System and method for determining battery state-of-health

• US 6,469,512 B2
• Filed: 12/22/2000
• Issued: 10/22/2002
• Est. Priority Date: 01/12/2000
• Status: Expired due to Term

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Honeywell International Inc.
• Inventors: Hovey, William C., Palanisamy, Thirumalai G., Singh, Harmohan, Huykman, Richard B.
• Primary Examiner(s): Tso, Edward H.
• Assistant Examiner(s): LUK, LAWRENCE W
• Application Number:
  US09/745,901
• Publication Number:
  US 20010033169A1
• Time in Patent Office: 669 Days
• Field of Search: 324/426, 324/429, 324/430, 324/434, 324/427, 320/132, 320/106
• 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 31/374 with means for correcting the measurement for temperature or ageing
• CPC Class Codes: G01R 31/3842 combining voltage and current measurements
• CPC Class Codes: G01R 31/389 Measuring internal impedance, internal conductance or related variables
• CPC Class Codes: G01R 31/392 Determining battery ageing or deterioration, e.g. state of health
• CPC Class Codes: G01R 31/52 Testing for short-circuits, leakage current or ground faults
• CPC Class Codes: H01M 10/48 Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals, H01M50/569
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A system and method for accurate and in real time determination of factors relating to the state of health of a storage battery. The system measures the values of battery temperature, voltage and current flow into and out of the battery. This data is multiplexed into a computer and the battery'"'"'s internal resistance (IR), polarization resistance (PR), state of charge (SOC) and its cold cranking amp (CCA) capability are computed and displayed. The presence of shorted and mismatched cells also can be determined and displayed. The state of health of the battery is related to these displayed measured values and calculated factors which are made known to the user of the battery.

Claims

1. A method for monitoring and displaying to user of a vehicle or a system on a real time basis the state of health (SOH) of a storage battery on which said vehicle or system relies, said method comprising the steps of:

measuring battery voltage and current under one of load and no load conditions for the battery;

computing from the data of the measured battery voltage and current the battery internal resistance and polarization resistance;

determining from said measured battery voltage and current and said computed battery internal resistance and polarization resistance the factors of battery state of change, cold cranking amperes, the presence of a shorted cell and the presence of a mismatched cell; and

displaying to the user of said battery all of said determined factors.

2. The method of claim 1 wherein the battery is a lead acid storage battery and the step of determining the cold cranking amperes (CCA) factor comprises computing the battery internal resistance and applying the formula

3. A method for monitoring and displaying to a user of a vehicle or a system on a real time basis the state of health (SOH) of a storage battery on which said vehicle or system relies, said method comprising the steps of:

measuring battery voltage and current under one of load and no load conditions for the battery;

computing from the data of measured battery voltage and current the battery internal resistance and polarization resistance;

determining from said measured battery voltage and current and said computed battery internal resistance and polarization resistance a plurality of the factors of battery state of charge, cold cranking amperes, the presence of a shorted cell and the presence of a mismatched cell;

displaying to the user of said battery said plurality of determined factors; and

wherein the step of computing the battery internal resistance is on a DC basis and comprises;

applying one of a voltage (V) and a current (I) of known amount to the battery;

determining the charge in battery current (dI) in response to the voltage of known amount and the change in battery voltage (dV) in response to the current of known amount; and

computing the battery internal resistance (IR) using the formula dV/dI.

4. A method for monitoring and displaying to a user of a vehicle or a system on a real time basis the state of health (SOH) of a storage battery on which said vehicle or system relies, said method comprising the steps of:

measuring battery voltage and current under one of load and no load conditions for the battery;

computing from the data of the measured battery voltage and current the battery internal resistance and polarization resistance;

determining from said measured battery voltage and current and said computed battery internal resistance and polarization resistance a plurality of factors of battery state of charge, cold cranking amperes, the presence of a shorted cell and the presence of mismatched cell;

displaying to the user of said battery said plurality of determined factors; and

wherein the step of computing the battery internal resistance is on an AC basis and comprises;

applying an alternating current voltage or current to the battery;

measuring the corresponding battery current and voltage response; and

calculating the resistance from the applied voltage or current and the measured response.

5. A method for monitoring and displaying to a user of a vehicle or a system on real time basis the state of health (SOH) of a storage battery on which said vehicle or system relies, said method comprising the steps of:

measuring battery voltage and current under one of load and no load conditions for the battery;

computing from the data of the measured battery voltage and current the battery internal resistance polarization resistance, wherein said computing of the battery internal resistance comprises computing the battery internal resistance on a DC basis and computing the battery internal resistance on an AC basis;

determining from said measured battery voltage and current and said computed battery internal resistance and polarization resistance the battery state of charge, cold cranking amperes, the presence of a shorted cell and the presence of a mismatched cell;

displaying to the user of said battery said determined factors; and

wherein the step of computing the polarization resistance comprises subtracting the internal resistance computed on an alternating current basis from the internal resistance computed on a direct current basis.

6. The method of claim 5 wherein said step of computing the battery internal resistance on a DC basis comprises applying one of a voltage (V) and a current (I) of known amount to the battery and determining the change in current (dI) in response to the voltage of known amount and the change in battery voltage (dV) in response to the current of known amount.

7. A system for monitoring and displaying to a user of a vehicle on a real time basis the state of health (SOH) of a lead acid storage battery on which said vehicles relies, said system comprising a circuit module mounted to the battery with a connection to at least one of the battery terminals and said circuit module including:

means for measuring the battery voltage and current under one of load and no load conditions and for producing voltage and current data values in digital form;

means for computing from the data values of the measured battery voltage and current the internal resistance and polarization resistance and for computing from the battery voltage, current, internal resistance (IR) and polarization resistance at least one of the factors of battery state of charge, cold cranking amperes (CCA), the presence of a shorted call and the presence of a mismatched cell, said cold cranking amperes factor being computed on the basis of