Method for the continuous measurement of the efficiency of a battery, especially a battery installed in motor vehicles, and a device utilizing this method

• US 8,788,142 B2
• Filed: 10/21/2010
• Issued: 07/22/2014
• Est. Priority Date: 10/27/2009
• Status: Active Grant

• Current Assignee: Fiamm Energy Technology SpA (Resonac Holdings Corp.)
• Original Assignee: FIAMM S.p.A. (Johnson Controls International plc)
• Inventors: Aliberti, Roberto, Cazzanti, Silvia
• Primary Examiner(s): Cheung, Mary
• Assistant Examiner(s): BERNS, MICHAEL ANDREW
• Application Number:
  US13/504,396
• Publication Number:
  US 20120265397A1
• Time in Patent Office: 1,370 Days
• Field of Search: 701/34.4, 702/63
• US Class Current: 701/34.4
• CPC Class Codes: B60L 58/10 for monitoring or controlling batteries
• CPC Class Codes: G01R 31/367 Software therefor, e.g. for battery testing using modelling or look-up tables
• CPC Class Codes: G01R 31/3835 involving only voltage measurements
• CPC Class Codes: G01R 31/388 involving voltage measurements
• CPC Class Codes: G01R 31/392 Determining battery ageing or deterioration, e.g. state of health
• CPC Class Codes: H01M 10/4257 Smart batteries, e.g. electronic circuits inside the housing of the cells or batteries
• CPC Class Codes: H01M 10/44 Methods for charging or discharging circuits for charging H02J7/00
• 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: H01M 10/486 for measuring temperature
• CPC Class Codes: H01M 10/488 Cells or batteries combined with indicating means for external visualization of the condition, e.g. by change of colour or of light density
• CPC Class Codes: H01M 2010/4271 Battery management systems including electronic circuits, e.g. control of current or voltage to keep battery in healthy state, cell balancing
• CPC Class Codes: H01M 2220/20 Batteries in motive systems, e.g. vehicle, ship, plane
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

A method for the continuous measurement of the efficiency of a battery, especially a battery installed in motor vehicles, comprising the following phases: —determination of the state of charge SOC % of the battery installed in the vehicle, both during key-off phase and key-on phase, without the direct measurement of current through progressive readings of battery voltage, both in the absence and in the presence of electrical load and considering the time elapsed since the beginning of each discharge phase; —determination of the state of health SOH of the same battery through the application of a controlled current load and the comparison of the resulting voltage drop compared to predetermined parameters; —determination of the state of function SOF of said battery through an estimation of its residual autonomy in function of the discharge rate or current rate and of the evolution of SOC %; —correlation and normalization of the above described parameters (SOC, SOH, and SOF) depending on the battery operating temperature;—memorization of at least the values of initial SOC % and SOH detected during the key—off phase.

Claims

1. A method, for a device including processing circuitry, for continuous measurement of efficiency of a battery, installed in a vehicle, the method comprising:

computing by the processing circuitry, a state of charge SOC of the battery installed in the vehicle throughout both a key-off phase and a key-on phase, without a direct measurement of current, the computing being performed by progressively reading a battery voltage, both in absence and in presence of an electrical load and considering a time elapsed since a beginning of each discharge phase;

determining a state of health SOH, of the battery by applying a controlled current load and comparing a resulting voltage drop to predetermined parameters;

determining a state of function SOF, of the battery by estimating a residual autonomy that is a function of a discharge rate or current rate, and of an evolution of the SOC;

correlating and normalizing the SOC, SOH, and SOF based on an operating temperature of the battery; and

storing at least an initial SOC and SOH that are determined during the key-off phase.

2. The method for continuous measurement of efficiency of a battery as in claim 1, further comprising:

repeating, a periodic determination of the SOC, SOH and SOF; and

storing the periodically determined SOC, SOH and SOF.

3. The method for continuous measurement of efficiency of a battery as in claim 1, wherein the progressively read battery voltage is used to determine when the battery is in a state of discharge.

4. The method for continuous measurement of efficiency of a battery as in claim 1, wherein the current rate or current discharge rate is determined based on the initial SOC, time in seconds counted from the beginning of the discharge phase (tn), and the battery voltage (Vn), determined at time tn.

5. The method for continuous measurement of efficiency of a battery as in claim 1, wherein a variation of the SOC is evaluated by determining the discharge rate.

6. The method for continuous measurement of efficiency of a battery as in claim 1, wherein the determination of SOH at an n-th time is correlated to the SOC at the n-th time by evaluating a voltage drop Δ

V that is determined by applying a controlled and constant current load of 15-50 A for a predetermined period of time of 0.1-30 seconds.

7. The method for continuous measurement of efficiency of a battery as in claim 1, wherein an initial SOH value is converted into a numerical value between 0 and 1 through the relation:

(b−

Δ

V)/(b−

a), wherein “

b”

is a voltage drop that occurs at a first predetermined value of the SOC by application of the controlled current load, and “

a”

is a minimum voltage drop that occurs by application of the controlled current load at a second predetermined value of the SOC.

8. The method for continuous measurement of efficiency of a battery as in claim 1, wherein the SOF is related to the residual autonomy of the battery at all times, the SOC and a SOC limit, the residual autonomy being determined by evaluation of the discharge rate and the SOC limit defining a guarantee of engine restart.

9. A device for continuous measurement of efficiency of a battery, the device being installed in a vehicle and being in electrical contact with the battery, by which it is powered, the device comprising:

at least one temperature sensor and one voltage sensor;

a predetermined and controlled resistive load; and

processing circuitry configured to

compute a state of charge SOC of the battery installed in the vehicle throughout both a key-off phase and a key-on phase, without a direct measurement of current, the computing being performed by progressively reading a battery voltage, both in absence and in presence of an electrical load and considering a time elapsed since a beginning of each discharge phase,

determine a state of health SOH of the battery by applying a controlled current load and comparing a resulting voltage drop to predetermined parameters;

determine a state of function SOF of the battery by estimating a residual autonomy that is a function of a discharge rate or current rate, and of an evolution of the SOC,

correlate and normalize the SOC, SOH, and SOF based on an operating temperature of the battery, and

store at least an initial SOC and SOH that are determined during the key-off phase.

10. The device of claim 9, wherein the processing circuitry is further configured to transmit an audible or visual signal to a driver of the vehicle, when the computed SOC is less than a predetermined minimum SOC value.