Abstract: The invention provides a vehicle battery system including a main and a reserve battery disposed within a battery housing (10) having conventional external dimensions and battery terminal locations. An illustrated embodiment includes a main battery, comprising a series of thin, flat cells (38) disposed along a first axis, and a reserve battery, comprising a series of cells (42) disposed along a second axis transverse to the first axis. An electrical circuit facilitates selective communication between the reserve battery and the vehicle starter in accordance with the position of a switch assembly (100). An electrically conductive fastener is disposed to simultaneously maintain electrical communication between a main battery termination and an external battery terminal and also between a reserve battery termination and the same external battery terminal.

Abstract: The invention provides a vehicle battery system including a main and a reserve battery disposed within a battery housing (10) having conventional external dimensions and battery terminal locations. An illustrated embodiment includes a main battery, comprising a series of thin, flat cells (38) disposed along a first axis, and a reserve battery, comprising a series of cells (42) diposed along a second axis transverse to the first axis. An electrical circuit facilitates selective communication between the reserve battery and the vehicle starter in accordance with the position of a switch assembly (100). The circuit illustratively includes a diode (110) configured to permit current flow into the reserve battery (104) during recharging, but which prevents reserve battery drain during normal vehicle operation. A variable resistor (112) is disposed in series with the diode to limit the amount of power, and hence the amount of heat, dissipated by the diode.