Method and apparatus for measuring and displaying remaining battery capacity as a two dimensional dot curve

• US 5,698,983 A
• Filed: 04/05/1996
• Issued: 12/16/1997
• Est. Priority Date: 04/07/1995
• Status: Expired due to Term

• Current Assignee: Yazaki Corporation
• Original Assignee: Yazaki Corporation
• Inventors: Kumagai, Ryo, Shimoyama, Kenichi, Arai, Youichi, Takada, Yoshihide
• Primary Examiner(s): Nguyen, Vinh P.
• Assistant Examiner(s): DO, DIEP N
• Application Number:
  US08/628,488
• Time in Patent Office: 620 Days
• Field of Search: 324/426, 324/427, 324/428, 324/429, 324/433, 324/771, 320/48, 320/44, 364/550, 364/551.01, 340/636
• US Class Current: 324/427
• CPC Class Codes: G01R 31/367 Software therefor, e.g. for battery testing using modelling or look-up tables
• CPC Class Codes: G01R 31/3828 using current integration
• CPC Class Codes: Y10S 320/21 State of charge of battery

Abstract

The apparatus and method of the present invention measure the remaining capacity of a battery connected to a fluctuating load. The apparatus senses dispersive terminal voltages and dispersive discharge currents from the battery, and samples the sensed terminal voltages and discharge currents. On the basis of the sampled terminal voltages and discharge currents, the apparatus calculates a watt-hour value of the battery for a predetermined time interval, and checks whether the calculated watt-hour value reaches a predetermined value. If the calculated watt-hour value reaches the predetermined value, the apparatus calculates an approximate linear function indicative of a trend of the sampled terminal voltages and discharge currents, and calculates a voltage corresponding to a reference discharge current in accordance with the calculated approximate linear function as a remaining capacity voltage. The apparatus then converts the calculated remaining capacity voltage into an ordinate position on a two-dimensional display screen, and a calculated total watt-hour value into an abscissa position on the same display screen, and displays the positions in the form of a dot curve.

Claims

1. A remaining battery capacity measuring method, comprising the steps of:

sensing dispersive terminal voltages and dispersive discharge currents from a battery connected to a fluctuating load;

sampling the sensed dispersive terminal voltages and the sensed dispersive discharge currents;

calculating a watt-hour value of the battery for a predetermined time interval on the basis of the sampled dispersive terminal voltages and dispersive discharge currents;

checking whether the calculated watt-hour value reaches a predetermined value;

if the calculated watt-hour value reaches the predetermined value, calculating an approximate linear function indicative of a trend of the sampled dispersive terminal voltages and the sampled dispersive discharge currents;

calculating a voltage corresponding to a reference discharge current in accordance with the calculated approximate linear function as a remaining capacity voltage;

converting the calculated remaining capacity voltage into an ordinate position on a two-dimensional display screen;

converting a calculated total watt-hour value into an abscissa position on the same display screen; and

displaying the two converted ordinate and abscissa positions on the display screen in a form of a dot curve.

2. The remaining battery capacity measuring method of claim 1, further comprising the steps of:

for each dot displayed on the dot curve, calculating a check voltage corresponding to a relatively high reference discharge current in accordance with the calculated approximate linear function;

discriminating whether the calculated check voltage reaches a final discharge voltage; and

when the check voltage reaches the final discharge voltage, displaying zero on the display screen.

3. A remaining battery capacity measuring apparatus, comprising:

sensing means for sensing dispersive terminal voltages and dispersive discharge currents from a battery connected to a fluctuating load;

voltage-current change trend calculating means for sampling the sensed dispersive terminal voltages and the dispersive discharge currents;

discharge rate deciding means for calculating a watt-hour value of the battery on the basis of the sampled dispersive terminal voltages and dispersive discharge currents, and for determining when the calculated watt-hour value reaches a predetermined value;

voltage-current approximate linear function calculating means for, whenever the calculated watt-hour value reaches the predetermined value, calculating an approximate linear function indicative of a trend of the sampled dispersive terminal voltages and the sampled dispersive discharge currents;

remaining battery capacity calculating means for calculating a voltage corresponding to a reference discharge current in accordance with the approximate linear function calculated by said voltage-current approximate linear function calculating means as a remaining capacity voltage;

coordinate converting means for converting the calculated remaining capacity voltage into an ordinate position on a two-dimensional display screen, and converting a calculated total watt-hour value into an abscissa position on the same display screen; and

displaying means for displaying the two converted ordinate and abscissa positions on the display screen in a form of a dot curve.

4. The remaining battery capacity measuring apparatus of claim 3, further comprising discharge end deciding means for calculating, for each dot displayed on the dot curve, a check voltage corresponding to a relatively high reference discharge current in accordance with the calculated approximate linear function, discriminating whether the calculated check voltage reaches a final discharge voltage, and when the check voltage reaches the final discharge voltage, displaying zero on the display screen.