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A dual voltage automotive electrical system includes a generator for generating a first nominal voltage on a first voltage bus and a bi-directional DC/DC converter for converting the first nominal voltage to a second nominal voltage on a second voltage bus, the second nominal voltage being lower tha

A dual voltage automotive electrical system includes a generator for generating a first nominal voltage on a first voltage bus and a bi-directional DC/DC converter for converting the first nominal voltage to a second nominal voltage on a second voltage bus, the second nominal voltage being lower than said first nominal voltage. A battery is coupled to the first voltage bus and selectably coupled to the second voltage bus, and is capable of supplying power to loads on both the first voltage bus and the second voltage bus.

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1. A dual voltage automotive electrical system, comprising:a generator for generating a first nominal voltage on a first voltage bus; a bi-directional DC/DC converter for converting said first nominal voltage to a second nominal voltage on a second voltage bus, said second nominal voltage being lowe

1. A dual voltage automotive electrical system, comprising:a generator for generating a first nominal voltage on a first voltage bus; a bi-directional DC/DC converter for converting said first nominal voltage to a second nominal voltage on a second voltage bus, said second nominal voltage being lower than said first nominal voltage; a battery, coupled to said first voltage bus and selectably coupled to said second voltage bus, said battery capable of supplying power to loads on both said first voltage bus and said second voltage bus; and a switching mechanism coupled between said battery and said second voltage bus, wherein said switching mechanism causes said battery to supply power to loads on said second voltage bus in response to the actual voltage on said second voltage bus from said bi-directional converter dropping below the voltage available to said second voltage bus from said battery. 2. The system of claim 1, wherein said battery further includes a ground terminal, a high voltage terminal connected to said first voltage bus, and a low voltage tap connected to said second voltage bus.3. The system of claim 2, wherein said switching mechanism causes said battery to supply power to loads on said second voltage bus whenever the actual voltage on said second voltage bus drops below the voltage on said low voltage tap.4. The system of claim 3, wherein said switching mechanism further comprises a diode coupled between said battery and said second voltage bus, said diode becoming forward biased whenever the actual voltage on said second voltage bus drops below the voltage on said low voltage tap.5. The system of claim 3, wherein said switching mechanism further comprises a MOSFET coupled between said battery and said second voltage bus, said MOSFET having a body-drain diode that becomes forward biased whenever the actual voltage on said second voltage bus drops below the voltage on said low voltage tap.6. The system of claim 2, further comprising a charge equalizing device coupled to said battery, and coupled to said bi-directional converter via said switching mechanism.7. The system of claim 2, wherein said battery further includes a jumper post coupled to said low voltage tap, said battery thereby capable of receiving a jump start from another battery having a voltage corresponding to said second nominal voltage.8. The system of claim 2, wherein said first voltage bus is used to supply power to at least one of: a starter motor, a cooling fan motor, an electric power steering motor, an HVAC (heating, ventilation and air conditioning) motor, and a PTC (positive temperature coefficient) heater.9. A dual voltage automotive electrical system, comprising:a generator for generating a first nominal voltage on a first voltage bus; a bi-directional DC/DC converter for converting said first nominal voltage to a second nominal voltage on a second voltage bus, said second nominal voltage being lower than said first nominal voltage; a battery, said battery having aground terminal, a high voltage terminal coupled to said first voltage bus, and a low voltage tap selectably coupled to said second voltage bus; and a switching mechanism, coupled between said low voltage tap of said battery and said second voltage bus, said switching mechanism causing said battery to supply power to loads on said second voltage bus in response to the actual voltage on said second voltage bus from said bi-directional converter dropping below the voltage on said low voltage tap from said battery. 10. The system of claim 9, further comprising a charge equalizing device coupled to said battery, and coupled to said bi-directional converter via said switching mechanism.11. The system of claim 9, wherein said battery further includes a jumper post coupled to said low voltage tap, said battery thereby capable of receiving a jump start from another battery having a voltage corresponding to said second nominal voltage.12. The system of claim 9, wherein said switching mechanism further comprise a diode coupled between said battery and said second voltage bus, said diode becoming forward biased whenever the actual voltage on said second voltage bus drops below the voltage on said low voltage tap.13. The system of claim 9, wherein said switching mechanism further comprises a MOSFET coupled between said battery and said second voltage bus, said MOSFET having a body-drain diode that becomes forward biased whenever the actual voltage on said second voltage bus drops below the voltage on said low voltage tap.14. The system of claim 9, wherein said first voltage bus is used to supply power to at least one of: a starter motor, a cooling fan motor, an electric power steering motor, an HVAC (heating, ventilation and air conditioning) motor, and a FTC (positive temperature coefficient) heater.15. The system of claim 9, wherein said first nominal voltage is about 42 volts and said second nominal voltage is about 14 volts.16. A dual voltage automotive electrical system, comprising:a generator for generating a first nominal voltage on a first voltage bus; a bi-directional DC/DC converter for converting said first nominal voltage to a second nominal voltage on a second voltage bus, said second nominal voltage being lower than said first nominal voltage; a battery, said battery having a ground terminal, a high voltage terminal coupled to said first voltage bus, and a low voltage tap selectably coupled to said second voltage bus; a switching mechanism, coupled between said low voltage tap of said battery and said second voltage bus, said switching mechanism causing said battery to supply power to loads on said second voltage bus in response to the actual voltage on said second voltage bus from said hi-directional converter dropping below the voltage on said low voltage tap from said battery; and a charge equalizing device, said charge equalizing device coupled to said battery, and said charge equalizing device coupled to said bi-directional converter via said switching mechanism such that said switching device causes said bi-directional converter to charge said battery in response to said charge equalizing device having insufficient capability to maintain a charge balance at said battery.