State of health for automotive batteries

• US 6,369,578 B1
• Filed: 06/05/2001
• Issued: 04/09/2002
• Est. Priority Date: 06/05/2001
• Status: Expired due to Fees

• Current Assignee: Johnson Controls Technology Company (Johnson Controls International plc)
• Original Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Inventors: Strickland, Tracy Frye, Crouch, Dell Albert Jr.
• Primary Examiner(s): TOATLEY, GREGORY J
• Application Number:
  US09/874,648
• Time in Patent Office: 308 Days
• Field of Search: 324/426, 320/132, 320/134
• US Class Current: 324/426
• 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
• CPC Class Codes: G01R 31/374 with means for correcting the measurement for temperature or ageing
• CPC Class Codes: G01R 31/382 Arrangements for monitoring battery or accumulator variables, e.g. SoC
• CPC Class Codes: G01R 31/392 Determining battery ageing or deterioration, e.g. state of health
• CPC Class Codes: H02J 7/005 Detection of state of health [SOH]

Abstract

Described is a method and apparatus for determining the state of battery life of a starting, lighting and ignition (SLI) battery comprising; 1) determining the number of starting engine cranks the battery has performed and comparing that number with a desired number for starting engine cranks to ascertain a state of health of the battery, calculated as a percentage of the desired number; 2) determining the percentage of battery life diminished due to battery exposure to a maximum temperature and the minimum state of charge the battery has been exposed to at that temperature, calculated as a decrease from 100 percent; and 3) calculating the lower of the values of step 1 or step 2 thereby determining the state of the battery life.

Claims

1. A method of determining the state of battery life of a starting, lighting and ignition (SLI) battery comprising;

1) determining the number of starting engine cranks the battery has performed and comparing that number with a desired number for starting engine cranks to ascertain a state of health of the battery, calculated as a percentage of the desired number;

2) determining the percentage of battery life diminished due to battery exposure to a maximum temperature and the minimum state of charge the battery has been exposed to at that temperature, calculated as a decrease from 100 percent; and

3) calculating the lower of the values of step 1 or step 2 thereby determining the state of the battery life.

2. The method of claim 1 wherein step 1 is performed by measuring the slope of the line formed when plotting on an X-Y two dimensional graph the equation

3. The method of claim 1 wherein step 2 is preformed by determining a battery crank value from the table below and subtracting it from the current state of charge of the battery.

4. An apparatus for determining the state of battery life of a starting, lighting and ignition (SLI) battery comprising;

1) a first register for storing a first numeric value which is obtained by determining the number of starting engine cranks the battery has performed and comparing that number with a desired number for starting engine cranks to ascertain the state of health of the battery, calculated as a percentage of the desired number;

     2) a second register storing a second numeric value which is obtained by determining the percentage of battery life diminished due to battery exposure to a maximum temperature and the minimum state of charge the battery has been exposed to at that temperature, calculated as a decrease from 100 percent; and

     3) means for calculating the difference between the values of the first register and the second register to determine the state of the battery life.