System and method for reconditioning spacecraft battery

• US 5,488,282 A
• Filed: 06/23/1993
• Issued: 01/30/1996
• Est. Priority Date: 06/23/1993
• Status: Expired due to Term

• Current Assignee: Hughes Electronics Corporation (Rtx Corporation)
• Original Assignee: Hughes Aircraft Company (Rtx Corporation)
• Inventors: Hayden, Joseph H., Stadnick, Steven J.
• Primary Examiner(s): Wong, Peter S.
• Assistant Examiner(s): NAPPI, ROBERT E
• Application Number:
  US08/081,503
• Time in Patent Office: 951 Days
• Field of Search: 320/5, 320/6, 320/14, 320/15, 320/17, 320/18, 320/19, 320/4
• US Class Current: 320/118
• CPC Class Codes: B64G 1/425 Power storage
• CPC Class Codes: B64G 1/428 Power distribution and management
• CPC Class Codes: H01M 10/345 Gastight metal hydride accumulators
• CPC Class Codes: H01M 10/441 for several batteries or cells simultaneously or sequentially
• CPC Class Codes: H02J 7/0013 acting upon several batteries simultaneously or sequentially H02J7/1423 takes precedence
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y10S 136/293 Circuits
• CPC Class Codes: Y10S 320/33 Aircraft or spacecraft application

Abstract

A battery reconditioning system and method for a spacecraft which utilizes a single battery as a secondary source of power for spacecraft electrical loads (10). The battery (14) includes a plurality of serially connected packs (30-36) each including a plurality of cells (40-46) connected in series. Sensors (50-56) are provided with each pack for sensing the state of charge of the pack. Battery charging circuitry (12,18,20) is controlled from control circuitry (22,52) which is responsive to the state of charge sensors as well as commands from a ground station transceiver (57). Reconditioning resistors (60-66) are adapted to be connected across the individual packs through switches (70-76) which are controlled by the control circuitry to discharge the pack at a relatively high rate when reconditioning is desired. After a pack is discharged to a desired low state of charge, its reconditioning resistor is disconnected and all packs are recharged in series. A pair of diodes (80A,80B-86A,86B) are connected across each pack and provide a low resistance current path in the event a fault clearing current is required from the battery during reconditioning of a pack.

Claims

1. A battery reconditioning system for a spacecraft having a single battery serving as a secondary source of electrical energy to support spacecraft electrical loads, said battery including a plurality of serially connected packs each comprising a plurality of cells, the system comprising:

sensor means for sensing the state of charge of each of said packs, reconditioning load means associated with each of said packs, battery charging means, switch means for connecting a reconditioning load means across its associated pack, switch control means responsive to the state of charge of said packs for controlling said switch means and said charging means to selectively and sequentially recondition each of said packs while said packs remain serially connected.

2. The system defined in claim 1 wherein said battery is a nickel hydrogen battery, said sensor means is responsive to the pressure in said packs to provide a state of charge indication, and diode means are connected in parallel with each of said packs for providing a current path to said spacecraft electrical loads which bypasses said packs when said diode means are forward biased.

3. The system defined in claim 2 wherein said control means includes transceiver means for transmitting and receiving data between the spacecraft and a ground station, at least one of said sensor means providing a charge termination signal to the spacecraft transceiver means for terminating charging of the battery.

7. The system of claim 1 wherein said battery is a nickel hydrogen battery.

8. The system of claim 1 wherein said sensor means is responsive to the pressure in said packs to provide a state of charge indication.

9. The system of claim 1 further comprising diode means connected in parallel with each of said packs for providing a current path to said spacecraft electrical loads which bypasses said packs when said diode means are forward biased.

4. A battery reconditioning system for a spacecraft having a secondary source of electrical power comprising a single battery, said battery comprising a plurality of serially connected packs each containing a plurality of cells, sensing means for sensing the state of charge of each of said packs, reconditioning load means associated with each of said packs, battery charging means, control means for selectively connecting a load means with its associated pack to discharge said associated pack to a predetermined low state of charge and for thereafter disconnecting the selected load means from its associated pack and connecting said battery charging means across said serially connected packs, at least one of said sensing means providing a charge termination signal to said control means when one of said packs reaches a predetermined state of charge, diode means connected with each of said packs and providing a shunt current path bypassing said packs when said diode means are forward biased.

5. A method of reconditioning a battery having a plurality of serially connected packs, each of the packs including a plurality of cells, the method comprising the steps of:

(a) discharging one of the packs to a predetermined low state of charge while the packs remain serially connected,

(b) charging all of the packs while the packs remain serially connected until another of the packs reaches a predetermined high state of charge,

(c) repeating steps (a) and (b) for each one of the packs.

6. A method of reconditioning a battery having a plurality of serially connected packs, each of said serially connected packs including a plurality of cells, the method comprising the steps of:

(a) connecting a reconditioning load corresponding to one of said serially connected packs, the reconditioning load connected across said one of said serially connected packs until said one of said serially connected packs is discharged to a predetermined low state of charge;

(b) disconnecting the reconditioning load corresponding to said one of said serially connected packs,

(c) applying a charging current to all of said serially connected packs and connecting reconditioning loads corresponding to remaining ones other than said one of said serially connected packs, said reconditioning loads connected across said remaining ones other than said one of said serially connected packs while said charging current is applied to all of said serially connected packs, wherein the charging current is applied until one of said remaining ones of said serially connected packs is charged to a predetermined high state of charge,

(d) removing the charging current from all of said serially connected packs until another one of said serially connected packs is discharged to said predetermined low state of charge,

(e) disconnecting the reconditioning load corresponding to said another one of said serially connected packs, and

(f) repeating steps (c), (d), and (e) until all of said serially connected packs have been reconditioned.