Method for detecting a motor vehicle battery failure

• US 6,472,875 B1
• Filed: 05/26/2000
• Issued: 10/29/2002
• Est. Priority Date: 10/01/1997
• Status: Expired due to Fees

• Current Assignee: Continental Automotive GmbH (Continental AG)
• Original Assignee: Continental Automotive GmbH (Continental AG)
• Inventors: Meyer, Henry-Louis
• Primary Examiner(s): Le, N.
• Assistant Examiner(s): Hamdan, Wasseem H.
• Application Number:
  US09/509,966
• Time in Patent Office: 886 Days
• Field of Search: 324/426, 324/430, 324/427, 324/431, 324/429, 701/29
• US Class Current: 324/327
• CPC Class Codes: G01R 19/16542 for batteries charge condition monitoring in G01R31/36
• CPC Class Codes: G01R 31/007 using microprocessors or computers
• CPC Class Codes: G01R 31/3647 for determining the ability of a battery to perform a critical function, e.g. cranking
• CPC Class Codes: G01R 31/3648 comprising digital calculation means, e.g. for performing an algorithm

Abstract

A process for the detection of a defect of an automotive vehicle battery includes analyzing the time dependence of the discharge voltage across the terminals of the battery. This process has the steps of measuring at least two successive values of the discharge voltage of the battery, during the phase of cranking the engine of the automotive vehicle, for at least two consecutive top dead center points, taking a difference of the measured voltage values, and deducing therefrom whether the battery is charged or defective. The process is built into an electronic computer carried on board the automotive vehicle.

Claims

1. A process for detecting a defect in a battery of an automotive vehicle with an internal combustion engine and an electric starter wired to the battery of the vehicle for cranking the engine during a cranking phase, the process which comprises:

cranking an internal combustion engine through consecutive engine cycles with a starter connected to the battery;

measuring at least two successive values U1 and U2 of a discharge voltage of the battery during two consecutive engine cycles;

calculating a difference Δ

U=U1−

U2 between the measured voltage values;

determining a state of charge of the battery from the difference Δ

U;

calculating a moving average of the measured discharge voltages (U1;

U2); and

deducing that the battery is defective if the first derivative of the average is less than or equal to zero.

2. The process according to claim 1, which comprises measuring the two successive values U1 and U2 at consecutive top dead center points of the engine.

3. The process according to claim 1, wherein the determining step comprises declaring the battery defective if the difference Δ

U of the measured voltages is less than or equal to zero.

4. The process according to claim 1, which comprises confirming that the battery is defective if an average of the discharge voltages during the cranking phase is less than a predetermined threshold as a function of a battery temperature.

5. The detection process according to claim 1, which comprises:

declaring that the battery is “

old”

if the battery is declared defective and if an average of the discharge voltages during the cranking phase is less than a predetermined threshold as a function of temperature; and

informing the driver of the vehicle that the battery will have to be changed shortly.