Patent ID: 8441228

Claim:
An electrical system for a vehicle, comprising: a system bus; an alternator supplying a current to the system bus when mechanically driven by a prime mover; an ignition switch selecting an operational state of the electrical system; a primary battery connected to the system bus; a first auxiliary battery module connected to the system bus comprising a first auxiliary battery, a second auxiliary battery, a bi-directional battery voltage converter, a module controller selectively connecting one of the first auxiliary battery, and the second auxiliary battery to the bi-directional battery voltage converter; and a main system controller operating the first auxiliary battery module in one of a null mode, wherein the first auxiliary battery and the second auxiliary battery are disconnected from the electrical system, a charging mode, wherein one of the first auxiliary battery and the second auxiliary battery receives a current via the bi-directional battery voltage converter, and a discharging mode, wherein one of the first auxiliary battery and the second auxiliary battery supplies a current via the bi-directional battery voltage converter, wherein the bi-directional battery voltage converter comprises an inductor, a first switch selectively coupling the inductor to one of the first auxiliary battery and the second auxiliary battery, a second switch selectively coupling the inductor to one of the first auxiliary battery and the second auxiliary battery, a third switch selectively coupling the inductor to the system bus, a fourth switch selectively coupling the inductor to the system bus, and a routing circuit controlled by the module controller and connected to each of the first, second, third, and fourth switches, the routing circuit controllably directing opening and closing of each of the first switch, the second switch, the third switch, and the fourth switch.