DE112021003562T5 - Electrical load for an electronic battery tester and electronic battery tester including such an electrical load - Google Patents

Abstract

A device (10) for testing a storage battery (12) in a motor vehicle (300) includes a controllable electrical load (70) which is designed to electrically couple to the storage battery (12) of the vehicle (300). A current sensor is configured (304) to electrically couple to a terminal (22) of the battery (12) and to measure current flow through the battery (12). A controller (56) is arranged to apply an electrical load (RL) to the battery (12) using the controllable load (70) and to adjust the electrical load (RL) while the electrical current sensed by the current sensor (70). is monitored to determine a charging current applied to the battery (12) by a generator of the vehicle (300), and is further configured to carry out a test on the battery (12). A method for testing a storage battery (12) in a motor vehicle (300) includes connecting a controllable electrical load (70) to the storage battery (12), connecting a current sensor (304) to a connection at a terminal (22) of the battery (12 ), applying an electrical load (RL) to the battery (12) using the controllable electrical load (70), adjusting the electrical load (RL) while monitoring an output from the current sensor (304) to generate a current applied to the battery (12 ) determining charging current applied by an alternator of the vehicle (304), and performing a test on the battery (12).

Description

background

The present invention relates to storage batteries. More specifically, the present invention relates to electronic battery testers used to test storage batteries.

Storage batteries, such as lead-acid storage batteries, are used in a variety of applications such as in automobiles and emergency power sources. Typical storage batteries consist of a plurality of individual storage cells that are electrically connected in series. Each cell may have a voltage potential of, for example, 2.1 volts. By connecting the cells in series, the voltages of the individual cells are cumulatively added. For example, in a typical automotive storage battery, six storage cells are used to achieve a total voltage of approximately 12.6 volts. The individual cells are housed in a housing and the entire assembly is commonly referred to as a "battery".

It is often desirable to determine the condition of a storage battery. Various test methods have been developed over the long history of storage batteries. For example, one technique involves using a hygrometer to measure the specific gravity of the mixed acid in the battery. Electrical testing has also been used to develop less invasive battery testing methods. A very simple electrical test is to simply measure the voltage across the battery. If the voltage is below a certain threshold, the battery is considered defective. Another technique used to test a battery is what is known as a stress test. A load test discharges the battery with a known load. As the battery is discharged, the voltage across the battery is monitored and used to determine battery health. More recently, dr. Keith S. Champlin and Midtronics, Inc. of Willowbrook, Illinois, pioneered testing of a storage battery by measuring a dynamic parameter of the battery, such as the battery's dynamic conductance.

Summary

An apparatus for testing a storage battery in a motor vehicle includes a controllable electrical load configured to be electrically coupled to the vehicle's storage battery. A current sensor is designed to be electrically connected to one terminal of the battery and to measure the current flow through the battery. A controller is arranged to electrically load the battery using the controllable load and to adjust the electrical load while monitoring the electrical current sensed by the current sensor to determine a charging current supplied to the battery from an alternator of the vehicle , and further arranged to perform a test on the battery. A method of testing a storage battery in a motor vehicle includes connecting a controllable electrical load to the storage battery, connecting a current sensor to a connection to a terminal of the battery, applying an electrical load to the battery using the controllable electrical load, adjusting the electrical load while monitoring an output signal of the current sensor to determine a charging current applied to the battery from an alternator of the vehicle, and performing a test on the battery.

An electrical load assembly is provided for use by an electronic battery tester used to perform an electronic battery test on a storage battery. The electrical assembly includes a load wire that provides an electrical load resistance and a housing that at least partially encloses the load wire. An airflow passage is provided in the housing near the load wire. Electrical connections connected to the load wire are configured to be connected to the electronic battery tester.

An electronic battery tester for testing a storage battery includes first and second Kelvin connections configured to connect to the battery. A forcing function applies a time varying signal to the battery across the first and second Kelvin connections. In addition, the electrical assembly is configured to be switched across the first and second poles of the battery and draw a relatively high current. The storage battery is tested as a function of a dynamic parameter measured across the first and second Kelvin connections and as a function of the storage battery's response to the relatively large current flowing through the resistive load.

This summary is provided to introduce a selection of concepts in a simplified form that are further described in the detailed description below. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to provide any assistance used to determine the scope of the claimed subject matter. The claimed subject matter is not limited to embodiments that solve any or all disadvantages noted in the background description.

character list

• 1 12 is a simplified block diagram showing an electronic battery tester according to an embodiment of the present invention.
• 2 Figure 12 is a simplified block diagram showing steps in accordance with one aspect of the invention.
• 3A , 3B , 3C and 3D 12 are perspective, plan, side, and exploded top views of an electrical load assembly for use with, for example, the electronic battery tester discussed above.
• 4 14 is a perspective view of an electronic battery tester including an adjustable load in accordance with an example configuration.
• 5 illustrates an example user interface for use with the electronic battery tester.
• 6 12 is a cross-sectional view of the electronic battery tester including an adjustable load.

Detailed Description of Illustrative Embodiments

Embodiments of the present disclosure are described in more detail below with reference to the accompanying drawings. Elements identified using the same or similar reference numbers refer to the same or similar elements. Some elements are not shown in all figures to simplify the illustrations.

The various embodiments of the present disclosure may be embodied in many different forms and should not be construed as limited to the specific embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present disclosure to those skilled in the art.

The present invention includes an electrical load assembly for use with an electronic battery tester used to test a storage battery. The electrical load assembly includes a load wire that provides an electrical load resistance in a housing that at least partially encloses the load wire. An air flow passage is provided in the housing adjacent the load wire so that air can be directed along the load wire. Electrical connections are provided for connecting the load wire to the electronic battery tester. Also provided in various aspects is an electronic battery tester that measures a dynamic parameter of a battery, such as that disclosed in U.S. Patent No. 6,456,045 , issued September 24, 2002. The dynamic parameter is measured in response to a small forcing function applied to the battery. The forcing function includes a time-varying component and can be any type of periodic or transient signal with such a component. Typically, the forcing function is of relatively small amplitude and can be any type of voltage or current signal either drawn from or applied to the battery. The load wire is used to draw a large current from the battery. A battery test is performed on the battery, providing a test result as a function of both the dynamic parameter and a response of the battery to the applied load resistance. The particular response or application of the load observed may vary for different embodiments. In one aspect, the dynamic parameter is measured using Kelvin connections on the battery. In some embodiments, the resistive load is connected to the battery using the same Kelvin connections. The combination of a test using both a dynamic parameter and a load resistance can provide improved accuracy in determining the condition of the storage battery. The internal resistive load can also be applied to test the alternator and starter to test the charging system and the starter motor of an automobile. A corresponding device is described in US publication no. 2018/0113171 shown. However, there is a continuing need for improved testing techniques.

1 1 is a simplified block diagram of an electronic battery tester 10 in accordance with an aspect of the invention. Tester 10 includes battery test electronic circuitry 16 that couples to battery 12 via Kelvin connections 18 . Circuit 16 determines the conductance of a battery 12. Circuit 16 includes forcing function 50, differential amplifier 52, analog to digital converter 54 and microprocessor 56. Amplifier 52 is capacitively coupled to battery 12 through capacitance C1 and C2, and has an output connected to a Input of analog-to-digital converter 54 is connected. microprocess sensor 56 is connected to system clock 58, memory 60 and warning display 62 and an input 66 and provides a data output, eg for a display.

In operation, forcing function 50 is controlled by microprocessor 56 and provides current in the direction shown by the arrow in the figure. In one embodiment, this is a square wave or a pulse. Typically source 50 is a small load applied to battery 12 . Differential amplifier 52 is connected to connections 22 and 24 of battery 12 and provides an output related to the voltage difference between those connections. Amplifier 52 has a high input impedance. Note that circuit 16 is connected to battery 12 via a four-point connection technique known as a Kelvin connection. Because very little current flows through amplifier 52, which has a high input impedance, the voltage drop through its connections to battery 12 is insignificant. The output of differential amplifier 52 is converted to digital format and provided to microprocessor 56. Microprocessor 56 operates at a frequency determined by system clock 58 in accordance with program instructions stored in memory 60.

wobei ΔI die Änderung im Strom ist, der durch Batterie 12 aufgrund Zwangsfunktion 50 fließt, und ΔV ist die Änderung in Batteriespannung aufgrund von angelegtem Strom ΔI. Der relative Leitwert von Batterie 12 kann unter Verwendung der Gleichung berechnet werden: $$RelativerLeitwert\left(\%\right)=\frac{G_{gemessen}}{G_{Bezug}}\times 100$$

wobei G_gemessen der gemessene Batterieleitwert in Übereinstimmung mit Gleichung 1 und G_reference ein im Speicher 60 gespeicherter Referenzleitwert ist, der durch Eingang 66 empfangen werden kann. Im Allgemeinen wird dieser Referenzleitwert auf der Grundlage des Typs und der Eigenschaften von Batterie 12 bestimmt. Mikroprozessor 56 kann auch unter Verwendung von Impedanz-, Admittanz- oder Widerstandsmessungen arbeiten.Microprocessor 56 determines the dynamic conductance of battery 12 by applying a current pulse with forcing function 50. Forcing function 50 includes a small load or active source. The microprocessor determines the change in battery voltage due to the current pulse using amplifier 52 and analog to digital converter 54. The amount of current I produced by forcing function 50 is known or can be measured and stored in memory 60. Microprocessor 56 calculates the conductance of battery 12 as follows: $$Leitwe\mathrm{right}t=G=\frac{\Delta I}{\Delta V}$$

where ΔI is the change in current flowing through battery 12 due to forcing function 50 and ΔV is the change in battery voltage due to applied current ΔI. The relative conductance of battery 12 can be calculated using the equation: $$Relative\mathrm{right}Leitwe\mathrm{right}t\left(\%\right)=\frac{G_{Gemessen}}{G_{Be\mathrm{e.g}\mathrm{and}G}}\times 100$$

where G _measured is the measured battery conductance in accordance with Equation 1 and G _reference is a reference conductance stored in memory 60 and receivable through input 66 . Generally, this reference conductance is determined based on the battery 12 type and characteristics. Microprocessor 56 can also operate using impedance, admittance, or resistance measurements.

1 12 also shows a load resistor 70, labeled R _L , coupled across connections 22 and 24 of battery 12 and in series with switch 72. FIG. This can be embodied in the electrical load arrangement discussed here. Switch 72 is coupled to and controlled by microprocessor 56 to selectively connect resistive load R _L in series with battery 12. Microprocessor 56 operates to perform the various tests described above to determine the condition of battery 12. A current sensor 305 is arranged to measure current through resistor R _L 70 . In another configuration, sensor 305 can sense voltage drop across resistor 70 to determine current flow.

2 10 is a simplified block diagram 100 illustrating steps performed by microprocessor 56 based on instructions stored in memory 60 in an example embodiment. The testing process begins at block 102 with control passed to block 104 . A dynamic parameter of battery 12 is measured using any suitable technique, such as the technique discussed above. At block 106, load resistor 70 R _L is applied by microprocessor 56 through switch 72 actuation. Microprocessor 56 observes a response from battery 12. For example, microprocessor 56, in which 1 1 embodiment, observe the voltage or change in voltage across battery 12 in response to applied resistance R _L using analog to digital converter 54 . At block 108, microprocessor 56 provides a test result output, eg, at the data output, the dynamic parameter measured at step 104 and the load resistance 70 and response observed at step 106. The particular order of steps or tests performed may be altered accordingly. The method ends at block 110.

The particular test performed using the addition of the load resistor 70 may be any battery test that provides a result that is a function of a dynamic parameter measurement and/or the load 70 applied. In one example, with the resistive load R _L connected to the battery 12, the battery test result is a function of the measured dynamic parameter. This can be combined with a dynamic parameter measurement where the resistive load is disconnected from the battery 12. Other exemplary load measurements Genes that may be combined with the dynamic parameter measurement include monitoring the battery voltage over an adjustable period of time while the load 70 is applied. This may be combined with monitoring the voltage during a recovery period after the load 70 is removed. In one embodiment, load R _L is a variable load 70 that can be controlled, for example, by microprocessor 56 during the testing process. The response of the battery 12 to the application of the variable load 70 and changing the variable load 70 can be monitored, as can its response once the load 70 is removed. In a specific example, the relative conductance determined in accordance with Equation 2 can be used as a multiplier against the nominal voltage of the battery, eg 12.7 volts, and in turn multiplied by a constant. This value can then be compared to the battery 12 voltage measured at a particular point in time during the application of the load resistor or after its removal. The various measurements may also be correlated to general health and/or battery life expectancy, which may then be provided as an output.

The voltage when the load 70 is applied can also be compared to a voltage range that can indicate that the battery 12 has a bad cell. This can then be provided as an output or a warning can be displayed using output 62. In a more specific example, a defective cell may be detected when a voltage measured with the load 70 applied at a first time and a voltage measured at a second time are within a range, such as 8.0 volts to 8.8 volts (two defective cells), or 10.1 volts to 10.9 volts (a defective cell), microprocessor 56 can determine that a defective cell exists in battery 12 and can provide an appropriate output. In addition, microprocessor 56 can determine if a battery has an open circuit by using the measured dynamic parameter in conjunction with the change in voltage across battery 12 with and without the resistive load R _L applied. The resistor R _L can also be used to remove a surface charge (a positive voltage polarization) on the battery 12. Once the surface charge is removed, the microprocessor 56 can compensate for the dynamic parameter measurement by determining battery condition based on the measured voltage after surface charge is removed.

The correlation between the dynamic parameter and measurements made that are a function of the load resistance R _L to the condition of the battery 12 can be determined through repeated laboratory testing to develop trends or equations that describe the relationship. Any suitable technique can be used, including models that model the battery, using multiple measurements to develop a model, neural networks, etc. Although the load resistance R _L in 1 as shown coupled to battery 12 via Kelvin connections 18, any suitable electrical coupling technique may be used. _This includes the use of fifth or sixth additional electrical contacts to connections 22 and 24 . The duration of application of the resistive load R _L or frequency of application can be selected according to the test format desired.

In one aspect, circuit 10 provides an alternator tester for testing an alternator of a vehicle. In such an embodiment, the load resistance R _L is used to place an additional load on the vehicle's electrical system. The response of the motor vehicle's alternator and regulator can be observed and the microprocessor 56 can provide an output indicative of the state of the alternator and/or regulator. If the load resistance R _L is a variable resistance, the voltage across the battery 12 or other point in the electrical system can be observed when various resistive loads are placed on the system.

The dynamic parameter used in the present invention can be determined in accordance with any suitable technique.

In various aspects, the dynamic parameter is measured before, during, or after the load resistor 70 is applied to battery 12 connections. Furthermore, the measured dynamic parameter can be compared with dynamic parameters that were measured at other points in time, eg dynamic parameters that were obtained before, during or after the application of the load resistance can be compared with one another. Voltage measurements can be obtained where a slope of the voltage measurement can be calculated and used in battery testing. In one example, the battery test is a function of a slope of the measured voltage while the load resistance is applied to the battery. The change in voltage rise can be used for the battery test. The voltage increase can be after Tren The load resistance of the battery can be measured. The battery test may be a function of a difference in voltage measured while the load resistor 70 is applied to the battery and a voltage measured after the load is disconnected. In one aspect, the battery test output may provide an indication that the battery has become sulfated. The voltage rise measured before, during or after disconnecting the load resistor can be used for the battery test. The increase in voltage, particularly the increase in voltage after the load is disconnected from the battery, can be used as an indication of an open circuit. In one embodiment, the in 1 Load resistor 70 shown outside of the battery tester. For example, the load resistor 70 is placed directly in the cable assembly used for the Kelvin connections 18.

3A , 3B , 3C and 3D 12 are perspective, plan, side, and exploded top views of an electrical load assembly 200 for use, for example, with the electronic battery tester 10 described above 3A until D The assembly 200 shown includes a housing 202 having a cover 204 supporting a load wire 208 formed from coiled nichrome wire. This provides the load resistor 70 ready. The housing 202 provides a clearance area 206 around the wire 208 that provides an airflow passage therethrough. End connections 210, 212 are provided for electrically connecting the load wire 208 to the electronic battery tester. Terminals 210, 212 may also include thermistors 214, 216 for measuring the temperature at the connector locations. Other types of temperature sensors 214, 216 may also be used and/or positioned in different locations. Typically, each temperature sensor 214, 216 requires two electrical connections 220, 222, however, these connections may be shared with other electrical connections in certain configurations. As in 3A As shown, connections 230,232 are provided for connection to the load wire 208 as well as to the thermistors 214,216. One or more fans 240 may be positioned adjacent the electrical load assembly to provide constant and/or controllable airflow through the enclosure 202 . The blower can operate independently or operate under the control of the electronic battery tester 10.

The electrical load 70 provided by the load assembly 200 can be used in a number of configurations. A conductance profiling technique can be used, where a load (e.g. 10 to 20 amps) is drawn while observing the behavior and combining the measurement with a dynamic conductance measurement. The load assembly 200 may be positioned inside or outside the battery tester 10, for example, near an electrical connection to the tester 10. During operation, the load assembly 200 generates a significant amount of heat. However, the air vent 200, including the optional fan 240, can be used to dissipate this heat. The fan 240 can be any suitable fan, including a box or sleeve fan. The load wire 208 may be formed from any suitable wiring material, such as nickel-chromium wire, and the tunnel 206 and housing 202, 204 should be heat resistant. The housing 202, 204 may be formed from a high temperature plastic such as Ryton, metal or ABS plastic with an insulating layer of mica paper.

The various components, such as the electrical connections, thermistors, and connections to the load wire, may be partially or fully fabricated on one or more printed circuit boards 250 . These circuit boards can include screw terminals for mounting the thermistors, and can be used to support the various components in the case.

Temperature sensors 214, 216 may be used to measure device 200 temperature. The temperature sensors 214, 216 can be used for diagnostics, such as determining if a particular location is getting too hot, or not heating up enough. In addition, a temperature difference between two locations can also be used for diagnostic purposes, e.g. to determine airflow or to provide feedback for fan control. This can also be used to determine if passageway 206 is clogged or if fan 240 has failed. Although only one fan 240 and one passage 206 are shown, multiple fans 240 and/or multiple air passages 206 may also be implemented. Thermal insulators 260 may be provided between load wire 208 and housing 202 . These can be made of mica paper, for example.

In yet another configuration, the battery tester 10 can be configured to operate with relatively high accuracy, requiring the operator to make minimal decisions, even when connected to a vehicle and the engine is running. In many cases, for example, a car owner brings his vehicle to a workshop and states that he is having difficulty starting the vehicle. The owner may be reluctant to park their vehicle because a jump start was required, or the owner may have had great difficulty starting the engine. Gas stations or auto parts stores may have limited staff and an employee who only has a few minutes to diagnose a vehicle. In such a situation, the operator may not have sufficient time or knowledge to enter battery reading or other information.

The battery tester off 1 can be designed as a small, lightweight, programmable discharger that connects to the battery under test and does not require an external power source. 4 FIG. 12 shows a configuration of the battery tester 10 in which a plurality of coils 306 are arranged in a housing 350. FIG. A large fan (see fan 240 in 3A) is located in the housing and blows air over the coils 306. The coils 306 operate like those in 1 load 70 shown, with the blower being powered by power from the battery under test. Such a configuration can, for example, dissipate 3,600 watts, with the air leaving the device only slightly warm. The electrical connections 18 used to couple to the battery or to couple the load 70 to the battery are preferably short and capable of carrying high currents, such as AWG4 wires. In addition, the circuitry in the battery tester 10 should be designed to operate regardless of the polarity of the connection to the battery 12. In the example configuration, eight individual 35 amp loads 306 are provided and can be controlled individually. Additionally, a single 10 amp load may be provided to match current battery performance data.

In such a configuration and with reference to 1 For example, the battery tester 10 may include a current clamp or other current sensor 304 configured to measure current flowing into or out of the battery 12 from an electrical system 302 of a motor vehicle 300 . Another current clamp/sensor 305 can be used to measure the current flowing through the resistive load 70 .

In order to test the battery 12, it is desirable to determine the current flowing into the battery tester 10 due to the battery and to eliminate any current flowing into the ( or from the) battery 12 flows. For example, at idle speed, a typical vehicle alternator may supply a charge current on the order of 50 amps. By increasing the value of R _L of the load 70 until the current sensed by the current sensor 304 stops changing, it can be determined that the maximum amount of current that the generator can supply has been reached. At this point, an additional state-dependent or time-varying load (forcing function) may be applied to the battery 12 to determine conductance as described herein or to perform other tests. This can be done with the forcing function 50 or the load 70.

Under heavy loads, it is also possible to determine whether the battery 12 has a short circuit. If a battery is shorted, the battery voltage will drop significantly under load.

Using the adjustable load provided by load 70, it is also possible to characterize batteries to infer or predict the battery's state of charge and reserve capacity. For example, the voltage and/or current may be monitored as the applied load is increased or decreased and correlated to an approximate value of the battery's state of charge or reserve capacity. This correlation may also include measuring a dynamic parameter using an applied forcing function 50 and/or time during resistive load 70 adjustment.

The load 70 can be used to at least partially discharge the battery. With the load removed, the charging current provided by the generator can be measured with the sensor 304 and the charge acceptance rate of the battery 12 monitored. The charge acceptance rate of the battery 12 can be used as an indication of the condition of the battery 12.

Also, by monitoring the current flowing into the battery 12 with the sensor 304, it can be determined whether the alternator is operating at full capacity.

Because the microprocessor 56 requires power to operate, it is possible for the microprocessor 56 to shut down and restart if the voltage provided by the battery 12 drops significantly when the load 70 is applied. To avoid such an event, a large capacitor may be included in the power supply circuit 309, allowing the microprocessor 56 to "ride" the transient voltage drop while the load 70 is removed.

In order to increase the ease of operation, the output 62 can consist of a series of lights tern showing the progress of testing. During an initial connection, an initial light may turn on and remain on. As the device increases the load 70 to address the current provided by the generator, a second light may illuminate, or the first light will begin flashing and illuminating when this step is complete. An additional code or lights may be used to provide additional information. At the end of the test, a red or green light can indicate whether the test passed or failed. Additional information about the condition of the generator or other test information may be provided. If desired, the data output from the microprocessor can be transmitted wirelessly via I/O 67 to a POS system or other data collection device. This can also be used to provide the tester with specific information about the vehicle or battery, which can be downloaded if available.

To provide a simple method of providing additional information about the battery 12, the input 66 can be used. For example, input 66 could simply be a three-position switch that an operator adjusts to indicate whether the vehicle has a 4, 6, or 8 cylinder engine. Such information can be generally associated with the appropriate size of the battery 12 as it relates to engine size.

The apparatus described herein can determine the condition of a battery using load tests and/or optional conductance-based tests in a very short amount of time, and without requiring the battery 12 to be disconnected from the vehicle. The device can be powered by the battery 12 itself and does not require an external power source. Memory 60 may include non-volatile memory such that device 10 does not require any internal batteries. Additionally, there is no requirement that the vehicle be parked for testing. This is particularly advantageous in situations where an operator is concerned that the battery does not have enough reserve capacity to start the vehicle. A very simple user interface can be provided using input 66 and output 62 such that no training is required. The output 62 can be any type of user output, including a display, audio output, a variety of visual components, etc. The connectors 18 can be configured to connect to either the positive or negative battery 12 terminal. Input 66 and data in/out 67 may include a wireless component such as Bluetooth, WiFi, etc., allowing data to be uploaded or downloaded as desired.

In some situations, high accuracy testing is not required. In such situations, a technician is not required to enter any specific information regarding the particular battery 12 under test. Instead, the device operates using generally acceptable parameters for vehicles. In one configuration, the load 70 may be of sufficient size such that all current generated by a vehicle's alternator and used to charge the battery is directed away from the battery and through the load 70 . In such a configuration, the load 70 can then be further increased or decreased such that the battery 12 is self-discharging or charging. During this discharge, additional measurements of current, voltage, and dynamic parameters can be obtained to test the battery 12.

To perform a conventional conductance test on an automotive battery, the battery is typically tested in isolation, without any significant external parallel paths that would effectively decrease or change the observed resistance of the battery under test. This is an issue hidden behind "system noise" that makes accurate testing in certain scenarios difficult. A generator that is operated in parallel with a running engine represents an approximately ideal voltage source. The defining characteristic of an ideal voltage source is that it provides the same voltage, regardless of the current drawn. This effectively results in zero impedance at the battery, or "infinite" conductance, making conventional conductance measurement impossible. In contrast, an "ideal current source" provides a constant current regardless of the applied voltage. This represents an infinite impedance and, when connected in parallel, is effectively removed from the circuit under test. If the running generator could be converted from an ideal voltage source to an ideal current source, it could be practically disconnected from the battery.

Every alternator in a motor vehicle has a maximum operating current. This current is reached when the generator is rotating above a certain minimum speed, with the generator fully loaded (demand is set to 100%). Typical maximum values for car generators are 60 - 140 amps. When the engine is idling, the maximum output of the generator remains the same (depending on the generator type) or is substantial lower, typically in the 40-60 amp range.

Kirchhoff's current law states that the algebraic sum of a current flowing through a junction is zero. So if a current can be provided that is equal and opposite to that provided by the alternator, the battery is effectively in an open circuit.

• • Generator-Ausgang - 91,3 Ampere
• • Zweiter Lastbox-Impulsstrom = 84 Ampere
• • Delta-Batteriespannung = 0,48 VDC
• • Leitwert = 84/0,48 = 175 mho
• • CCA(100) = (100/12)*500/160 = 26 CCA
  • ◯ (Geschätzter Überstrom nach Null)
• • CCA = (175*500/160) - 26 = 521 CCA
  • ◯ 15% hoch

Using an example configuration with the following parameters:

• • Generator output - 91.3 amps
• • Second load box impulse current = 84 amps
• • Delta battery voltage = 0.48 VDC
• • Conductance = 84/0.48 = 175 mho
• • CCA(100) = (100/12)*500/160 = 26 CCA
  • ◯ (Estimated post-zero overcurrent)
• • CCA = (175*500/160) - 26 = 521CCA
  • ◯ 15% high

• • Generator-Ausgang - 14,2 Ampere
• • Zweiter Lastbox-Impulsstrom = 83 Ampere
• • Delta-Batteriespannung = 0,40 VDC
• • Leitwert = 83/0,40 = 208 mhos
• • CCA(100) = (100/12)*500/160 = 26 CCA
  • • (Geschätzter Überstrom nach Null) CCA = (208*500/160) - 26 = 624 CCA
  • • 11% hoch

In another sample test:

• • Generator output - 14.2 amps
• • Second load box impulse current = 83 amps
• • Delta battery voltage = 0.40 VDC
• • Conductance = 83/0.40 = 208 mhos
• • CCA(100) = (100/12)*500/160 = 26 CCA
  • • (Estimated post-zero overcurrent) CCA = (208*500/160) - 26 = 624 CCA
  • • 11% high

• • Leerlaufspannung (kann nicht direkt gemessen werden, da Generator in Betrieb)
  • ◯ Vbat= (V1*I2-V2*I1)/(I2-I1)
• • CCA
  • ◯ Rbat= (Vbat-V2)/I2
  • ◯ CCAbat= (1/Rbat)*500/160
• • Definitionen:
  • ◯ Vorlast
    • • Laststrom I_L > Generator-Maximalstrom
• • Impuls
  • ◯ Ungefähr 100 Ampere-Stufenlast über Vorlaststrom
• • V1 = Vorlastspannung, Kelvin-Verbindung
• • V2 = Impulsspannung, Kelvin-Verbindung
• • I1 = Imdt-ABS(lalt) während Vorlast
• • I2 = Imdt-ABS(lalt) während Impuls
• • Imdt = interner Strom, gemessen mit Sensor 305
• • Ialt = externer Strom, gemessen mit Verstärkerklemmensensor 304.

In a specific example, the invention may be used to determine the approximate cold cranking current of the battery 12 using the following equations:

• • No-load voltage (cannot be measured directly as the generator is in operation)
  • ◯ Vbat= (V1*I2-V2*I1)/(I2-I1)
• • CCA
  • ◯ Rbat= (Vbat-V2)/I2
  • ◯ CCAbat= (1/Rbat)*500/160
• • Definitions:
  • ◯ Preload
    • • Load current I _L > maximum generator current
• • Impulse
  • ◯ Approximately 100 amp step load over preload current
• • V1 = preload voltage, Kelvin connection
• • V2 = pulse voltage, Kelvin connection
• • I1 = Imdt-ABS(lalt) during preload
• • I2 = Imdt-ABS(lalt) during impulse
• • Imdt = internal current measured with sensor 305
• • Iold = external current measured with amplifier clamp sensor 304.

As in 4 As shown, multiple loads 306 may be included and selectively switched using switch 72 . Multiple switches 72 may be provided and operated by microprocessor 56 and arranged to connect loads 306 in series and/or in parallel as desired to achieve desired resistive load R _L 70 . A large capacitor in power supply circuit 309 may also be provided to smooth the power consumed by device 10 during operation and to provide more power if desired.

In one configuration, it is possible to eliminate the need for an external current sensor or amplifier clamp to measure current flowing into the battery from the vehicle. This can be achieved by incrementally increasing the current through the load applied to the battery and measuring the conductance at each point. The conductance measurement can be a dynamic parameter-based measurement, or can be a static-based measurement by increasing the applied load and measuring the resulting voltage. Once a stable value for conductance is observed, it can be determined that the alternator is delivering a maximum amount of current, with any resultant change in voltage being the result of the battery alone. Once the load current flowing into the battery from the alternator has been eliminated, a battery test can be performed as described above, including conductance, load or other tests. In another example configuration, the current flowing through the load applied to the system is incremented as described above. The voltage on the battery is measured after each increase. As soon as a significant change in the voltage measured at the battery is observed, it can be concluded that the generator has reached maximum performance, with all further voltage changes due to the battery alone.

5 FIG. 4 shows an example user interface 400 implemented using components 62 and 66 of FIG 1 can be formed. In the bei game user interface, an operator can select different test standards based on the number of cylinders of the vehicle by pressing the corresponding in 5 button 402 shown. This information can be used by the tester to determine the appropriate battery rating for the vehicle based on an engine size. Visual outputs are provided to indicate that the device is powered up and to indicate test progress. Finally, a test result is provided, illustrating that the battery is either good, should be replaced, or should be recharged. Preferably, user interface 400 is waterproof. In addition, a power indicator 404 may be arranged to illuminate only when the Kelvin connectors 18 are properly connected to the battery connections 22,24. In a specific configuration, once the amplifier clamp 304 is properly connected, the 4-6-8 CYLINDER buttons 402 may light up in sequence to indicate that one of them must be pressed to initiate the test, at which point the respective button 402 remains lit.

Various progress bars 406 indicated in the test flow portion of user interface 400 can be used to indicate various steps in the test flow. This can include e.g. As previously mentioned, once the test is complete, one of the three test result icons 408 will be illuminated.

6 12 is a cross-sectional view of the electronic battery tester 10 and illustrates the arrangement of a fan 250, which is a rotary fan positioned within a cylindrical housing 350. FIG. As discussed above, coils 306 provide load 70 and are disposed within housing 350 . Switches 72 are arranged to selectively connect coils 306 to battery 12 such that a desired load R _L is achieved as desired. The coils can be arranged in parallel, in series and/or in series in parallel in order to achieve specific resistance values. 6 also illustrates that the display 400 is received in a handle 450 of the tester 10 . This allows the display to be easily viewed during actuation. Various cable connections are also provided for the current sensor 304 and Kelvin connections 18 .

Although the present invention has been described with reference to preferred embodiments, those 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. Although specific embodiments describe increasing load or current, it should be understood that the change in applied load or current drawn may be either increasing or decreasing.

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• US6456045 [0010]
• US2018/0113171 [0010]

Claims (42)

Device for testing a storage battery in a motor vehicle, comprising: a controllable electrical load configured to electrically couple to the vehicle's storage battery; a current sensor configured to electrically connect to a terminal of the storage battery and configured to measure current flow; a controller arranged to apply an electrical load to the storage battery using the controllable load and to adjust the electrical load while monitoring the electrical current sensed by the current sensor to determine a charging current to be supplied from an alternator of the vehicle to the Storage battery is applied, and is further designed to carry out a test on the storage battery. device after claim 1 , wherein the current sensor includes a first current sensor arranged to measure a current provided by an electrical system of the vehicle. device after claim 1 , wherein the current sensor includes a first current sensor arranged to measure a current flowing through the controllable electrical load. device after claim 1 , wherein the controller adjusts the controllable electrical load such that substantially all charging current flows through the controllable electrical load. device after claim 4 , wherein the test is performed on the storage battery while substantially all charging current is flowing through the controllable electrical load. device after claim 5 , wherein the storage battery test comprises measuring a parameter of the storage battery while changing a resistance of the controllable electrical load. device after claim 6 , where the parameter comprises a dynamic parameter. device after claim 6 , wherein the parameter includes a voltage measured at terminals of the storage battery. device after claim 6 , wherein the parameter includes determining a current flowing through the storage battery. device after claim 1 , wherein the test includes identifying a shorted cell in the storage battery. device after claim 1 , wherein the test includes a charge acceptance rate of the storage battery. device after claim 1 , wherein the test includes determining a state of charge of the storage battery. device after claim 1 , wherein the test comprises determining a storage battery capacity. device after claim 1 , where the test includes a stress test. device after claim 1 , wherein the test is performed on the storage battery while an engine of the vehicle is running. device after claim 1 , wherein the controller is powered by the storage battery. device after Claim 16 including a capacitor to store energy from the storage battery. device after claim 1 including an input configured to receive information about an engine of the vehicle. device after Claim 18 , wherein the information includes a number of cylinders of the engine of the vehicle. device after claim 1 , wherein the controllable electrical load is coupled to the storage battery using Kelvin connections. device after claim 1 , wherein the controllable electrical load is used to apply a forcing function to the storage battery. device after claim 1 including providing a pass/fail output based on the test performed on the storage battery. device after claim 1 including an output configured to indicate a progress of the test performed on the storage battery. device after claim 1 including a cylindrical housing arranged to house the controllable electrical load. device after Claim 24 wherein the housing includes a rotary fan arranged to direct air over the controllable electrical load. device after claim 1 , wherein the controllable electrical load comprises a plurality of coils of wire. device after claim 1 , including a wireless input/output circuit. device after claim 1 , wherein the controller controls the controllable electrical load to cause a current pulse to flow through the storage battery. device after claim 1 wherein the controller determines the charging current applied to the storage battery by changing the controllable electrical load and by observing a change in a measured parameter of the battery. device after claim 29 , wherein the measured parameter comprises a conductivity. device after claim 29 , where the measured parameter comprises a voltage. A method for testing a storage battery in a motor vehicle, comprising: connecting a controllable electrical load to the storage battery; connecting a current sensor to a connection to a terminal of the storage battery; applying an electrical load to the storage battery using the controllable electrical load; adjusting the electrical load while monitoring an output from the current sensor to determine a charging current applied to the storage battery via an alternator of the vehicle to the storage battery; and Performing a test on the backup battery. procedure after Claim 32 , wherein the current sensor includes a first current sensor to measure a current provided by an electrical system of the vehicle. procedure after Claim 33 , wherein the current sensor includes a second current sensor arranged to measure a current flowing through the controllable electrical load. procedure after Claim 32 including adjusting the controllable electrical load such that substantially all charging current flows through the controllable electrical load. procedure after Claim 35 , wherein the test is performed on the storage battery while substantially all charging current is flowing through the controllable electrical load. procedure after Claim 32 including receiving an input comprising information regarding an engine of the vehicle. procedure after Claim 37 , wherein the information includes a number of cylinders of the engine of the vehicle. procedure after Claim 32 , wherein the controllable electrical load is used to apply a forcing function to the storage battery. Device for testing a storage battery in a motor vehicle, comprising: a controllable electrical load configured to electrically couple the vehicle's storage battery; a current sensor electrically connected to the controllable electrical load and configured to measure current flow through the controllable electrical load; a voltage sensor configured to electrically connect to connections of the storage battery and measure a voltage across the storage battery; and a controller arranged to adjust the controllable electrical load while monitoring the sensed current and the sensed voltage and to determine a charging current applied to the storage battery from an alternator of the vehicle based on the measured voltage and the measured current is. device after Claim 40 , where the charging current is determined based on a dynamic parameter measurement. device after Claim 40 , where the charging current is determined based on a measured conductivity.

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