hybrid vehicle's hybrid control system to maintain the gasoline engine in a deactivated condition over an extended driving range.

Abstract: A system for monitoring a plurality of battery cells using the switch and multiplexing circuits with the plurality of monitored signal indicating the battery voltage levels for each cell by switching the measured voltage of each cell and using switching of the monitored cell voltage to selectively measure each selected signal (10).