Battery charger for lithium based batteries

• US 6,366,056 B1
• Filed: 03/31/2000
• Issued: 04/02/2002
• Est. Priority Date: 06/08/1999
• Status: Expired due to Fees

• Current Assignee: Enrev Corp.
• Original Assignee: Enrev Corp.
• Inventors: Podrazhansky, Yury M., Cope, Richard C., Kusharskaya, Galina K.
• Primary Examiner(s): Tso, Edward H.
• Application Number:
  US09/539,858
• Time in Patent Office: 732 Days
• Field of Search: 320/127, 320/128, 320/130, 320/133, 320/135, 320/137, 320/139, 320/141, 320/145, 320/160
• US Class Current: 320/141
• CPC Class Codes: H01M 10/052 Li-accumulators
• CPC Class Codes: H01M 10/44 Methods for charging or discharging circuits for charging H02J7/00
• CPC Class Codes: H02J 7/00711 with introduction of pulses during the charging process
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A method for charging a battery, such as a lithium based battery, which applies different charge pulses and discharge pulses to the battery, takes voltage measurements during those charge pulses, discharge pulses, and rest periods between the charge pulses and discharge pulses, and determines whether to terminate or to continue charging the battery. The full sequence of charge pulses, discharge pulses, and rest periods, includes a plurality of charge pulses (1), separated by rest periods (2) and followed by a rest period (3). This is then followed by a plurality of discharge pulses (4), separated by rest periods (5) and followed by a rest period (6). This is then followed by a plurality of extended charge pulses (7), separated by rest periods (8) and followed by a rest period (9). Then another discharge pulse (10) is applied, followed by a rest period (11). This is followed by a plurality of alternating charge pulses (13) and discharge pulses (12), separated by rest periods (13, 15) and followed by a rest period (16). Then another plurality of discharge pulses (17) is applied, separated by rest periods (18) and followed by a rest period (19). Open circuit voltage measurements taken during the rest periods, loaded circuit voltage measurements taken during the discharge pulses, and charge pulse voltage measurements taken during the charge pulses, are used to determine whether to continue or to terminate the charging of the battery.

Claims

1. A method for charging a battery, comprising the steps of:

applying a plurality of charge pulses to said battery, said charge pulses each having a duration and being separated by a corresponding plurality of rest periods;

applying an extended charge pulse to said battery, said extended charge pulse having a duration greater than said durations of said charge pulses;

measuring the charge pulse voltage (CPV) of said battery during said extended charge pulse;

applying a subsequent rest period to said battery after said extended charge pulse;

measuring the open circuit voltage (OCV) of said battery during said subsequent rest period;

determining the difference between said CPV and said OCV; and

terminating charging of said battery if said difference is less than a predetermined value.

18. The method of any one of claims 1, 2, 4, 9, 15 or 16, and further comprising the step of:

increasing a predetermined parameter of said charge pulses of said plurality of charge pulses from the beginning of said plurality to the end of said plurality so that said parameter of the last charge pulse of said plurality of charge pulses is greater than said parameter of the charge pulse of said plurality of charge pulses, and wherein said predetermined parameter is a selected one of the amplitude of a said charge pulse or the duration of a said charge pulse.

19. The method of any one of claims 1, 2, 4, 9, 15 or 16, and further comprising the steps of:

if said difference is greater than said predetermined value then increasing the number of said charge pulses of said plurality of charge pulses, and

repeating the steps previous to these steps.

20. The method of any one of claims 1, 2, 4, 9, 15 or 16 and further comprising the steps of:

if said difference is greater than said predetermined value, but less than a second predetermined value, then increasing the durations of said rest periods between said plurality of charge pulses.

2. A method for charging a battery, comprising the steps of:

applying a plurality of charge pulses to said battery, said charge pulses each having a duration and being separated by a corresponding plurality of rest periods;

applying a plurality of alternating charge pulses and discharge pulses to said battery;

measuring the charge pulse voltage (CPV) of said battery during at least one of said alternating charge pulses;

applying a subsequent rest period to said battery after said plurality of alternating charge pulses and discharge pulses;

measuring the open circuit voltage (OCV) of said battery during said subsequent rest period;

determining the difference between said CPV and said OCV; and

terminating charging of said battery if said difference is less than a predetermined value.

3. The method of claim 2 and, after said step of applying said plurality of charge pulses, further comprising the steps of:

applying an extended charge pulse to said battery, said extended charge pulse having a duration greater than said durations of said charge pulses, and

applying a rest period to said battery after said extended charge pulse.

4. A method for charging a battery, comprising the steps of:

applying a plurality of charge pulses to said battery, said charge pulses being separated by a corresponding plurality of rest periods;

applying a subsequent discharge pulse to said battery;

measuring the loaded circuit voltage (LCV) of said battery during said subsequent discharge pulse;

applying a subsequent rest period to said battery after said subsequent discharge pulse;

measuring the open circuit voltage (OCV) of said battery during said subsequent rest period;

determining the difference between said LCV and said OCV; and

terminating charging of said battery if said difference is less than a predetermined value.

5. The method of claim 4 and, after said step of applying said plurality of charge pulses, said charge pulses each having a duration, and further comprising the steps of:

applying an extended charge pulse to said battery, said extended charge pulse having a duration greater than said durations of said charge pulses; and

applying a rest period to said battery after said extended charge pulse.

6. The method of claim 4 and, after said step of applying said plurality of charge pulses, further comprising the steps of:

applying a plurality of alternating charge pulses and discharge pulses to said battery, each said discharge pulse having an amplitude; and

applying a rest period to said battery after said plurality of alternating charge pulses and discharge pulses;

wherein said discharge pulse has an amplitude greater than said amplitudes of said discharge pulses of said plurality of alternating charge pulses and discharge pulses.

7. The method of claim 4 and, after said step of applying said plurality of charge pulses, said charge pulses each having a duration, further comprising the steps of:

applying an extended charge pulse to said battery, said extended charge pulse having a duration greater than said durations of said charge pulses;

applying a rest period to said battery after said extended charge pulse;

applying a plurality of alternating charge pulses and discharge pulses to said battery, each said discharge pulse having an amplitude; and

applying a rest period to said battery after said plurality of alternating charge pulses and discharge pulses;

wherein said discharge pulse has an amplitude greater than said amplitudes of said discharge pulses of said plurality of alternating charge pulses and discharge pulses.

8. The method of claim 4 and further comprising the steps of:

if said difference is greater than said predetermined value, but less than a second predetermined value, then increasing at least one of amplitude or the duration of said subsequent discharge pulse, and

repeating the steps previous to these steps.

9. A method of charging a battery, comprising the steps of:

applying a plurality of charge pulses to said battery, said charge pulses each having a duration and being separated by a corresponding plurality of rest periods;

applying a rest period to said battery after said plurality of charge pulses;

applying a subsequent discharge pulse to said battery, said subsequent discharge pulse having an amplitude greater than said amplitudes of said plurality of charge pulses;

measuring the loaded circuit voltage (LCV) of said battery during said subsequent discharge pulse;

applying a subsequent rest period to said battery after said subsequent discharge pulse;

measuring the open circuit voltage (OCV) of said battery during said subsequent rest period;

determining the difference between said LCV and said OCV; and

terminating charging of said battery if said difference is less than a predetermined value.

10. The method of claim 9 and, after said step of applying said rest period to said battery after said plurality of charge pulses, further comprising the steps of:

applying an extended charge pulse to said battery, said extended charge pulse having a duration greater than said durations of said charge pulses, said extended charge pulse having an amplitude; and

applying a rest period to said battery after said extended charge pulse; and

wherein said amplitude of said subsequent discharge pulse is greater than said amplitude of said extended charge pulse.

11. The method of claim 9 and, after said step of applying said rest period to said battery after said plurality of charge pulses, further comprising the steps of:

applying a plurality of alternating charge pulses and discharge pulses to said battery, each said discharge pulse having an amplitude;

applying a rest period to said battery after said plurality of alternating charge pulses and discharge pulses; and

wherein said subsequent discharge pulse has an amplitude greater than said amplitudes of said discharge pulses of said plurality of alternating charge pulses and discharge pulses.

12. The method of claim 9 and, after said step of applying said rest period to said battery after said plurality of charge pulses, further comprising the steps of:

applying an extended charge pulse to said battery, said extended charge pulse having a duration greater than said durations of said charge pulses, said extended charge pulse having an amplitude; and

applying a rest period to said battery after said extended charge pulse;

applying a plurality of alternating charge pulses and discharge pulses to said battery, each said discharge pulse having an amplitude;

applying a rest period to said battery after said plurality of alternating charge pulses and discharge pulses; and

wherein said amplitude of said subsequent discharge pulse is greater than said amplitude of said extended charge pulse and greater than said amplitudes of said discharge pulses of said plurality of alternating charge pulses and discharge pulses.

13. The method of claim 9 and further comprising the steps of:

if said difference is greater than said predetermined value, but less than a second predetermined value, then increasing at least one of amplitude or the duration of said subsequent discharge pulse, and

repeating the steps previous to these steps.

14. A method of charging a battery, comprising the steps of:

applying a discharge pulse to said battery;

applying a rest period to said battery after said discharge pulse;

applying an extended charge pulse to said battery;

applying a rest period to said battery after said extended charge pulse;

applying a plurality of alternating charge pulses and discharge pulses to said battery;

measuring the loaded circuit voltage (LCV) of said battery during a discharge pulse of said plurality of alternating charge pulses and discharge pulses;

applying a rest period to said battery after said plurality of alternating charge pulses and discharge pulses;

measuring the open circuit voltage (OCV) of said battery during said rest period after said plurality of alternating charge pulses and discharge pulses;

determining the difference between said LCV and said OCV; and

terminating charging of said battery if said difference is less than a predetermined value.

15. The method of claim 14 and, prior to said step of applying said discharge pulse to said battery, further comprising the step of:

applying a plurality of charge pulses to said battery, said charge pulses each having an amplitude and being separated by a corresponding plurality of rest periods, said discharge pulse having an amplitude greater than said amplitudes of said plurality of charge pulses.

16. The method of claim 14 and, prior to said step of applying said discharge pulse to said battery, further comprising the steps of:

applying a plurality of charge pulses to said battery, said charge pulses each having an amplitude and being separated by a corresponding plurality of rest periods, said discharge pulse having an amplitude greater than said amplitudes of said plurality of charge pulses; and

applying a rest period to said battery after said plurality of charge pulses.

17. The method of claim 14 and further comprising the steps of:

if said difference is greater than said predetermined value, but less than a second predetermined value, then increasing at least one of amplitude or the duration of said subsequent discharge pulse, and

repeating the steps previous to these steps.

21. An apparatus for charging a battery, comprising:

a charging circuit for applying charge pulses to said battery; and

a controller for;

causing said charging circuit to apply a plurality of charge pulses to said battery, said charge pulses each having a duration and being separated by a corresponding plurality of rest periods;

causing said charging circuit to apply an extended charge pulse to said battery, said extended charge pulse having a duration greater than said durations of said charge pulses;

measuring the charge pulse voltage (CPV) of said battery during said extended charge pulse;

applying a subsequent rest period to said battery after said extended charge pulse;

measuring the open circuit voltage (OCV) of said battery during said subsequent rest period;

determining the difference between said CPV and said OCV; and

terminating charging of said battery if said difference is less than a predetermined value.

22. An apparatus for charging a battery, comprising:

a charging circuit for applying charge pulses to said battery;

a discharging circuit for applying discharge pulses to said battery; and

a controller for;

causing said charging circuit to apply a plurality of charge pulses to said battery, said charge pulses each having a duration and being separated by a corresponding plurality of rest periods;

causing said charging circuit and said discharging circuit to apply a plurality of alternating charge pulses and discharge pulses to said battery;

measuring the charge pulse voltage (CPV) of said battery during at least one of said alternating charge pulses;

applying a subsequent rest period to said battery after said plurality of alternating charge pulses and discharge pulses;

measuring the open circuit voltage (OCV) of said battery during said subsequent rest period;

determining the difference between said CPV and said OCV; and

terminating charging of said battery if said difference is less than a predetermined value.

23. An apparatus for charging a battery, comprising:

a charging circuit for applying charge pulses to said battery;

a discharging circuit for applying discharge pulses to said battery; and

a controller for;

causing said charging circuit to apply a plurality of charge pulses to said battery, said charge pulses being separated by a corresponding plurality of rest periods;

causing said discharging circuit to apply a subsequent discharge pulse to said battery;

measuring the loaded circuit voltage (LCV) of said battery during said subsequent discharge pulse;

applying a subsequent rest period to said battery after said subsequent discharge pulse;

measuring the open circuit voltage (OCV) of said battery during said subsequent rest period;

determining the difference between said LCV and said OCV; and

terminating charging of said battery if said difference is less than a predetermined value.

24. An apparatus for charging a battery, comprising:

a charging circuit for applying charge pulses to said battery;

a discharging circuit for applying discharge pulses to said battery; and

a controller for;

causing said charging circuit to apply a plurality of charge pulses to said battery, said charge pulses each having a duration and being separated by a corresponding plurality of rest periods;

applying a rest period to said battery after said plurality of charge pulses;

causing said discharging circuit to apply a subsequent discharge pulse to said battery, said subsequent discharge pulse having an amplitude greater than said amplitudes of said plurality of charge pulses;

measuring the loaded circuit voltage (LCV) of said battery during said subsequent discharge pulse;

applying a subsequent rest period to said battery after said subsequent discharge pulse;

measuring the open circuit voltage (OCV) of said battery during said subsequent rest period;

determining the difference between said LCV and said OCV; and

terminating charging of said battery if said difference is less than a predetermined value.

25. An apparatus for charging a battery, comprising:

a discharging circuit for applying discharge pulses to said battery;

a charging circuit for applying charge pulses to said battery; and

a controller for;

causing said discharging circuit to apply a discharge pulse to said battery;

applying a rest period to said battery after said discharge pulse;

for causing said charging circuit to apply an extended charge pulse to said battery;

applying a rest period to said battery after said extended charge pulse;

causing said charging circuit and said discharging circuit to apply a plurality of alternating charge pulses and discharge pulses to said battery;

measuring the loaded circuit voltage (LCV) of said battery during a discharge pulse of said plurality of alternating charge pulses and discharge pulses;

applying a rest period to said battery after said plurality of alternating charge pulses and discharge pulses;

measuring the open circuit voltage (OCV) of said battery during said rest period after said plurality of alternating charge pulses and discharge pulses;

determining the difference between said LCV and said OCV; and

terminating charging of said battery if said difference is less than a predetermined value.