Battery pack with a discharge control mechanism

• US 7,501,797 B2
• Filed: 06/12/2007
• Issued: 03/10/2009
• Est. Priority Date: 08/30/2002
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Satoh, Yuji, Kishi, Takashi, Kanda, Motoya
• Primary Examiner(s): TSO, EDWARD H
• Application Number:
  US11/761,494
• Publication Number:
  US 20070231680A1
• Time in Patent Office: 637 Days
• Field of Search: 320/107, 320/112, 320/114, 320/134, 320/136, 320/150
• US Class Current: 320/136
• 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 10/443 in response to temperature
• CPC Class Codes: H01M 10/486 for measuring temperature
• CPC Class Codes: H01M 50/103 prismatic or rectangular H01M50/109, H01M50/11 take precedence
• CPC Class Codes: H02J 7/0031 using battery or load disconnect circuits H02J9/002 takes precedence
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A battery pack including: a nonaqueous electrolyte secondary battery including an external connection terminal; and a discharge control mechanism which controls discharge of the nonaqueous electrolyte secondary battery when a surface temperature of the nonaqueous electrolyte secondary battery exceeds a discharge control temperature T₁ (° C.) represented by
T₁=T₀+QA  (1)
where T₀ is an ambient temperature in a range of 0 to 60° C., Q is 8 (° C./C), and A is a discharge rate (C) of the nonaqueous electrolyte secondary battery in a case where a current required for discharging a nominal capacity of the nonaqueous electrolyte secondary battery in one hour is 1C, and is within a range of 4C to 7C.

Claims

1. A battery pack comprising:

a nonaqueous electrolyte secondary battery including an external connection terminal; and

a discharge control mechanism which controls discharge of the nonaqueous electrolyte secondary battery when a surface temperature of the nonaqueous electrolyte secondary battery exceeds a discharge control temperature T₁ (°

C.) represented by

T₁=T₀+QA 

 

(1)

where T₀ is an ambient temperature in a range of 0 to 60°

C., Q is 8 (°

C./C), and A is a discharge rate (C) of the nonaqueous electrolyte secondary battery in a case where a current required for discharging a nominal capacity of the nonaqueous electrolyte secondary battery in one hour is 1 C, and is within a range of 4 C to 7 C.

2. The battery pack according to claim 1, wherein the discharge control temperature T₁ (°

C.) is not more than a melting point of a separator of the nonaqucous electrolyte secondary battery.

3. The battery pack according to claim 1, wherein the discharge control temperature T₁ (°

C.) is not more than 120°

C.

4. The battery pack according to claim 1, further comprising a temperature detecting mechanism which measures the surface temperature of the nonaqueous electrolyte secondary battery.

5. The battery pack according to claim 4, wherein the temperature detecting mechanism comprises at least one of a thermocouple and a thermistor.

6. The battery pack according to claim 1, wherein the discharge control mechanism comprises a temperature comparator which compares the surface temperature with the discharge control temperature T₁, and a discharge control/discharge stop circuit which performs discharge stop and discharge control on the basis of an output from the temperature comparator.

7. A battery pack comprising:

a battery in which units each obtained by connecting nonaqueous electrolyte single cells in parallel are connected in series, said battery including an external connection terminal; and

a discharge control mechanism which, when a surface temperature of the battery exceeds a discharge control temperature T₁ (°

C.) represented by equation (1) below, stops discharge of the battery pack if a voltage of the battery is not more than a discharge stop voltage V_a (V) represented by equation (2) below or a voltage of the single cell is less than 3 V, and lowers a discharge rate of the battery pack if the voltage of the battery is higher than the discharge stop voltage V_a (V) and the voltage of the single cell is not less than 3 V;

T₁=T₀÷

QA 

 

(1)

where T₀ is an ambient temperature (°

C.), Q is 8 (°

C./C), and A is a discharge rate (C); and

V_a=n×

3(V) 

 

(2)

where n is the number of series-connected units in the battery.

8. The battery pack according to claim 7, wherein the ambient temperature T₀ is 0°

C. to 60°

C.

9. The battery pack according to claim 7, wherein the discharge rate A is 4 C to 7 C.

10. The battery pack according to claim 7, wherein the discharge control temperature T₁ (°

C.) is not more than a melting point of a separator of the nonaqueous electrolyte single cell.

11. The battery pack according to claim 7, wherein the discharge control temperature T₁ (°

C.) is not more than 120°

C.

12. The battery pack according to claim 7, further comprising a temperature detecting mechanism which measures the surface temperature of the battery.

13. The battery pack according to claim 12, wherein the temperature detecting mechanism comprises at least one of a thermocouple provided on a surface of the single cell and a thermistor electrically connected to the single cell.

14. The battery pack according to claim 7, wherein the discharge control mechanism comprises a temperature comparator which compares the surface temperature with the discharge control temperature T₁, a voltage comparator which compares the voltage of the battery with the discharge stop voltage V_a and the voltage of the single cell with 3 V, and a discharge control/discharge stop circuit which performs discharge stop and discharge control on the basis of outputs from the temperature comparator and voltage comparator.