EP0873522A4 - - Google Patents

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Publication number
EP0873522A4
EP0873522A4 EP96931483A EP96931483A EP0873522A4 EP 0873522 A4 EP0873522 A4 EP 0873522A4 EP 96931483 A EP96931483 A EP 96931483A EP 96931483 A EP96931483 A EP 96931483A EP 0873522 A4 EP0873522 A4 EP 0873522A4
Authority
EP
European Patent Office
Prior art keywords
current
battery
voltage
resistance
apparams
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP96931483A
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English (en)
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EP0873522A1 (fr
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Publication date
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Publication of EP0873522A4 publication Critical patent/EP0873522A4/en
Publication of EP0873522A1 publication Critical patent/EP0873522A1/fr
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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/005—Testing of electric installations on transport means
    • G01R31/006—Testing of electric installations on transport means on road vehicles, e.g. automobiles or trucks

Definitions

  • This invention relates to a method and apparatus for measuring electrical characteristics of an electrical system and, in particular, the characteristics of an electrical energy delivery system.
  • the invention is particularly adapted for evaluating characteristics of a vehicle electrical system, but has applications in many different types of electrical systems. In many test settings, it is usefiil to be able to determine circuit parameters, such as resistance, total energy source and cable performance, and current flowing in a circuit. This is especially useful for troubleshooting electrical problems in vehicles, such as automobiles, trucks, boats and the like. Very often components, such as batteries, starter motors, alternators, and the like, are returned under warranty to the manufacturer, only to find that they are not defective.
  • the common method of assessing battery condition is to connect a voltmeter to the terminals of the battery, to apply a small value resistor capable of dissipating a large amount of heat to the battery terminals, and to observe terminal voltage as a function of time while the battery discharges.
  • This test permanently changes the battery, the test cannot effectively be performed unless the battery is fully charged, and the results must be compensated for battery temperature in order to be accurate.
  • Another alternative for testing a battery is to apply a small AC signal to the terminals of the battery, and use a Wheatstone (or one of its derivatives) bridge to measure the internal resistance of the battery.
  • Battery internal resistance is related to battery condition, and this test has the advantages of allowing a relatively small test apparatus that does not materially affect the condition of the battery, and which can be applied to batteries that are less than fully charged.
  • a conventional ohmmeter is useless in determining wire and connection resistance because the resistance is too small.
  • approximately 200 amperes are required to crank the engine.
  • resistances as small as 10 milliohms are a significant problem, but well below the range of a conventional ohmmeter.
  • the usual recommended procedure is, again, to attach a low value resistance to the system, drawing a large current through the wire(s) and/or connection(s) to be tested, and quickly measuring the voltage drop(s) to infer system resistance.
  • the measurement of current is usually accomplished in one of two ways: an in- circuit ammeter, or a clamp-on device that infers current from the surrounding magnetic field.
  • Clamp-on current probes that infer current from the magnetic field surrounding a current are more convenient.
  • inexpensive models offer only limited accuracy and are unable to measure currents below roughly 10 amperes with acceptable accuracy.
  • Accurate models tend to be quite expensive. There is no commonly available means of making a one-step assessment of a system consisting of an electrical energy source and conductors used to deliver the electrical energy to a destination.
  • the apparatus described here has many applications, including tests of vehicle and stationary batteries, measurement of resistances as small as a fraction of a milliohm, one- step appraisal of a system consisting of a source of electrical energy and connecting cables, and measurement of current flowing in a circuit, all using the same basic circuit.
  • the present invention provides a method and apparatus which quickly and accurately measures various parameters of the electrical system of a vehicle in a manner which avoids the known drawbacks of the prior art.
  • the invention is primarily applicable to the electrical system of vehicles, it finds application in other electrical systems such as those employing DC motors, namely material handling equipment and the like.
  • the present invention provides a method and apparatus for measuring the conductance, or milliohm resistance, of electrical connections, such as those that occur between vehicle battery cables and a vehicle battery, across the magnetic starter switch connecting the vehicle starter motor to the battery, between a vehicle alternator and battery, and similar such ohmic connections.
  • the invention also provides a method and apparatus for determining a figure of merit, such as cold-cranking amps, of an energy delivery system, such as a vehicle battery circuit, in a manner which is repeatable and which does not put undue stress on the battery.
  • a figure of merit such as cold-cranking amps
  • accurate measurements may be made without requiring a break in the circuit to insert a test instrument and may even be carried out with a non-test load current flowing through the circuit.
  • An electrical system measurement method and apparams includes providing a controllable current source, a voltage sensitive circuit, and a microcomputer.
  • the microcomputer controls the current source in order to apply at least one predetermined current pattern to at least a portion of an energy delivery system.
  • the microcomputer additionally responds to a voltage developed in response to the current pattern being applied by the current source to the portion of the energy delivery system.
  • the microcomputer calculates a value of at least one electrical characteristic of the energy delivery system as a function of the developed voltage.
  • the resistance, or conductance, of a path is measured according to an aspect of the invention by applying electrical energy for a momentary period of time at a level that is sufficient to overcome DC circuit noise. Measurements of an electrical parameter are taken and converted into electrical resistance, or conductance, using linear superposition principles.
  • An electrical source under the control of a microcomputer, is applied to the electrical path utilizing a high-speed switching device, such as a field-effect transistor (FET).
  • FET field-effect transistor
  • a storage battery device may be tested according to another aspect of the invention by sourcing a current to, or sinking a current from, a battery at less than maximum battery capacity during one or more brief intervals of time. Terminal voltage and internal impedance, along with battery temperature, are measured and used to infer a figure of merit. The figure of merit may be, for example, cold-cranking amps.
  • the internal impedance of the battery may be measured utilizing resistance/conductance measurement techniques according to other aspects of the invention.
  • the sourcing of current to, or sinking of current from, the battery along with the attendant measurements of electrical parameters is under the control of a microcomputer.
  • the microcomputer controls the measurement circuit and calculates the results, which may be readily displayed for the user from the measured electrical parameters.
  • a compact measurement instrument When the invention is applied to the electrical system of a vehicle, a compact measurement instrument is provided, which is fully integrated and facilitates accurate tests to be performed without putting undue stress on the vehicle's electrical system or components thereof.
  • the measurement When the invention is applied to other electrical systems, such as to measuring the resistance/conductance of a DC motor, the measurement may be made without causing rotation of the motor. This is accomplished notwithstanding the fact that currents of a sufficient magnitude to avoid DC circuit noise are utilized because the currents are applied for a brief period of time that is insufficient to apply sufficient energy to rotate the motor.
  • DRAWINGS Fig. 1 is a block diagram of an electrical system measurement apparams according to the invention
  • Fig. 2 is an exploded perspective, of a battery temperamre sensor useful with the invention
  • Fig. 3 is a flow chart of a method of measuring a battery figure of merit according to the invention
  • Fig. 4 is a flow chart of a method of measuring the value of a resistance according to the invention
  • Fig. 5 is a flow chart of a method of measuring a figure of merit of a circuit according to the invention.
  • Fig. 6 is a flow chart of a method of measuring a current flowing in a circuit according to the invention. DESCRIPTION OF THE PREFERRED EMBODIMENT
  • D ctrl is a current control device, such as a transistor or field effect transistor, which controls the current through a sense resistor, R s , and another resistance, R x .
  • confrol system 22 When a voltage is applied by the memory, data processor, and control system, collectively referred to as confrol system 22, to a current control point A of a confrol amplifier 25, which amplifies the difference between the voltage at point A and the output of point B of a differential amplifier 27, which senses the voltage across resistor R s , causes current is drawn through R s and R x such that the voltage at points A and B will be equal.
  • any desired current amplitude and waveform may be drawn through R s and R x under the control of control system 22.
  • control system 22 By setting switches SI and S2, and drawing test currents through R s and R x , simultaneously observing the voltage measured by a voltmeter 26, and, in some cases, performing mathematical operations on the values of voltage and current, useful diagnostic information is produced.
  • an optional thermal sensor 28 is shown for measuring battery temperature. For battery measurements, the information produced by this device allows for temperamre compensation, producing a more accurate result, as will be described in more detail below.
  • the memory, data processing, and control system 22 will be a microprocessor, either with a built-in digital-to-analog converter or driving an external digital-to-analog converter.
  • voltmeter 26 is preferably a sampling type, so that measurements may be taken during a brief interval.
  • the condition of a battery can be inferred from three variables: state of charge, temperature, and internal resistance. If the battery is free from polarization (also known as "surface charge"), state of charge may be estimated by the terminal voltage of the battery with no load applied. Call this variable V QC - Call temperamre T. Let the internal resistance of the battery be R,. Let the figure of merit for the battery be FOM. In the illustrated embodiment, FOM is the Cold Crank Ampere rating (CCA) of the battery. Thus, FOM is some function of WQ C , T, and R-.
  • CCA Cold Crank Ampere rating
  • FOM f(V 0C , T, * )
  • R is determined by applying and/or removing power to/from the battery, BAT, observing the resulting changes in terminal voltage, and performing calculations in memory, data processor, and confrol system 22.
  • FOM can be expressed directly in terms of VQ C , T, E MEASURED , and I TEST *, where I J - EST is the known test current, and E M ⁇ - JRED is the battery terminal voltage while I- ⁇ EST is flowing.
  • Control system 22 will: (1) determine whether the battery is 12 or 24 volts, whether it is charged enough to make a test, and whether the "surface charge" of the battery has been drained, then (2) measure temperamre, terminal voltage (to determine state of charge), and internal impedance, and (3) calculate and display a figure of merit, such as CCA. Thus, the operator has little to do except attach the test leads and read the result on a display 30.
  • a thermal sensor, TS is in the voltage probe of the instrument, which is in intimate thermal contact with the battery (BAT).
  • BAT battery
  • the temperamre of the battery is "read” by the data processor and stored for calculations.
  • the terminal voltage of the battery is measured with no (or infinitesimally small) test current drawn.
  • the voltage drop across the internal resistance of battery BAT, designated R l5 is then EQ, which will be zero if no non-test current is flowing.
  • control system 22 produces an output, and the test current is drawn, a voltage drop will appear across R l5 and the terminal voltage of the battery will be reduced accordingly.
  • the Loop Rule provides that the unloaded voltage minus the loaded voltage is the drop across the internal resistance. R, is then (E Q - E TEST )/I TEST .
  • a variable current sink or source is applied to the terminals of the battery.
  • Battery terminal voltage is momtored through a voltmeter 26, which, in turn, connects to a comparator internal to confrol system 22.
  • the current sink or source draws or supplies increasing current, until the comparator changes state. This change of state is signaled to the data processor.
  • a constant current equal to about half of the battery's rated cold-cranking amps capacity is drawn from the battery.
  • the terminal voltage declines at a rate on the order of .2 volts per second, or .2 millivolts per millisecond. If current is drawn for a few milliseconds, the battery terminal voltage will change by several tenths of a millivolt, which is quite measurable. Knowing the test current, and the slope of the discharge curve during the test interval, the rate of change of internal resistance can be calculated. From this, the time required for the battery to reach the minimum acceptable terminal voltage can be calculated.
  • control system 22 sets a test current from battery BAT through R s .
  • me data processor commands voltmeter 26 to sample BAT voltage.
  • the reading is then stored in memory for future calculations.
  • the data processor waits a predetermined time and commands a second sample to be taken.
  • the second sample is then stored. From the two stored voltage values, the slope of the voltage decline curve is determined and a figure of merit for the battery calculated and displayed.
  • One of the variables used in battery figure of merit calculations is battery temperamre. Existing products require the user to manually enter an estimate of battery temperature. This slows the measurement and introduces error. A more preferable arrangement is to automatically acquire a real measurement of temperamre. In Fig.
  • a thermal sensor, TS is embedded in a hollow metal part 32 with a point, or probe tip, 34 that makes contact with a wire in the circuit under test (voltage probe tip) in order to supply a voltage signal on a line 44 to voltmeter 26 indicative of battery terminal voltage.
  • This wire may be lead 40 to one of the kelvin clips connecting measurement apparams 20 to the positive terminal of battery BAT.
  • Part 32 is, in mm, encased in an insulating sleeve 26 with metal point 34 protmding. This whole assembly is then held inside a metal sleeve 38 with a notch 39 cut in the end. This notch ensures that the voltage probe tip is centered on wire 40.
  • Thermal sensor TS reports battery temperamre data to control system 22 over lines 42. If kelvin clips are used to connect measurement apparams 20 to battery BAT, thermal sensor TS may simply be attached to the clip, but thermally insulated from it, so that it comes into contact with the battery post and "reports" battery temperamre relatively unaffected by the thermal characteristics of the kelvin clip.
  • the flowchart in Fig. 3 shows how the battery test can be performed using a simple, short, current pulse.
  • temperamre sensor 28 is read and it is determined at 50 whether the temperamre reading has settled. If not, the control waits at 54 for a period of time and takes another temperamre reading at 48. If the temperamre reading has settled, the temperamre reading is stored in memory at 52. Switch SI is then set in the A position and switch S2 in the C position. Battery voltage V ⁇ is then read with voltmeter 26 and stored in memory.
  • Control system 22 tiien either causes a known test current to be supplied to the battery while reading and storing battery terminal voltage V ⁇ ., or causes a known test current to be sank from the battery while reading and storing battery terminal voltage. Control system 22 then computes CCA using principles set forth above and displays the value on display 30.
  • other, more complex forms of applied current provide advantages of noise immunity and cancellation of second order errors.
  • the difference of two pulses may be used to cancel errors due to battery terminal voltage drop during the voltage measurement interval or AC may be used with synchronous detection to remove artifacts caused by nearby conductors.
  • RESISTANCE OF WIRES AND CONNECTIONS A very similar procedure can be used for making measurements of small resistances.
  • the battery BAT is no longer the device under test. Instead, the resistance of a resistance under test (RUT) R x , which may be a length of conductor, an electrical joint, or a combination of conductors and joints is measured.
  • RUT resistance under test
  • any connection between battery BAT and RUT is broken and a small battery internal to the measurement apparams 20 supplies current to the RUT.
  • This procedure is shown in Fig.4, which utilizes short duration pulses to measure the resistance of RUT.
  • the test may be performed with non-test current flowing through R x , this current being ignored. In a vehicle, this might be the current used to supply some device that is never tumed off, such as a clock.
  • switch SI When a resistance test measurement method is started at 64, switch SI is set to position B and switch S2 is set to position D at 66.
  • the initial voltage EQ across R x is measured using voltmeter 26 and stored in memory at 68.
  • Confrol system 22 then causes amplifiers 25, 27 to draw a known current through resistor R x while voltmeter 26 samples, and holds voltage El across resistor R x .
  • the value of voltage El is stored in memory at 70.
  • Confrol system 22 then computes the resistance of R x at 72 using the linear superposition principle. This effectively ignores any non-test current flowing in the circuit by using the formula:
  • kelvin connections, or clips are used to connect measurement apparams 20 to the resistance under test (RUT).
  • Test current plus non-test current is designated I 2 .
  • Resistance R x may be derived by using a "ramp" (linearly increasing current). The time required for the voltage across the RUT to reach the comparator reference voltage with no test ramp applied (T,), is compared with the time required for the voltage across the RUT to reach the comparator reference with the test ramp applied (T 2 ). The resistance of the RUT is then linearly proportional to T 2 - T- . Similarly, T, and T 2 can be found by a dual slope technique (time to integrate up, divided by time to integrate down to some known V REF ).
  • R x is proportional to T 2 - T,.
  • the ramp may be allowed to increase until a known voltage drop is reached. By measuring the voltage before the current ramp is started, and then increasing the current until a known difference (like 1 or 10 mV) is reached, then noting the current that causes that difference, a simple calculation of resistance is possible.
  • the increase in speed may be achieved by using a simple voltage comparator set to the proper offset value to "flag" when the proper current was reached. This is much faster than waiting for the analog-to-digital converter in voltmeter 26 to measure the voltage after each current increase step.
  • the time until the 63 percent point on the RC curve will equal R x x C, so R x can easily be calculated by the data processor.
  • This circuit can be made immune to DC components (created by other current through RUT) by AC coupling the input to voltmeter 26, so the RC decay created by the capacitor and RUT is all that is measured.
  • the capacitor is initially held discharged by the connections through a shunt resistor to ground.
  • the switch D ctri is turned on, the capacitor begins to charge, and a voltage V + appears across the RUT.
  • the capacitor is fully charged, there is no current through RUT.
  • the RUT is connected in a leg of a classical bridge circuit.
  • the voltage applied to the bridge may be DC or AC.
  • the bridge When the bridge is balanced, no output will be seen, regardless of whether the applied voltage is AC or DC.
  • a calculation made by the data processor eliminates the effects of non-test current flowing through RUT.
  • the AC case synchronous detection may be used so that non-test DC currents, and AC currents not at the frequency of the impressed AC, are ignored.
  • any of the fixed resistors of the bridge may be replaced with an active device, such as a FET, and using the data processor in an iterative manner to achieve bridge balance and measure R x .
  • Output of voltmeter 26 is momtored so that the data processor senses whether the bridge is balanced.
  • control system 22 causes amplifiers 25, 27 to generate a sine wave at one or more frequencies in the 10-2,000 Hz range.
  • a synchronous detector is used to monitor the voltage across R x . All frequencies other than the test frequency are rejected, as is DC.
  • the data processor can conveniently cause the generation of several test frequencies, and, from this, the value of any reactance in the circuit may be inferred. Vector subtraction of the reactance leaves only the resistance portion, which gives the resistance of R x . Further, the magnitude and sign of the reactance portion may be used to infer the inductance or capacitance of the circuit.
  • a basic system for delivering electrical energy to a load is the very familiar electrical circuit, consisting of an energy source (generator, battery, etc.) and a load (light bulb, heater coil, or television receiver).
  • the current drawn from the source is determined by the terminal voltage of the battery and the sum of all of the resistances in the circuit including the internal resistance of the battery.
  • An electrical energy delivery system has in the past been characterized solely in terms of the terminal voltage of the supply. While terminal voltage does supply useful information, it is not sufficient information for full characterization of the system. To characterize the system's ability to deliver energy, it is important to also specify the resistance of the delivery system including the internal resistance of the source.
  • the pertinent resistances are the internal resistance of the battery and the resistances of the connecting wires, plus the resistance of any electrical junctions in the circuit.
  • the total resistance of the delivery system including the internal resistance/impedance of the source may be determined.
  • the circuit may be broken, and the load left undisturbed, and the total resistance of the circuit measured, including the resistance of the load, in order to determine useful information regarding the circuit.
  • Measurement apparams 20 can be attached to the battery terminal of the starter solenoid and case ground terminal of the electric starter.
  • Measurement apparams 20 can also be attached to the battery and starter terminals of the solenoid, and the total DC resistance of the circuit can be measured. If this is much greater than the resistance of the delivery system alone, electrical energy will be efficiently transferred to the starter. With minor adaptations, these same techniques can be used for any load, using AC excitation as well as the DC excitation.
  • the ability of an electrical system to deliver power to a load is determined by the terminal voltage of the source of electrical energy, the internal resistance of the source of electrical energy, and the sum of all of the resistances in the cables and connectors.
  • an electrical motor with constant efficiency, F is connected to a source of electrical energy with voltage V, which has an internal resistance R INT .
  • the cables and connectors in the electrical system have a total resistance R EXT *
  • the maximum amount of power, P MAX that can be delivered to the shaft of the electric motor is found to be:
  • MAX is a ver y useful figure of merit, or FOM.
  • the FOM of a system in terms of the maximum current it can deliver to the terminals of a load, without the voltage at the load falling below some selected level.
  • the current that can be delivered to a vehicle starter motor, without the voltage at the terminals of the starter falling below 10 volts may be determined.
  • the calculation is a direct application of Ohm's Law.
  • the same technique can be used in reverse to assess the ability of a secondary battery to accept charge through its cables and connections. In this case, measurement apparams 20 would be attached to the alternator and the test applied. In either case, the assessment can be performed with two connections and a single test. This procedure is simple to use, and it saves a considerable amount of time.
  • BAT is the source of electrical energy
  • R x is R EX -*-.
  • BAT would be the vehicle battery, and the test device might be applied to the starter motor input terminals to determine whether the quality of the battery and cables combined are of sufficient quality to operate the starter motor.
  • switch SI is set to position A and switch S2 is set to position B at 76.
  • the voltage across the battery is measured with voltmeter 26 with no test current flowing through the circuit at 78.
  • Switch S2 is then set to position D x .
  • a known current is then applied through the battery and R- JXT using amplifiers 25, 27 and the voltage across resistance R INT and R EJ ⁇ - is measured with voltmeter 26 at 80.
  • the figure of merit of the circuit is calculated by control circuit 22 at 82, using the principles previously described and is displayed on display device 30.
  • the previously described techniques may be used for finding the resistance of any piece of conducing wire and storing the value in memory.
  • the circuit may then be energized; for example, engaging a starter motor on a vehicle. While current is flowing, the voltage across R x is measured. From the resistance and the voltage, the current that is flowing in the circuit can be calculated. The logic for this is shown in Fig. 6.
  • the switch SI is set to position B and switch S2 is set to position D at 86.
  • the voltage across conductor R x is measured with the R x open-circuited at 88.
  • a known current is then applied to R x by amplifiers 25, 27, and the voltage across R x is measured with voltmeter 26 at 90.
  • the value of the resistance R x is calculated using previously described techniques, and it is then determined at 92 whether the resistance of R x is sufficiently low to allow a meaningful measurement of current to be made. If the resistance of R x is too high, or infinite, application of test current might pose a hazard to the circuit under test. If it is determined at 92 that the resistance of R x is too high, the operator is notified at 94 and the process is exited at 96 in order to protect the circuit under test. If it is determined at 92 that the resistance of R x is within an acceptable range, the circuit under test is activated at 98 and the voltage across R x is measured with voltmeter 26 at 100. Control system 22 then calculates the current flowing through R x at 103 and displays the results on display device 30. If one of the AC-excitation schemes is used, it is possible to make the resistance measurement while large DC circuit currents are flowing, simplifying the procedure.
  • a method of measuring electrical characteristics of an electrical energy delivery system including: providing a voltage sensitive circuit and a controllable current source or sink; controlling said one of a controllable current source and a controllable current sink with a microcomputer in order to apply at least one predetermined current pattem to or sink at least one predetermined current pattem from at least a portion of an energy delivery system; responding with said voltage sensitive circuit to a voltage developed in response to the current pattem being applied or sunk; and calculating a value of at least one electrical characteristic of said energy delivery system as a function of said responding.
  • said at least one electrical characteristic of said energy delivery system is an internal resistance of an electrical source and an external resistance and further including calculating a figure of merit of said energy delivery system as a function of said internal resistance and said external resistance.
  • P MAX maximum power transferred from the electrical source to the load
  • V measured source terminal voltage
  • R 1NT internal resistance of the electrical source
  • R EXT local resistance
  • F is a constant.

Abstract

Appareil et procédé d'évaluation des caractéristiques électriques d'un système fournissant de l'énergie, au moyen d'un circuit sensible à la tension tel qu'un voltmètre (26), d'une source ou d'un écoulement de courant pouvant être commandés et d'un micro-ordinateur (22). Le micro-ordinateur commande la source ou l'écoulement de courant de façon à produire au moins un schéma de courant prédéterminé ou d'absorber au moins un schéma de courant prédéterminé dans une partie d'un système fournissant de l'énergie. Le circuit (26) sensible à la tension réagit à une tension produite en réaction au schéma de courant et le micro-ordinateur (22) calcule au moins une caractéristique électrique du système énergétique en fonction de cette réaction.
EP96931483A 1995-09-08 1996-09-06 Appareil et procede d'evaluation de systeme electrique Withdrawn EP0873522A1 (fr)

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
US346395P 1995-09-08 1995-09-08
US3463 1995-09-08
US1048796P 1996-01-23 1996-01-23
US10487 1996-01-23
PCT/US1996/014351 WO1997011361A1 (fr) 1995-09-08 1996-09-06 Appareil et procede d'evaluation de systeme electrique

Publications (2)

Publication Number Publication Date
EP0873522A4 true EP0873522A4 (fr) 1998-10-28
EP0873522A1 EP0873522A1 (fr) 1998-10-28

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EP96931483A Withdrawn EP0873522A1 (fr) 1995-09-08 1996-09-06 Appareil et procede d'evaluation de systeme electrique

Country Status (4)

Country Link
EP (1) EP0873522A1 (fr)
JP (1) JP2000502177A (fr)
AU (1) AU7015296A (fr)
WO (1) WO1997011361A1 (fr)

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JP7172838B2 (ja) * 2019-04-26 2022-11-16 株式会社デンソー 電池監視装置

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WO1997011361A1 (fr) 1997-03-27
AU7015296A (en) 1997-04-09
EP0873522A1 (fr) 1998-10-28
JP2000502177A (ja) 2000-02-22

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