JPH097642A - Battery charger with diagnostic function - Google Patents

Abstract

PURPOSE: To provide a battery charger provided with a function for diagnosing and judging the abnormality of a secondary battery or the deterioration of the performance. CONSTITUTION: A battery charger 1 with diagnostic function has three operation modes of charge mode, refresh mode and diagnostic mode. When a secondary battery to be used is new or nearly new, charge and discharge are once performed in diagnostic mode, and a central processing unit 10 measures the charge capacity and discharge capacity at that time and the terminal voltage when the charge is completed, and stores them in a memory part 40. When the secondary battery is connected to terminals 5, 5' to start the diagnostic operation after the secondary battery is used plural times, the central processing unit 10 charges and discharges the battery and measures the charge capacity and discharge capacity at that time and the terminal voltage when the charge is completed. The measured values are compared with the data for the new one stored in the memory part 40 to judge the degree of deterioration and displays the result on a display part 20.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a nickel-cadmium storage battery (hereinafter referred to as "NiCd battery") and a nickel-cadmium storage battery.
The present invention relates to a charger for a secondary battery such as a hydrogen storage battery (hereinafter referred to as "NiMH battery").

[0002]

2. Description of the Related Art Secondary batteries such as NiCd batteries and NiMH batteries are reusable and economical, have a high capacity and can discharge a large current, are easy to handle, and require no maintenance. It has characteristics and is widely used in various fields such as industrial and hobby. In addition, the form is also varied from a single cell to a plurality of cells having uniform characteristics connected in series or in parallel and stored in a single package to obtain a predetermined voltage or capacity. Type is used.

Various types of chargers are also used for charging these secondary batteries. As a charging method, a current of about 1/10 of the capacity value C of the secondary battery is 14 to Known are standard charging for 16 hours, and rapid charging for charging with a relatively large current and controlling the current and voltage at the end of charging for a short time. This quick charge can be applied only to secondary batteries of the type that can be rapidly charged, but this quick charge battery is also excellent in large current discharge characteristics and is suitable for hobbies such as radio-controlled automobiles and power tools. Many are used. This rapid charging control method uses the voltage control method that detects and controls the voltage of the battery being charged, and the characteristic that the battery voltage drops after passing the peak after completion of the rapid charging. The temperature at which the battery reaches a certain temperature is determined by using the temperature increase due to the heat of the chemical reaction generated when overcharging, and the temperature at which charging is completed by detecting the point (-ΔV) A detection control method is adopted.

As is known, a NiCd battery or the like has a memory effect, and in order to eliminate the effect, a charger with a discharging function is used which is almost completely discharged before starting charging. There is. Furthermore, the remaining capacity of the secondary battery has also been displayed by integrating the current and voltage during charging to calculate the amount of charge and similarly calculating the amount of discharge during use.

[0005]

In general, NiCd batteries and NiMH batteries can be repeatedly used (charge / discharge cycle) several hundred times for charging and discharging. However, it is known that this cycle life is affected by usage conditions such as charge current, temperature, depth of discharge, and overcharge period, and when attempting to extract a large capacity with a large current, the life generally tends to be shortened. . Then, when a secondary battery such as a NiCd battery or a NiMH battery is repeatedly used, an abnormality such as a cell defect occurs or the performance deteriorates as described above.

For example, in a multi-cell type secondary battery in which a plurality of cells are stored in one package to obtain a desired voltage, one cell or a plurality of cells are short-circuited or open. There is a case where it becomes. In such a case, if a voltmeter is attached to the charger, the abnormality of the secondary battery can be temporarily detected by checking whether or not the charging voltage is a predetermined voltage. However, when a plurality of cells are connected in parallel and one or more of them are opened, the abnormality cannot be detected only by looking at the charging voltage. Further, when the charger is not equipped with a voltmeter, it is necessary to measure the charging voltage using another voltmeter or to judge the abnormality by intuition based on experience.

In addition, when the performance of the secondary battery gradually deteriorates, it is the present situation that the usable time is gradually shortened during repeated use, and the judgment is made based on the intuition. In particular, radio-controlled automobiles and electric tools are being used in extreme ways, such as being fully discharged from a fully charged state within a short period of time. Deterioration often occurs. Therefore, it is unknown how much the secondary battery used is deteriorated, and the anxiety during use could not be wiped out.

[0008] Therefore, an object of the present invention is to provide a charger having a function of judging the occurrence of abnormality or deterioration of the secondary battery and displaying the judgment result.

[0009]

In order to achieve the above object, the charger with a diagnostic function of the present invention stores reference data relating to the characteristics of the secondary battery in the charger for charging the secondary battery. Storage means, means for measuring data relating to the characteristics of the secondary battery, means for comparing the data measured by the measuring means with the reference data, and means for determining the quality of the secondary battery, and the determining means. And a means for displaying the determination result by. Further, it further comprises second measuring means for measuring the reference data concerning the characteristics of the secondary battery, and means for storing the reference data concerning the characteristics of the secondary battery measured by the second measuring means in the storage means. It is a thing.

[0010]

Since the reference data regarding the characteristics of the secondary battery is stored in the storage means, the characteristic data measured by the means for measuring the data regarding the characteristics of the secondary battery at the time of charging or diagnosis and the storage means stores the characteristic data. By comparing and determining the reference data regarding the characteristics of the secondary battery, the failure and deterioration of the secondary battery can be determined, and the determination result can be displayed.

[0011]

1 is a diagram showing the configuration of a quick charger with a diagnostic function according to an embodiment of the present invention. In this figure, 1 is a quick charger with a diagnostic function, 2 is a DC power supply, and 3 is a secondary battery such as a NiCd battery or a NiMH battery. The output of the DC power supply 2 is input to the charger 1 via the terminals 4 and 4 ′,
The secondary battery 3 is connected to the output terminals 5 and 5 ′ of the charger 1. The DC power supply 2 may be one that rectifies an AC commercial power supply to obtain a DC voltage, one that directly uses the voltage of a battery such as an automobile, or a DC / DC converter that outputs the output of a battery such as an automobile by a predetermined value. What converts into a voltage can be used.

As shown in the figure, the quick charger 1 with a diagnostic function includes a central processing unit 10, a display unit 20, and an operation unit 3.
0, storage unit 40, DC / DC converter 50, discharge control transistor 60, resistor 70, resistor 80, and voltage stabilizing circuit 90. The central processing unit 10 is, for example, a single-chip microcomputer incorporating an AD / DA converter, and determines the connection state of the secondary battery and the abnormality of the secondary battery by the program stored in the built-in program memory, and charges the secondary battery. The operation of the charger 1 is comprehensively controlled such as control of discharge. Further, 11 is an output port for outputting an operation control signal to the DC / DC converter 50, 12 is an analog input port to which the voltage at the point A in the figure is input, and 13 is a voltage at the point B in the figure. Is an analog input port, 14 is an analog output port for outputting a conduction control signal to the discharge control transistor 60, and 15 is an analog input port for inputting a voltage at point C in the figure. Also, 16, 17
And 18 are input / output ports connected to the display unit 20, the operation unit 30, and the storage unit 40, respectively. Furthermore, 19 is a power supply terminal to which the output of the voltage stabilizing circuit 90 is input.

The display unit 20 is for displaying the operating state of the charger 1 such as the charging / discharging current value, the operating mode and the battery state discrimination result, and employs various display devices such as a liquid crystal display device and an LED. You can The operation unit 30 is operated by a user to select an operation mode (charge mode, refresh mode, and battery diagnosis mode) of the charger 1, set a charging current, register and call individual battery data, and the like. Is. The storage unit 40 is a non-volatile memory including, for example, a battery backed-up RAM and the like, and has a nominal voltage, a nominal capacity, a charging current, a
Rating data such as charging time is stored in advance or by the user input from the operation unit 30. In addition, measurement data relating to characteristics such as charge amount, discharge amount, and final charge voltage measured in a diagnostic mode described later is also stored. The DC / DC converter 50 is controlled by the central processing unit 10 to step up or step down the voltage of the DC power supply 2 to a voltage required to obtain a current required for charging. Then, the output is sent to the secondary battery 3 after being rectified without passing through the smoothing circuit,
The secondary battery 3 is adapted to be charged by a pulsating flow.

The discharge control transistor 60 is a transistor that becomes a load of the secondary battery 3 during the discharge operation in the refresh mode or the battery diagnosis mode, and its conduction state is controlled by the output from the analog output port 14 of the central processing unit 10. It is what is done. The resistor 70 is a resistor inserted in series with the discharge control transistor 60,
A voltage proportional to the discharge current at the time of discharging the secondary battery 3 is generated at both ends thereof. Further, the resistor 80 is the secondary battery 3
Is a resistor connected between the negative electrode and the ground, and a voltage proportional to the charging current at the time of charging the secondary battery 3 is generated across the resistor. The voltage stabilizing circuit 90 stabilizes the voltage supplied from the DC power supply 2 to generate the operating voltage of the central processing unit 10.

The quick charger 1 with a diagnostic function of the present invention thus configured has three operation modes: (1) charging mode, (2) refresh mode, and (3) battery diagnostic mode. There is. The operation in each of these operation modes will be described below.

(1) Charging Mode Immediately after the power is turned on, the charger 1 enters this mode. This charging mode is a well-known mode for performing rapid charging, and in this mode, when the start button of the operation unit 30 is pressed, rapid charging is started for the secondary battery 3. The charging current at this time can be set to an arbitrary current value with a current setting button provided on the operation unit 30. The central processing unit 10 measures the charging current from the voltage at the point B input from the input port 13, and outputs the output voltage of the DC / DC converter 50 so that the charging current set in the operation unit 30 flows. It is controlled by the signal output from. Further, at the same time when the charging is started, the central processing unit 10 starts a time counting operation by a timer (not shown), and the charging is forcibly stopped when the charging time exceeds a predetermined time. There is.

FIG. 2 shows the charging characteristics of the NiCd battery and the NiMH battery. As shown in this figure, as the charging proceeds, the terminal voltage of the battery 3 gradually rises, reaches a peak near the full charge, and then drops. The voltage drops in this way because the battery temperature rises due to overcharge. The central processing unit 10 monitors the terminal voltage of the secondary battery 3 by the voltage at the point A input from the input port 12, and when it detects that it drops from the peak value by a predetermined voltage, that is, the delta peak voltage, When detected, D
The C / DC converter 50 is controlled to stop the rapid charging. This is a so-called -ΔV control method. And after fully charging in this way,
The DC / DC converter 50 is controlled so as to be in a trickle charge state in which the battery is charged with a minute current that compensates for the self-discharge of the battery. That is, trickle charging is performed after the end of rapid charging to increase the charging rate.

Further, the central processing unit 10 compares the terminal voltage of the battery 3 with the nominal voltage of the battery stored in advance in the storage unit 40 after the end of charging or after the lapse of the predetermined time. As a result of this comparison, when the terminal voltage of the battery 3 is not charged to the nominal voltage, it is determined that an abnormality such as a cell short circuit has occurred in the secondary battery, and the display unit 20 indicates that the battery is abnormal. Display that there is. This display may be performed by turning on an LED or the like, or by displaying a message to that effect.

(2) Refresh Mode When the refresh mode is selected by the operation unit 13, the charger 1 operates in the refresh mode. This mode is a mode for eliminating the influence of the memory effect, and when the start button is pressed, the secondary battery 3 starts to be discharged, and after the discharge is completed, a certain period of time is taken to perform rapid charging. It is a thing. Further, it is possible to perform only the operation of discharging according to the user's selection.

When the start button is pressed in this mode, the secondary battery 3 is first discharged. If the discharge current supplied at this time is too high, the lead wires and connectors will heat up, which is dangerous, and discharging at an extremely high rate will adversely affect the battery, so it will be safe and fast to discharge the battery. It is necessary to set a discharge current value that can be set.

A method for automatically setting the optimum value of the discharge current will be described with reference to FIG. a. First, the discharge control transistor 60 is made non-conductive, and the terminal voltage (V ₀ ) of the secondary battery 3 under no load is measured by input from the input port 12. Thereby, the number of cells of the battery 3 can be determined. b. Next, the output port 14 controls the impedance of the discharge control transistor 60 while monitoring the voltage at the point C, which is proportional to the discharge current, by the input from the input port 15. The value I ₁ is discharged, and the terminal voltage V ₁ is measured after a certain period of time. c. Then, in the same manner, the discharge current value is increased to I ₂ and the terminal voltage V ₂ after a certain period of time is measured. d. This is repeated several times (current value I ₃ ... I
_n , terminal voltage V ₃ ... V _n ). e. Then, when the voltage V ₁ -V _n exceeds a certain reference voltage V _TH , the current value I _n-1 immediately before that is determined as the discharge current value, and the secondary battery 3 is a constant current with the current I _n-1. To discharge. The reference voltage V _TH is a voltage determined by the product of the number of cells of the battery and a predetermined constant (allowable voltage drop per cell).

After the discharge is started with the discharge current set as described above, the timing of ending the discharge is determined as follows. This will be described with reference to FIG. FIG. 4 shows the discharge characteristics of the NiCd battery and the NiMH battery. As shown in the figure, the terminal voltage is stable until the end of discharge, and has a characteristic of sharply decreasing near the end of discharge. The discharge end timing is determined by detecting a sharp drop in the terminal voltage near the end of the discharge. That is, after the start of discharge, the central processing unit 10
Using the voltage at the point A input from the input port 12, the amount of voltage drop (-ΔV / Δt) within a unit time is sequentially monitored. Then, the voltage drop amount within this unit time (-ΔV / Δ
t) is compared with the set value determined by the number of cells of the battery determined from the voltage (V ₀ ) at no load and the allowable voltage drop amount per unit time per cell, and the unit time is compared. When the amount of voltage drop (-ΔV / Δt) inside exceeds the set value, the discharge control transistor 60 is made non-conductive to terminate the discharge. However, even if the current value is being set, (V
The relationship between _0- V _n ) and V ₀ is monitored, and if it exceeds a certain set value, the discharge is stopped.

After the completion of discharging, a fixed time has elapsed, and then rapid charging is performed. At this time, referring to the discharge current value automatically set at the time of discharging, the value obtained by multiplying the discharge current value by a predetermined coefficient (usually 0.5 to 0.7) is set as the charge current Rapid charging is performed in the same manner as in. If the discharge current cannot be set automatically, charging is performed using the current value preset in the storage unit 40.

(3) Battery diagnosis mode In this mode, deterioration and abnormality of the secondary battery are diagnosed and judged. Diagnosis of deterioration and abnormality of the secondary battery is performed by storing the reference characteristic data initially held by the secondary battery and comparing it with the characteristic data measured after being used a plurality of times. Therefore, in this mode, the following two operations are performed.

A. Acquisition of initial performance data First, when the secondary battery to be used is new or is in a state similar to a new one after being used 2-3 times, connect the secondary battery to terminals 4 and 4'and specify it by the user. Charge and discharge under the conditions. In this process, the central processing unit 10
Measures characteristic data such as charge capacity, discharge capacity, terminal voltage at the time of completion of charging, voltage drop within a fixed time, voltage increase at the time of charging of the secondary battery, and stores it in the storage unit 40. . Since there are variations in the characteristics of each battery, these data are acquired for each battery and stored in the storage unit 40.
Stored in.

B. Diagnosis of Degradation of Battery Performance When diagnosing the performance of the secondary battery, the target secondary battery was connected to the terminals 4 and 4 ′, and the operation unit 30 specified the battery to be diagnosed and specified the charge / discharge conditions. Then, the diagnostic start button is pressed to start the diagnostic operation. When the diagnostic operation is started, the central processing unit 10 first charges the secondary battery under the designated conditions. However,
When the secondary battery has a remaining capacity, it is discharged as in the refresh mode and then charged. During this charging operation, the central processing unit 10 measures the charging current and the charging time to calculate the charging capacity, and also acquires the terminal voltage at the completion of charging. Then, the central processing unit 10
Causes the secondary battery, which has just been charged, to be discharged under the condition specified by the user. Also at this time, the discharge current and the discharge time are measured to calculate the discharge capacity.

After charging / discharging for one cycle in this way, the central processing unit 10 stores from the storage unit 40 the initial performance data, which is the reference of the secondary battery stored in the storage unit 40 according to the above a. The data is read out and compared with the data acquired by this one-cycle charge / discharge operation. As the charging and discharging capacity of the secondary battery is repeated, the charging capacity and discharging capacity gradually decrease.Compare the charging capacity and discharging capacity in the initial state with the charging capacity and discharging capacity after multiple uses. Thus, the degree of deterioration can be known. Further, when the secondary battery deteriorates, its internal resistance rises and the terminal voltage during charging rises. Therefore, the degree of deterioration can also be determined by comparing the terminal voltages during charging. Therefore, the central processing unit 10
Judges the quality of the secondary battery using these data. The result is displayed on the display unit 12. Note that this display form may be one in which the degree of deterioration is displayed in%, or when the deterioration state of the battery is expressed in a plurality of stages, the display shows which stage of the stages the battery is in. It may be in the form. Further, not only the judgment result but also the measured value may be displayed as it is.

In the above embodiment, the secondary battery 3
As an example, the NiCd battery or the NiMH battery has been described as an example. However, the present invention is not limited to this, and the charger of the present invention can be used in the case of a small sealed lead acid battery or an ion battery. .

In the above embodiment, a single chip microcomputer having a microprocessor, a program memory, an input / output port, a timer counter, an AD / DA converter, etc. on a single substrate is used as the central processing unit. However, it is not necessarily limited to this, and an ordinary microprocessor, ROM, RAM, AD
Obviously, a converter and a DA converter may be used.

Further, in the above embodiment, the -ΔV control method is adopted as the quick charging control method, but it is not limited to this and it is clear that any control method may be adopted. is there.

[0031]

According to the charger of the present invention, a function is provided to judge the degree of deterioration or abnormality of the secondary battery that has been used a plurality of times. You can know what kind of condition it is and you can use it with confidence.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a charger with a diagnostic function of the present invention.

FIG. 2 is a diagram showing charging characteristics of a NiCd battery and a NiMH battery.

FIG. 3 is a diagram showing a process of determining a discharge current value in the present invention.

FIG. 4 is a diagram showing discharge characteristics of a NiCd battery and a NiMH battery.

[Explanation of symbols]

1 Quick Charger with Diagnostic Function 2 DC Power Supply 3 Secondary Battery 4, 4 ', 5, 5'Terminal 10 Central Processing Unit 11, 12, 13, 14, 15, 16, 17, 18 Port 19 Power Supply Terminal 20 Display 30 Operation Section 40 Storage Section 50 DC / DC Converter 60 Discharge Control Transistors 70, 80 Resistor 90 Voltage Stabilizing Circuit

Claims (2)

[Claims] 1. A charger for charging a secondary battery, comprising: storage means for storing reference data regarding characteristics of the secondary battery, means for measuring data regarding characteristics of the secondary battery, and the measuring means. A charger with a diagnostic function, comprising: means for comparing the measured data with the reference data to determine the quality of the secondary battery; and means for displaying the determination result by the determining means. 2. A second measuring means for measuring reference data concerning characteristics of the secondary battery, and a means for storing reference data concerning characteristics of the secondary battery measured by the second measuring means in the storage means. The charger with a diagnostic function according to claim 1, further comprising: