Apparatus for indicating remaining battery capacity

• US 4,626,765 A
• Filed: 05/25/1984
• Issued: 12/02/1986
• Est. Priority Date: 05/25/1983
• Status: Expired due to Fees

• Current Assignee: Japan Storage Battery Company Limited (GS Yuasa Corporation)
• Original Assignee: Japan Storage Battery Company Limited (GS Yuasa Corporation)
• Inventors: Tanaka, Masafumi
• Primary Examiner(s): Hickey, R. J.
• Application Number:
  US06/614,092
• Time in Patent Office: 921 Days
• Field of Search: 320/2-5, 320/13, 320/39, 320/40, 320/48, 340/636, 324/429
• US Class Current: 320/127
• CPC Class Codes: G01R 13/406 representing measured value by a dot or a single line G01R13/408 takes precedence
• CPC Class Codes: G01R 19/16542 for batteries charge condition monitoring in G01R31/36
• CPC Class Codes: Y10S 320/21 State of charge of battery

Abstract

When the discharging of a battery is suspended, its open-circuit voltage or a voltage corresponding to the open-circuit voltage is detected, and with the voltage thus detected, as a start point an imaginary voltage curve having a certain decreasing rate is set for instance (by discharging a capacitor which has been charged by the voltage). When the discharging of the battery is suspended, the voltage detected at that time is used to correct the start point voltage of the imaginary voltage curve. According to the voltage obtained from the imaginary voltage curve, the number of LEDs turned on is changed or one of the LEDs is selected or liquid crystal display means is operated to display the remaining capacity of the battery.

Claims

1. A device for displaying a remaining capacity of a battery, which comprises:

means for detecting an open-circuit voltage of a battery or a voltage corresponding to said open-circuit voltage;

means for setting a first imaginary voltage curve whose start point is determined by said voltage detected immediately before the discharging of said battery with respect to the open-circuit voltage of said battery which decreases as said battery is discharged and increases after a predetermined period during which discharge is suspended;

means, responsive to a battery no-load condition existing for a predetermined time, for correcting said start point, whereby a corrected imaginary voltage curve is produced; and

means for displaying a remaining capacity of said battery according to a voltage obtained from one of said first and corrected imaginary voltage curves, wherein said display means comprises;

amplifier means;

a plurality of LEDs connected in series to one after another in such a manner that one end of said series circuit of LEDs is connected through a current limiting resistor (13) to a power source and the other end is connected to the output terminals of the last stage of said amplifier means (8) which is activated lastly as the level of an input to said amplifier means increases; and

NPN transistors connected between connecting points of said LEDs and the output terminals of said amplifier means, except for the last of said LEDs, in such a manner that the collectors of said NPN transistors are connected to said connecting points and the emitters of said NPN transistors are connected to said output terminals, the base of each transistor being connected to the output terminal of the rear stage of said amplifier means which is activated by an input level higher than that which activates the output terminal to which the emitter of said transistor is connected;

said plurality of LEDs being successively turned off by said amplifier means to display a remaining capacity of said battery in response to a voltage drop of said capacitor.

4. A device as claimed in claim 1, wherein said display means further comprises an oscillating IC connected between said power source and a predetermined one of said LEDs, for causing said predetermined one of said LEDs to flicker, thereby to draw attention to said display means.

2. A device for displaying a remaining capacity of a battery, which comprises:

circuit means for detecting a voltage substantially corresponding to an open-circuit voltage of a battery, said circuit means being connected between both terminals of said battery to obtain said voltage which is provided by subtracting a predetermined voltage from the open-circuit voltage of said battery;

a reverse current preventing element;

capacitor means for setting a first imaginary voltage curve with said voltage detected immediately before the discharging of said battery as a first start point of said first imaginary voltage curve with respect to the open-circuit voltage of said battery which decreases as said battery is discharged, said capacitor being charged by a voltage provided by said circuit means after discharge of said battery is suspended for a predetermined time, and connected through said reverse current preventing element in parallel to said circuit means, whereby said first start point is corrected, whereby a corrected imaginary voltage curve is produced;

amplifier means for subjecting a voltage of said capacitor to impedance conversion and amplification; and

display means for displaying a remaining capacity of said battery according to a voltage obtained from one of said first and corrected imaginary voltage curves, said display means comprising a plurality of LEDs connected to the output terminals of said amplifier means, and said plurality of LEDs being successively turned off by said amplifier means to display a remaining capacity of said battery in response to a voltage drop of said capacitor, and wherein said display means further comprises;

a plurality of LEDs connected in series to one after another in such a manner that one end of said series circuit of LEDs is connected through a current limiting resistor (13) to a power source and the other end is connected to the output terminals of the last stage of said amplifier means (8) which is activated lastly as the level of an input to said amplifier means increases; and

NPN transistors connected between connecting points of said LEDs and the output terminals of said amplifier means, except for the last of said LEDs, in such a manner that the collectors of said NPN transistors are connected to said connecting points and the emitters of said NPN transistors are connected to said output terminals, the base of each transistor being connected to the output terminal of the rear stage of said amplifier means which is activated by an input level higher than that which activates the output terminal to which the emitter of said transistor is connected;

said plurality of LEDs being successively turned off by said amplifier means to display a remaining capacity of said battery in response to a voltage drop of said capacitor.

5. A device as claimed in claim 2, wherein said display means further comprises an oscillating IC connected between said power source and a predetermined one of said LEDs, for causing said predetermined one of said LEDs to flicker, thereby to draw attention to said display means.

3. A device for displaying a remaining capacity of a battery, said device comprising:

means for detecting an open-circuit voltage of a battery or a voltage corresponding to said open-circuit voltage;

means for setting an imaginary voltage curve whose start point is determined by said voltage detected immediately before the discharging of said battery with respect to the open-circuit voltage of said battery which decreases as said battery is discharged; and

means for displaying a remaining capacity of said battery according to a voltage obtained from said imaginary voltage curve, said display means comprising;

amplifier means;

a plurality of LEDs each having first and second ends, said first ends being connected to output terminals of said amplifier means;

a plurality of diodes, different from said LEDs, each of said diodes being connected between pairs of second ends of said LEDs, whereby all of said second ends of said LEDs are connected, and whereby all of said second ends of said LEDs are connected at a single point to a power source,

one of said LEDs being selectively turned on to indicate a remaining capacity of said battery.

6. A device as claimed in claim 3, wherein said display means further comprises an oscillating IC connected between said power source and a predetermined one of said LEDs, for causing said predetermined one of said LEDs to flicker, thereby to draw attention to said display means.