Apparatus and method for testing remaining capacity of a battery

• US 6,823,274 B2
• Filed: 11/08/2002
• Issued: 11/23/2004
• Est. Priority Date: 04/13/1999
• Status: Expired due to Fees

• Current Assignee: ZTS, Inc.
• Original Assignee: ZTS, Inc.
• Inventors: Claypoole, Gary Lee, Zimmerman, David Eric, Zimmerman, Phillip David
• Primary Examiner(s): Bui, Bryan
• Application Number:
  US10/291,008
• Publication Number:
  US 20030088376A1
• Time in Patent Office: 746 Days
• Field of Search: 702/57, 702/63, 702/64, 702/65, 702/79, 702/117, 702/182-184, 320/106, 320/110, 320/125, 320/135, 320/136, 320/139, 324/426, 324/427
• US Class Current: 702/63
• CPC Class Codes: G01R 19/16542 for batteries charge condition monitoring in G01R31/36
• CPC Class Codes: G01R 31/378 specially adapted for the type of battery or accumulator
• CPC Class Codes: G01R 31/386 using test-loads

Abstract

An apparatus and method of determining remaining capacity in a battery, including the following steps: detecting the presence of a battery within one of a plurality of specified terminals; automatically initiating a timed pulse load test on the battery upon detection in a terminal; continuously passing current from the battery through a specified resistive load for the terminal; measuring a voltage of the battery while under the resistive load; comparing the measured voltage to a discharge voltage profile of the battery; and, computing the measured voltage as a percent of remaining battery capacity.

Claims

1. A method of determining remaining capacity in a battery, comprising the following steps:

(a) detecting the presence of a battery within one of a plurality of specified terminals;

(b) automatically initiating a timed pulse load test on said battery upon detection in a terminal;

(c) continuously passing current from said battery through a specified resistive load for said terminal;

(d) measuring a voltage of said battery while under said resistive load;

(e) comparing said measured voltage to a discharge voltage profile of said battery; and

,

(f) computing said measured voltage as a percent of remaining battery capacity.

2. The method of claim 1, further comprising the step of scaling said measured voltage as a function of a measured reference voltage to a supply voltage.

3. The method of claim 1, further comprising the step of identifying said battery from said terminal.

4. The method of claim 1, further comprising the step of identifying a test in progress.

5. The method of claim 1, further comprising the step of scanning said terminals in sequence to detect the presence of a battery therein.

6. The method of claim 1, wherein said specified resistive load is in accordance with a type of said battery detected in said terminal.

7. The method of claim 1, wherein said specified resistive load is in accordance with a size of said battery detected in said terminal.

8. The method of claim 1, wherein said specified resistive load is in accordance with an application for said battery detected in said terminal.

9. The method of claim 1, wherein a single pulse load test is conducted.

10. The method of claim 1, wherein multiple pulse load tests are conducted.

11. The method of claim 1, further comprising the step of passing said current of said battery through a voltage dividing resistor prior to said measuring step when said measured voltage is greater than a predetermined level.

12. The method of claim 1, wherein said discharge voltage profile is a function of said terminal.

13. The method of claim 1, further comprising the step of operating said timed pulse load test directly via a supply voltage from a plurality of supply batteries.

14. The method of claim 13, further comprising the following steps:

(a) enabling a high tolerance voltage reference;

(b) storing a voltage output from said voltage reference; and

,

(c) scaling said measured voltage as a function of said supply voltage and said reference voltage.

15. The method of claim 1, further comprising the step of storing a discharge voltage profile for a battery associated with each terminal.

16. The method of claim 1, further comprising the step of displaying a signal indicative of said computed remaining battery capacity.

17. The method of claim 1, wherein said remaining battery capacity is computed as a function of a change in voltage for said battery during said pulse load test.

18. The method of claim 1, further comprising the step of disconnecting said specified resistive load upon completion of said pulse load test.

19. The method of claim 1, wherein said specified resistive load is substantially similar to a load experienced by said battery operating under normal conditions.

20. An apparatus for determining remaining capacity in a battery, comprising:

(a) a microcontroller having a plurality of battery discharge profiles stored therein;

(b) a plurality of terminals connected to said microcontroller, wherein each of said terminals is identified as being applicable for a specified battery;

(c) a resistive load associated with each terminal;

(d) a power supply for providing a supply voltage to operate said microcontroller;

wherein a timed pulse load test is automatically initiated by said microcontroller upon detection of a battery on any of said terminals so that current from said battery is passed through said associated resistive load and a voltage for said battery is measured, said measured voltage being compared to a battery discharge profile for said battery and a remaining battery capacity being computed therefrom.

21. The apparatus of claim 20, further comprising a multiplexer for scanning said terminals in sequence for the presence of a battery.

22. The apparatus of claim 20, further comprising a plurality of light emitting diodes to indicate a corresponding remaining capacity for said battery computed by said microcontroller.

23. The apparatus of claim 20, further comprising a voltage reference for providing a measured reference voltage, wherein said measured voltage of said battery is scaled by comparing said measured reference voltage and said supply voltage.

24. The apparatus of claim 20, wherein said resistive load is a function of the type of said battery specified for said terminal.

25. The apparatus of claim 20, wherein said resistive load is a function of the size of said battery specified for said terminal.

26. The apparatus of claim 20, wherein said resistive load is a function of an application for said battery specified for said terminal.

27. The apparatus of claim 20, wherein said microcontroller initiates a plurality of timed pulse load tests on said battery.

28. The apparatus of claim 20, further comprising a voltage divider for reducing said measured voltage when above a specified level.

29. The apparatus of claim 20, further comprising a current limiting resistor located between each said terminal and said microcontroller.

30. The apparatus of claim 20, further comprising a relay connected to each terminal and ground, wherein the connection of said resistive load to said battery is controlled thereby.