Automatic vehicle stop restart system
View Patent ↗An electrical system for vehicles that connects multiple batteries in parallel during normal operation but isolates the cranking battery and the starter system from the other batteries and their loads when the engine is started. A common charging system simultaneously maintains all of the batteries. Efficiency and EMC considerations are addressed in the design.
1. A vehicular electrical system including an engine starting portion and a non-engine starting portion, said electrical system comprising:
a main and a secondary battery, said main battery is non-switchably connected to an engine starting portion of a vehicular electrical system, said secondary battery is non-switchably connected to a non-starting portion of said vehicular system;
a battery switch that, in a first switch state, is configured to connect said main and said secondary batteries and their respective loads in parallel in response to a first signal waveform, and, in a second switch state, is configured to isolate said first and second batteries and their respective loads from each other in response to a second signal waveform, wherein said signal waveforms are received via a switch control input port;
a wave shaping network connected to said switch control input port, said wave shaping network comprises a separate first waveform shaping portion and a separate second waveform shaping portion;
a charge switch, configured to switchably connect an electrical charge source to said first waveform shaping portion of said wave shaping network, wherein switch state of said charge switch is controlled by an externally applied command signal;
a discharge switch, configured to switchably connect a charge sink to said second waveform shaping portion of said wave shaping network, wherein switch state of said discharge switch is controlled by said externally applied command signal.
2. The vehicular electrical system in accordance with claim 1 wherein said electrical charge source further comprises:
a charge reservoir;
a charge pump electrically connected to said charge-reservoir, said charge pump configured to charge charge-reservoir to a voltage greater than nominal voltage of said first or second batteries.
3. The vehicular electrical system in accordance with claim 2 wherein said charge reservoir comprises a capacitor.
4. The apparatus in accordance with claim 1 wherein said externally applied command signal is input via an opto-electrical isolator.
5. The apparatus in accordance with claim 1 wherein said battery switch is one or more paralleled field effect transistors with each of the source electrodes connected to a terminal of said main battery and all of the drain electrodes connected to a same polarity terminal of said secondary battery.
6. The apparatus in accordance with claim 1 wherein said charge pump obtains bias power from an or-gate configured to select battery having the highest voltage from said main battery and said secondary battery.
7. The apparatus in accordance with claim 1 further comprising a single battery charging system that maintains the state of charge of said main battery and said secondary battery.