Fuel saving multi-battery charging system and method

• US 5,602,459 A
• Filed: 06/06/1995
• Issued: 02/11/1997
• Est. Priority Date: 07/13/1988
• Status: Expired due to Term

• Current Assignee: Charles W Bradley
• Original Assignee: Electronic Development Inc.
• Inventors: Rogers, Wesley A.
• Primary Examiner(s): Wong, Peter S.
• Assistant Examiner(s): SHIN, KYUNG E
• Application Number:
  US08/468,210
• Time in Patent Office: 616 Days
• Field of Search: 320/15, 320/27-28, 320/48, 320/56, 322/25, 322/28
• US Class Current: 320/138
• CPC Class Codes: B60L 58/12 responding to state of charge [SoC]
• CPC Class Codes: B60L 58/20 having different nominal voltages
• CPC Class Codes: G01R 31/006 on road vehicles, e.g. automobiles or trucks testing of ignition installations peculiar to internal combustion engines F02P17/00
• CPC Class Codes: G01R 31/382 Arrangements for monitoring battery or accumulator variables, e.g. SoC
• CPC Class Codes: H02J 2310/40 The network being an on-board power network, i.e. within a vehicle
• CPC Class Codes: H02J 2310/46 for ICE-powered road vehicles
• CPC Class Codes: H02J 7/1423 with multiple batteries
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y10S 320/21 State of charge of battery

Abstract

A multi-battery charging system and for reduced fuel consumption and associated emissions for an automotive vehicle. The system starts the vehicle with a start battery in a fuel saving manner, removing electrical torque from alternator shaft, and allows a second (run) battery to provide all or some of the current required by the vehicle loads as fuel savings measure. The start battery is typically recharged after start using the alternator and then switched out of the system in a fully charged state for future vehicle starts. The run battery is typically recharged when its charge level drops below a predetermined level using an on-board battery charging device. The on-board battery charging device is powered from a power line source (e.g., 115 volt or 220 volt ac) external to the vehicle. The system controls the alternator field current with a voltage regulator. The voltage regulator senses the charge level of the two batteries and vehicle operating conditions and provides the proper current into the alternator rotor for maximum fuel savings. The voltage regulator may be a non-microprocessor or a microprocessor controlled device.

Claims

1. A method for operating a rechargeable storage battery for operating accessory circuits in an automotive vehicle, comprising:

consuming fuel in an engine of the automotive vehicle while the engine is running;

discharging the battery to operate vehicle accessory circuits while not recharging the battery and while the engine is running;

monitoring the state of charge of the battery;

indicating whether the battery state of charge is below a first charge threshold; and

recharging the battery, whether or not the engine is running, using a line power charger having an input for receiving a supply of electricity thereby saving fuel.

2. The method of claim 1 further comprising:

providing an alternator having a selectable output voltage;

coupling the alternator to the engine;

applying the alternator output voltage to the battery for charging the battery; and

selecting the output voltage of the alternator in response to the indicated state of charge of the battery wherein the alternator output voltage has a first level when the sensed state of charge is above the first charge threshold and a second level when the sensed state of charge is below the first charge threshold.

3. The method of claim 2 further comprising selecting the second voltage level to charge the battery to a full state of charge.

4. The method of claim 1 further comprising mounting the line power charger on board the vehicle.

26. The method of claim 1 wherein the monitoring step further comprising integrating a battery current through a shunt connected to the battery.

5. A fuel saving battery charging system for an automotive vehicle having electrical accessory circuits and a starter motor for starting a fuel consuming engine, comprising:

a start battery for providing a discharge current for operating the starter motor;

a run battery for operating accessory circuits;

a line power charger for recharging at least one of the start battery and the run battery, the charger having an input for receiving a supply of electricity; and

a switch for selectively connecting the charger to one of both of the run battery and the start battery, thereby saving fuel.

6. The system of claim 5 further comprising:

an alternator having an output condition including a regulatable output voltage at a selectable level and an output current, said alternator being driven by the engine;

a first circuit for electrically connecting the alternator output to the start battery for charging the start battery;

a second circuit for electrically connecting the alternator output to the run battery for charging the run battery;

a first device for monitoring the state of charge of the start battery;

a second device for monitoring the state of charge of the run battery; and

a control circuit for controlling the output of the alternator in response to the sensed states of charge of the start battery and the run battery, wherein the alternator output has

a first voltage level when the sensed state of charge of the start battery is at or above a first preselected charge level and the sensed state of charge of the run battery is at or above a second preselected charge level,

a second voltage level and a charging current when the sensed state of charge of the start battery is below the first charge level, and

a third voltage level and a charging current when the sensed state of charge of the start battery is at or above the first charge level and the sensed state of charge of the run battery is below the second charge level.

7. The system of claim 6 wherein the first charge level corresponds to the start battery having a full charge and the second charge level corresponds to the run battery having from between 40% and 100% of a full state of charge.

8. The system of claim 7 wherein the second and third voltage levels are the same.

9. The system of claim 6 wherein the control circuit selects the output of the alternator to have a fourth voltage level and a charging current in response to the sensed state of charge of the run battery falling below a third preselected charge level, the third charge level being lower than the second charge level and the fourth voltage level being greater than the third voltage level.

10. The system of claim 6 wherein the first circuit further comprises a switch for disconnecting the start battery from the alternator.

11. The system of claim 6 further comprising a display for indicating the run battery state of charge.

12. The system of claim 11 further comprising a selector device for selecting to display one or more of the start battery state of charge, run battery state of charge, the time required to recharge the run battery using the battery charge, wherein the display is responsive to the selector device for displaying the selected information.

13. The system of claim 6 wherein the first circuit further comprises a switch for automatically disconnecting the start battery from the alternator output when the start battery is fully charged.

14. The system of claim 5 wherein the line power charger in mounted on board the vehicle.

15. A fuel saving method for operating a battery charging system for an automotive vehicle having electrical accessory circuits and a starter motor for starting a fuel consuming engine, comprising:

providing a start battery for providing a discharge current for operating the starter motor;

providing a run battery for operating accessory circuits;

providing a line power charger having an input for receiving a supply of electricity;

selectively connecting the charger to one or both of the run battery and the start battery; and

recharging at least one of the start battery and the run battery using the line power charger, thereby saving fuel.

16. The method of claim 15 in which the vehicle includes an alternator having an output including a regulated output voltage at a selectable level, and an output current, the alternator being driven by the engine, further comprising:

monitoring the state of charge of the start battery;

monitoring the state of charge of the run battery;

coupling the alternator to said engine;

controlling the output of the alternator in response to the sensed states of charge of the start battery and the run battery;

connecting the alternator output to the start battery for charging the start battery following a discharge of the start battery for starting the engine; and

selectively connecting the alternator output to the run battery for charging the run battery.

17. The method of claim 16 wherein the alternator output has:

a first voltage level when the sensed state of charge of the start battery is at or above a first preselected charge level and the sensed state of charge of the run battery is at or above a second preselected charge level,

a second voltage level and a charging current when the sensed state of charge of the start battery is below the first charge level, and

a third voltage level and a charging current when the sensed state of charge of the start battery is at or above the first charge level and the sensed state of charge of the run battery is below the second charge level.

18. The method of claim 17 wherein the first charge level corresponds to the start battery having a full charge.

19. The method of claim 17 wherein the second charge level corresponds to the run battery having from between 40% and 100% of a full state of charge.

20. The method of claim 17 wherein the second and third voltage levels are the same.

21. The method of claim 17 further comprising disconnecting the start battery from the alternator when the start battery is fully charged.

22. The method of claim 17 wherein controlling alternator output further comprises providing the alternator with a fourth voltage level and a charging current in response to the sensed state of charge of the run battery falling below a third preselected charge level, the third charge level being lower than the second charge level and the fourth voltage level being greater than the third voltage level.

23. The method of claim 17 further comprising displaying the run battery state of charge to a vehicle operator.

24. The method of claim 17 further comprising selectively displaying to a vehicle operator one or more of the start battery state of charge, run battery state of charge, and the time required to recharge the run battery using the battery charger.

25. The method of claim 15 further comprising mounting the line power charger onboard the vehicle.