METHOD AND APPARATUS FOR MEASURING A PARAMETER OF A VEHICLE ELECTRICAL SYSTEM
A vehicle electrical system tester for testing the electrical system of a vehicle is provided. The electrical system has a wiring harness which extends between components of the vehicle and includes a plurality of wires. The vehicle electrical system tester is configured to measure an electrical parameter of at least one of the plurality of wires through a first connection to coupled to a first end of the at least one of the plurality of wires and a second connection coupled to a second end of the at least one of the plurality of wires. An electrical signal is applied between the first and second ends of the at least one of the plurality of wires and the electrical parameter of the at least one of the plurality of wires is responsively measured.
The present application is based on and claims the benefit of U.S. provisional patent application Ser. No. 61/330,497, filed May 3, 2010, the present application is also a Continuation-In-Part of and claims priority of U.S. patent application Ser. No. 12/261,336, filed Oct. 30, 2008, which is a Continuation-In-Part of U.S. patent application Ser. No. 11/641,594, filed Dec. 19, 2006, which is a Divisional of U.S. patent application Ser. No. 10/656,526, filed Sep. 5, 2003, now U.S. Pat. No. 7,154,276, the contents of which are hereby incorporated by reference in their entirety.
BACKGROUND OF THE INVENTIONThe present invention relates to the measurement of electrical parameters of a vehicle electrical system. More specifically, the present invention relates to measuring an electrical parameter of an electrical system of a vehicle using a plurality of connections to the electrical system.
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No. 60/713,168, filed Aug. 31, 2005, entitled LOAD TESTER SIMULATION WITH DISCHARGE COMPENSATION, U.S. Ser. No. 60/731,881, filed Oct. 31, 2005, entitled PLUG-IN FEATURES FOR BATTERY TESTERS; U.S. Ser. No. 60/731,887, filed Oct. 31, 2005, entitled AUTOMOTIVE VEHICLE ELECTRICAL SYSTEM DIAGNOSTIC DEVICE; U.S. Ser. No. 11/304,004, filed Dec. 14, 2005, entitled BATTERY TESTER THAT CALCULATES ITS OWN REFERENCE VALUES; U.S. Ser. No. 60/751,853, filed Dec. 20, 2005, entitled BATTERY MONITORING SYSTEM; U.S. Ser. No. 11/304,004, filed Dec. 14, 2005, entitled BATTERY TESTER WITH CALCULATES ITS OWN REFERENCE VALUES; U.S. Ser. No. 60/751,853, filed Dec. 20, 2005, entitled BATTERY MONITORING SYSTEM; U.S. Ser. No. 11/356,443, filed Feb. 16, 2006, entitled ELECTRONIC BATTERY TESTER WITH NETWORK COMMUNICATION; U.S. Ser. No. 11/519,481, filed Sep. 12, 2006, entitled BROAD-BAND LOW-CONDUCTANCE CABLES FOR MAKING KELVIN CONNECTIONS TO ELECTROCHEMICAL CELLS AND BATTERIES; U.S. Ser. No. 60/847,064, filed Sep. 25, 2006, entitled STATIONARY BATTERY MONITORING ALGORITHMS; U.S. Ser. No. 11/641,594, filed Dec. 19, 2006, entitled METHOD AND APPARATUS FOR MEASURING A PARAMETER OF A VEHICLE ELECTRONIC SYSTEM; U.S. Ser. No. 60/950,182, filed Jul. 17, 2007, entitled BATTERY TESTER FOR HYBRID VEHICLE; U.S. Ser. No. 60/973,879, filed Sep. 20, 2007, entitled ELECTRONIC BATTERY TESTER FOR TESTING STATIONARY BATTERIES; U.S. Ser. No. 11/931,907, filed Oct. 31, 2007, entitled BATTERY MAINTENANCE WITH PROBE LIGHT; U.S. Ser. No. 60/992,798, filed Dec. 6, 2007, entitled STORAGE BATTERY AND BATTERY TESTER; U.S. Ser. No. 61/061,848, filed Jun. 16, 2008, entitled KELVIN CLAMP FOR ELECTRONICALLY COUPLING TO A BATTERY CONTACT; U.S. Ser. No. 12/168,264, filed Jul. 7, 2008, entitled BATTERY TESTERS WITH SECONDARY FUNCTIONALITY; U.S. Ser. No. 12/174,894, filed Jul. 17, 2008, entitled BATTERY TESTER FOR ELECTRIC VEHICLE; U.S. Ser. 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No. 12/712,456, filed Feb. 25, 2010, entitled METHOD AND APPARATU FOR DETECTING CELL DETERIORATION IN AN ELECTROCHEMICAL CELL OR BATTERY; U.S. Ser. No. 61/311,485, filed Mar. 8, 2010, entitled BATTERY TESTER WITH DATABUS FOR COMMUNICATING WITH VEHICLE ELECTRICAL SYSTEM; U.S. Ser. No. 61/313,893, filed Mar. 15, 2010, entitled USE OF BATTERY MANUFACTURE/SELL DATE IN DIAGNOSIS AND RECOVERY OF DISCHARGED BATTERIES; U.S. Ser. No. 12/758,407, filed Apr. 12, 2010, entitled ELECTRONIC BATTERY TESTER WITH NETWORK COMMUNICATION; U.S. Ser. No. 12/765,323, filed Apr. 22, 2010, entitled AUTOMOTIVE VEHICLE ELECTRICAL SYSTEM DIAGNOSTIC DEVICE; U.S. Ser. No. 12/769,911, filed Apr. 29, 2010, entitled STATIONARY BATTERY TESTER; U.S. Ser. No. 61/330,497, filed May 3, 2010, entitled MAGIC WAND WITH ADVANCED HARNESS DETECTION; U.S. Ser. No. 12/786,890, filed May 25, 2010, entitled BATTERY TESTER WITH PROMOTION FEATURE; U.S. Ser. No. 61/348,901, filed May 27, 2010, entitled ELECTRONIC BATTERY TESTER; U.S. Serial No. 29/362,827, filed Jun. 1, 2010, entitled ELECTRONIC BATTERY TESTER; U.S. Ser. No. 61/351,017, filed Jun. 3, 2010, entitled IMPROVED ELECTRIC VEHICLE AND HYBRID ELECTRIC VEHICLE BATTERY MODULE BALANCER; U.S. Ser. No. 12/818,290, filed Jun. 18, 2010, entitled BATTERY MAINTENANCE DEVICE WITH THERMAL BUFFER; U.S. Ser. No. 61/373,045, filed Aug. 12, 2010, entitled ELECTRONIC BATTERY TESTER FOR TESTING STATIONERY STORAGE BATTERY; U.S. Ser. No. 12/888,689, filed Sep. 23, 2010, entitled BATTERY TESTER FOR ELECTRIC VEHICLE; U.S. Ser. No. 12/894,951, filed Sep. 30, 2010, entitled BATTERY PACK MAINTENANCE FOR ELECTRIC VEHICLES; U.S. Ser. No. 61/411,162, filed Nov. 8, 2010, entitled ELECTRONIC BATTERY TESTER; U.S. Ser. No. 13/037,641, filed Mar. 1, 2011, entitled MONITOR FOR FRONT TERMINAL BATTERIES; U.S. Ser. No. 13/048,365, filed Mar. 15, 2011, entitled ELECTRONIC BATTERY TESTER WITH BATTERY AGE UNIT; which are incorporated herein by reference in their entirety.
There is an ongoing need to measure parameters of electrical systems of vehicles and heavy equipment. Such measurements can be used to diagnose operation, failure or impending failure of components or subsystems of electrical systems. For example, in electrical systems used in vehicles, measurement of electrical parameters of such systems can be used to diagnose operation of the system or indicate that maintenance is required before ultimate failure.
One particular measurement is the resistance of cabling used in the vehicle. For example, one such cable or set of cables connects the battery the of vehicle to the starter motor. The starter motor has a relatively large current draw and even a relatively small cable resistance can have a significant impact on operation of the starter motor.
Because the cable resistance is relatively small it typically cannot be measured using a standard ohm meter or other techniques which are normally used to measure resistance. One technique which has been used to measure the cable resistance is to run a very large current through the cable and measure the voltage drop. However, this is cumbersome and requires components capable of handling the large current.
SUMMARY OF THE INVENTIONA vehicle electrical system tester for testing the electrical system of a vehicle is provided. The electrical system has a wiring harness which extends between components of the vehicle and includes a plurality of wires. The vehicle electrical system tester is configured to measure an electrical parameter of at least one of the plurality of wires through a first connection to coupled to a first end of the at least one of the plurality of wires and a second connection coupled to a second end of the at least one of the plurality of wires. An electrical signal is applied between the first and second ends of the at least one of the plurality of wires and the electrical parameter of the at least one of the plurality of wires is responsively measured.
As discussed in the Background section, the resistances R1 and R2 of cables 24 or 26 can impact the amount of power which can be delivered to load 22. Even if the resistance values are relatively small, if a relatively large current passes through cables 24 and 26, the resultant voltage drop can significantly reduce the voltage across load 22 and therefore the amount of power which can be delivered to load 22. In many instances, it is desirable to measure the resistance R1 and R2 of cables 24 and 26, respectively, in order to identify a cable with a resistance which is too high. One technique which has been used to measure the resistance of the cables is to pass a large current through the cable and measure the resulting voltage drop across the cable. However, this is a cumbersome test and requires electrical test equipment which is capable of handling the large current draw. The present invention provides an apparatus and technique for measuring the resistance of a cable in a configuration similar to that shown in
The load 22 of the vehicle can be any type of load including loads which draw high current levels, for example, a starter motor, a magnetic switch, a ground connection, wiring harness, a terminal which may be susceptible to corrosion, a connection through a bolt which may have inappropriate torque or otherwise provide a poor connection, data carrying wires, sensor wiring, trailer wiring, etc. The invention is applicable to all wire sizes including small, medium and large gauge and is not limited to those discussed herein. In one example embodiment, the output is related to a particular current draw through the cabling. For example, the output can comprise an indication that there is a 0.5 volt drop through the cable when carrying a 500 amp current. Such parameter can also be used, for example, in a pass/fail test, i.e., if the voltage drop is more than a particular threshold at a given current level, a failure indication can be provided as an output. In one embodiment, the measured parameters comprise dynamic parameters such as dynamic conductance. However, any dynamic parameter can be used in accordance with the present invention including dynamic resistance, reactance, impedance, conductance, susceptance, and/or admittance, including any combination of these parameters, or others.
During operation, microprocessor 108 shown in
In one configuration, the user I/O 112 is used by an operator to instruct the microprocessor 108 as to the particular circuit configuration to be used as illustrated in
Button 204 can be configured as a “enter” button and buttons 206 and 208 can be configured as “up” and “down” buttons for scrolling through and selecting menu items displayed on display 208. For example, this can be used to also to receive information regarding the “gauge” of the wire under test. LED's 210 and 212A and 212B can be used to display test information. For example, when a wire of a positive polarity is detected either or both LED's 212 or 212B may be illuminated. Similarly, when test probe 242 is connected is wired to a wire of negative polarity, either or both of the LED 210A/210B may be illuminated. Button 204 can be used for initiate test button and cause the test to begin. Upon completion of the test, the microprocessor 108 can be configured to illuminate LED 210B or 212B if the test is successful. If the wire fails the test, LED 210A or 212B may be illuminated. In a similar configuration, an audio output can be provided, for example, a high pitch solid continuous tone to indicate a “good” wire, a “good” power wire, a high pitch beeping tone to indicate a “bad” power wire, a low pitch solid tone to indicate a “good” ground wire, and a low beeping tone to indicate a “bad” ground wire.
In another example configuration, a wire size gauge 250 is provided on the side of housing 200. In this example, the wire size gauge 250 provides three wire size gauges, 252A, 252B and 252C. These may be used by an operator to determine the gauge of the wire under test and input into the microprocessor 108 using user I/O 112. In another example configuration, wire size gauge 250 comprises an automatic gauge in which the wire under test is placed into a slot or the like and a sensor automatically determines the gauge of the wire and provides this information to microprocessor 108.
In one example configuration, a small gauge wire is tested with a current load of 1.25 amps, a medium gauge wire is tested with a current load of 2.5 amps, and a large gauge wire is tested with a current load of 5.0 amps, all with a fixed failure threshold of 0.2 volts. (i.e., if the measured voltage across the wire is greater than 0.2 volts, a failure is indicated). In another example embodiment, a fixed current load is provided and microprocessor 108 scales the measured result based upon the gauge of the wire.
Although the above description shows two different Kelvin connections to the battery terminals, in one configuration, Kelvin connections are not used and another example configuration, only a single Kelvin connection is used or no Kelvin connections are used. Similarly, only a single test connector may be employed and the invention does not require the two test connectors described above. Such an embodiment may be employed if desired, for example, to simultaneously measure the resistances of two separate wires. In a typical configuration, a single test connector will be employed. Similarly, the test connector may be a single connector and a Kelvin connection is not required. If a Kelvin connection is used, the Kelvin connection point can be configured anywhere along the test connector wiring and may be at a point that the test connector couples to the wiring of the vehicle, or at some other point in the wiring between the distal end of the test connector and the circuitry of the tester. The measurements may be made using static measurement techniques to obtain a static parameter or may be made using dynamic measurement techniques to obtain a dynamic parameter. Although the discussion above has generally referred to “resistance”, the present invention is not limited to resistance and the parameter measured may be any parameter of the wire including those which have frequency dependent components. The tester may be powered with power from the battery of the electrical system or may contain an independent power source, for example, an internal battery. As discussed above, in some embodiments, Kelvin connections are provided to the terminals of the battery. In such a configuration, a parameter of the battery may be measured using the techniques discussed in the Background section, or other techniques.
The connection tip may be interchangeable and may be comprised a test probe, piercing tip, connector coupled to a particular type of electrical connection on the vehicle, or other configurations. As these tips are interchangeable, the overall resistance of the test connection may vary. Thus, in some configurations, the microprocessor 108 can be configured to implement a zeroing function whereby an operator can calibrate the measurement for the resistance of the wire based upon the selected probe tip. Such a configuration would typically not be required for a Kelvin connection. The zeroing function can be performed automatically by the microprocessor by measuring the resistance through the electrical connection, can be entered manually by an operator, may be selected by an operator scrolling through a table and selecting the probe in use. In such a configuration, memory 110 shown in
In one configuration the measurement is presented to the operator in the form of “voltage drop at XX amps”. However, the actual measurement may be performed at a current level other than that presented to the operator. If a small current is employed, conductance measurement techniques can be used to determine the voltage drop. If a current other than the displayed current is employed, the microprocessor 180 performs a scaling on the measurement. For example, if 5 amps is used to perform the measurement, the microprocessor 108 can compute the results in voltage drops at a different value such as 25 amps for display to the operator. This scaling can occur automatically, or can be selected by an operator. Such selection may be, for example, by scrolling through a utility menu presented to the operator using user I/O 110. In such a configuration, memory 110 can contain a scaling factor for use by the microprocessor 108.
In one embodiment, a relatively small current is employed. This reduces the amount of heat generated and reduces the power requirements of the testing device. The measurement can be performed using a dynamic forcing function such as a time varying current signal. For example, short pulses can be used if the device is not capable of sustaining a large current output for an extended period of time. In one example, a pulse width between 10 and 100 msec is used to perform the measurement.
The microprocessor can be configured to automatically sense the polarity of the connection. In such a configuration, the microprocessor sense the voltage measured and determines whether the probe is coupled to a power wire or to a ground wire and the appropriate load is applied. For example, if zero volts is sensed, the wire being tested is most likely a ground wire. Similar, if twelve volts is sensed, the wire being tested is most likely used to supply power. However, in some example configurations, a zero voltage reading may also indicate that the wire being tested is not connected. Similarly, a twelve volt reading may not be a power supplying wire if, for example, the alternator of the vehicle is generating a fifteen volt output. One example configuration to address this concern is to bias the probe tip to a voltage level. For example, circuitry within component 104 (or 102) can be provided to bias the probe tip to a value somewhere between the voltage at the two power leads coupled to the battery 20. When the probe tip is then coupled to the vehicle, the voltage at the probe tip will be pulled to either a more negative or positive value. Microprocessor 108 can sense this voltage and make a determination as to whether the probe is connected to a power lead or a ground lead. For example, if the probe tip voltage is within a predetermined voltage level from electrical ground, microprocessor can determine that the probe is connected to a ground connection. Similarly, if the probe tip is pulled within a predetermined voltage level from the plus connection of the battery, a microprocessor 108 can determine that a power lead is under test. In one example, the predetermined voltage is one volt which is advantageous if a protective diode is employed in the lead which would provide a voltage drop of 0.6 volts.
In one configuration, the tester 100 is configured to test an electrical connection in a wiring harness of an automotive vehicle. For example, referring to
Once the correct ends of the wire have been connected to the circuitry, the microprocessor 108 performs tests on the selected wire. Such tests include determining the current load capacity of the wire, identifying electrical short circuits or leakage to other wires, identifying leakage to electrical ground or power sources, testing the load carrying capacity of the wire for DC or AC signals including signals of different frequencies, etc. These tests can be performed for both AC and DC signals. For example, although a particular wiring connection may be capable of carrying a DC signal, AC signals (such as those used for data transmission, etc.) may be significantly degraded through the wiring due to stray inductance or capacitance. These tests can be performed by disconnecting both ends of the wire 24.
An operator can be prompted by the microprocessor 108 to perform the particular steps required for such a test. A memory 110 can be configured to contain a database of information related to the proper characteristics for wires used to connect to different types of systems. For example, data transmission wires may have one set of requirements whereas wiring used to connect to an analog sensor may have a different set of requirements. In such a configuration, the operator can scroll through a list of components and select the proper component for the particular wire being tested.
Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention. The measurements can be taken using multiple connections to the electrical system or by moving a single pair of connections to various positions on the electrical system. An output can be provided to instruct the operator where to place the connections.
Claims
1. A vehicle electrical system tester for testing the electrical system of a vehicle, the electrical system having a wiring harness which extends between electrical components of the vehicle, the wiring harness including a plurality of wires, the vehicle electrical system tester configured to measure an electrical parameter of at least one of the plurality of wires and comprising:
- a first connection configured to couple to a first end of the at least one of the plurality of wires of the wiring harness;
- a second connection configured to couple to a second end of the at least one of the plurality of wires of the wiring harness;
- test circuitry coupled to the first and second connections, the test circuitry applying an electrical signal between the first and second ends of the at least one of the plurality of wires and responsively measuring the electrical parameter of the at least one of the plurality of wires of the wiring harness.
2. The vehicle electrical system tester of claim 1 including a connection to a battery of the vehicle and wherein the measured parameter is further based upon a measurement made through the connection to the battery.
3. The vehicle electrical system tester of claim 1 including an electrical connection to a battery of the vehicle and wherein circuitry of the vehicle system electrical tester is powered with power from the battery.
4. The vehicle electrical system tester of claim 1 wherein the test circuitry is further configured to provide an output to an operator, the output to the operator assisting the operator in identifying the second end of the at least one of the plurality of wires of the wiring harness.
5. The vehicle electrical system tester of claim 4 wherein the output comprises a tone.
6. The vehicle electrical system tester of claim 5 wherein the test circuitry applies a tone signal to the first end of the wire and the tone signal is received by the second connection.
7. The vehicle electrical system tester of claim 1 including an input configured to receive information from an operator related to at least one of the components of the vehicle coupled to the first end of the at least one of the plurality of wires of the wiring harness.
8. The vehicle electrical system tester of claim 7 including a user output displaying a plurality of vehicle components and wherein the operator selects a vehicle component coupled to one end of the at least one of the plurality of wires of the wiring harness from the plurality of components through a user input.
9. The vehicle electrical system tester of claim 1 wherein the signal comprises a DC signal.
10. The vehicle electrical system tester of claim 1 wherein the signal comprises a AC signal.
11. The vehicle electrical system tester of claim 1 wherein the parameter relates to the ability of the at least one of the plurality of wires to carry digital data.
12. The vehicle electrical system tester of claim 1 including a user output and wherein the test circuitry prompts an operator to disconnect at least one end of the plurality of wires from the vehicle electrical system through the user output.
13. The vehicle electrical system tester of claim 1 wherein the first and second connections comprise Kelvin connections.
14. The vehicle electrical system tester of claim 1 wherein the first connection comprises a piercing probe configured to pierce insulation of the at least one of the plurality of wires.
15. The vehicle electrical system tester of claim 1 including a user input coupled to the test circuitry.
16. The vehicle electrical system tester of claim 15 when the user input is configured to receive information related to a gauge of the at least one of the plurality of wires.
17. The vehicle electrical system tester of claim 1 wherein the test circuitry provides an output in the form of “voltage drop at XX amps”.
18. The vehicle electrical system tester of claim 1 wherein the test circuitry provides an output related to electrical parameter of the at least one of the plurality of wires and a scaling factor.
19. The vehicle electrical system tester of claim 1 wherein the electrical parameter of the at least one of the plurality of wires comprises a dynamic parameter
20. A method of testing wiring of an electrical system of a vehicle, the wiring including a wiring harness which extends between electrical components of the vehicle, the wiring harness including a plurality of wires, the method comprising:
- coupling test circuitry to one end of at least one the plurality of wires in the wiring harness;
- coupling the test circuitry to a second end of the at least one of the plurality of wires of the wiring harness;
- applying a signal between the first and second ends of the at least one of the plurality of wires of the wiring harness; and
- measuring a parameter of the at least one of the plurality of wires of the wiring harness using the test circuitry based upon the signal applied to the at least one of the plurality of wires of the wiring harness.
21-26. (canceled)
Type: Application
Filed: Feb 8, 2016
Publication Date: Jun 2, 2016
Inventor: Kevin I. Bertness (Batavia, IL)
Application Number: 15/017,887