Power supply apparatus and electronic appliance equipped with the power supply apparatus

• US 5,717,256 A
• Filed: 06/05/1995
• Issued: 02/10/1998
• Est. Priority Date: 06/08/1994
• Status: Expired due to Fees

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Ozawa, Hidekiyo, Yano, Hidetoshi, Okumura, Masafumi, Saeki, Mituo
• Primary Examiner(s): Shoop, Jr., William M.
• Assistant Examiner(s): PALADINI, ALBERT WILLIAM
• Application Number:
  US08/463,702
• Time in Patent Office: 981 Days
• Field of Search: 307/66, 307/64, 307/43, 320/2, 320/13, 320/48, 320/43, 324/426, 324/433, 324/435, 324/427, 340/635, 340/636
• US Class Current: 307/66
• CPC Class Codes: G01R 19/16542 for batteries charge condition monitoring in G01R31/36
• CPC Class Codes: G01R 31/3648 comprising digital calculation means, e.g. for performing an algorithm
• CPC Class Codes: G01R 31/3842 combining voltage and current measurements
• CPC Class Codes: H02J 2207/20 Charging or discharging characterised by the power electronics converter
• CPC Class Codes: Y10S 320/21 State of charge of battery

Abstract

A power supply apparatus includes a battery, a voltage converter for converting the output of the battery to a different D.C. voltage by ON/OFF action of a main voltage converter control switch circuit, and a device for estimating a remaining capacity of the battery. The remaining battery capacity estimation device detects a non-load voltage of the battery when the main voltage converter control switch circuit is OFF, and estimates the remaining capacity of the battery.

Claims

1. A power supply apparatus comprising:

a battery;

a voltage conversion means for converting an output voltage of the battery to a predetermined voltage value and for outputting the converted voltage, said voltage conversion means having a main voltage conversion control switch which turns said voltage conversion means ON and OFF periodically and alternately so as to continuously generate the predetermined voltage value; and

a remaining battery capacity estimation means including

battery voltage measuring means for measuring a voltage of the battery when the main voltage conversion control switch means is OFF and the battery is in a non-load state, and

a remaining battery capacity calculation means for calculating a remaining battery capacity on the basis of the voltage measured by the battery voltage measuring means.

2. A power supply apparatus according to claim 1, including:

a display means for displaying the remaining battery capacity calculated.

3. A power supply apparatus according to claim 1, wherein said remaining battery capacity estimation means further comprises:

a switch circuit for alternately and periodically switching the battery voltage measuring means in such a way that an ON-OFF condition of the switch circuit becomes substantially phase-revered to that of the main voltage conversion control switch.

4. A power supply apparatus according to claim 2, wherein the remaining battery capacity calculation means causes the display means to display the state where the remaining battery capacity is small, when the voltage measured by the battery voltage measuring means is lower than a rated value.

5. A power supply apparatus comprising:

plural batteries;

a switching means for switching periodically and alternately output of the plural batteries so that the power supply apparatus continuously outputs electric power; and

a remaining battery capacity estimation means including

a battery voltage measuring means for measuring voltages from each battery when the switching means of the battery is OFF and the battery is in a non-load state, and

a remaining battery capacity calculation means for calculating a remaining capacity of each battery on the basis of the voltage measured by the battery voltage measuring means and for calculating the total remaining capacity of all of the batteries.

6. A power supply apparatus according to claim 5, including:

a display means for displaying the remaining battery capacity calculated.

7. A power supply apparatus according to claim 5, wherein the remaining battery capacity calculation means causes the display means to display the state where the remaining battery capacity is small, when the voltage measured by the battery voltage measuring means is lower than a predetermined value.

8. A power supply apparatus comprising:

a battery;

a voltage conversion means, having a main voltage conversion control switch which turns said voltage conversion means ON and OFF, for converting an output voltage of the battery to a predetermined voltage value and for outputting the converted voltage; and

a remaining battery capacity estimation means including;

a battery capacity memory means for storing capacity of the battery,

a battery voltage measuring means for measuring a voltage of the battery when the main voltage conversion control switch means is OFF,

a battery current obtaining means for obtaining a discharge current of the battery by measuring the battery current,

a battery current accumulating means for calculating an accumulated value of the battery current obtained by the battery current obtaining means,

a remaining battery capacity calculation means for calculating the remaining battery capacity from the battery capacity stored in the battery capacity memory means and the accumulated value of the battery current, and

a judgement means for determining a state where the remaining battery capacity is small, when the voltage measured by the battery voltage measuring means drops lower than a predetermined value.

9. A power supply apparatus according to claim 8 including a means for storing a battery current accumulated value in the remaining battery capacity calculation means, into the battery capacity memory means when the voltage measured by the battery voltage measuring means is lower than a predetermined value.

10. A power supply apparatus according to claim 8, including a display means for displaying the remaining battery capacity calculated.

11. A power supply apparatus according to claim 8, wherein the remaining battery capacity calculation means causes the display means to display the state where the remaining battery capacity is small, on the basis of the determination said judgement means.

12. A power supply apparatus comprising:

a battery;

a voltage conversion means, having a main voltage conversion control switch which turns said voltage conversion means ON and OFF, for converting an output voltage of the battery to a predetermined voltage value and for outputting the converted voltage; and

a remaining battery capacity estimation means including;

a battery capacity memory means for storing capacity of the battery,

a battery voltage measuring means for measuring a voltage of the battery when the main voltage conversion control switch means is OFF,

a battery current obtaining means for obtaining a discharge current of the battery by measuring the battery current,

a discharged power calculating means for calculating the discharged power from the battery voltage measured by the battery voltage measuring means and the battery current obtained by the battery current obtaining means,

a discharged quantity accumulation means for calculating an accumulated value of the discharged power obtained by the discharged power calculating means,

a remaining battery capacity calculation means for calculating the remaining battery capacity from the battery capacity stored in the battery capacity memory means and the accumulated value of the discharged power, and

a judgement means for determining a state where the remaining battery capacity is small, when the voltage measured by the battery voltage measuring means drops lower than a predetermined value.

13. A power supply apparatus according to claim 12, including a means for storing a battery current accumulated value in the remaining battery capacity calculation means, into the battery capacity memory means when the voltage obtained by the battery voltage measuring means is lower than a predetermined value.

14. A power supply apparatus according to claim 12, including a display means for displaying the remaining battery capacity calculated.

15. A power supply apparatus according to claim 12, wherein the remaining battery capacity calculation means causes the display means to display the state where the remaining battery capacity is small, on the basis of the determination by said judgement means.

16. A power supply apparatus comprising:

a battery;

a voltage conversion means, having a main voltage conversion control switch which turns said voltage conversion means ON and OFF, for converting an output voltage of the battery to a predetermined voltage value and for Outputting the converted voltage and for working as a self-excited switch regulator;

a counting means for counting a number of ON or OFF actions of the main voltage conversion control switch means; and

a remaining battery capacity estimation means including;

a battery capacity memory means for storing the capacity of the battery,

a battery voltage measuring means for measuring a voltage of the battery when the main voltage conversion control switch means is OFF,

a battery current obtaining means for obtaining a discharge current of the battery from the counted numbers obtained by the counting means,

a battery current accumulating means for calculating an accumulated value of the battery current obtained by the battery current obtaining means,

a remaining battery capacity calculation means for calculating the remaining battery capacity from the battery capacity stored in the battery capacity memory means and the accumulated value of the battery current, and

a judgement means for determining a state where the remaining battery capacity is small, when the voltage measured by the battery voltage measuring means drops lower than a predetermined value.

17. A power supply apparatus according to claim 16 including a means for storing a battery current accumulated value in the remaining battery capacity calculation means, into the battery capacity memory means when the voltage measured by the battery voltage measuring means is lower than a predetermined value.

18. A power supply apparatus according to claim 16 including a display means for displaying the remaining battery capacity calculated.

19. A power supply apparatus according to claim 17 wherein the remaining battery capacity calculation means causes the display means to display the state where the remaining battery capacity is small, on the basis of the determination by said judgement means.

20. A power supply apparatus comprising:

a battery;

a voltage conversion means, having a main voltage conversion control switch which turns said voltage conversion means ON and OFF, for converting an output voltage of the battery to a predetermined voltage value and for outputting the converted voltage and for working as a self-excited switching regulator;

a counting means for counting a number of ON or OFF actions of the main voltage conversion control switch means; and

a remaining battery capacity estimation means including;

a battery capacity memory means for storing a capacity of the battery,

a battery voltage measuring means for measuring a voltage of the battery when the main voltage conversion control switch means is OFF,

a battery current obtaining means for obtaining a discharge current of the battery from the counted numbers obtained by the counting means,

a discharged power calculating means for calculating the discharged power from the battery voltage measured by the battery voltage measuring means and the battery current obtained by the battery current obtaining means,

a discharged quantity accumulation means for calculating an accumulated value of the discharged power obtained by the discharged power calculating means,

a remaining battery capacity calculation means for calculating the remaining battery capacity from the battery capacity stored in the battery capacity memory means and the accumulated value of the discharged power, and

a judgement means for determining a state where the remaining battery capacity is small, when the voltage measured by the battery voltage measuring means drops lower than a predetermined value.

21. A power supply apparatus according to claim 20 including a means for storing a battery current accumulated value in the remaining battery capacity calculation means, into the battery capacity memory means when the voltage measured by the battery voltage measuring means is lower than a predetermined value.

22. A power supply apparatus according to claim 20 including a display means for displaying the remaining battery capacity calculated.

23. A power supply apparatus according to claim 20 wherein the remaining battery capacity calculation means causes the display means to display the state where the remaining battery capacity is small, on the basis of the determination by said judgement means.

24. A power supply apparatus comprising:

a battery;

a voltage conversion means, having a main voltage conversion control switch which turns said voltage conversion means ON and OFF, for converting an output voltage of the battery to a predetermined voltage value and for outputting the converted voltage and for working as a self-excited switching regulator or a separately excited switching regulator;

a counting means for counting a number of ON or OFF actions of the main voltage conversion control switch means; and

a remaining battery capacity estimation means including;

a battery capacity memory means for storing capacity of the battery,

a battery voltage measuring means for measuring a voltage of the battery when the main voltage conversion control switch means is OFF,

a first battery current obtaining means for obtaining a discharge current of the battery from the counted number obtained by the counting means while the voltage conversion means is working as the self-excited switching regulator,

a second battery current obtaining means for obtaining a discharge current of the battery by measuring the battery current while the voltage conversion means is working as the separately excited switching regulator,

a battery current accumulating means for calculating an accumulated value of the battery current obtained by the first battery current obtaining means and the second battery current obtaining means,

a remaining battery capacity calculation means for calculating the remaining battery capacity from the battery capacity stored in the battery capacity memory means and the accumulated value of the battery current, and

a judgement means for determining a state where the remaining battery capacity is small, when the voltage measured by the battery voltage measuring means drops lower than a predetermined value.

25. A power supply apparatus according to claim 24 including a means for storing a battery current accumulated value in the remaining battery capacity calculation means, into the battery capacity memory means when the voltage measured by the battery voltage measuring means is lower than a predetermined value.

26. A power supply apparatus according to claim 24, including a display means for displaying the remaining battery capacity calculated.

27. A power supply apparatus according to claim 24, wherein the remaining battery capacity calculation means causes the display means to display the state where the remaining battery capacity is small, on the basis of the determination by said judgement means.

28. A power supply apparatus comprising:

a battery;

a voltage conversion means, having a main voltage conversion control switch which turns said voltage conversion means ON and OFF, for converting an output voltage of the battery to a predetermined voltage value and for outputting the converted voltage and for working as a self-excited switching regulator or a separately excited switching regulator;

a counting means for counting a number of ON or OFF actions of the main voltage conversion control switch means; and

a remaining battery capacity estimation means including;

a battery capacity memory means for storing capacity of the battery,

a battery voltage measuring means for measuring a voltage of the battery when the main voltage conversion control switch means is OFF,

a first battery current obtaining means for obtaining a discharge current of the battery from the counted number obtained by the counting means while the voltage conversion means is working as the self-excited switching regulator,

a second battery current obtaining means for obtaining a discharge current of the battery by measuring the battery current while the voltage conversion means is working as the separately excited switching regulator,

a discharged power calculating means for calculating the discharged power from the battery voltage measured by the battery voltage measuring means and the battery current obtained by the first battery current obtaining means or the second battery current obtaining means,

a discharged quantity accumulation means for calculating an accumulated value of the discharged power obtained by the discharged power calculating means,

a remaining battery capacity calculation means for calculating the remaining battery capacity from the battery capacity stored in the battery capacity memory means and the accumulated value of the discharged power, and

a judgement means for determining a state where the remaining battery capacity is small, when the voltage measured by the battery voltage measuring means drops lower than a predetermined value.

29. A power supply apparatus according to claim 28 including a means for storing a battery current accumulated value in the remaining battery capacity calculation means, into the battery capacity memory means when the voltage measured by the battery voltage measuring means is lower than a predetermined value.

30. A power supply apparatus according to claim 28 including a display means for displaying the remaining battery capacity calculated.

31. A power supply apparatus according to claim 28, wherein the remaining battery capacity calculation means causes the display means to display the state where the remaining battery capacity is small, on the basis of the determination by said judgement means.

32. An electronic appliance comprising:

a power supply apparatus including

a battery;

a voltage conversion means for converting an output voltage of the battery to a predetermined voltage value and for outputting the converted voltage, said voltage conversion means having a main voltage conversion control switch which turns said voltage conversion means ON and OFF periodically and alternately so as to continuously generate the predetermined voltage value; and

a remaining battery capacity estimation means including

a battery voltage measuring means for measuring a voltage of the battery when the main voltage conversion control switch means is OFF and the battery is in a non-load state, and

a remaining battery capacity calculation means for calculating a remaining battery capacity on the basis of the voltage measured by the battery voltage measuring means.

33. A power supply apparatus according to claim 32, wherein said remaining battery capacity estimation means further comprises:

a switch circuit for alternately and periodically switching the battery voltage measuring means in such a way that an ON-OFF condition of the switch circuit becomes substantially phase-revered to that of the main voltage conversion control switch.

34. An electronic appliance equipped with a power supply apparatus according to claim 32 including a display means for displaying the remaining battery capacity calculated.

35. An electronic appliance equipped with a power supply apparatus according to claim 34, wherein the remaining battery capacity calculation means causes the display means to display the state where the remaining battery capacity is small, when the voltage measured by the battery voltage measuring means is lower than a rated value.

36. An electronic appliance comprising:

a power supply apparatus including

plural batteries;

a switching means for switching periodically and alternately output of the plural batteries so that the power supply apparatus continuously outputs electric power; and

a remaining battery capacity estimation means including

a battery voltage measuring means for measuring voltages from each battery when the switching means of the battery is OFF and the battery is in a non-load state; and

a remaining battery capacity calculation means which calculates a remaining capacity of each battery on the basis of the voltage measured by the battery voltage measuring means and calculates the total remaining capacity of all the batteries.

37. An electronic appliance equipped with a power supply apparatus according to claim 36, including a display means for displaying the remaining battery capacity calculated.

38. An electronic appliance equipped with a power supply apparatus according to claim 37, wherein the remaining battery capacity calculation means causes the display means to display the state where the remaining battery capacity is small, when the voltage measured by the battery voltage measuring means is lower than a predetermined value.

39. An electronic appliance equipped with a power supply apparatus comprising:

a battery;

a voltage conversion means, having a main voltage conversion control switch which turns said voltage conversion means ON and OFF, for converting an output voltage of the battery to a predetermined voltage value and for outputting the converted voltage; and

a remaining battery capacity estimation means including;

a battery capacity memory means for storing capacity of the battery,

a battery voltage measuring means for measuring a voltage of the battery when the main voltage conversion main control switch means is OFF,

a battery current obtaining means for obtaining a discharge current of the battery by measuring the battery current,

a battery current accumulating means for calculating an accumulated value of the battery current obtained by the battery current obtaining means,

a remaining battery capacity calculation means for calculating the remaining battery capacity from the battery capacity stored in the battery capacity memory means and the accumulated value of the battery current, and

a judgement means for determining a state where the remaining battery capacity is small, when the voltage measured by the battery voltage measuring means drops lower than a predetermined value.

40. An electronic appliance equipped with a power supply apparatus according to claim 39 including a means for storing a battery current accumulated value in the remaining battery capacity calculation means, into the battery capacity memory means when the voltage measured by the battery voltage measuring means is lower than a predetermined value.

41. An electronic appliance equipped with a power supply apparatus according to claim 39 including a display means for displaying the remaining battery capacity calculation calculated.

42. An electronic appliance equipped with a power supply apparatus according to claim 39, wherein the remaining battery capacity calculation means causes the display means to display the state where the remaining battery capacity is small, on the basis of the determination by said judgement means.

43. An electronic appliance equipped with a power supply apparatus comprising:

a battery;

a voltage conversion means, having a main voltage conversion control switch which turns said voltage conversion means ON and OFF, for converting an output voltage of the battery to a predetermined voltage value and for outputting the converted voltage; and

a remaining battery capacity estimation means including;

a battery capacity memory means for storing capacity of the battery,

a battery voltage measuring means for measuring a voltage of the battery when the main voltage conversion control switch means is OFF,

a battery current obtaining means for obtaining a discharge current of the battery by measuring the battery current,

a discharged power calculating means for calculating the discharged power from the battery voltage measured by the battery voltage measuring means and the battery current obtained by the battery current obtaining means,

discharged quantity accumulation means for calculating an accumulated value of the discharged power obtained by the discharged power calculating means,

a remaining battery capacity calculation means for calculating the remaining battery capacity from the battery capacity stored in the battery capacity memory means and the accumulated value of the discharged power, and

a judgement means for determining a state where the remaining battery capacity is small, when the voltage measured by the battery voltage measuring means drops lower than a predetermined value.

44. An electronic appliance equipped with a power supply apparatus according to claim 43 including a means for storing a battery current accumulated value in the remaining battery capacity calculation means, into the battery capacity memory means when the voltage measured by the battery voltage measuring means is lower than a predetermined value.

45. An electronic appliance equipped with a power supply apparatus according to claim 43 including a display means for displaying the remaining battery capacity calculated.

46. An electronic appliance according to claim 43, wherein the remaining battery capacity calculation means causes the display means to display the state where the remaining battery capacity is small, on the basis of the determination said judgement means.

47. An electronic appliance equipped with a power supply apparatus comprising:

a battery;

a voltage conversion means, having a main voltage conversion control switch which turns said voltage conversion means ON and OFF, for converting an output voltage of the battery to a predetermined voltage value and for outputting the converted voltage and for working a self-excited switching regulator;

a counting means for counting a number of ON or OFF actions of the main voltage conversion control switch means; and

a remaining battery capacity estimation means including;

a battery capacity memory means for storing capacity of the battery,

a battery voltage measuring means for measuring a voltage of the battery when the main voltage conversion control switch means is OFF,

a battery current obtaining means for obtaining a discharge current of the battery from the counted numbers obtained by the counting means,

a battery current accumulating means for calculating an accumulated value of the battery current obtained by the battery current obtaining means,

a remaining battery capacity calculation means for calculating the remaining battery capacity from the battery capacity stored in the battery capacity memory means and the accumulated value of the battery current, and

a judgement means for determining a state where the remaining battery capacity is small, when the voltage measured by the battery voltage measuring means drops lower than a predetermined value.

48. An electronic appliance equipped with a power supply apparatus according to claim 47 including a means for storing a battery current accumulated value in the remaining battery capacity calculation means, into the battery capacity memory means when the voltage measured by the battery voltage measuring means is lower than a predetermined value.

49. An electronic appliance equipped with a power supply apparatus according to claim 47 including a display means for displaying the remaining battery capacity calculated.

50. An electronic appliance equipped with a power supply apparatus according to claim 48, wherein the remaining battery capacity calculation means causes the display means to display the state where the remaining battery capacity is small, on the basis of the determination the judgement means.

51. An electronic appliance equipped with a power supply apparatus comprising:

a battery;

a voltage conversion means, having a main voltage conversion control witch which turns said voltage conversion means ON and OFF, for converting an output voltage of the battery to a predetermined voltage value and for outputting the converted voltage and for working as a self-excited switching regulator;

a counting means for counting a number of ON or OFF actions of the main voltage conversion control switch means; and

a remaining battery capacity estimation means including;

a battery capacity memory means for storing capacity of the battery,

a battery voltage measuring means for measuring a voltage of the battery when the main voltage conversion control switch means is OFF,

a battery current obtaining means for obtaining a discharge current of the battery from the counted numbers obtained by the counting means,

a discharged power calculating means for calculating the discharged power from the battery voltage measured by the battery voltage measuring means and the battery current obtained by the battery current obtaining means,

a discharged quantity accumulation means for calculating an accumulated value of the discharged power obtained by the discharged power calculating means,

a remaining battery capacity calculation means for calculating the remaining battery capacity from the battery capacity stored in the battery capacity memory means and the accumulated value of the discharged power, and

a judgement means for determining a state where the remaining battery capacity is small, when the voltage measured by the battery voltage measuring means drops lower than a predetermined value.

52. An electronic appliance equipped with a power supply apparatus according to claim 51 including a means for storing a battery current accumulated value in the remaining battery capacity calculation means, into the battery capacity memory means when the voltage measured by the battery voltage measuring means is lower than a predetermined value.

53. An electronic appliance equipped with a power supply apparatus according to claim 51 including a display means for displaying the remaining battery capacity calculated.

54. An electronic appliance equipped with a power supply apparatus according to claim 51, wherein the remaining battery capacity calculation means causes the display means to display the state where the remaining battery capacity is small, on the basis of the determination of said judgement means.

55. An electronic appliance equipped with a power supply apparatus comprising:

a battery;

a voltage conversion means, having a main voltage conversion control switch which turns said voltage conversion means ON and OFF, for converting an output voltage of the battery to a predetermined voltage value and for outputting the converted voltage and for working as a self-excited switching regulator or a separately excited switching regulator;

a counting means for counting a number of ON or OFF actions of the main voltage conversion control switch means; and

a remaining battery capacity estimation means including;

a battery capacity memory means for storing capacity of the battery,

a battery voltage measuring means for measuring a voltage of the battery when the main voltage conversion control switch means is OFF,

a first battery current obtaining means for obtaining a discharge current of the battery from the counted number obtained by the counting means while the voltage conversion means is working as the self-excited switching regulator,

a second battery current obtaining means for obtaining a discharge current of the battery by measuring the battery current while the voltage conversion means is working as the separately excited switching regulator,

a battery current accumulating means for calculating an accumulated value of the battery current obtained by the first battery current obtaining means and the second battery current obtaining means,

a remaining battery capacity calculation means for calculating the remaining battery capacity from the battery capacity stored in the battery capacity memory means and the accumulated value of the battery current, and

a judgement means for determining a state where the remaining battery capacity is small, when the voltage measured by the battery voltage measuring means drops lower than a predetermined value.

56. An electronic appliance equipped with a power supply apparatus according to claim 55 including a means for storing a battery current accumulated value in the remaining battery capacity calculation means, into the battery capacity memory means when the voltage measured by the battery voltage measuring means is lower than a predetermined value.

57. An electronic appliance equipped with a power supply apparatus according to claim 55 including a display means for displaying the remaining battery capacity calculated.

58. An electronic appliance equipped with a power supply apparatus according to claim 55, wherein the remaining battery capacity calculation means causes the display means to display the state where the remaining battery capacity is small, on the basis of the determination by said judgement means.

59. An electronic appliance equipped with a power supply apparatus comprising:

a battery;

a voltage conversion means, having a main voltage conversion control switch which turns said voltage conversion means ON and OFF, for converting an output voltage of the battery to a predetermined voltage value and for outputting the converted voltage and for working as a self-excited switching regulator or a separately excited switching regulator;

a counting means for counting a number of ON or OFF actions of the main voltage conversion control switch means; and

a remaining battery capacity estimation means including;

a battery capacity memory means for storing capacity of the battery,

a battery voltage measuring means for measuring a voltage of the battery when the main voltage conversion control switch means is OFF,

a first battery current obtaining means for obtaining a discharge current of the battery from the counted number obtained by the counting means while the voltage conversion means is working as the self-excited switching regulator,

a second battery current obtaining means for obtaining a discharge current of the battery by measuring the battery current while the voltage conversion means is working as the separately excited switching regulator,

a discharged power calculating means for calculating the discharged power from the battery voltage measured by the battery voltage measuring means and the battery current obtained by the first battery current obtaining means or the second battery current obtaining means,

a discharged quantity accumulating means for calculating an accumulated value of the discharged power obtained by the discharged power calculating means,

a remaining battery capacity calculation means for calculating the remaining battery capacity from the battery capacity stored in the battery capacity memory means and the accumulated value of the discharged power, and

a judgement means for determining a state where the remaining battery capacity is small, when the voltage measured by the battery voltage measuring means drops lower than a predetermined value.

60. An electronic appliance equipped with a power supply apparatus according to claim 59 including a means for storing a battery current accumulated value in the remaining battery capacity calculation means, into the battery capacity memory means when the voltage measured by the battery voltage measuring means is lower than a predetermined value.

61. An electronic appliance equipped with a power supply apparatus according to claim 59 including a display means for displaying the remaining battery capacity calculated.

62. An electronic appliance equipped with a power supply apparatus according to claim 59, wherein the remaining battery capacity calculation means causes the display means to display the state where the remaining battery capacity is small, on the basis of the determination by said judgement means.