Apparatus for detecting cell reversal in rechargeable batteries

• US 5,773,958 A
• Filed: 01/03/1997
• Issued: 06/30/1998
• Est. Priority Date: 01/03/1997
• Status: Expired due to Term

• Current Assignee: Chevron Texaco Corporation (Chevron Corp.)
• Original Assignee: Ovonic Battery Company, Inc (BASF SE)
• Inventors: Rogers, Robert A., Lijoi, Andrea L., Gow, Philippe H.
• Primary Examiner(s): TSO, EDWARD H
• Application Number:
  US08/778,486
• Time in Patent Office: 543 Days
• Field of Search: 320/5, 320/6, 320/7, 320/11, 320/15, 320/16, 320/18, 320/25, 320/30, 320/39, 320/40, 320/48, 320/118, 320/134, 320/165, 320/DIG. 20, 324/426, 324/433, 324/434
• US Class Current: 320/118
• 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 31/3648 comprising digital calculation means, e.g. for performing an algorithm
• CPC Class Codes: G01R 31/396 Acquisition or processing of data for testing or for monitoring individual cells or groups of cells within a battery
• CPC Class Codes: H01M 50/597 Protection against reversal of polarity
• CPC Class Codes: H02J 7/0063 with circuits adapted for supplying loads from the battery
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y10S 320/20 Polarity

Abstract

An apparatus for monitoring a battery pack having a plurality of serially connected rechargeable batteries. The apparatus comprises a means of detecting cell reversal and a means of protecting the batteries of the battery pack upon detection of cell reversal.

Claims

1. An apparatus for monitoring a battery pack having two or more serially connected rechargeable batteries, said battery pack divided into N serially connected battery segments (S₁ . . . S_N) where N is an integer greater than or equal to one, each of said battery segments (S₁ . . . S_N) having two or more of said serially connected rechargeable batteries, said apparatus comprising:

a detection means for detecting cell reversal in said battery pack, said detection means comprising;

N divider networks (D₁ . . . D_N), each including a first divider resistor serially connected to a second divider resistor at a resistor junction, each of said divider networks (D₁ . . . D_N) connected across the respective of said battery segments (S₁ . . . S_N);

N test points (P₁ . . . P_N) each located at a junction between two of said rechargeable batteries within the respective of said battery segments (S₁ . . . S_N);

a voltage comparison means for comparing voltage at each of said test points (P₁ . . . P_N) to voltage at said resistor junction of the respective of said divider networks (D₁ . . . D_N); and

N voltage drop devices (VD₁ . . . VD_N), each serially connected between said first divider resistor and said second divider resistor of the respective of said divider networks (D₁ . . . D_N), wherein said voltage comparison means compares voltage at each of said test points (P₁ . . . P_N) to a voltage window defined by voltage at opposite terminals of the respective of said voltage drop devices (VD₁ . . . VD_N), said voltage comparison means providing a detection signal when voltage at any one of said test points (P₁ . . . P_N) is outside said voltage window of the respective of said voltage drop devices (VD₁ . . . VD_N).

2. The apparatus of claim 1, wherein voltage drop across each of said voltage drop devices (VD₁ . . . VD_N) is less than or equal to nominal battery voltage.

3. The apparatus of claim 1, wherein said first and said second divider resistors of each of said divider networks (D₁ . . . D_N) are sized so that nominal voltage at each of said test points (P₁ . . . P_N) is the average of nominal voltage at opposite terminals of the respective of said voltage drop devices (VD₁ . . . VD_N).

4. The apparatus of claim 1, wherein said voltage comparison means includes one or more window comparators.

5. The apparatus of claim 1, wherein each of said voltage drop devices (VD₁ . . . VD_N) includes one or more voltage regulator diodes.

6. The apparatus of claim 1, further comprising:

a protection means, responsive to said detection means, for limiting current drawn from said battery pack upon detection of cell reversal.

7. The apparatus of claim 6, wherein said protection means comprises a motor regulating means, responsive to said detection means, for limiting voltage powering an electric motor that is drawing current from said battery pack.

8. The apparatus of claim 7, wherein said motor regulating means regulates a voltage control signal transmitted from a motor throttle to a motor control unit whereby, upon detection of cell reversal by said detection means, said motor regulating means adjusts said voltage control signal causing said motor control unit to limit said voltage powering said electric motor.

9. An apparatus for monitoring a battery pack having a plurality of serially connected rechargeable batteries, a positive battery pack terminal, and a negative battery pack terminal, said apparatus comprising:

a detection means for detecting cell reversal in said battery pack, said detection means comprising;

N test points (P₁ . . . P_N) each located at a unique junction between two of said batteries of said battery pack, N being an integer greater than or equal to one, said test points (P₁ . . . P_N) sequentially ordered from high to low voltage;

a divider network including N+1 serially connected divider resistors (DR₁ . . . DR_N+1), said divider resistors (DR₁ . . . DR_N+1) forming N resistor junctions (J₁ . . . J_N) where each of said resistor junctions (J₁ . . . J_N) is between the respective of said divider resistors (DR₁ . . . DR_N+1) and the next of said divider resistors (DR₁ . . . DR_N+1), said divider network connected across said battery pack wherein first of said divider resistors (DR₁ . . . DR_N+1) is connected to said positive battery pack terminal, and last of said divider resistors (DR₁ . . . DR_N+1) is connected to said negative battery pack terminal;

a voltage comparison means for comparing voltage at each of said test points (P₁ . . . P_N) to voltage at the respective of said resistor junctions (J₁ . . . J_N); and

N voltage drop devices (VD₁ . . . VD_N) each serially connected between the respective of said divider resistors (DR₁ . . . DR_N+1) and the next of said divider resistors (DR₁ . . . DR_N+1), said voltage comparison means compares voltage at each of said test points (P₁ . . . P_N) to a voltage window defined by voltage at opposite terminals of the respective of said voltage drop devices (VD₁ . . . VD_N).

10. The apparatus of claim 9, wherein said voltage comparison means provides a detection signal when voltage at any one of said test points (P₁ . . . P_N) is outside said voltage window of the respective of said voltage drop devices (VD₁ . . . VD_N).

11. The apparatus of claim 9, wherein voltage drop across each of said voltage drop devices (VD₁ . . . VD_N) is less than or equal to nominal battery voltage.

12. The apparatus of claim 9, wherein said divider resistors (DR₁ . . . DR_N+1) are sized so that nominal voltage at each of said test points (P₁ . . . P_N) is the average of nominal voltages on opposite terminals of the respective of said voltage drop devices (VD₁ . . . VD_N).

13. The apparatus of claim 9 further comprising:

a protection means, responsive to said detection means, for limiting current drawn from said battery pack upon detection of cell reversal.

14. A method of detecting cell reversal in a battery pack having two or more serially connected rechargeable batteries, said method comprising the steps of:

dividing said battery pack into N serially connected battery segments (S₁ . . . S_N) wherein N is an integer greater than or equal to one, each of said battery segments including two or more of said serially connected rechargeable batteries;

connecting each of N divider networks (D₁ . . . D_N) across the respective of said battery segments (S₁ . . . S_N), each of said divider networks (D₁ . . . D_N) including a first divider resistor serially connected to a second divider resistor through a voltage drop device;

locating each of N test points (P₁ . . . P_N) at a junction between two of said rechargeable batteries within the respective of said battery segments (S₁ . . . S_N);

comparing voltage at each of said test points (P₁ . . . P_N) to a voltage window defined by voltage at opposite terminals of said voltage drop device of the respective of said divider networks (D₁ . . . D_N); and

providing a detection signal when voltage at any one of said test points (P₁ . . . P_N) is outside said voltage window across said voltage drop device of the respective of said divider networks (D₁ . . . D_N).

15. The method of claim 14, wherein said first and said second divider resistors of each of said divider networks (D₁ . . . D_N) are sized so that nominal voltage at each of said test points (P₁ . . . P_N) is substantially equal to the average of nominal voltage at opposite terminals of said voltage drop device of the respective of said divider networks (D₁ . . . D_N).

16. The method of claim 14, wherein voltage drop across said voltage drop device of each of said divider networks (D₁ . . . D_N) is less than or equal to nominal battery voltage.

17. The method of claim 14, wherein said voltage drop device of each of said divider networks (D₁ . . . D_N) includes one or more voltage regulator diodes.