Motor vehicle battery disconnect circuit having electronic disconnects

A method for protecting a battery bank having one or more D.C. storage batteries in an electrical system of an engine-powered land vehicle against loss of charge that renders the battery bank incapable of operating an electric starter motor that draws current from the battery bank to crank the engine at starting, the electrical system having electric load circuits that are fed from the battery bank through a disconnect switch module that comprises controlled conduction solid-state switch devices through which current can bi-directionally flow between the battery bank and the electric load circuits, the method comprising:

• processing data relevant to operation of the solid-state switch devices and developing from that processed data control data for controlling the solid-state switches to either a) limit charge current to the battery bank to a defined charge current limit without regulating battery bank voltage, b) regulate battery bank voltage to a first defined limit of regulation when charge current is within a defined range immediately below the defined charge current limit, or c) regulate battery bank voltage to a second defined limit of regulation that is less than the first defined limit of regulation when charge current is less than the defined range;
• and
• processing data corresponding to battery bank voltage and causing the solid-state switches to disconnect battery bank from the electric load circuits when data corresponding to battery bank voltage indicates that a battery has been connected in the battery bank to create a double battery.