Automotive battery status monitor

• US 5,281,919 A
• Filed: 01/13/1992
• Issued: 01/25/1994
• Est. Priority Date: 10/14/1988
• Status: Expired due to Term

• Current Assignee: Alliedsignal Inc.
• Original Assignee: Alliedsignal Inc.
• Inventors: Palanisamy, Thirumalai G.
• Primary Examiner(s): Wieder, Kenneth A.
• Assistant Examiner(s): BROWN, GLENN WARNER
• Application Number:
  US07/819,255
• Time in Patent Office: 743 Days
• Field of Search: 324/426, 324/427, 324/430, 324/432, 324/434, 320/48, 340/636, 364/481, 364/483, 364/550
• US Class Current: 324/427
• CPC Class Codes: G01R 31/006 on road vehicles, e.g. automobiles or trucks testing of ignition installations peculiar to internal combustion engines F02P17/00
• CPC Class Codes: G01R 31/007 using microprocessors or computers
• CPC Class Codes: G01R 31/3648 comprising digital calculation means, e.g. for performing an algorithm
• CPC Class Codes: G01R 31/374 with means for correcting the measurement for temperature or ageing
• CPC Class Codes: G01R 31/379 for lead-acid batteries
• CPC Class Codes: G01R 31/3842 combining voltage and current measurements

Abstract

A vehicle storage battery is monitored to determine battery capacity, state of charge and certain fault conditions. The ambient temperature, battery voltage alternator/regulator output voltage and current to and from the battery are continuously measured. Current voltage (I-V) data is analyzed to determine the internal resistance and polarization of the battery. A determination is made regarding state of charge and fault conditions produced by corroded terminals and low electrolyte level. The low temperature starting limit is determined by comparing the battery'"'"'s power output capability with starting power requirements of the vehicle. Data produced by the comparison are indicated on the dashboard of the vehicle.

Claims

1. A battery condition monitoring apparatus for providing status and information concerning maintenance and replacement requirements and power output capability of a storage battery in a motor vehicle, comprising;

(a) microprocessor means located on said vehicle for controlling the operations of said apparatus;

(b) first software means for instructing said microprocessor means to control the sequence of said operations;

(c) memory means connected to said microprocessor means for storing the instructions given by said first software means, predetermined relationships between the internal resistance of said battery and the limit of said internal resistance below which said battery is operable to start said vehicle at the ambient temperature;

(d) digital to analog converter means connected to said microprocessor means for converting digital signals from said microprocessor means to analog signals;

(e) direct current power generator means, connected to said digital to analog converter means for producing electric power, required by said microprocessor means;

(f) current sensor means, connected to a terminal of said battery, for measuring the current passing into and out of said battery;

(g) temperature sensor means, located near said battery, for measuring the ambient temperature of said battery;

(h) voltmeter means for measuring the voltages of said battery, current sensor, temperature sensor and direct current power generator means;

(i) analog to digital converter means, connected to said voltmeter, for converting the analog signals from the said voltage measurements to digital signals appointed for transfer to said microprocessor;

(j) second software means for analyzing said current, voltages and temperature, and for determining the state of charge, capacity, internal resistance and polarization of said battery, said internal resistance of said battery being determined from the instantaneous change in voltage at the beginning or at the end of a current input to or output from said battery in which an instantaneous change in voltage is caused by switching on or switching off charge pulse current to or discharge pulse current from said battery and said polarization of said battery being determined from a change in said battery voltage during a predetermined time interval immediately following said instantaneous change, to establish said battery maintenance and replacement requirements;

(k) third software means for determining a low temperature starting limit of said vehicle by comparing said battery'"'"'s power output capability with starting power requirements of said vehicle, said starting power requirements being determined at various temperatures by extrapolating the power required or actually used by the engine at any one temperature using a predetermined mathematical function or graphical data and said battery'"'"'s power output capability being determined from a second predetermined mathematical relationship or graphical data that relates the battery'"'"'s internal resistance with various temperatures;

(l) fourth software means for determining defects in said battery wherein first defect caused by low state of charge of said battery is indicated when said battery'"'"'s voltage excluding said polarization is smaller than a preset limit;

second defect caused by low electrolyte level is indicated when said polarization and internal resistance are larger than a predetermined limit and state of charge and capacity of said battery are above preset levels;

third defect caused by corroded terminals is indicated when state of charge and capacity of said battery are above preset levels, said internal resistance is higher than a preset limit and said polarization is lower than a preset limit;

fourth defect caused by end of useful life of said battery is indicated upon detection of said internal resistance being higher than a preset limit together with normal polarization and state of charge higher than a preset limit;

(m) actuator means for controlling the electrical circuits connecting said sensors, said direct current power generator means and said battery; and

(n) display means, controlled by said microprocessor for indicating said battery status and information.

2. An apparatus according to claim 1, wherein said storage battery is a rechargeable lead acid battery and said direct current power generator means is an alternator/rectifier/regulator means.