Method of determining the charging state of a zinc-bromine battery and method of charging such battery

• US 5,459,390 A
• Filed: 01/24/1994
• Issued: 10/17/1995
• Est. Priority Date: 05/24/1991
• Status: Expired due to Term

• Current Assignee: Elin Energieanwendung GmbH, Vionx Energy Corp.
• Original Assignee: Elin Energieanwendung GmbH
• Inventors: Tomazic, Gerd
• Primary Examiner(s): Dougherty, Thomas M.
• Application Number:
  US08/185,223
• Time in Patent Office: 631 Days
• Field of Search: 320/7, 320/30, 320/32, 320/33, 320/35, 320/36, 320/39, 320/44
• US Class Current: 320/134
• CPC Class Codes: G01R 31/3835 involving only voltage measurements
• CPC Class Codes: G01R 31/3842 combining voltage and current measurements
• CPC Class Codes: G01R 31/386 using test-loads
• CPC Class Codes: H01M 10/365 Zinc-halogen accumulators
• CPC Class Codes: H01M 10/48 Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals, H01M50/569
• CPC Class Codes: H02J 7/007188 the charge cycle being controlled or terminated in response to non-electric parameters
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y10S 320/21 State of charge of battery

Abstract

The method of determining the charging state of a rechargeable zinc-bromine battery which contains a plurality of series connected bipolar electrodes and circulating aqueous electrolytes, wherein oxidized bromine ions in conjunction with a complexing agent dissolved in aqueous electrolyte form a complex which is essentially insoluble in the electrolyte and zinc is separated at the electrode, and wherein a respective diaphragm is arranged between electrode chambers, entails determining the electrical voltage of one or a number of cells connected in series, especially during a predetermined removal of current per predetermined time interval, and evaluating the determined electrical voltage, especially indicating or displaying the same.

Claims

1. A method for determining the charging state of a zinc-bromine battery, comprising the steps of:

determining, directly prior to measuring of at least one cell of a rechargeable zinc-bromine battery comprising at least one cell and a plurality of series connected bipolar electrodes and circulating aqueous electrolytes, wherein oxidized bromine ions in conjunction with a complexing agent dissolved in aqueous electrolyte form a complex which is difficult to dissolve in the electrolyte, and zinc is separated at the electrode, and a respective diaphragm is arranged between electrode chambers, whether current is being drawn from or delivered to the at least one cell;

measuring the electrical voltage of the at least one cell; and

evaluating the measured electrical voltage.

2. The method according to claim 1, wherein:

the step of determining the electrical voltage comprises determining the electrical voltage of a number of series connected cells of the zinc-bromine battery.

3. The method according to claim 1, wherein:

the step of determining the electrical voltage of at least one cell is carried out during a predetermined discharge of current per predetermined time interval from the cell.

4. The method according to claim 1, wherein:

the step of evaluating the determined electrical voltage includes displaying such evaluated electrical voltage.

5. The method according to claim 1, further including the step of:

comparing the determined electrical voltage with predetermined values, in order to obtain an indication of the amount of stored charge of the battery; and

indicating the amount of stored charge of the battery.

6. The method according to claim 5, wherein:

the determination of the amount of stored charge of the battery constitutes an absolute stored quantity of charge.

7. The method according to claim 5, wherein:

the determination of the amount of stored charge of the battery constitutes a relative stored quantity of charge.

8. The method according to claim 1, further including the step of:

comparing a digital value representative of the determined electrical voltage with predetermined values, in order to obtain an indication of the amount of stored charge of the battery; and

indicating the amount of stored charge of the battery.

9. The method according to claim 1, wherein:

the step of determining the electrical voltage of at least one cell is determined during discharge of current from the cell under an operating load of the battery.

10. The method according to claim 1, further including the step of:

determining the temperature of each electrolyte; and

using the determined electrolyte temperatures in the evaluation of the measured electrical voltage in the determination of the charging state of the battery, so that temperature compensation of the determination of the charging state is applied for electrolyte temperatures above 30°

C.

11. The method according to claim 10, wherein the

using the determined electrolyte temperatures in the evaluation of the measured electrical voltage in the determination of the charging state of the battery is performed so that temperature compensation of the determination of the charging state is applied for electrolyte temperatures ranging from 30°

C. to 40°

C.

12. The method according to claim 1, further comprising:

initiating the measuring the electrical voltage of at least one cell whenever the battery is subjected to a predetermined load range.

13. The method according to claim 1, further comprising:

initiating the measuring the electrical voltage of at least one cell whenever the battery is subjected to a change in load value which is greater than or equal to a predetermined change in load value.

14. The method according to claim 1, further comprising:

connecting a charging device to the battery whenever the measured voltage is less than a predetermined voltage value.

15. The method according to claim 1, further comprising:

interrupting the charging of the zinc-bromine battery only after determining by the evaluation step, that the measured voltage has reached or exceeded a predetermined value.

16. In a method of determining the charging state of a zinc bromine battery having at least one cell and which contains a plurality of series connected bipolar electrodes and circulating aqueous electrolytes, wherein oxidized bromine ions in conjunction with a complexing agent dissolved in aqueous electrolyte form a complex which is difficult to dissolve in the electrolyte and zinc is separated at the electrode, and a respective diaphragm is arranged between electrode chambers, the improvement comprising:

determining the electrical voltage of at least one cell of the zinc-bromine battery including measuring the electric voltage;

evaluating the determined electrical voltage; and

determining directly prior to said measuring of the electrical voltage whether current is being drawn from or delivered to the cell.