Apparatus and method for carrying out diagnostic tests on batteries and for rapidly charging batteries

• US 6,424,158 B2
• Filed: 07/10/2001
• Issued: 07/23/2002
• Est. Priority Date: 07/27/1998
• Status: Expired due to Term

• Current Assignee: Midtronics Incorporated
• Original Assignee: Midtronics Incorporated
• Inventors: Klang, James K.
• Primary Examiner(s): Tso, Edward H.
• Application Number:
  US09/902,492
• Publication Number:
  US 20020008523A1
• Time in Patent Office: 378 Days
• Field of Search: 320/124, 320/125, 320/132, 320/134, 320/136, 320/148, 320/152, 320/151, 320/157, 320/156, 320/159, 320/160, 320/161, 320/162, 320/163, 320/165, 324/426, 324/433, 324/434
• US Class Current: 324/433
• 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 31/3842 combining voltage and current measurements
• CPC Class Codes: G01R 31/386 using test-loads
• CPC Class Codes: H02J 7/0069 Charging or discharging for charge maintenance, battery initiation or rejuvenation
• CPC Class Codes: H02J 7/0071 with a programmable schedule
• CPC Class Codes: H02J 7/007194 of the battery

Abstract

A method and system for performing automatic and rapid diagnostic testing and charging of a battery. The diagnostic test unit utilizes a charger combined with a rapidly variable load. After inputting battery characteristics including the cranking rating (CCA or CA) and the temperature of the battery, a diagnostic ramp procedure is utilized to provide an instantaneous current versus voltage analysis to determine the instantaneous cranking value (i.e., the single crank capability at full charge) of the battery being tested. If the instantaneous cranking value of the battery is above a level determined acceptable, a sustained discharge is carried out to tax the capacity of the battery.

At the end of the constant current discharge, the current is again to determine a loaded cranking value which simulates the battery power after multiple cranking attempts. If the loaded cranking value is below a desired percentage of the cranking rating, then the battery is put into charge. If a battery cannot be acceptably charged within the time of a given number of diagnostic probes, the battery is deemed to be a bad battery. The charging steps utilized during the diagnostic testing, as well as any charging of batteries determined to be good, utilizes a novel interactive stepping procedure which allows batteries determined to be good to be recharged in a minimum period of time without overheating the battery.

Claims

1. A method of charging a battery, comprising:

outputting a charge voltage to the battery in dependence on a base voltage level;

adjusting the charging voltage in steps of predetermined magnitude to provide first, second and third voltage levels;

measuring first, second, third and fourth currents, wherein the first current is measured at the first voltage level, the fourth current is measured at the third voltage level, and the second and third currents are measured at the second voltage level at differing times;

calculating a first differential from the difference in the first and second currents and calculating a second differential from the difference in the third and fourth currents;

comparing the first differential to the second differential; and

adjusting the base voltage as a function of the comparison.

2. The method as recited in claim 1, wherein the first voltage level is less than the second voltage level and the second voltage level is less than the third voltage level.

3. The method as recited in claim 1, wherein the first voltage level is greater than the second voltage level and second voltage level is greater than the third voltage level.

4. The method as recited in claim 1, wherein the step of adjusting the base voltage further comprises the step of increasing the base voltage a selected increment amount if the first differential is greater than the second differential.

5. The method as recited in claim 1, wherein the step of adjusting the base voltage further comprises the step of decreasing the base voltage a selected increment amount if the first differential is less than the second differential.

6. The method as recited in claim 1, wherein the step of measuring further comprises delaying the measurement of the first current for a predetermined time increment.

7. The method as recited in claim 1, wherein the step of measuring further comprises delaying the measurement of the second current for a first predetermined time increment and the measurement of the third current for a second predetermined time increment greater than the first predetermined time increment.

8. The method as recited in claim 7, wherein the first predetermined time increment is selected to allow the current to become substantially stable.

9. The method as recited in claim 8, wherein the second predetermined time increment is selected to allow the current to become substantially stable.

10. The method as recited in claim 1, wherein the step of measuring further comprises delaying the measurement of the fourth current for a predetermined time increment.

11. The method as recited in claim 1, wherein the first and second voltage levels and the second and third voltage levels generally differ by a predetermined voltage step.

12. The method as recited in claim 11, wherein the predetermined voltage step is selected to generate a minimal measurable current response.

13. The method as recited in claim 1, further comprising the step of accumulating in a moving average the result of the step of comparing each time the step of comparing is performed.

14. The method as recited in claim 13, further comprising the step of making the accumulated moving average relative on a zero to one scale and using the relative, accumulated moving average multiplied by a predetermined voltage when adjusting the charging voltage.

15. The method as recited in claim 11, wherein the first and second voltage levels and the second and third voltage levels generally differ by the predetermined voltage step.

16. The method as recited in claim 1, further comprising the steps of determining if the battery is effectively charged and, if the battery is effectively charged, conditioning the battery.

17. The method as recited in claim 16, wherein the step of conditioning the battery comprises supplying a constant current to the battery to generally equalize the battery cells and substantially destratify the battery electrolyte.

18. The method as recited in claim 17, wherein the step of determining if the battery is effectively charged comprises determining if the charging current falls below a fraction of a determined capacity of the battery in ampere-hours.

19. The method as recited in claim 17, wherein the step of determining if the battery is effectively charged comprises determining if the charging current falls below a predetermined fraction of an estimate of the cranking power of the battery at full charge.

20. The method as recited in claim 1, further comprising the step of monitoring for a drop in current and, if a drop in current is detected, stopping the charging of the battery.

21. The method as recited in claim 1, further comprising the step of performing a diagnostic test on the battery to determine if the battery is in a condition to be effectively charged.

22. A readable medium having processor-executable instructions for use in charging a battery, the instructions performing the steps comprising:

outputting a charge voltage to the battery in dependence on a base voltage level;

adjusting the charging voltage in steps of predetermined magnitude to provide first, second and third voltage levels;

measuring first, second, third and fourth currents, wherein the first current is measured at the first voltage level, the fourth current is measured at the third voltage level, and the second and third currents are measured at the second voltage level at differing times;

calculating a first differential from the difference in the first and second currents and calculating a second differential from the difference in the third and fourth currents;

comparing the first differential to the second differential; and

adjusting the base voltage as a function of the comparison.

23. A method of charging a battery, comprising:

outputting a charge current to the battery in dependence on a base current level;

adjusting the charging current in steps of predetermined magnitude to provide first, second and third current levels;

measuring first, second, third and fourth voltages, wherein the first voltage is measured at the first current level, the fourth voltage is measured at the third current level, and the second and third voltages are measured at the second current level at differing times;

calculating a first differential from the difference in the first and second voltages and calculating a second differential from the difference in the third and fourth voltages;

comparing the first differential to the second differential; and

adjusting the base current as a function of the comparison.

24. The method as recited in claim 23, wherein the step of measuring further comprises the step of delaying each of the measurements of the first, second, third and fourth voltages for a respective, predetermined time increment.

25. The method as recited in claim 24, wherein the respective, predetermined time increments for measuring the first, third and fourth voltages are selected to allow the current to become substantially stable.

26. A battery tester and charger system, comprising:

an adjustable power source adapted to electrically charge a battery at variable current or voltage levels;

an adjustable load adapted to electrically discharge the battery at variable current or voltage levels;

feedback sensors adapted to generate signals indicative of conditions within the system;

a controller in communication with the feedback sensors, the power source and the load, the controller adapted, as a function of the signals, to engage and disengage the power source and the load with a battery and to adjust the power source and the load to effectively test and charge the battery.

27. The system as recited in claim 26, wherein the controller is further adapted to stop the test and charge of the battery as a function of the signals.

28. The system as recited in claim 26, wherein the feedback sensors are selected from a group consisting of a charging current sensor, a discharging current sensor, a voltage sensor, a reverse polarity sensor, a temperature sensor, and a proximity sensor.

29. The system as recited in claim 26, wherein the controller issues commands to the power source to output a charge voltage to the battery in dependence on a base voltage level and to adjust the charge voltage in steps of predetermined magnitude to provide first, second and third voltage levels to the battery, wherein the feedback sensors measure first, second, third and fourth currents being supplied to the battery, the first current being measured at the first voltage level, the fourth current being measured at the third voltage level, and the second and third currents being measured at the second voltage level at differing times, and wherein the controller is further adapted to calculate a first differential from the difference in the first and second currents and a second differential from the difference in the third and fourth currents, to compare the first differential to the second differential and to command the power source to adjust the base voltage as a function of the comparison thereby effectively charging the battery.

30. The system as recited in claim 26, further comprising a display and an input device in communication with the controller, the display providing feedback to an operator of the system and the input device receiving input from the operator to control the operation of the system.

31. The system as recited in claim 26, further comprising a printer for outputting information representative of the signals generated by the sensors.

32. The system as recited in claim 30, wherein the controller causes the battery to be automatically tested and charged in response to the operator using the input device to initiate the operation of the system.

33. The system as recited in claim 26, wherein the controller is adapted to perform a diagnostic ramp procedure to provide an instantaneous current versus voltage analysis to determine if the controller should proceed with causing the battery to be charged.

34. The system as recited in claim 26, further comprising a cabinet in which is carried the adjustable power source, the rapidly adjustable load, the feedback sensors and the controller, the cabinet further comprising a safety chamber adapted to carry the battery.

35. The system as recited in claim 34, wherein the safety chamber further comprises a safety glass cover.

36. The system as recited in claim 34, wherein the safety chamber has a proximity sensor for detecting the presence of the battery.

37. The system as recited in claim 34, wherein the safety chamber has a temperature sensor.

38. In a battery diagnostic and charging system connectable to a battery, a method for operating the system, comprising:

performing a diagnostic test on the battery;

if the battery passes the diagnostic test, charging the battery; and

during the steps of performing the diagnostic test and charging the battery, sensing if a disconnection of the battery from the system occurs and, in response to a sensed disconnect, automatically discontinuing the steps of performing the diagnostic test and charging the battery.

39. The method as recited in claim 38, further comprising the step of testing the state of the battery while determining if the battery is in a condition to be recharged and recharging the battery.

40. In a battery diagnostic and charging system connectable to a battery, a method for operating the system, comprising:

sensing if a reverse connection exists between the battery and the system;

if the reverse connection is not sensed, performing a diagnostic test on the battery; and

if the battery passes the diagnostic test, charging the battery.