Method of determining the energy capacity of a battery

• US 20080197807A1
• Filed: 02/20/2007
• Published: 08/21/2008
• Est. Priority Date: 02/20/2007
• Status: Active Grant

• Current Assignee: Aptiv Technologies AG (Aptiv PLC)
• Original Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Inventors: Caputo, John V., Fattic, Gerald T., Simopoulos, Gregory N.
• Granted Patent: US 7,800,344 B2
• Time in Patent Office: Days
• US Class Current: 320/132
• CPC Class Codes: G01R 31/3835 involving only voltage measurements
• CPC Class Codes: G01R 31/392 Determining battery ageing or deterioration, e.g. state of health

Abstract

A method of determining the available energy of a battery provides for measuring first and second open circuit voltage of the battery with a change of energy level occurring therebetween. The two open circuit voltages are correlated to a state of charge level and the measured amount of change of energy is divided by the change of the state of charge.

Claims

1. A method of determining the available energy of a battery comprising:

measuring a first open circuit voltage of said battery to correlate to and determine a first state of charge;

changing the level of energy available in said battery by a measured amount;

measuring a second open circuit voltage of said battery after changing the level of energy to determine a second state of charge; and

dividing the measured amount of energy change in said battery by the calculated change in the state of charge from the first state of charge to the second state of charge to determine the available energy capacity of said battery.

2. The method as defined in claim 1 further comprising:

resting said battery before each step of measuring said first open circuit voltage and said second open circuit voltage to obtain a diffusion equilibrium state in said battery.

3. A method as defined in claim 2 further comprising:

said changing the level of energy including a discharge event.

4. A method as defined in claim 1 further comprising:

said changing the level of energy step includes charging the battery with an over voltage down to a predetermining low current.

5. A method as defined in claim 4 further comprising:

said predetermined low current being substantially at or below three amps.

6. A method as defined in claim 4 further comprising:

said overcharge voltage being at a level lower than a gassing threshold for said battery; and

said predetermining low current being substantially at or below three amps.

7. A method as defined in claim 6 further comprising:

the predetermined low current is at substantially zero amps.

8. A method as defined in claim 1 further comprising:

said changing the level of energy including a discharge event at approximately a constant current.