Electronic battery tester

• US 6,310,481 B2
• Filed: 03/26/1999
• Issued: 10/30/2001
• Est. Priority Date: 01/13/1997
• Status: Expired due to Term

• Current Assignee: Midtronics Incorporated
• Original Assignee: Midtronics Incorporated
• Inventors: Bertness, Kevin I.
• Primary Examiner(s): Brown, Glenn W.
• Assistant Examiner(s): Nguyen, Vincent Q.
• Application Number:
  US09/280,133
• Publication Number:
  US 20010002792A1
• Time in Patent Office: 949 Days
• Field of Search: 324/427, 324/430, 324/433, 340/636, 320/151, 320/156, 320/161
• US Class Current: 324/430
• CPC Class Codes: G01R 31/36 Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
• CPC Class Codes: G01R 31/389 Measuring internal impedance, internal conductance or related variables
• CPC Class Codes: H01M 10/48 Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals, H01M50/569
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A microprocessor couples to a voltage sensor through an analog to digital converter. The voltage sensor is adapted to be coupled across terminals of a battery. A small current source is also provided and adapted to be coupled across the terminal to the battery. The current source is momentarily applied to the battery and the resulting change in voltage is monitored using the microprocessor. The microprocessor calculates battery conductance based upon the magnitude of the differential current and the change in voltage and thereby determines the condition of the battery.

Claims

1. An apparatus for measuring condition of a storage battery, comprising:

a first connector adapted to connect to a positive terminal of the storage battery;

a second connector adapted to connect to a negative terminal of the battery;

an analog to digital converter coupled to the first and second connectors adapted to amplify a signal from the battery developed between the positive terminal of the battery and the negative terminal of the battery and responsively provide a digital output;

a memory storing a calibration value, the calibration value related to lumped sum non-linearities in the apparatus; and

a microprocessor coupled to the analog to digital converter adapted to measure condition of the storage battery in response to the digital output, and wherein the measurement is a function of the calibration value whereby the calibration value is used to reduce offsets in the measurement due to lumped sum non-linearities.

2. The apparatus of claim 1 wherein the calibration value comprises a voltage value and the condition of the battery is a function of battery conductance.

3. The apparatus of claim 1 wherein the first and second connectors comprise Kelvin connections.

4. The apparatus of claim 1 wherein the calibration value is determined by measuring an offset in the digital output.

5. The apparatus of claim 4 wherein the calibration value is determined during manufacture.

6. The apparatus of claim 1 wherein the signal from the battery is developed in response to an applied current.

7. The apparatus of claim 1 wherein the signal from the battery is developed in response to an applied voltage.

8. The apparatus of claim 1 wherein the signal from the battery is developed in response to an applied load.

9. A method of measuring condition of a storage battery, comprising:

applying a signal to the storage battery;

sensing a response signal from the storage battery generated in response to the applied signal;

digitizing the response signal;

retrieving a calibration value from a memory, the calibration value related to lumped sum non-linearities of battery test circuitry; and

determining condition of the battery as a function of the response signal and the calibration value whereby the calibration value is used to reduce offsets in the measurement due to lumped sum non-linearities.

10. The method of claim 9 wherein the applied signal is a current.

11. The method of claim 9 wherein the applied signal is a voltage.

12. The method of claim 9 wherein the applied signal is a load.

13. The method of claim 9 wherein the calibration value is determined by measuring an offset in the digital output.

14. The method of claim 13 wherein the calibration value is determined during manufacture.