Battery Monitor

• US 5,130,659 A
• Filed: 12/03/1990
• Issued: 07/14/1992
• Est. Priority Date: 08/21/1990
• Status: Expired due to Fees

• Current Assignee: Jeffrey M. Sloan
• Original Assignee: Jeffrey M. Sloan
• Inventors: Sloan, Jeffrey M.
• Primary Examiner(s): Snow, Walter E.
• Assistant Examiner(s): Solis, Jose M.
• Application Number:
  US07/620,741
• Time in Patent Office: 589 Days
• Field of Search: 320/13, 320/48, 340/636, 324/426, 324/427, 324/428, 324/435
• US Class Current: 324/435
• CPC Class Codes: G01R 31/006 on road vehicles, e.g. automobiles or trucks testing of ignition installations peculiar to internal combustion engines F02P17/00
• 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 31/374 with means for correcting the measurement for temperature or ageing
• CPC Class Codes: G01R 31/3835 involving only voltage measurements
• CPC Class Codes: Y10S 320/21 State of charge of battery

Abstract

A battery monitor is disclosed for indicating the projected time until the battery reaches a lower threshold value indicative of the energy capacity of the battery. The battery monitor includes a microprocessor which iteratively reads the value of the battery voltage. The microprocessor then determines the rate of discharge of the battery and projects the future values of the battery voltage as well as the projected time at which the battery voltage attains the threshold voltage. This projected time is then displayed on a visual indicator, such as an LCD display. In an alternate embodiment, warning lights are selectively illuminated to indicate a full charge, medium charge and low charge conditions.

Claims

1. For use in conjunction with a battery electrically connected with a starter circuit for an internal combustion engine, a battery monitor comprising:

means for sensing an electrical characteristic of the battery,

means responsive to said sensing means for determining the rate of discharge of the battery and for projecting future values of said electrical characteristic as a function of time,

means for establishing a predetermined lower threshold value of said characteristic, said threshold value varying as a function of time, said lower threshold value indicative of the energy capacity of the battery necessary to start the engine through the starter circuit,

means for determining the projected time at which said projected future value of said electrical characteristic equals said threshold value and for determining a remaining time duration between a present time and said projected time, and

means for displaying said remaining time duration.

2. The invention as defined in claim 1 wherein said battery electrical characteristic is the battery voltage.

3. The invention as defined in claim 1 wherein said indicator periodically determines said time duration and further comprising means for calculating an average time duration, and wherein said displaying means displays said average time duration.

4. The invention as defined in claim 1 and further comprising means for determining an ambient temperature of said battery, and means responsive to said temperature determining means for varying said lower threshold value.

5. The invention as defined in claim 1 wherein said battery is electrically connected with a starter circuit for an internal combustion engine and wherein said lower threshold value is indicative of the energy capacity of the battery necessary to start the engine through the starter circuit.

6. The invention as defined in claim 5 and comprising means for detecting and saving a minimum battery voltage during an engine starting condition and means for varying said lower threshold value as a function of said minimum battery voltage.

7. The invention as defined in claim 1 wherein said determining means comprises a microprocessor.

8. The invention as defined in claim 1 wherein said displaying means comprises a liquid crystal display.

9. For use in conjunction with a battery, a battery monitor comprising:

means or sensing an electrical characteristic of the battery,

means responsive to said sensing means for determining the rate of discharge of the battery and for projecting the future values of the electrical characteristic as a function of time,

means for establishing a predetermined lower threshold value of said characteristic, said threshold value varying as a function of time,

means for determining the projected time at which the electrical characteristic equals said threshold value at said projected time and for determining the time duration until said projected time, and

means for comparing said time duration with a preset time span,

an indicator, and

means responsive to said comparing means for activating said indicator when said time duration is less than said time span.

10. The invention as defined in claim 9 wherein said battery electrical characteristic is the battery voltage.

11. The invention as defined in claim 9 and further comprising means for determining an ambient temperature of said battery, and means responsive to said temperature determining means for varying said threshold value.

12. The invention as defined in claim 9 wherein said battery is electrically connected with a starter circuit for an internal combustion engine and wherein said lower threshold value is indicative of the energy capacity of the battery necessary to start the engine through the starter circuit.

13. The invention as defined in claim 12 and comprising means for detecting and saving a minimum battery voltage during an engine starting condition and means for varying said lower threshold value as a function of said minimum battery voltage.

14. The invention as defined in claim 9 wherein said determining means comprises a microprocessor.

15. For use in conjunction with a battery, a battery monitor comprising:

means for sensing an electrical characteristic of the battery to generate an output signal representative thereof,

means for establishing a first predetermined lower threshold value of said characteristic, said first threshold value varying as a function of time,

means for establishing a second threshold value, said second threshold value exceeding said first threshold value by a preset amount,

means for comparing said output signal with said threshold values to determine which of said threshold values of said characteristic is appropriate,

a first and a second indicator,

means for activating said first indicator when said output signal exceeds said second threshold value, and

means for activating said second indicator instead of said first indicator when said output signal is less than said second threshold value.

16. The invention as defined in claim 15 and comprising means for establishing a third threshold value which exceeds said second threshold value by a second preset amount, a third indicator, and means for activating said third indicator when said output signal exceeds said third threshold value, and

wherein said means for activating said second indicator activates said second indicator only when said output signal is between said second and third threshold values.

17. The invention as defined in claim 15 wherein said indicators comprise lights.

18. The invention as defined in claim 15 wherein said battery electrical characteristic is the battery voltage.

19. The invention as defined in claim 15, and further comprising means for determining an ambient temperature of said battery, and means responsive to said temperature determining means for varying said lower threshold value.

20. The invention as defined in claim 15 wherein said battery is electrically connected with a starter circuit for an internal combustion engine and wherein said lower threshold value is indicative of the energy capacity of the battery necessary to start the engine through the starter circuit.

21. The invention as defined in claim 20 and comprising means for detecting and saving a minimum battery voltage during an engine starting condition and means for varying said lower threshold value as a function of said minimum battery voltage.