Single wire battery pack temperature and identification method

• US 8,823,321 B2
• Filed: 12/30/2010
• Issued: 09/02/2014
• Est. Priority Date: 12/30/2010
• Status: Active Grant

• Current Assignee: Duracell U.S. Operations, Inc. (Berkshire Hathaway Incorporated)
• Original Assignee: Gillette Company (The Procter & Gamble Company)
• Inventors: Dvorkin, Elik, Gajjar, Tanmay P.
• Primary Examiner(s): Dunn, Drew A
• Assistant Examiner(s): GRANT, ROBERT J
• Application Number:
  US12/981,737
• Publication Number:
  US 20120169271A1
• Time in Patent Office: 1,342 Days
• Field of Search: 320/113
• US Class Current: 320/113
• CPC Class Codes: G01K 13/00 Thermometers specially adapted for specific purposes
• CPC Class Codes: G01R 31/378 specially adapted for the type of battery or accumulator
• CPC Class Codes: H01M 10/0525 Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• CPC Class Codes: H01M 10/425 Structural combination with electronic components, e.g. electronic circuits integrated to the outside of the casing printed circuits H05K1/00
• CPC Class Codes: H01M 10/443 in response to temperature
• CPC Class Codes: H01M 10/446 Initial charging measures
• CPC Class Codes: H01M 10/486 for measuring temperature
• 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 7/007182 in response to battery voltage
• CPC Class Codes: H02J 7/007194 of the battery
• CPC Class Codes: H02J 7/04 Regulation of charging current or voltage
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

Disclosed are techniques for identifying battery pack types and by inference battery chemistries by measuring a transient response of the battery pack to signal applied to the battery pack.

Claims

1. A method for identifying a type of battery pack, the battery pack having a rechargeable battery, a power terminal, a reference terminal, and a sense terminal, the method comprising:

detecting installation of the battery pack;

measuring voltage on the sense terminal of the battery pack that has a thermistor coupled to the sense terminal;

verifying from the measured voltage, battery pack temperature;

applying a signal to the sense terminal of the battery pack;

measuring a time constant as a transient response at the sense terminal of the battery pack, in response to the applied signal; and

determining from the measured transient response at the sense terminal the battery pack battery type, by;

comparing a time constant to a predefined time constant, if much larger identifying the battery pack as a battery pack including a capacitor and if the measured time constant is about the same as the predefined time constant identifying the battery pack as a battery pack not including a capacitor.

2. The method of claim 1, further comprising

determining a charging current to be applied to the battery based on the measured transient response;

and

applying the determined charging current to the battery.

3. The method of claim 1, further comprising:

applying the signal by causing a first terminal of a controller unit of a battery charger to a low state; and

measuring the transient response of the battery to the signal at a second, different terminal of the controller unit of the battery charger.

4. The method of claim 1, wherein measuring the transient response comprises:

measuring a voltage between the sense terminal of the battery pack and an input to a controller in response to applying the signal at a first time instance; and

measuring the voltage between the sense terminal of the battery pack and the input of the controller in response to applying the signal at a subsequent time instance.

5. The method of claim 4, wherein measuring the transient response further comprises:

computing value of the transient response over the first and subsequent instances of time.

6. The method of claim 1, wherein determining the battery pack comprises:

accessing a lookup table storing transient response values, associated with plural, different types of battery packs to provide an indication of battery pack type.

7. The method of claim 1, wherein the battery is lithium-iron-phosphate electrochemical cell.

8. The method of claim 1, further comprising:

accessing a lookup table storing multiple charging current values, associated with a corresponding identified battery type;

periodically measuring the voltage between terminals of the battery; and

adjusting the charging current applied to the battery when the measured voltage between the terminals of the battery reaches a pre-determined voltage value such that the voltage between the terminals of the battery is maintained at the pre-determined voltage value.

9. The method of claim 1 wherein the battery pack comprises a resistor and the transient response of the battery pack is measured taking into consideration the value of resistance of the resistor.

10. The method of claim 9 wherein the resistor is a thermistor and the transient response of the battery pack is measured taking into consideration the value of resistance of the thermistor.

11. The method of claim 10, further comprising:

measuring the value of resistance of the thermistor to infer a value of temperature of the battery in the battery pack.

12. A charging device configured to charge a rechargeable battery having a power and a reference terminal and a sense terminal, and housed in a battery pack, comprising at least one rechargeable electrochemical cell, the device comprising:

a charging compartment configured to receive the battery pack, the charging compartment having electrical contacts configured to be coupled to respective terminals of the battery; and

a controller configured to;

measure a resistance at the sense terminal;

determine from the measured resistance temperature of the battery pack;

apply a signal to the sense terminal of the battery pack; and

measure a transient response of the battery pack to the applied signal at the sense terminal;

determine the battery pack from the measured transient response by the controller configured to;

compare a time constant to a predefined time constant, if much larger identifying the battery pack as a battery pack including a capacitor and if the measured time constant is about the same as the predefined time constant identifying the battery pack as a battery pack not including a capacitor.

13. The device of claim 12 wherein the controller is further configured to:

cause the determined charging current to be applied to the battery.

14. The device of claim 12 further comprising:

a first resistor coupled to a voltage source that powers the charging device;

a capacitor coupled to a first input of the controller; and

a second resistor coupled to an input/output terminal of the controller and the capacitor and the first resistor, with the input/output terminal configured to supply the signal to the battery pack in a first configuration and to provide a voltage divider in conjunction with a resistance of the sense terminal and the first resistor in a second configuration of the input/output terminal.

15. The device of claim 12 wherein the controller is configured to determine the transient response of the battery pack to the signal by:

τ

_BP1=R_th∥

R_pd∥

R_pu×

(C<sub>—

a/d</sub>)

where R_th is a resistor in the battery pack R_pd and R_pu are resistors coupled to the output terminal and a voltage supply of the controller, respectively, and C<sub>—

a/d</sub> is the capacitor coupled to the first input of the controller.

16. The device of claim 12 wherein the controller is configured to determine the transient response of the battery pack to the signal by:

τ

_BP2=R_th∥

R_pd∥

R_pu×

(C<sub>—

a/d</sub>+C<sub>—

bp2</sub>)

where R_th is a resistor in the battery pack R_pd and R_pu are resistors coupled to the output terminal and a voltage supply of the controller, respectively, C<sub>—

a/d</sub> is a capacitor coupled to the first input of the controller and C<sub>—

bp2</sub> is a capacitor coupled to a terminal of the battery pack in parallel with the resistor R_th.

17. The device of claim 12 wherein the rechargeable battery includes a lithium-iron-phosphate rechargeable battery.

18. A charging device configured to charge a rechargeable battery comprising at least one rechargeable electrochemical cell and having a power terminal, a sense terminal and a reference terminal and housed in a battery pack, the device comprising:

a charging compartment configured to receive the battery pack, the charging compartment having a first set of electrical contacts configured to be coupled to respective bower and reference terminals of the battery pack to supply charging current to a battery in the battery pack and having a sense terminal this is isolated from one of the first set of terminals of the battery pack; and

a controller configured to;

apply a signal to the sense terminal of the battery pack; and

measure a transient response of the battery pack to the applied signal at the sense terminal, with the sense terminal conveying an impedance having a resistance and capacitance component to the controller; and

the controller further configured to;

determine the battery pack from the measured transient response by;

compare a time constant to a predefined time constant, if much larger identifying the battery pack as a battery pack including a capacitor and if the measured time constant is about the same as the predefined time constant identifying the battery pack as a battery pack not including a capacitor.

19. The device of claim 18 wherein the controller is further configured to determine the transient response to the signal of the battery pack at the sense terminal of the battery pack that has a thermistor R_th by:

τ

_BP1=R_th∥

R_pd∥

R_pu×

(C<sub>—

a/d</sub>)

where R_th is the resistor in the battery pack R_pd and R_pu are resistors coupled to the output terminal and a voltage supply of the controller, respectively, and C<sub>—

a/d</sub> is the capacitor coupled to the first input of the controller and the controller is further configured to;

measure a resistance value of the thermistor using the sense terminal of the battery pack to determine a temperature of the battery.

20. The device of claim 18 wherein the controller is further configured to determine the transient response to the signal of the battery pack at the sense terminal of the battery pack that has a thermistor R_th and a capacitor C_—

bp2 in shunt with resistor R_th by;

τ

_BP2=R_th∥

R_pd∥

R_pu×

(C<sub>—

a/d</sub>+C<sub>—

bp2</sub>)

where R_th is a resistor in the battery pack R_pd and R_pu are resistors coupled to the output terminal and a voltage supply of the controller, respectively, C<sub>—

a/d</sub> is a capacitor coupled to the first input of the controller and C_bp2 is a capacitor coupled to a terminal of the battery pack in parallel with the resistor R_th and the controller is further configured to;

measure a resistance value of the thermistor using the sense terminal of the battery pack to determine a temperature of the battery.

21. The device of claim 18 wherein the controller is further configured to:

determine a charging current to be applied to the battery based on the measured transient response; and

apply the determined charging current to the battery.

22. The device of claim 18 wherein the controller is further configured to:

cause the device to apply the signal by causing a first terminal of the controller unit to a low state; and

measuring the transient response of the battery to the signal at a second, different terminal of the controller unit of the battery charger.

23. The device of claim 18 wherein the controller is further configured to:

measure a voltage between the sense terminal of the battery pack and an input to a controller in response to applying the signal at a first time instance; and

measure the voltage between the sense terminal of the battery pack and the input of the controller in response to applying the signal at a subsequent time instance; and

compute value of the transient response over the first and subsequent instances of time.