Method and circuit for controlling charging in a dual battery electrical system

• US 6,057,666 A
• Filed: 10/27/1998
• Issued: 05/02/2000
• Est. Priority Date: 09/17/1997
• Status: Expired due to Fees

• Current Assignee: Johnson Controls Technology Company (Johnson Controls International plc)
• Original Assignee: Johnson Controls Technology Company (Johnson Controls International plc)
• Inventors: Watts, Dan L., Dougherty, Thomas J., Iverson, Michael E., Segall, William P.
• Primary Examiner(s): Wong, Peter S.
• Assistant Examiner(s): TOATLEY, GREGORY J
• Application Number:
  US09/179,709
• Time in Patent Office: 553 Days
• Field of Search: 320/103, 320/104, 320/162
• US Class Current: 320/104
• CPC Class Codes: H02J 7/1423 with multiple batteries
• CPC Class Codes: H02J 7/342 The other DC source being a battery actively interacting with the first one, i.e. battery to battery charging with circuits for polarity protection H02J7/0034
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

A control circuit for controlling the recharging of two batteries in a dual battery vehicle electrical system includes a charging circuit (20) for stepping up the voltage of a reserve battery (RES.), so that it can be applied to a starting battery (HPB), an alternative circuit path (18, 19) to allow charging of both batteries by the alternator (A) when the vehicle engine is running, and a controller (30) for switching the connection of the batteries through the charging circuit (20) and the alternative circuit path (18, 19) under various combinations of conditions.

Claims

1. A circuit for controlling the charging of a starting charge energy source in a vehicle and for controlling a supply of charge from a reserve charge energy source in the vehicle, the circuit comprising:

a charging circuit in a circuit path between the starting charge energy source and the reserve charge energy source for converting a voltage of the reserve charge energy source to a voltage necessary to fully charge the starting charge energy source;

a controller operably connected to sense the level of charge on starting charge energy source and on the reserve charge energy source, said controller enabling and disabling the charging circuit to connect and disconnect the starting charge energy source to the charging circuit in response to the level of voltage on the starting charge energy source, in response to the level of voltage on the reserve charge energy source, and in response to an on-off state of a vehicle engine; and

a switchable device connected in the circuit path from the starting charge energy source to the reserve charge energy source, said switchable device being switchable to disconnect the starting charge energy source from the charging circuit and to connect the starting charge energy source to the reserve charge energy source and an alternator.

2. The circuit of claim 1, wherein the controller is further operable to connect the reserve charge energy source to the starting charge energy source through the charging circuit in response to a vehicle off condition as represented by a level of voltage on the starting charge energy source.

3. The circuit of claim 1, wherein the controller is further operable to coupling the charge current from the reserve charge energy source to the starting charge energy source for a predetermined time period in response to a vehicle on condition.

4. The circuit of claim 1, wherein the switchable device is a relay.

5. The circuit of claim 1, further comprising a circuit path from the alternator to the starting charge energy source, and further comprising a current limiting device in said circuit path.

6. The circuit of claim 5, wherein the current limiting device is a positive temperature coefficient resistance in said circuit path.

7. The circuit of claim 1, wherein the controller includes a programmable logic circuit and a timing circuit.

8. The circuit of claim 1, wherein the starting charge energy source is optimized for a high rate of discharge during vehicle starting operations.

9. The circuit of claim 1, wherein the reserve charge energy source is optimized for total energy capacity.

10. The circuit of claim 1, wherein the controller is operable to detect a voltage potential of one of the starting charge energy source and the reserve charge energy source with respect to a threshold and to selectively decouple the reserve charge energy source from the starting charge energy source upon detection of said voltage potential relative to said threshold.

11. The circuit of claim 10, wherein the threshold represents a fully charged condition for the starting charge energy source.

12. The circuit of claim 10, wherein the threshold is a battery low condition for the reserve charge energy source.

13. The circuit of claim 1, wherein the starting charge energy source is a battery.

14. The circuit of claim 1, wherein the reserve charge energy circuit is a battery.

15. A method for controlling the charging of a starting charge energy source in a vehicle and for controlling a supply of charge from a reserve charge energy source in the vehicle, the method comprising:

sensing the level of charge on the starting charge energy source;

sensing the level of charge on the reserve charge energy source;

sensing the on-off state of a vehicle engine;

electrically connecting the starting charge energy source through a charging circuit to the reserve charge energy source or electrically connecting the starting charge energy source to the reserve charge energy source and to an alternator in response to the level of voltage on the starting charge energy source, in response to the level of voltage on the reserve charge energy source, and in response to the on-off state of the vehicle engine; and

converting a voltage of the reserve charge energy source to a voltage necessary to fully charge the starting charge energy source.

16. The method of claim 15, wherein the connecting of the starting charge energy source through the charging circuit is to the reserve charge energy source in response to a vehicle off condition as represented by a level of voltage on the starting charge energy source.

17. The method of claim 15, wherein the connecting of the starting charge energy source through the charging circuit is for a predetermined time period in response to a vehicle on condition.

18. The method of claim 15, further comprising detecting a voltage potential of one of the starting charge energy source and the reserve charge energy source with respect to a threshold and selectively electrically disconnecting the reserve charge energy source from the starting charge energy source upon detection of said voltage potential relative to said threshold.