Vehicle battery discharging indicator

• US 4,803,417 A
• Filed: 12/22/1986
• Issued: 02/07/1989
• Est. Priority Date: 12/22/1986
• Status: Expired due to Fees

• Current Assignee: General Motors Corporation (General Motors Company)
• Original Assignee: General Motors Corporation (General Motors Company)
• Inventors: Nowakowski, Robert J., Riesberg, Van V. Jr.
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): Ault, Anita M.
• Application Number:
  US06/944,753
• Time in Patent Office: 778 Days
• Field of Search: 320/37, 320/39, 320/48, 340/636, 324/424, 324/433, 364/481, 364/483, 364/424
• US Class Current: 320/136
• 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 31/3648 comprising digital calculation means, e.g. for performing an algorithm
• CPC Class Codes: H02J 7/00306 Overdischarge protection
• CPC Class Codes: H02J 7/0048 Detection of remaining charge capacity or state of charge [SOC]
• CPC Class Codes: H02J 7/14 for charging batteries from dynamo-electric generators driven at varying speed, e.g. on vehicle

Abstract

An apparatus for and method of indicating when the battery in a motor vehicle is discharging is disclosed in which the battery voltage during vehicle operation is monitored and compared to a stored value representing the open-circuit voltage of the battery measured prior to the vehicle engine being cranked for starting. An indication that the battery is discharging is provided only after a discharging condition, i.e., the battery voltage is less than the stored value, is detected at each of a predetermined member of consecutive timed intervals.

Claims

1. In a motor vehicle powered by an internal combustion engine including a storage battery having an open-circuit emf dependent upon battery conditions, an electrical load, and a unidirectional current source supplying current to the parallel combination of the battery and the load, the current source normally providing sufficient current to the battery and the load to impress upon the battery a voltage greater than the open-circuit emf of the battery thereby causing the battery to charge, wherein the battery discharges when the voltage impressed upon the battery is below the open-circuit emf of the battery, a method of indicating when the battery is discharging, comprising the steps of:

a. measuring a first voltage of the battery before cranking the engine each time the engine is started;

b. storing the first voltage as a reference voltage value, the reference voltage value representing the open-circuit emf of the battery compensated for the battery conditions existing when the first voltage is measured;

c. measuring a second voltage of the battery after the engine is started, the second voltage having a value less than the open-circuit emf of the battery when the battery is discharging;

d. comparing the second voltage with the stored reference voltage value; and

e. indicating that the battery is discharging when the second voltage is less than the reference voltage value.

2. The method of indicating when the battery is discharging of claim 1 in which step b is performed by storing as a reference voltage value the lesser of the first voltage and a predetermined voltage value representing the maximum open-circuit emf of the battery without a surface charge.

3. The method of indicating when the battery is discharging of claim 1 in which steps c and d are performed at predetermined first timed intervals and step e is performed after the occurrence of a predetermined number of consecutive first timed intervals for which the second voltage is less than the reference voltage value.

4. The method of indicating when the battery is discharging of claim 3 in which step e is performed during a predetermined second timed interval less than the first timed intervals, whereby step e may be initiated after each comparing step and terminated prior to the next comparing step.

5. A discharging indicator for a storage battery of a motor vehicle powered by an internal combustion engine, the vehicle including an electrical load coupled in parallel to the battery during engine operation and the battery having an open-circuit emf, the indicator comprising:

indicator means effective when energized for indicating battery discharging;

a unidirectional current source for supplying current to the battery and the load at a system voltage normally greater than the open-circuit emf of the battery for charging the battery, the battery discharging when the system voltage is less than the open-circuit emf of the battery; and

means for (A) measuring a first voltage of the battery before cranking the engine each time the engine is started, (B) storing the first voltage as a reference voltage value, (C) measuring a second voltage of the battery after the engine is started, (D) comparing the second voltage with the stored reference voltage value and (E) energizing the indicator means when the second voltage is less than the reference voltage value to provide a indication of battery discharging.

6. A discharging indicator for a storage battery of a motor vehicle powered by an internal combustion engine, the vehicle including an electrical load coupled in parallel to the battery during engine operation and an ignition switch operable to a run position and then to a crank position at which current is supplied from the battery to a cranking motor for starting the engine, the battery having an open-circuit emf, the indicator comprising:

indicator means effective when energized for indicating battery discharging;

means for supplying current to the battery and the load at a system voltage normally greater than the open-circuit emf of the battery for charging the battery, the battery discharging when the system voltage is less than the open-circuit emf of the battery; and

means for (A) measuring a first voltage of the battery after the ignition switch is operated to the run position and before being operated to the crank position so that the first voltage is measured before current is supplied from the battery to the cranking motor, (B) storing the first voltage as a reference voltage value, the reference voltage value representing the open-circuit emf of the battery compensated for the battery conditions existing when the first voltage is measured, (C) measuring a second voltage of the battery at predetermined first time intervals after the engine is started, (D) comparing the second voltage with the stored reference voltage value at each of the predetermined first timed intervals and (E) energizing the indicator means for a second timed interval less than the first timed interval to indicate that the battery is discharging after the occurrence of a predetermined number of consecutive first timed intervals for which the second voltage is less than the reference voltage value.