Method and apparatus for determining the status of a battery in a vehicle

• US 10,023,066 B2
• Filed: 09/12/2016
• Issued: 07/17/2018
• Est. Priority Date: 09/17/2015
• Status: Active Grant

• Current Assignee: Volvo Car Corporation (AB Volvo)
• Original Assignee: Volvo Car Corporation (AB Volvo)
• Inventors: Larsson, Torbjorn, Engstrom, Alexander, Franzen, Linus, Thorngren, Mats, Fogelberg, Fabian, Thorson, Pelle, Almhagen, Petter, Wall, Emil, Midholm, Daniel
• Primary Examiner(s): LANG, MICHAEL DEAN
• Application Number:
  US15/262,455
• Publication Number:
  US 20170080819A1
• Time in Patent Office: 673 Days
• CPC Class Codes: B60L 58/12 responding to state of charge [SoC]
• CPC Class Codes: B60W 20/13 in order to stay within battery power input or output limits; in order to prevent overcharging or battery depletion
• CPC Class Codes: G01R 31/3648 comprising digital calculation means, e.g. for performing an algorithm
• CPC Class Codes: G01R 31/371 with remote indication, e.g. on external chargers
• CPC Class Codes: G01R 31/387 Determining ampere-hour charge capacity or SoC
• CPC Class Codes: G01R 31/392 Determining battery ageing or deterioration, e.g. state of health
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y10S 903/904 Component specially adapted for hev

Abstract

A method for determining a status of a vehicle battery includes determining an initial temperature and an initial state of charge of the battery, determining a current threshold value based on the initial temperature and the initial state of charge of the battery, starting the vehicle engine, charging the battery for a predetermined charging period t₁, measuring two charging currents, I₁ and I₂, to the battery at two predetermined points in time during the charging period t₁, determining an expected current value at a time t₃=t₁+t₂ based on the measured charging currents, comparing the expected current value with the current threshold value, and determining the battery is faulty if the expected current value is lower than the current threshold value.

Claims

1. A method for determining a status of a battery in a vehicle via a communication interface connectable to a communication interface of the vehicle and via a control unit configured to communicate with the vehicle, the method comprising:

determining an initial temperature, T, and an initial state of charge, SoC, of the battery;

determining a current threshold value, I_th, based on the initial temperature and the initial state of charge of the battery;

starting an engine of the vehicle;

charging the battery for a predetermined charging period t₁;

measuring two charging currents I₁ and I₂ to the battery at two predetermined points in time during the charging period t₁;

based on the measured charging currents, determining an expected current value at a time t₃=t₁+t₂;

comparing the expected current value with the current threshold value; and

if the expected current value is lower than the current threshold value, determining that the battery is faulty providing an indication of a faulty battery.

2. The method according to claim 1 further comprising controlling the initial battery temperature and the initial state of charge so that the initial battery temperature is not below a predetermined initial battery temperature threshold value and the initial state of charge does not exceed a predetermined initial state of charge threshold value.

3. The method according to claim 2 wherein the predetermined initial state of charge threshold value is lower than or equal to 70%.

4. The method according to claim 2 wherein the initial battery temperature threshold value is larger than or equal to 0°

C.

5. The method according to claim 1 further comprising, if the expected current value is higher than the current threshold value,

turning off the engine;

creating a constant current load using vehicle electrical system loads for the battery for a predetermined period t₄,

measuring a battery voltage after the period t₄;

comparing the measured battery voltage to a predetermined voltage threshold value; and

determining that the battery is faulty if the measured battery voltage is lower than the predetermined voltage threshold value.

6. The method according to claim 5 wherein the constant current load is 20 A±

10%.

7. The method according to claim 5 wherein t₄ is 4 min±

10%.

8. The method according to claim 5 wherein the predetermined voltage threshold value is 11V.

9. The method according to claim 1 wherein the charging current I₁ is measured at t₁-10s and the charging current I₂ is measured at t₁.

10. The method according to claim 1 wherein t₁ is 2 min±

10%.

11. The method according to claim 1 wherein t₂ is 1 min±

10%.

12. The method according to claim 1 wherein the expected current value is calculated by extrapolation.

13. The method according to claim 1 wherein the current threshold value is calculated as I_th(SoC,T)=p₁+p₂SoC+p₃T+p₄SoCT+p₅T²+p₆SoCT²+p₇T³, where p₁-p₇ are empirically determined parameters.

14. The method according to claim 1 wherein the step of charging the battery is performed using an alternator of the vehicle.

15. A battery tester comprising:

a communication interface connectable to a communication interface of a vehicle; and

a control unit configured for communicating with the vehicle to;

determine an initial temperature and an initial state of charge of the battery;

start an engine of the vehicle;

charge the battery for a predetermined charging time t₁;

measure two charging currents I₁ and I₂ to the battery at two predetermined points in time during the charging time;

based on the measured charging currents, determine an expected current value at a time t₃=t₁+t₂;

determine a current threshold value based on the initial temperature and the initial state of charge of the battery;

compare the expected current value with the current threshold value; and

if the expected current value is lower than the current threshold value, provide an indication that the battery is faulty.

16. The battery tester according to claim 15 wherein, if the expected current value is higher than the current threshold value, the battery tester is configured to

turn off the engine;

create a constant current load using vehicle electrical system loads for the battery for a predetermined period t₄,

measure the battery voltage after the period t₄;

compare the measured battery voltage to a predetermined voltage threshold value; and

if the measured battery voltage is lower than the voltage threshold value, provide an indication that the battery is faulty.

17. The battery tester according to claim 15 further configured to control the initial state of charge and the initial battery temperature so that the initial state of charge does not exceed a predetermined initial sate of charge threshold value and the initial battery temperature is not below a predetermined initial battery temperature threshold value.