Static random access memory backup

• US 6,445,986 B1
• Filed: 07/28/2000
• Issued: 09/03/2002
• Est. Priority Date: 07/28/2000
• Status: Expired due to Fees

• Current Assignee: Meritor Heavy Vehicle Technology, LLC (Cummins Incorporated)
• Original Assignee: Meritor Heavy Vehicle Technology, LLC (Cummins Incorporated)
• Inventors: Costello, Robert E.
• Primary Examiner(s): Nguyen, Tan
• Assistant Examiner(s): Tran, Dalena
• Application Number:
  US09/627,857
• Time in Patent Office: 767 Days
• Field of Search: 701/22, 701/29, 701/35, 702/63, 307/66, 307/9.1, 713/340, 713/300, 714/22, 714/14, 714/24, 365/229, 320/107
• US Class Current: 701/35
• CPC Class Codes: B60R 16/03 for supply of electrical power to vehicle subsystems or for circuit arrangements for charging batteries H02J7/00
• CPC Class Codes: G06F 1/263 Arrangements for using multiple switchable power supplies, e.g. battery and AC G06F1/30 takes precedence
• CPC Class Codes: G06F 1/28 Supervision thereof, e.g. detecting power-supply failure by out of limits supervision
• CPC Class Codes: H02J 2310/46 for ICE-powered road vehicles
• CPC Class Codes: H02J 9/00 Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting

Abstract

A data logging system includes a data logging unit, a primary power source, an auxiliary power source and a controller. The controller detects whether the primary power source is available or unavailable and the time at which it became available or unavailable. From the time data the controller will then determine the total time the primary power source was unavailable to power the system. The controller adjusts or increases a predetermined auxiliary power source value by the auxiliary power source usage time period. Upon each occurrence in which the primary power source again becomes unavailable, the controller performs the same operations and further adjust or increases the previously reduced predetermined auxiliary power source value by the next auxiliary power source usage time period. Adjusting or increasing the predetermined auxiliary power source value will continue until a predetermined value is reached which triggers an alert. The alert indicates to an operator that the system requires service.

Claims

1. A vehicle data logging system comprising:

a data logging unit;

a primary power source to power said data logging unit;

an auxiliary power source to power said data logging unit when said primary power source is unavailable; and

a controller in communication with said data logging unit, said controller operable to determine a cumulative auxiliary power source usage time period by determining a total time during which said primary power source is unavailable.

2. The system as recited in claim 1, wherein said controller reduces a predetermined auxiliary power source value by said auxiliary power source usage time period each time said primary power source is unavailable.

3. The system as recited in claim 1, further comprising a clock, said controller operable to identify a time at which said primary power source becomes unavailable and available.

4. The system as recited in claim 3, further comprising a memory, said controller operable to store said time within said memory.

5. The system as recited in claim 3, further comprising an alert, said controller operable to trigger said alert when said predetermined calculated auxiliary power source value is reduced to a predetermined value.

6. The system as recited in claim 1, wherein said data logging unit is in communication with a vehicle system.

7. The system as recited in claim 1, wherein said auxiliary power source is a battery.

8. The system as recited in claim 1, wherein said auxiliary power source is a non-rechargeable battery.

9. A method of monitoring an auxiliary power source in a vehicle data logging system comprising the steps of:

(1) measuring a time period during which a primary power source is unavailable; and

(2) adjusting a predetermined auxiliary power source value by said time period each time said primary power source is unavailable.

10. A method as recited in claim 9, wherein said step (1) further comprising the step of detecting whether said primary power source is available and unavailable.

11. A method as recited in claim 9, further comprising the step of storing a time at which said primary power source becomes unavailable and available.

12. A method as recited in claim 9, further comprising the step of activating an alert when said predetermined auxiliary power source value is reduced to a predetermined value.

13. A method as recited in claim 9, wherein said step (2) is performed when said primary source again becomes available.

14. A method as recited in claim 9, wherein said predetermined calculated auxiliary power source value is less than a value at which the auxiliary power source fails.

15. A method as recited in claim 9, wherein said step (2) further comprises determining a cumulative time during which the primary power source is unavailable.

16. A method as recited in claim 9, wherein said step (5) further comprises determining a cumulative time during which the primary power source is unavailable.

17. A method of monitoring an auxiliary power source in a vehicle data logging system comprising the steps of:

(1) detecting when a primary power source is unavailable;

(2) storing a time when said primary power source becomes unavailable;

(3) detecting when said primary power source is available;

(4) storing a time when said primary power source becomes available;

(5) determining a time period during which said primary power source is unavailable from said step (2) and said step (4); and

(6) adjusting a predetermined calculated auxiliary power source value by said time period determined in said step (5) each time said primary power source is unavailable.

18. A method as recited in claim 17, further comprising the step of activating an alert when said predetermined auxiliary power source value is reduced to a predetermined value.

19. A method as recited in claim 17, further comprising the step of resetting said predetermined auxiliary power source value upon replacement of an auxiliary power source.

20. A method as recited in claim 17, wherein said step (6) is performed when said primary source again becomes available.

21. A method as recited in claim 17, wherein said predetermined calculated auxiliary power source value is less than a value at which the auxiliary power source fails.

22. A vehicle data logging system comprising:

a data logging unit;

a primary power source to power said data logging unit;

an auxiliary power source to power said data logging unit when said primary power source is unavailable; and

a controller in communication with said data logging unit, said controller operable to determine an auxiliary power source usage time period during which said primary power source is unavailable, said controller reducing a predetermined auxiliary power source value by said auxiliary power source usage time period each time said primary power source is unavailable.

23. The system as recited in claim 22, wherein said auxiliary power source is a non-rechargeable battery.