JP4041313B2 - Battery inspection method and battery inspection apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a battery inspection method and an inspection apparatus in a charge / discharge test process for a battery produced in a factory.
[0002]
[Prior art]
Secondary batteries such as mobile phones are mass-produced at the factory, and after the first charge, they are subjected to chemical conversion treatment to give the function as a battery. Is shipped from the factory. The charge / discharge inspection including the chemical conversion treatment of the secondary battery is performed by repeating a charging operation by constant current charging and constant voltage charging and a discharging operation by constant current for several cycles as shown in FIG.
[0003]
A large amount of secondary batteries (hereinafter simply referred to as batteries) produced in the factory are set in a charge / discharge circuit as shown in FIG. 5, and the batteries are first charged with a target constant current (target charge current Ia). When the battery voltage is raised and the battery voltage rises to a target constant voltage (target voltage Va) [end point of constant current region T1], switching to constant voltage charging is performed so as to keep the target voltage Va. When the constant voltage charging reaches a predetermined end condition, the charging operation is terminated [end point of constant voltage region T2], and immediately after that or after a desired time has elapsed, switching to constant current discharging is performed. The constant current discharge is executed at a predetermined target discharge current Ib, and when the battery reaches a predetermined battery voltage value at which the battery is not overdischarged or reaches a predetermined end condition, the constant current discharge is terminated [constant current region T3. End point].
[0004]
FIG. 5 shows a general charge / discharge circuit of a battery inspection apparatus for simultaneously charging / discharging a large number of batteries 5, and includes an analog device such as a comparison circuit 6 and a control unit 10 with a built-in CPU. A large number of batteries 5 are set in one control unit 10. Each of the batteries 5 is connected to a common control unit 10 via an individual charge / discharge circuit 20. Each charging / discharging circuit 20 includes a DC power source 1, a charging switching element 2, a discharging switching element 3, a current detection device 4, a current detection unit 7, and a voltage detection unit 8, and the charging / discharging circuit 20 and the control unit 10. The AD converter and the DA converter 9 are arranged in the current path.
[0005]
The charging / discharging operation of the battery 5 includes an actual current value based on the current current Ix that flows through the battery 5 and is measured by the current detector 7, and an actual voltage value that is based on the current voltage Vx of the battery 5 that is measured by the voltage detector 8. This is done by feedback through a hard loop through an analog device. For example, during the constant current charging operation in which the charging switching element 2 is turned on and the charging current is supplied to the battery 5 via the current detection device 4, the setting (target charging) current is output from the CPU of the control unit 10 and output. The current value command signal and the current current Ix are compared and detected by the comparison circuit 6, and an analog comparison signal is input to the charging switching element 2. By controlling this input voltage, the charging current of the battery 5 is controlled. Is called. Further, during a discharging operation in which the discharging switching element 3 is conducted to discharge the battery 5, a set (target discharge) current is output from the CPU of the control unit 10, and the output current value command signal is compared with the current current Ix. The comparison detection is performed by the circuit 6, and an analog comparison signal is input to the discharging switching element 3. The discharge current of the battery 5 is controlled by controlling the input voltage.
[0006]
[Problems to be solved by the invention]
Current / voltage accuracy that is regarded as important in charge / discharge inspection of secondary batteries as described above, current accuracy during constant current charge, voltage accuracy during constant voltage charge, current accuracy during constant current discharge, termination at discharge There is voltage accuracy, and the reliability of the battery inspection device is determined by the quality. In the case of the battery inspection apparatus of FIG. 5, since current / voltage control during charging / discharging of the battery is performed by hard loop feedback control using an analog device such as a comparison circuit, the current value and voltage value during charging / discharging are as shown in FIG. It becomes a good one resembling a waveform, the above four important current / voltage accuracies can always be ensured with high accuracy, and the reliability of the battery charge / discharge inspection is good. However, there are the following problems (1) to (4) associated with a hard loop structure using an analog device.
[0007]
(1) Since a battery inspection apparatus for simultaneously charging and discharging a large number of batteries mass-produced at a factory requires a charge / discharge circuit using thousands or tens of thousands of batteries and the same or more analog devices. As a result, the number of circuit parts in the entire inspection apparatus increases, and the entire inspection apparatus becomes large and expensive.
[0008]
(2) Since the number of circuit parts in the entire inspection device increases, the frequency of maintenance and inspection due to failure of individual circuit parts and quality deterioration increases, and adjustment to calibrate variations in the quality of individual circuit parts The time becomes enormous and the operating rate of the battery inspection device decreases.
[0009]
(3) Since the number of circuit components increases, it is difficult to change the control algorithm for battery charge / discharge accompanying the change in battery type.
[0010]
(4) It is difficult to change the wiring of the analog device due to the change of the battery type, and due to this difficulty, the charge / discharge control algorithm is not compatible with the change of the battery type and lacks versatility.
[0011]
The object of the present invention is to reduce the number of circuit parts of an analog device to facilitate cost reduction, and to improve the compatibility of the charge / discharge control algorithm for changing the type of battery. Is to provide.
[0012]
[Means for Solving the Problems]
According to the first aspect of the present invention, there is provided a charging operation in which a battery is constant-current charged to a predetermined target voltage with a predetermined target charging current via a charging switching element, and then the constant voltage is charged while holding the target voltage. A battery inspection method in which a discharge operation of a constant current discharge at a predetermined target discharge current is controlled by a CPU of a computer until a predetermined end condition is reached via a discharge switching element after the charging operation is performed. The CPU calculates the difference between the current current flowing through the battery during current charging and the target charging current, and the difference between the battery current voltage and target voltage during constant voltage charging, and the calculated current difference signal and voltage difference signal. Is output as a digital charging current command signal to the charging switching element at a predetermined cycle time determined by the CPU to control the battery charging operation, and further flows to the battery during constant current discharge. The difference between the current and the target discharge current is calculated by the CPU, and the calculated current difference signal is output as a digital discharge current command signal to the discharge switching element at a predetermined cycle time determined by the CPU to discharge the battery. The operation is controlled.
[0013]
The battery here is a secondary battery, etc., and the conventional constant current charging and constant voltage charging charging operation and the constant current discharging discharging operation are digitally controlled by the CPU soft loop as described above. Compared with the inspection method by analog control of the hard loop using an analog device, the CPU is used more effectively, and accordingly, the analog device can be reduced, the battery inspection apparatus becomes small, and the cost can be easily reduced.
[0014]
According to the second aspect of the present invention, the degree of the current current approaching the target charging or discharging current is determined by multiplying the difference between the current current of the battery and the target charging or discharging current during constant current charging and constant current discharging. By setting the current operation coefficient in the CPU as a calculation coefficient that can be varied with respect to the difference between the current current and the target charging or discharging current, and further multiplying the difference between the current voltage of the battery and the target charging voltage during constant voltage charging. A voltage operation coefficient that determines the degree to which the current voltage approaches the target charging voltage is set in the CPU as a calculation coefficient that can be varied with respect to the difference between the current voltage and the target charging voltage.
[0015]
Here, the smaller the current operation coefficient is, the more difficult the current current of the battery reaches the target charging or discharging current, and the larger the current operating coefficient, the more the current current of the battery overshoots the target charging or discharging current and the target charging or discharging current. Therefore, it is difficult to converge within the permissible range, so the current operation coefficient is automatically controlled to the optimum value by monitoring the current operation coefficient with the CPU, so that the current current of the battery can be allowed for the target charge or discharge current in a short time. Try to reach the range. In the case of the other voltage operation coefficient, the current voltage of the battery is less likely to reach the target charge voltage as the voltage becomes smaller, and the current voltage of the battery overshoots the target charge voltage and converges within the allowable range of the target charge voltage as the value increases. Since the voltage operation coefficient is also monitored by the CPU and automatically controlled to an optimum value, the charging current is adjusted so that the current voltage of the battery reaches the allowable range of the target charging voltage in a short time. To control.
[0016]
Further, the invention of claim 3 is directed to increase the target charge or discharge current of the battery at the time of constant current charge and constant current discharge in a stepwise manner smaller than the target charge or discharge current, and finally target charge or discharge. It is divided into a plurality of temporary target charging or discharging currents that reach the current, and the current of the battery is stepped up in order from the smallest temporary target charging or discharging current during constant current charging or discharging so that constant current charging or discharging is performed step by step. It is characterized by that.
[0017]
In other words, by starting up constant current charging or discharging in a plurality of steps, the current current of the battery reaches a temporary target charging or discharging current in small steps, and each time a plurality of temporary target charging or discharging currents are reached. Thus, the overshoot phenomenon is suppressed, and overshoot when the final target charge or discharge current is reached is prevented.
[0018]
According to a fourth aspect of the present invention, there is provided a battery inspection apparatus, wherein in the battery inspection method using the CPU soft loop according to the present invention, the difference between the current and the target charging current flowing in the battery during constant current charging, and constant voltage charging. The difference between the current voltage of the battery at the time and the target voltage is calculated by the CPU, and the calculated current difference signal and the voltage difference signal are digitally charged to the charging switching element at a predetermined cycle time determined by the CPU. A charging circuit that outputs a command signal and controls the charging operation of the battery, a voltage holding circuit that holds the digital voltage of the charging current command signal input to the switching element for charging during the cycle time; and The difference between the current battery current and the target discharge current during constant current discharge is calculated by the CPU, and the calculated voltage difference signal is released at a predetermined cycle time determined by the CPU. A discharge circuit that outputs a digital discharge current command signal to the switching element for control and controls the discharge operation of the battery, and holds the digital voltage of the discharge current command signal input to the discharge switching element for the cycle time. A circuit is attached.
[0019]
That is, the time period from when a digital charging current command signal is input to the charging switching element at a predetermined cycle time set by the CPU until the next charging current command signal is input (the CPU has one cycle time). The scanning operation time) is a time zone in which the digital voltage of the charging current command signal is not input to the switching element. If this time period becomes longer, the operation of the switching element becomes unstable. Is added to stabilize the operation of the CPU in the scanning time zone, thereby ensuring current accuracy during constant current charging. In addition, a voltage holding circuit is also attached to the discharge switching element to ensure current accuracy during constant current discharge. These voltage holding circuits can be configured with simple and inexpensive circuits using electronic components.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows an embodiment of the battery inspection apparatus according to the present invention. The battery inspection apparatus of the same figure charges and discharges a large number of batteries 5 at the same time. It has a charge / discharge circuit 40 to which four channel switching elements 33a to 33d are connected via two AD converters 31c and 31d, two DA converters 31a and 31b, and four operational amplifiers 32a to 32d. N (a large number of several tens to several hundreds) batteries 5 are connected to each of the channel switching elements 33a to 33d. Each battery 5 is connected to a charging / discharging circuit comprising a charging switching element 2, a discharging switching element 3, and a current detection device 4 similar to those in FIG. 5, and the plurality of battery charging / discharging circuits share a common DC power source 1. Connected to.
[0021]
The four channel switching elements 33a to 33d are a charging channel switching element 33a and a discharging channel switching element 33b, a charging current detecting channel switching element 33c, and a battery voltage detecting channel switching element 33d. Each of the channel switching elements 33a to 33d performs a scanning operation for switching N switches for each input of the channel select signal f output from the CPU of the control unit 30 one pulse at a time in one cycle time. The charging channel switching element 33 a has N output terminals connected to the N charging switching elements 2, and a voltage holding circuit 50 is connected between the output terminals and the gates of the switching elements 2. . The discharge channel switching element 33 b has N output terminals connected to the N discharge switching elements 3, and a voltage holding circuit 51 formed of an electronic component between the output terminal and the gate of the switching element 3. Is connected.
[0022]
The charging current detection channel switching element 33c is for sequentially measuring the current flowing through the N batteries 5, and the charging current (current current) measured here is the timing of the scanning operation of the channel switching element 33c. A current monitor output to the operational amplifier 32c and the AD converter 31c and converted into a digital value is sent to the CPU of the control unit 30. The battery voltage detection channel switching element 33d is for sequentially measuring the terminal voltages of the N batteries 5, and the battery voltage (current voltage) measured here is the timing of the scanning operation of the channel switching element 33d. A voltage monitor output to the operational amplifier 32d and the AD converter 31d and converted into a digital value is sent to the CPU of the control unit 30.
[0023]
The CPU of the control unit 30 performs feedback control of the current monitor and voltage monitor to control a soft loop that outputs the charge current command signal and the discharge current command signal to the channel switching elements 33a and 33b via the DA converters 31a and 31b. . The CPU of the control unit 30 calculates the difference between the current and target charging current flowing through the battery 5 when the battery 5 is charged with constant current, and the difference between the current voltage and target voltage of the battery 5 when charging with constant voltage. A soft loop function for controlling the charging operation of the battery 5 by outputting the current difference signal and the voltage difference signal as a digital charging current command signal to the charging switching element 2 at a predetermined cycle time determined by the CPU. The difference between the current current of the battery 5 and the target discharge current during constant current discharge is calculated, and the calculated voltage difference signal is digitally sent to the discharge switching element 3 at a predetermined cycle time determined by the CPU. As a soft loop function for controlling the discharging operation of the battery.
[0024]
The charging current command signal input from the CPU of the control unit 30 to the charging channel switching element 33a is one base for each scanning cycle of the channel switching element 33a by the CPU. Is input. The input voltage for one pulse is held by the voltage holding circuit 50. As a result, the charging current command signal is continuously input to the base (or gate) of the switching element 2 even during the scanning time of the CPU. Thus, constant current charging and constant voltage charging of the battery 5 are performed. The current control at the time of constant current charging and the voltage control at the time of constant voltage charging are performed with high accuracy as in the prior art by a charging current command signal from the CPU.
[0025]
Further, the discharge current command signal input from the CPU of the control unit 30 to the discharge channel switching element 33b is equivalent to one base for each scanning cycle of the channel switching element 33b by the CPU. The input voltage for one pulse is held by the voltage holding circuit 51. As a result, the discharge current command is also sent to the base (or gate) of the switching element 3 even during the scanning time of the CPU. The signal is continuously input and constant current discharge of the battery 5 is executed, and current control at the time of constant current discharge is performed with high accuracy by a discharge current command signal from the CPU.
[0026]
By configuring the battery detection device as described above, it is possible to control charging / discharging of a plurality of batteries with one charging / discharging circuit 40, and it is easy to reduce circuit components of the charging / discharging circuit, in particular, to greatly reduce analog devices. Become. In fact, the number of analog devices can be reduced by about 70% in comparison with the conventional analog type battery inspection apparatus, and the cost can be greatly reduced. In addition, since the CPU of the controller 30 has many charge / discharge soft loop functions, instability and trouble due to hardware factors such as IC characteristics are reduced, and the hardware part of the CPU is simplified. be able to. In addition, because of the charge / discharge control by software mainly composed of the CPU of the control unit 30, the change of the charge / discharge control algorithm accompanying the change of the battery type or the like can be easily executed only by changing the CPU software. Further, if necessary, charging / discharging can be executed by changing the current / voltage setting for each battery individually.
[0027]
In the case of the battery inspection method of the present invention, since the charge / discharge of the battery is controlled by a digital charge / discharge command signal, the current and voltage measured at the time of charge / discharge vibrate overshooting the target value, Instability factors may occur, such as it takes time to reach the value. For example, the CPU of the control unit 30 of the battery inspection apparatus in FIG. 1 sets the current operation coefficient Ki to the difference (Ia−Ix) between the current current Ix flowing through the battery 5 during constant current charging and a predetermined target charging current Ia (see FIG. 2). In this case, if the current operation coefficient Ki is too small, the current current Ix may not fall within the allowable range Iy of the target charging current Ia as shown in FIG. On the other hand, if the current operation coefficient Ki is too large, as shown in FIG. 2C, an overshoot phenomenon occurs in which the current current Ix oscillates greatly deviating from the allowable range Iy at the start-up of constant current charging, and the current current Ix It may take a long time to not converge within the allowable range Iy or to converge completely.
[0028]
The current operation coefficient Ki is an arithmetic coefficient that determines the degree to which the current current Ix approaches the target charging current Ia, whereas the inherent coefficient is applied in the conventional analog loop charging / discharging circuit of FIG. In the present invention, the CPU sets a coefficient that can be varied with respect to the difference between the current current Ix and the target charging current Ia so that the current current Ix converges to the allowable range Iy in a short time as shown in FIG. Like that. That is, until the current current Ix approaches the allowable range Iy, the current operation coefficient Ki is increased to shorten the start-up time during constant current charging, and the current current Ix overshoots the allowable range Iy with a large current operation coefficient Ki. The current operation coefficient Ki is automatically controlled to be small by the CPU to suppress the vertical vibration within the allowable range Iy of the current current Ix. With this increase / decrease control of the current operation coefficient Ki, the current current Ix is suppressed in a stepwise manner and converges within the allowable range Iy, and constant current control is performed with high accuracy in a short time.
[0029]
The current control using the current operation coefficient as described above is also applied to the current control in the constant current region T3 in FIG. Furthermore, the current Ix that has converged within the allowable range Iy in FIG. 2A may oscillate out of the allowable range Iy for some reason, such as a change in ambient temperature or a change in battery type. There is also an effect of suppressing the deviation of the current current that deviates by setting the current operation coefficient. Such an effect is also exhibited in the next setting of the voltage operation coefficient Kv.
[0030]
In the present invention, the voltage operation coefficient Kv that determines the degree to which the current voltage approaches the target charging voltage Va by multiplying the difference between the current voltage of the battery during constant voltage charging and the target charging voltage Va (see FIG. 4) is obtained. , The CPU is set as a calculation coefficient that varies in proportion to the difference between the current voltage and the target charging voltage Va. In this case, when the current current overshoots the allowable range of the predetermined target charging voltage Va during constant voltage charging, the voltage operation coefficient Kv is automatically controlled to be small by the CPU so that the voltage control is performed with high accuracy in a short time. To do.
[0031]
Furthermore, in the present invention, in order to improve start-up during constant current charging, the target charging current Ia of the battery 5 during constant current charging is set smaller than the target charging current Ia as shown in FIG. .., And finally set to a plurality of temporary target charging currents I1y, I2y,... That reach the target charging current Ia. Starting up the constant current charging from the smallest temporary target charging current I1y, when the current current Ix of the battery 5 rises and converges to the allowable range of the initial temporary target charging current I1y, the current increase amount is added to the temporary target charging current I1y. The charging step-up is performed toward the added temporary target charging current I2y, and this charging step-up is repeated in order to finally converge the current current Ix to the allowable range Iy of the target charging current Ia.
[0032]
In the charging step-up operation of FIG. 3, the overshoot when the current current Ix reaches the first temporary target charging current I1y from zero is more than the overshoot when the current current Ix reaches the maximum target charging current Ia from zero. Appear small. When the step-up current amount between the temporary target charging currents I1y, I2y,... Is set so as to decrease in order, the current current Ix overshoots at the temporary target charging currents I1y, I2y,. The amount decreases in order, and the final target charging current Ia converges to the allowable range Iy of the target charging current Ia at once without overshooting. Therefore, even if constant current charging is started up at high speed, there is no possibility of overshooting, it is easy to speed up startup, and smooth startup is realized. Further, if the current operation coefficient software described in FIG. 2 is applied to the convergence region due to the oscillation of the current current Ix in each of the temporary target charging currents I1y, I2y,... In FIG. This will further improve the startup.
[0033]
【The invention's effect】
The invention of claim 1 calculates the difference between the current flowing through the battery during constant current charging and the target charging current in a soft loop by the CPU of the computer, and calculates the calculated current difference signal at a cycle time determined by the CPU. The constant current charging operation is controlled by outputting it as a digital charging current command signal to the switching element for charging, and the constant voltage charging and constant current discharging operations are similarly controlled. The CPU takes charge of the analog device function of the battery inspection method by analog control of the hard loop that has been used, and the CPU can be used effectively, and the analog device can be greatly reduced, and the size of the battery inspection device can be reduced by reducing the number of parts. Costs can be reduced, and maintenance and inspection of parts and wiring changes are facilitated. In addition, since the battery charge / discharge control is performed by the CPU soft loop, it is easy to change the charge / discharge control algorithm accompanying the change of the battery type and to calibrate it, making it easy to handle a wide variety of batteries. There is an effect of excellent versatility.
[0034]
According to the second aspect of the present invention, since the operation coefficient that brings the current current and current voltage of the battery at the time of charging / discharging closer to the target value is a variable coefficient on the CPU side, the CPU controls the operation coefficient so that it always becomes the optimum value. Thus, the current and voltage of the battery at the time of charging / discharging can always be efficiently converged within the allowable range of the target value, and the battery inspection can be speeded up and the performance can be improved.
[0035]
In the invention of claim 3, since the current current of the battery is increased stepwise from the temporary target charging current to the final target charging current at the time of constant current charging, the current current is targeted even if the start-up at constant current charging is accelerated. The problem of large overshooting of the charging current can be solved, and therefore there is an effect that a start-up operation with smooth and low overshoot can be performed. In addition, because overshoot during constant current charging can be suppressed, stress due to abnormal current to the battery due to overshoot is reduced, and reliability that does not give stress to small and lightweight batteries such as secondary batteries of mobile phones in particular There is an effect that a high-performance battery inspection can be executed.
[0036]
According to a fourth aspect of the present invention, there is provided a battery inspection apparatus in which a voltage holding circuit attached to a charging / discharging switching element holds a voltage value of a digital command signal inputted to the switching element with a time interval, Since the operation is stabilized, there is an effect that current accuracy during constant current charging, voltage accuracy during constant voltage charging, and current accuracy during constant current discharging can be constantly secured. The voltage holding circuit can be a simple and inexpensive circuit using electronic components.
[Brief description of the drawings]
1 is a circuit diagram of a battery testing device showing an embodiment of the present invention.
2A is a current waveform diagram when constant current charging is controlled by the control unit CPU of the circuit in FIG. 1, and FIGS. 2B and 2C are explanatory diagrams comparing the effectiveness of the current waveform of FIG. FIG.
FIG. 3 is a current waveform diagram at the time of constant current charging and discharging start-up by the control unit CPU of the circuit of FIG. 1;
FIG. 4 is a charge / discharge current waveform diagram and a voltage waveform diagram for explaining a general battery charge / discharge test.
FIG. 5 is a circuit diagram of a conventional battery inspection apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 DC power supply 2 Charging switching element 3 Discharging switching element 4 Current detection resistor 5 Battery 20 Charge / discharge circuit 30 Control unit 31a, 31b AD converter 31c, 31d DA converter 32a-32d Operational amplifier 33a-33d Channel switching element 40 Charging / discharging Circuit 50 Voltage holding circuit 51 Voltage holding circuit Ib Target discharge current Ix Current current Iy Allowable range I1y Temporary target charging current I2y Temporary target charging current Va Target voltage Vx Current voltage f Channel select signal

Claims (4)

A charging operation in which the battery is constant-current charged to a predetermined target voltage with a predetermined target charging current via the charging switching element, and then the target voltage is maintained and constant voltage charging is performed. A battery testing method in which a discharge operation of discharging a constant current at a predetermined target discharge current is controlled by a CPU of a computer until a predetermined end condition is reached.
The CPU calculates the difference between the current flowing through the battery during constant current charging and the target charging current, and the difference between the current voltage of the battery during constant voltage charging and the target voltage, and the calculated current difference signal, and The voltage difference signal is output as a digital charging current command signal to the charging switching element at a predetermined cycle time determined by the CPU to control the charging operation of the battery.
Further, the CPU calculates the difference between the current flowing through the battery during constant current discharge and the target discharge current, and the calculated current difference signal is digitally transmitted to the discharge switching element at a predetermined cycle time determined by the CPU. A battery inspection method comprising: outputting a discharge current command signal to control a discharge operation of the battery. By multiplying the difference between the current battery current and the target charging or discharging current during constant current charging and constant current discharging, the current operation coefficient that determines the degree to which the current current approaches the target charging or discharging current is determined as the current current and the target charging. Or set it in the CPU as a calculation coefficient that can be varied with respect to the difference in discharge current,
In addition, the voltage operation coefficient that determines the degree to which the current voltage approaches the target charging voltage by multiplying the difference between the current voltage of the battery and the target charging voltage during constant voltage charging can be varied with respect to the difference between the current voltage and the target charging voltage. The battery inspection method according to claim 1, wherein the calculation coefficient is set in the CPU. The target charging current of the battery during constant current charging and constant current discharging is divided into a plurality of temporary target charging currents that are smaller than this target charging current and gradually increase to finally reach the target charging current. 3. The battery inspection method according to claim 1 or 2, wherein the current of the battery is stepped up in order from the smallest temporary target charging current to perform constant current charging step by step. A charging operation in which the battery is constant-current charged to a predetermined target voltage with a predetermined target charging current via the charging switching element, and then the target voltage is maintained and constant voltage charging is performed. A battery inspection device in which a discharge operation of constant current discharge at a predetermined target discharge current is controlled by a CPU of a computer until a predetermined end condition is reached via
The CPU calculates the difference between the current flowing through the battery during constant current charging and the target charging current, and the difference between the current voltage of the battery during constant voltage charging and the target voltage, and the calculated current difference signal, and The charging signal input to the charging switching element is output to the charging circuit that controls the charging operation of the battery by outputting the voltage difference signal as a digital charging current command signal to the charging switching element at a predetermined cycle time determined by the CPU. A voltage holding circuit for holding the digital voltage of the current command signal for the cycle time is attached,
The difference between the current battery current and the target discharge current during constant current discharge is calculated by the CPU, and the calculated voltage difference signal is digitally supplied to the discharge switching element at a predetermined cycle time determined by the CPU. A voltage holding circuit for holding the digital voltage of the discharge current command signal input to the discharge switching element for the cycle time is added to the discharge circuit that outputs the output of the battery and controls the discharge operation of the battery. Inspection device.

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