Battery charger and battery charging method

• US RE39,691 E1
• Filed: 12/02/2002
• Issued: 06/12/2007
• Est. Priority Date: 03/26/1999
• Status: Active Grant

• Current Assignee: Makita Corporation
• Original Assignee: Makita Corporation
• Inventors: Sakakibara, Kazuyuki
• Primary Examiner(s): Tso; Edward H.
• Application Number:
  US10/308,082
• Time in Patent Office: 1,653 Days
• Field of Search: 320/124, 320/125, 320/127, 320/128, 320/137, 320/144, 320/150, 320/152, 320/153
• US Class Current: 320/150
• CPC Class Codes: H01M 10/443 in response to temperature
• CPC Class Codes: H02J 7/0091 in response to temperature of the battery

Abstract

A temperature rise pattern is retrieved from charging time based on the difference between a battery temperature at the beginning of battery charge and a target temperature value which a battery is intended to reach (in S116). The battery is charged while adjusting a current value so that a temperature rise value becomes the temperature rise pattern (in S118 and S120). Thus, by optimizing the temperature rise pattern, it is possible to charge the battery so that the temperature at the time of the completion of battery charge becomes the target temperature value (the lowest temperature value).

Claims

1. A battery charger characterized by comprising:

a temperature detecting section for detecting a present battery temperature;

a temperature rise value outputting section for obtaining a temperature rise value from the temperature detected by said temperature detecting section;

a current value retrieving section for retrieving a current value with which the temperature rise value outputted from said temperature rise value outputting section is constant; and

a charge control section for charging a battery with the current value retrieved by said current value retrieving section.

2. A battery charger characterized by comprising:

a storage device storing a target temperature value which a battery temperature is intended to reach;

a temperature detecting section for detecting a present battery temperature;

a temperature gradient calculating section for calculating a temperature rise gradient from charging time based on a difference between a battery temperature at the beginning of battery charge and said target temperature value held by said storage device;

a temperature rise value outputting section for obtaining a temperature rise value from the temperature detected by said temperature detecting section;

a current value retrieving section for retrieving a current value with which the temperature rise value outputted from said temperature rise value outputting section becomes said temperature rise gradient; and

a charge control section for charging the battery with the current value retrieved by said current value retrieving section.

3. A battery charger characterized by comprising:

a storage device storing a target temperature value which a battery is intended to reach;

a temperature detecting section for detecting a present battery temperature;

a temperature rise pattern retrieving section for retrieving a temperature rise pattern for completing battery charge at said target temperature value based on a difference between a battery temperature at the beginning of the battery charge and said target temperature value held by said storage device;

a temperature rise value outputting section for obtaining a temperature rise value from the temperature detected by said temperature detecting section;

a current value retrieving section for retrieving a current value with which the temperature rise value outputted from said temperature rise value outputting section becomes said temperature rise pattern; and

a charge control section for charging the battery with the current value retrieved by said current value retrieving section.

4. A battery charger according to claim 3, characterized in that said temperature rise pattern is such that the temperature rise value is relatively high in a first half of battery charge and is relatively low in a second half of battery charge.

5. A battery charger according to claim 3, characterized in that said temperature rise pattern is approximated polygonally.

6. A battery charger according to claim 4, characterized in that said temperature rise pattern is approximated polygonally.

7. A battery charger according to claim 3, characterized in that said target temperature value is a value for comprising the battery charge at the lowest temperature.

8. A battery charger according to claims 4, characterized in that said target temperature value is a value for completing the battery charge at the lowest temperature.

9. A battery charger according to claim 5, characterized in that said target temperature value is a value for completing the battery charge at the lowest temperature.

11. A battery charging method according to claim 7, characterized in that said target temperature value is a value for completing the battery charge at the lowest temperature.

10. A battery charging method for making a battery side hold information on a target temperature value, which a battery is intended to reach, corresponding to charging time and charging the battery by means of a battery charger in accordance with the target temperature value, characterized in that said battery charger comprises:

a storage device storing a temperature rise pattern for completing battery charge at the target temperature value read out from the battery side;

a temperature detecting section for detecting a present battery temperature;

a temperature rise pattern retrieving section for retrieving a temperature rise pattern from said storage device based on a battery temperature at the beginning of the battery charge and charging time;

a temperature rise value outputting section for obtaining a temperature rise value from the temperature detected by said temperature detecting section;

a current value retrieving section for retrieving a current value with which the temperature rise value outputted from said temperature rise value outputting section becomes said temperature rise pattern; and

a charge control section for charging the battery with the current value retrieved by said current value retrieving section.

12. An apparatus for charging a battery comprising:

a controller coupled to a temperature sensing terminal, a charging terminal and a power supply, wherein the controller adjusts the amount of current supplied to the charging terminal by the power supply in order to maintain an actual rate of battery temperature increase approximately equal to a predetermined pattern of battery temperature increase.

13. An apparatus as in claim 12, wherein the controller comprises instructions for stopping the supply of current to the battery if the current being supplied to the battery falls below a predetermined current value.

14. An apparatus in claim 12, wherein the controller stores a curve of final battery temperatures versus charging times and generates the predetermined pattern of battery temperature increase based at least in part upon an initial battery temperature and the curve of final battery temperatures.

15. An apparatus for supplying current to a rechargeable battery comprising:

a first terminal arranged and constructed to connect to a battery temperature sensor disposed proximally to the rechargeable battery,

a power supply,

a second terminal coupled to the power supply and adapted to supply current to the rechargeable battery, and

a controller coupled to the first terminal and the power supply, wherein the controller adjusts the amount of current supplied to the second terminal by the power supply in order to maintain an actual rate of battery temperature increase approximately equal to a predetermined rate of battery temperature increase.

16. An apparatus as in claim 15, wherein the controller stops the supply of current to the battery when the current being supplied to the battery is less than a predetermined current value.

17. An apparatus as in claim 15, wherein the controller is further arranged and constructed to:

(i) reduce the amount of current supplied to the rechargeable battery, if the actual rate of battery temperature increase is greater than the predetermined rate of battery temperature increase, and

(ii) increase the amount of current supplied to the rechargeable battery, if the actual rate of battery temperature increase is less than the predetermined rate of battery temperature increase.

18. An apparatus as in claim 17, wherein the predetermined rate of battery temperature increase is a constant rate.

19. An apparatus as in claim 17, wherein the predetermined rate of battery temperature increase is a rate that varies over time.

20. An apparatus as in claim 19, wherein the predetermined rate of battery temperature increase is greater at the beginning of a charging cycle than at the end of the charging cycle.

21. An apparatus as in claim 15, further comprising a memory storing an equation for calculating the predetermined rate of battery temperature increase based at least in part upon an initial battery temperature detected before the charging operation has begun.

22. An apparatus as in claim 15, wherein the controller is further arranged and constructed to stop current to the battery in the event of an overshoot condition.

23. An apparatus as in claim 22, wherein the controller is further arranged and constructed to stop current to the battery when the current being supplied to the battery falls below a predetermined current value.

24. An apparatus as in claim 15, wherein the controller stores a curve of final battery temperatures versus charging times and generates the predetermined pattern of battery temperature increase based at least in part upon an initial battery temperature and the curve of final battery temperatures, wherein the controller is arranged and constructed to stop the supply of current to the battery (1) when the actual current supplied to the battery is less than a predetermined current value and (2) in the event of an overshoot condition.

25. An apparatus as in claim 24, wherein the controller is further arranged and constructed to:

(i) reduce the amount of current supplied to the rechargeable battery, if the actual rate of battery temperature increase is greater than the predetermined rate of battery temperature increase, and

(ii) increase the amount of current supplied to the rechargeable battery, if the actual rate of battery temperature increase is less than the predetermined rate of battery temperature increase.

26. An apparatus as in claim 25, wherein the predetermined rate of battery temperature increase is a constant rate.

27. An apparatus as in claim 25, wherein the predetermined rate of battery temperature increase is a rate that varies over time.

28. An apparatus as in claim 27, wherein the predetermined rate of battery temperature increase is greater at the beginning of a charging cycle than at the end of the charging cycle.

29. A method for charging a battery comprising:

detecting an initial battery temperature,

generating a predetermined pattern of battery temperature increase rate based at least in part upon the initial battery temperature,

supplying charging current to the battery,

determining an actual battery temperature increase rate while charging the battery, and

adjusting the amount of current supplied to the battery in order to substantially equalize the actual battery temperature increase rate with the predetermined battery temperature increase rate.

30. A method as in claim 29, wherein the current adjusting step comprises:

(i) reducing the amount of charging current supplied to the battery, if the actual battery temperature increase rate is greater than the predetermined battery temperature increase rate and

(ii) increasing the amount of charging current supplied to the battery, if the actual battery temperature increase rate is less than the predetermined battery temperature increase rate.

31. A method as in claim 30, further comprising:

stopping the supply of charging current to the battery when the amount of charging current being supplied to the battery falls below a predetermined current value.

32. A method as in claim 31, further comprising:

stopping the supply of charging current to the battery when an overshoot condition is detected.

33. A method as in claim 29, further comprising:

stopping the supply of charging current to the battery when the amount of current being supplied to the battery falls below a predetermined current value.

34. A method as in claim 29, further comprising:

stopping the supply of charging current to the battery when an overshoot condition is detected.

35. An apparatus for charging a battery, comprising:

means for sensing a battery temperature of the battery,

means for predetermining a pattern of battery temperature increase rate during battery charging based at least in part upon an initial battery temperature, and

means for supplying varying charging currents to the battery so that the battery temperature increases during charging substantially according to the predetermined pattern of battery temperature increase rate.

36. An apparatus as in claim 35, wherein the means for supplying varying charging currents to the battery comprises:

(i) means for reducing the amount of charging current supplied to the battery, if the actual battery temperature increase rate is greater than the predetermined battery temperature increase rate and

(ii) means for increasing the amount of charging current supplied to the battery, if the actual battery temperature increase rate is less than the predetermined battery temperature increase rate.

37. An apparatus as in claim 36, further comprising:

means for stopping the supply of charging current to the battery when the amount of charging current being supplied to the battery falls below a predetermined current value.

38. An apparatus as in claim 37, further comprising:

means for stopping the supply of charging current to the battery when an overshoot condition is detected.

39. An apparatus as in claim 35, further comprising:

means for stopping the supply of charging current to the battery when the amount of charging current being supplied to the battery falls below a predetermined current value.

40. An apparatus as in claim 35, further comprising:

means for stopping the supply of charging current to the battery when an overshoot condition is detected.

41. A method for charging a battery, comprising:

selecting a predetermined pattern of battery temperature increase rate, and

supplying varying charging currents to the battery so that the battery temperature increases during charging substantially according to the predetermined pattern of battery temperature increase rate.

42. A method as in claim 41, wherein the predetermined battery temperature increase rate is selected at least in part based upon an initial battery temperature.

43. A method as in claim 41, wherein the step of supplying varying charging currents to the battery comprises:

(i) reducing the amount of charging current supplied to the battery, if the actual battery temperature increase rate is greater than the predetermined pattern of battery temperature increase rate and

(ii) increasing the amount of charging current supplied to the battery, if the actual battery temperature increase rate is less than the predetermined pattern of battery temperature increase rate.

44. A method as in claim 43, further comprising:

stopping the supply of charging current to the battery when the amount of charging current being supplied to the battery falls below a predetermined current value.

45. A method as in claim 44, further comprising:

stopping the supply of charging current to the battery when an overshoot condition is detected.

46. A method as in claim 41, further comprising:

stopping the supply of charging current to the battery when the amount of current being supplied to the battery falls below a predetermined current value and

stopping the supply of charging current to the battery when an overshoot condition is detected.

47. A method for charging a battery comprising:

generating a predetermined pattern of battery temperature increase during a charging operation,

supplying charging current to the battery and monitoring an actual battery temperature increase rate while charging the battery,

reducing the amount of charging current supplied to the battery, if the actual battery temperature increase rate is greater than the predetermined pattern of battery temperature increase rate and

increasing the amount of charging current supplied to the battery, if the actual battery temperature increase rate is less than the predetermined pattern of battery temperature increase rate.