CHARGING METHODS FOR BATTERY POWERED DEVICES

• US 20100013430A1
• Filed: 12/11/2007
• Published: 01/21/2010
• Est. Priority Date: 12/11/2006
• Status: Active Grant

• Current Assignee: Tower Semiconductor Limited
• Original Assignee: Techtium Ltd.
• Inventors: Manor, Dror, Saar, Amnon, Weinstein, Guy
• Granted Patent: US 8,080,976 B2
• Time in Patent Office: Days
• US Class Current: 320/106
• CPC Class Codes: H02J 7/00041 in response to measured battery parameters, e.g. voltage, current or temperature profile
• CPC Class Codes: H02J 7/00047 with provisions for charging different types of batteries
• CPC Class Codes: H02J 7/0016 using shunting, discharge or bypass circuits

Abstract

A battery charge control system including an algorithm for determining whether the battery chemistry of a battery pack for use in a portable electronic device is primary, in which case charging is prevented, or secondary, in which case charging is enabled. The routine operates by measuring the terminal voltage and temperature of the battery under certain predetermined tests, which generally include a combination of voltage and internal impedance tests performed during charge or discharge. Additionally, a method is described to detect and to correct for lack of cell balance within the rechargeable battery pack of a portable electronic device. A cell or cells of the battery pack which are close to depletion, or are completely depleted, are detected, and a discharge/charge routine is executed to provide for optimum recharging of all of the cells of the battery, thus ensuring proper cell balance, and most efficient power usage.

Claims

1. A method of determining the nature of an electrochemical battery, comprising the steps of:

(a) measuring the initial voltage of said battery;

(b) according to said initial voltage, determining the initial impedance of said battery by generating a current flow through said battery, and measuring the voltage change of said battery as a result of said current flow;

(c) according to said initial impedance, performing the steps of;

(i) applying a pre-charge current, and measuring the voltage of said battery at intervals during said application of pre-charge current; and

(ii) according to the voltage of said battery during said application of pre-charge current, making at least one internal impedance determination of said battery by generating at least one increased current flow through said battery, and measuring the voltage change of said battery as a result of said at least one increased current flow; and

(d) utilizing at least one of said initial measured voltage, said measured voltage of said battery during said application of pre-charge current, said initial impedance, and said internal impedance to determine the nature of said electrochemical battery.

2. A method according to claim 1 and wherein if said initial voltage is above a first predetermined voltage said battery is considered to be a primary battery, and if said initial voltage is below a second predetermined voltage, said battery is considered to be unusable.

3. A method according to claim 1 and wherein if said initial impedance is above a first predetermined impedance, said battery is considered to be a primary battery, and if said initial impedance is below a second predetermined impedance, said battery is considered to be a secondary battery.

4. A method according to claim 3, wherein said pre-charge current is applied if said initial impedance falls between said first predetermined impedance and said second predetermined impedance.

5. A method according to claim 2 and wherein if said voltage measured during said pre-charge application rises above said first predetermined voltage, said battery is considered to be a primary battery.

6. A method according to claim 2 and wherein if, at the end of said predetermined time, said voltage measured during said pre-charge application has not risen above a third predetermined voltage between said second and first predetermined voltages, said battery is considered to be unusable.

7. A method according to claim 1 and wherein said internal impedance is measured at intervals during said pre-charge application, and if at least one of said internal impedance determinations is found to be above a first predetermined impedance, said battery is considered to be a primary battery, and if at least one of said internal impedance determinations is found to be below a second predetermined impedance, said battery is considered to be a secondary battery.

8. A method according to claim 1 and wherein said internal impedance is measured after said application of pre-charge current, and if said internal impedance is found to be above said second predetermined impedance, charging of said battery is prevented, and if said internal impedance is found to be below said second predetermined impedance, said battery is considered to be a secondary battery.

9. A method according to claim 1, and wherein said at least one internal impedance determination comprises any one of a single point impedance measurement, an averaged impedance measurement over one application of at least one increased current flow, the final impedance measurement after one application of at least one increased current flow, and a combination of impedance measurements from a plurality of increased current flows.

10. A method according to claim 1, and wherein said at least one increased current flow is generated by at least one of applying a charge current to said battery and discharging a current from said battery.

12. A method according to claim 1 and wherein said at least one increased current flow through said battery is an incrementally increasing current flow.

13. A method according to claim 12 and wherein said incrementally increasing current flow is continued until either one of a predetermined battery voltage and a predetermined charge current is reached.

14. A method according to claim 1 and wherein said pre-charge current is a predetermined fraction of the recommended charge current of said battery

15. A method according to claim 1 and wherein if said battery is determined to be any one of a primary battery, an unusable battery, or a full rechargeable battery, charging of said battery is prevented, and if said battery is determined to be a secondary battery, charging of said battery is enabled.

11. (canceled)

16. (canceled)

17. A method of determining the nature of an electrochemical battery, comprising the steps of:

(a) measuring the initial voltage of said battery;

(b) according to said initial voltage, performing one of the steps of;

(i) applying a pre-charge current of a predetermined fraction of the recommended charge current of said battery for a predetermined time, and measuring the voltage of said battery during said predetermined time; and

(ii) generating an incrementally increasing current flow in said battery, and measuring the voltage of said battery during said application of said incrementally increasing current flow; and

(c) utilizing at least one of said measured voltages to determine the nature of said electrochemical battery.

18. A method according to claim 17 and wherein if said initial voltage is above a first predetermined voltage said battery is considered to be a primary battery, and if said initial voltage is below a second predetermined voltage, said battery is considered to be unusable.

19. A method according to claim 18, wherein said precharge current step is applied if said initial voltage falls between said first predetermined voltage and a third predetermined voltage less than said second predetermined voltage, and wherein if, during said precharge step, said voltage does not rise above a fourth predetermined value, said battery is considered to be unusable.

20. A method according to claim 18, wherein said incrementally increasing current flow is applied if said initial voltage falls between said third predetermined voltage and said second predetermined voltage.

21. A method according to claim 20 and wherein if said voltage measured during said incrementally increasing current flow rises above a fifth predetermined voltage, greater than said first predetermined voltage, said battery is considered to be unusable.

22. A method according to claim 20 and wherein said voltage measured during said incrementally increasing current flow is utilized to determine the internal impedance of said battery, and if said internal impedance is greater than a predetermined level, said battery is considered to be unusable.

23. A method according to claim 20 and wherein if said internal impedance is less than said predetermined level, said battery is considered to be a secondary battery fit for charging.

24. A method according to claim 17 and wherein said at least one incrementally increasing current flow is generated by at least one of applying an incrementally increasing charge current to said battery, and discharging an incrementally increasing charge current from said battery.

25. (canceled)

26. A method of ensuring cell charge balance in a rechargeable battery comprising a plurality of cells;

comprising the steps of;

determining the state of charge of each cell of said battery;

locating at least one deficient cell, the deficiency of said cell being in that its state of charge is significantly less than that of at least one other cell;

discharging all of the cells located from said at least one deficient cell towards one end of said battery; and

recharging said at least one deficient cell together with all of said cells located from said at least one deficient cell towards said one end of said battery.