Rechargeable battery and charging system

• US 5,747,964 A
• Filed: 01/17/1997
• Issued: 05/05/1998
• Est. Priority Date: 02/22/1994
• Status: Expired due to Term

• Current Assignee: NEC Corporation
• Original Assignee: Packard Bell NEC
• Inventors: Turnbull, Robert R.
• Primary Examiner(s): Berhane, Adolf
• Assistant Examiner(s): Law, Patrick B.
• Application Number:
  US08/785,474
• Time in Patent Office: 473 Days
• Field of Search: 320/2, 320/6, 320/15, 320/17, 320/18, 320/26, 320/39, 320/40
• US Class Current: 320/124
• CPC Class Codes: H01M 10/441 for several batteries or cells simultaneously or sequentially
• CPC Class Codes: H01M 10/46 Accumulators structurally combined with charging apparatus circuits for charging H02J7/00
• CPC Class Codes: H01M 50/213 adapted for cells having curved cross-section, e.g. round or elliptic H01M50/209, H01M50/216 take precedence
• CPC Class Codes: H02J 7/00 Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
• CPC Class Codes: H02J 7/0016 using shunting, discharge or bypass circuits
• CPC Class Codes: H02J 7/00302 Overcharge protection
• CPC Class Codes: H02J 7/0042 characterised by the mechanical construction
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A battery charging system for multiple series connected battery cells which includes a plurality of shunt regulators, adapted to be connected in parallel with each of the cells. The voltage of each cell is monitored during charging. When a cell is fully charged, excess charging current is shunted around the fully charged cell to enable the remaining cells to continue to charge. Circuitry is also provided to prevent the charging system from discharging the cells when the battery is not being charged. In an alternative battery charging system, a voltage source is connected across each of the serially connected batteries. Each voltage source is capable of sourcing or sending charging current. During charging conditions, the voltage sources source charging current to the cells. In order to prevent fully charged cells from being overcharged, the voltage across each cell is monitored. When the cell becomes fully charged, as indicated by the cell voltage, excess charging current is sunk to ground. In another embodiment of the invention, a rechargeable battery, formed from multiple internally series connected cells is provided with an integral battery charger within the battery housing.

Claims

1. A rechargeable multiple cell battery comprising:

a plurality of serially connected cells, each having a positive and negative terminal,

a plurality of conductive straps for connecting said positive and negative terminals from different cells together to form a series connection among said plurality of cells defining a voltage between a first positive terminal of one of said cells and a second negative terminal from another cell representing the sum of the individual cell voltages and further defining intermediate terminals between said first and second terminals, said intermediate terminals representing the junction between the series connected cells;

a housing for housing said plurality of cells;

an external positive and negative terminal, electrically connected to said first and second terminals, respectively, said external positive and negative terminals carried externally by said housing; and

a plurality of external auxiliary terminals carried externally by said housing, said external auxiliary terminals being electrically connected to said intermediate terminals.

2. A rechargeable multiple cell battery as recited in claim 1, wherein said housing includes a elongated housing adapted to be disposed around said plurality of cells, open on each end and first and second end caps for closing said ends of said housing and wherein said external positive and negative terminals being carried by said first end cap.

3. A rechargeable multiple cell battery as recited in claim 2, wherein said auxiliary terminals are carried by said first end cap.

4. A rechargeable multiple cell battery as recited in claim 2, wherein said auxiliary terminals are carried by said second end cap.

5. A rechargeable multiple cell battery as recited in claim 4, wherein said auxiliary terminals are carried on a plane different than said plane of said end cap.

6. A rechargeable multiple cell battery as recited in claim 2, further including a plurality of shunt regulators within said housing, said shunt regulators being connected in parallel across said cells.

7. A rechargeable multiple cell battery as recited in claim 6, wherein said plurality of shunt regulators are carried by one or the other of said first and second end caps.

8. A rechargeable multiple cell battery as recited in claim 6, wherein one or the other of said first end cap or said second end cap is formed as a printed circuit board for said shunt regulators.

9. A rechargeable multiple cell battery as recited in claim 2, further including means for charging said plurality of cells, said charging means being disposed within said housing.

10. A rechargeable multiple cell battery as recited in claim 9, wherein said charging means includes:

means for receiving a source of charging current;

means for sensing the voltage across each of said serially connected cells; and

means responsive to said sensing means for shunting the charging current around individual cells whose voltage is above a predetermined value.

11. A rechargeable multiple cell battery as recited in claim 10, wherein said sensing means includes a differential amplifier for comparing the voltage of each of the cells with a predetermined reference voltage.

12. A rechargeable battery as recited in claim 9, further including means for preventing discharging of said plurality of said cells in the absence of a source of charging current.

13. A rechargeable multiple cell battery comprising:

a plurality of serially connected cells, each having

a positive and negative terminal, said serially connected cells being coupled to connect said positive and negative terminals from different cells together to form a series connection among said plurality of cells defining a voltage between a first positive terminal of one of said cells and a second negative terminal from another cell representing the sum of the individual cell voltages and further defining intermediate terminals between said first and second terminals, said intermediate terminals representing the junction between the series connected cells;

a housing configured to house said plurality of cells;

an external positive and negative terminal, electrically connected to said first and second terminals, respectively, said external positive and negative terminals carried externally by said housing; and

a plurality of external auxiliary terminals carried externally by said housing, said external auxiliary terminals being electrically connected to said intermediate terminals.

14. A rechargeable multiple cell battery as recited in claim 13, wherein said housing includes a elongated housing adapted to be disposed around said plurality of cells, open on each end and first and second end caps for closing said ends of said housing and wherein said external positive and negative terminals being carried by said first end cap.

15. A rechargeable multiple cell battery as recited in claim 14, wherein said auxiliary terminals are carried by said first end cap.

16. A rechargeable multiple cell battery as recited in claim 14, wherein said auxiliary terminals are carrier by said second end cap.

17. A rechargeable multiple cell battery as recited in claim 16, wherein said auxiliary terminals are carried on a plane different than said plane of said end cap.

18. A rechargeable multiple cell battery as recited in claim 14, further including a plurality of shunt regulators within said housing, said shunt regulators being connected in parallel across said cells.

19. A rechargeable multiple cell battery as recited in claim 18, wherein said plurality of shunt regulators are carried by one or the other of said first and second end caps.

20. A rechargeable multiple cell battery as recited in claim 19, wherein one or the other of said first end cap or said second end cap is formed as a printed circuit board for said shunt regulators.

21. A rechargeable multiple cell battery as recited in claim 14, further including a battery charger disposed within said housing and configured to charge said plurality of cells.

22. A rechargeable multiple cell battery as recited in claim 21, wherein said battery charger includes:

means for receiving a source of charging current;

means for sensing the voltage across each of said serially connected cells; and

means responsive to said sensing means for shunting the charging current around individual cells whose voltage is above a predetermined value.

23. A rechargeable multiple cell battery as recited in claim 22, wherein said sensing means includes a differential amplifier for comparing the voltage of each of the cells with a predetermined reference voltage.

24. A rechargeable battery as recited in claim 21, further including means for preventing discharging of said plurality of said cells in the absence of a source of charging current.