JPS5926905B2 - Storage battery remaining capacity detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device suitable for detecting the remaining capacity of a storage battery. Through a differential amplifier circuit that detects the terminal voltage that recovers after being discharged, an amplification degree that is preset from the characteristic curve shown by the storage battery depending on whether the storage battery has been in the charging process or the discharging process is obtained. Two operational amplifier circuits are connected in parallel, and a display device is connected to the output terminal of this operational amplifier circuit via a changeover switch, and this changeover switch is connected between the differential amplifier circuit and one terminal of the storage battery. The storage battery is provided to be switched and controlled by one of the signals of the comparison detection circuit which discriminates whether the storage battery is in the charging process or the discharging process, and the battery is discharged at a constant current by the constant current discharge circuit. A changeover switch is controlled by a comparison detection circuit for the terminal voltage of the storage battery that is later recovered, and a display device is activated in response to a command from either one of the operational amplifier circuits to detect and display the remaining capacity of the storage battery.

Traditionally, the remaining capacity of a storage battery has been detected by measuring the specific gravity of the electrolyte in the storage battery, or by detecting the amount of electricity used with a coulomb meter and subtracting this value from the nominal capacity of the storage battery to determine the remaining capacity. There are methods to detect the remaining capacity based on the terminal voltage drop during discharge, but the detection method based on specific gravity requires measurement for each cell, which requires considerable effort for multi-cell storage batteries. Moreover, it cannot be applied to anything other than lead-acid batteries.

In addition, the method using a coulomb meter requires complicated equipment;
Moreover, it must always be installed in the storage battery, making it impossible and uneconomical to measure a large number of storage batteries with one detection device. Furthermore, the method based on the terminal voltage drop during discharge has the disadvantage that the load conditions are not constant and the indicated value fluctuates greatly, making accurate measurement difficult. In order to improve these problems, the storage battery to be measured is heated for 5 seconds at IC level (the unit of current is attached to a multiple of the numerical value (anonymous number) representing the nominal capacity. If the nominal capacity is 100 Ah, for example, 100
The so-called 5-second voltage measuring method is used, which discharges with a large current of about 100 A) and measures the terminal voltage at the end (after 5 seconds) to statistically estimate the capacity. This method causes a problem of heat generation due to the flow of a large current, and cannot be applied to large-capacity storage batteries.Furthermore, it causes errors due to the resistance of the measurement lead wires, and also makes it difficult to determine whether the state before measurement was charging or discharging. There is no way to tell the difference, and as a result, measurement errors are large.In some older storage batteries, the discharge characteristics do not shift in parallel, making it impossible to determine the state of deterioration. Further, since the influence of specific gravity cannot be removed, the error is large, and there are also problems in that the measurement results vary greatly due to differences in measurement timing, for example, differences in the length of time the device is left unloaded. The purpose of the present invention is to reduce the measurement current for detecting the remaining capacity to suppress heat generation and to make it applicable to large capacity storage batteries. It is an object of the present invention to provide a storage battery remaining capacity detection device that eliminates errors and reduces differences in measurement results due to differences in measurement timing.

These and other objects and features of this invention,
The benefits will become clearer from the detailed description and drawings below.

Therefore, in view of the above object, in the present invention, the terminal voltage when the storage battery is discharged into a constant current circuit for a predetermined period of time (for example, 5 seconds) and the terminal voltage recovered after a certain period of time (for example, 250 milliseconds) after the discharging is stopped. By measuring the difference between the terminal voltages and comparing the terminal voltages with a predetermined standard, the remaining capacity of the storage battery is detected from the relationship between the current and hour product.

Now, the discharge characteristic when a storage battery is continuously discharged at a constant current is generally known as curve A shown in FIG.

This discharge characteristic curve A shows that the electromotive force E in the initial state (t=o) of the storage battery is activated by a decrease in electromotive force E due to a decrease in specific gravity, a resistance overvoltage η due to internal resistance, and a reaction in the charge transfer process. It can be seen that this is a characteristic that changes over time depending on various factors such as the overvoltage η2 and the diffusion overvoltage ηd, which is dominated by the diffusion of ions involved in the reaction from the pores of the electrode plate to the reaction surface. Of the above factors, it is known that the decrease in electromotive force E and the resistance overvoltage η due to a decrease in specific gravity change linearly with time, and that their effects are generally small. It is also known that the diffusion overvoltage η2 and the diffusion overvoltage ηd are particularly dominant. Therefore, if the curve of the electromotive force E in the initial state is D, the curve C is a characteristic due only to the decrease in the electromotive force E due to a decrease in specific gravity, and the curve B is a characteristic due to the resistance overvoltage η, and the electromotive force E due to a decrease in specific gravity. This curve B is a characteristic dominated by a decrease in
activation overvoltage η. The discharge characteristic curve A is obtained by adding the diffusion overvoltage ηd. Therefore, in FIG. 1, if the remaining capacity is CR, the remaining capacity CR is the time T from an arbitrary time Tx until reaching the discharge end voltage Ve.
. Since this is the time product of the constant current 1 until 1, it can be said to be -in.

In the above equation (1), the terminal voltage Vx at any time Tx is the time T. Since it relates to the history from Tx to Tx, it can be considered that it is related to the internal state of the storage battery, that is, the internal resistance, the activity of the active material, and the diffusion of ions in the electrolyte. Also, as shown in Fig. 2, when the storage battery is discharged at a constant current for t1 time (for example, 5 seconds), the terminal voltage after t1 time is VL, and after discharging is stopped, T2 time (for example, 250 milliseconds) is set. If the terminal voltage in the subsequent recovery process is VH, the current is considered to be zero since this terminal voltage H is under no load, and the resistance overvoltage η, and the transient overvoltage η3
and the diffusion overvoltage ηd can be considered to be zero. That is, the terminal voltage H can be expressed as.

On the other hand, the terminal voltage L after the initial period t1 can be seen as a voltage dominated by the resistance overvoltage η, the activation overvoltage η8, and the diffusion overvoltage ηd. That is, the terminal voltage L can be expressed as follows.

Therefore, in equations (2) and (3) above, if T2 time is set to a short time (for example, 250 milliseconds), it is thought that there will be almost no change in the specific gravity of the electrolyte in the pores of the electrode plate. , the electromotive forces EH and EL can be considered to be approximately equal (EHZEL), and the difference voltage d(V
H-L) (hereinafter referred to as recovery voltage) is determined by (2) above, (
3) It becomes better. That is, the recovery voltage d is the resistance overvoltage η,
is the sum of the activation voltage η8 and the diffusion overvoltage ηd, which can be regarded as an apparent internal resistance. The relationship between this recovery voltage Va and time t is a characteristic that shows the difference between curve C and curve A in Figure 1, and when shown in Figure 3, it is expressed by the relational expression t = f (Vd). Since rain can occur, the time Tx in equation (1) above is Tx=f(Vd)
Then, the remaining capacity CR can be transformed from the above equation (1) as follows. In the above equation (5), I and tO are constant, so the remaining capacity CR can be detected by measuring the recovery voltage d. Becomes powerful and capable.

However, as shown in equation (4) above, the recovery voltage d can be regarded as the apparent internal resistance and is the sum of the resistance overvoltage η, the activation overvoltage η2 and the diffusion overvoltage ηd, but the The concentration distribution of ions involved in the reaction inside the battery differs depending on the conditions in which the battery is placed. For example, if the conditions before measurement were in the charging process, the concentration of ions involved in the reaction in the pores of the electrode plate will vary depending on the electrolyte phase. higher than the concentration,
On the other hand, if the conditions before measurement were in the discharging process, the opposite would be true, as shown in Figure 6. Therefore, even if the remaining capacity of the storage battery is the same, if the conditions before measurement were in the charging process, the reaction surface would flow from inside the pores. Because the diffusion rate of ions involved in the reaction is in the opposite direction to the electrolyte phase, it is slower than when the conditions before measurement were during the discharging process, so the conditions before measurement were during the charging process. The diffusion overvoltage ηd is larger than that during the discharge process, and the recovery voltage Vd is also larger, and this recovery voltage V
d and remaining capacity CR. As shown in Figure 4, the relationship between
It has been confirmed that there is approximately a linear approximation up to 00%. Therefore, the remaining capacity CR can be detected from the recovery voltage Vd by distinguishing and correcting whether the storage battery was charging or discharging before measurement based on this characteristic. Therefore, in order to distinguish this, the recovery voltage Vd and t
As shown in Figure 5, the relationship with the terminal voltage VL of the storage battery after constant current discharge for 1 hour (for example, 5 seconds) is approximately linear from the terminal voltage VLl to VL2 if the state before measurement is in the charging process. It has been confirmed that during the discharging process, the voltage changes almost linearly from VL, which is a value smaller than the terminal voltage VLl, to L2. Therefore, first, the terminal voltage VL after constant current discharge for t1 time (for example, 5 seconds) is VL
By comparing whether it is larger or smaller than L and VL2, it is determined that if it is larger than VL2, it is in the charging process, and if it is smaller than L1, it is in the discharging process, and furthermore, the terminal voltage V
For discrimination within the region shown between Ll and L2, the values of the recovery voltages Vd corresponding to VLl during the discharging process and VL2 during the charging process are compared to see if they are larger or smaller than the preset Vdl level. By doing so, if the value is large, it means that the charging process has occurred, and if it is small, it is determined that the discharging process has occurred, thereby making it possible to determine which of the charging and discharging processes the state before measurement was in. This work was done by focusing on the point that the remaining capacity of the storage battery can be detected from the recovery voltage Vd by distinguishing the state before measurement and converting and detecting the linear slope according to the characteristics shown in FIG. 4 mentioned above. Hereinafter, the embodiment will be explained with reference to FIG. 7. 1 is the storage battery to be measured, 2 is the storage battery 1
A constant current discharge circuit is connected between the terminals of a resistor through a semiconductor switching element 3 consisting of a transistor, etc., and is configured to control a resistor and the current flowing through this resistor so that a constant current flows. By closing the switching element 3 for a predetermined period of time, the storage battery 1 is discharged by the constant current discharge circuit 2. Reference numeral 4 denotes an operational amplifier circuit connected to the P terminal of the storage battery 1. The operational amplifier circuit 4 is composed of an amplifier and converts the terminal voltage B of the storage battery 1, which drops due to constant current discharge for a predetermined period of time (for example, 5 seconds), into the storage battery 1. The difference (VB-Vs) between the discharge end voltage and the set reference voltage Vs is operationally amplified.

5 and 6 are memory circuits connected in parallel to the output terminal of the operational amplifier circuit 4, which are composed of a capacitor, a high input impedance amplifier, etc. The opening/closing of the input terminal is controlled by the output signal sent out, and the output voltage of the operational amplifier circuit 4 is stored by a capacitor, and the output voltage is supplied to the next stage.

Therefore, the memory circuit 5 has a constant current discharge time t shown in FIG.
The input terminal is opened in synchronization with the switching element 3, which receives the output voltage of the operational amplifier circuit 4 for a period of T, and is opened by the output signal of the timer circuit 7 after T, and stores the terminal voltage L. On the other hand, the memory circuit 6 closes its input terminal at the same time as the memory circuit 5, and the constant current discharge time t1 and the discharge stop to T2.
After the elapse of time, that is, after t1+T2 time, the input terminal is opened by an output signal sent from the time limit circuit 7, and the terminal voltage VH of the storage battery 1 in the recovery process is stored. Further, the time limit circuit 7 is connected to the constant voltage power supply device 1 as shown in FIG.
A series circuit of a starting switch SWl and a resistor R1 and a series circuit of a capacitor C1 and a resistor R2 are inserted in parallel between the starting switch SWl and the resistor R1, and the connection point of the starting switch SWl and the resistor R1 is connected to the S of the NOR circuit NORl. Connected to the input terminal, and a NOR circuit NOR2 is connected to the connection point of the capacitor C1 and resistor R2.
The 9R input terminals of the NOR circuit NOR and NOR2 are connected to each other's input terminals to form a reset flip-flop circuit.
The output terminal of OR2 is connected to one input terminal of the NOR circuit NOR3 via a NOTl circuit, and is also connected to the other input terminal of the NOR circuit NOR3 via a CR delay circuit consisting of a resistor R3 and a capacitor C2. The output terminal of this NOR circuit NOR3 is connected to one input terminal of each of the NOR circuits NOR4 and NOR5, and also connected to the gate of the switching element 3, and the output terminal of the NOR circuit NOR4 and NOR5 is connected to the other input terminal of the NOR circuit NOR4 and NOR5. Connect the output terminal of the Noah one circuit NORl to the terminal, and connect the output terminal of the Noah one circuit NOR1.
The output terminal of No. 4 is connected to the memory circuit 5 through the NOT circuit NOT2, and the input terminal of the memory circuit 5 is controlled to open/close by the output signal sent through the NOT circuit NOT2.
The output terminal of the above NOR circuit NOR5 is connected to the NOR circuit NO through a CR delay circuit consisting of a resistor R4 and a capacitor C3.
The output terminal of this NOT circuit NOT3 is connected to the above-mentioned memory circuit 6, and the input terminal of the memory circuit 6 is controlled to open and close by the output signal sent through the above-mentioned NOT circuit NOT3. 8 is the memory circuit 5 and 6 mentioned above.
A differential amplifier circuit connected to the output terminal of the differential amplifier, which is configured with a differential amplifier, operationally amplifies the difference between the input voltages H and VL (VH - VL), and sends out the recovery voltage Vd as an output. There is.

Reference numeral 9 denotes a comparison detection circuit connected to the output terminals of the memory circuit 5 and the differential amplifier circuit 8, which discriminates which state of the charging/discharging process the storage battery 1 was in before the measurement shown in FIG. 1,
Is it configured so that the second and third discrimination circuits and the output signals of these discrimination circuits are discriminated based on logical conditions and the relay is actuated? is connected in parallel to the output terminal of the differential amplifier circuit 8 by a changeover switch 10 that opens and closes in conjunction with the relay of the comparison and detection circuit 9, and is connected in parallel to the output terminal of the differential amplifier circuit 8 to detect different amplification degrees, that is, the storage battery 1 before measurement as shown in FIG. The output terminals of the operational amplifier circuit 11 for the discharging process and the operational amplifier circuit 12 for the charging process, which are configured by amplifiers each having an amplification degree set from a linear approximation equation in the characteristics of the charging and discharging process, are controlled to open and close. It is provided.

As shown in FIG.
1 is connected to compare the input with the reference voltage L1.
A first discrimination circuit 9a to which the non-inverting input terminal of MPl is connected, and a reference voltage setting circuit VS to the non-inverting input terminal.
Comparator CO which connects 2 and compares the input with reference voltage L2
A second discrimination circuit 9b is connected to the inverting input terminal of MP2, and a reference voltage setting circuit VS3 is connected to the non-inverting input terminal of the differential amplifier circuit 8 to set the input to the reference voltage. A third discrimination circuit 9C is provided which connects the inverting input terminal of the comparator COMP3 to be compared with Vdl, and one output terminal of the comparator COMP1 of the first discrimination circuit 9a is connected to the One circuit 0R1 is connected to the output terminal of the comparator COMP2 of the second discrimination circuit 9b, and the other is connected to the AND circuit ANDl connected to the output terminal of the comparator COMP2 of the second discrimination circuit 9b. AND circuit AND connected to the output terminal of the device COMP3
2 to the above OR circuit 0R1, and insert a relay X between the output terminal of this OR circuit 0R1 and the ground.
is energized, and is de-energized when it is at the JlLl level, thereby controlling the opening and closing of the changeover switch 10.
A display device 13 is connected to the output terminals of the operational amplifier circuits 11 and 12 via a changeover switch 10, and is composed of a meter such as a DC voltmeter. (%CR).

Note that the display device 13 may be configured to display digitally via an analog-to-digital conversion circuit instead of displaying the scale.

The present invention is constructed as described above, and its remaining capacity detection operation will be explained with reference to FIGS.
Since the potential difference across the capacitor C1 when C1 receives the power supply voltage Cc of the constant voltage power supply 14 is zero, the input terminal R of the NOR circuit NOR2 is 1! It receives an input of Hll level and its output becomes 11L0 level.

This 1WL1 level output is sent to the input terminal of the NOR circuit NORl, and the input terminal S of this NOR circuit NOR.
Since the start switch SWl is open, it receives an input at the 11L1 level, so the output of the NOR circuit NORl becomes the 11H]V level. In addition, the above Noah circuit NO.
The input to the input terminal R of R2 is 11H when the power supply voltage Cc is applied! V level, but as the capacitor C1 starts charging, it becomes 1゛Ll゛ level, so even if it receives the 1H1V level output of the above NOR circuit NORl, the output of the NOR circuit NORl is held at the 11L1 level and reset. SET Flip-flop circuit is in reset state. Therefore, the outputs of the Noah circuits NOR4 and NOR5, which received the 1H1 level output of the Noah circuit NORl, are 1.
! The NOT circuit that received this became Lll level.
The 15H1 level output is sent to the memory circuits 5 and 6 via the terminals 2 and NOT3, and the input terminals of the memory circuits 5 and 6 are closed. On the other hand, the output of the NOT circuit NOTl which receives the 11L11 level output of the NOR circuit NOR2 becomes the 1H1 level, and the output of the NOR circuit NOR3? Since the signal reaches the 1L1 level and is sent to the gate of the switching element 3, the switching element 3 is in a non-conductive state. In this state, when the start switch SW is turned on, the input terminal S of the NOR circuit NORl receives an input at the 33H'1 level, and the output of the NOR circuit NORl is? WLl
level and sends it to the NOR circuit NOR2, so the output of the NOR circuit NOR2 becomes the 11H1 level. That is, the reset flip-flop circuit is in the set state. So, 7WH of the above-mentioned Noah circuit NOR2? Is the output of NOTl, which receives an output of L level, 1L? l
It is sent out as a level. This IlLf! Since the other input of the NOR circuit NOR3 which received the level output is also at the 1L'' level at this point, its output becomes the 1H11 level and is sent to the gate of the switching element 3, making the switching element 3 conductive. , Noah one circuit NO
One circuit NOR is generated by the 1VH11 level output of R3.
4 and one input of NOR5 is 11 from the VlLO level.
Hq1 level is reached, but the other input is NOR1
Since it receives the output of 11L1 level, its output is 1.
Lv? held at the level.

Due to the conduction of this switching element 3, the constant current discharge circuit 2
is connected between the terminals of the storage battery 1, and the storage battery 1 starts constant current discharge. From the start of this discharge, the preset t
1 hour (for example, 5 seconds), that is, the time limit circuit 7's Noah 1 circuit N
The capacitor C2 charged via the resistor R3 by the 1H1 level output of OR2 brings one input of the NOR circuit NOR3 to the FWHL level in a time period determined by the time constant of CR (T, time shown in Figure 2). Therefore, the corresponding Noah circuit N
The output of OR3 becomes 1L1 level and is sent to the gate of switching element 3, so switching element 3 becomes non-conductive, stopping constant current discharge of storage battery 1, and
t]L1 level output of the above NOR circuit NOR3 makes both inputs of the NOR circuit NOR4 and NOR5 13Lt'
The output becomes 8H1 level, and the NOT circuit receiving this changes the output to 1H? 1 to 1L1 level, the input terminal of the storage circuit 5 was opened, and the terminal voltage VB of the storage battery 1, which drops through the differential amplifier circuit 4 during constant current discharge, was received as a differential voltage from the reference voltage Vs. The memory circuit 5 stores the terminal voltage VL when the discharge is stopped. On the other hand, both inputs of the NOR circuit NOR5 go to the 11L1 level as described above, and the output changes from the 71L1 level to the 1H1 level, but for a time limit determined by the CR time constant of the resistor R4 and the capacitor C3, that is, the time T2 shown in FIG. 2 (for example, 250 milliseconds), the input terminal of the memory circuit 6 maintains the closed circuit state, and when the time T2 elapses,
When the input of the NOT circuit NOT3 reaches the 11H1 level, its output becomes the ``3L1 level'' and the input terminal of the storage circuit 6 is opened, and the terminal voltage of the storage battery 1 recovers after the discharging is stopped via the operational amplifier circuit 4 as described above. The memory circuit 6, which was receiving the voltage difference between B and the reference voltage s, receives the terminal voltage V during the recovery process.
Remember H. The differential amplifier circuit 8, which receives the terminal voltages VL and -VH stored by the memory circuits 5 and 6 as output signals, operationally amplifies and recovers the difference (H-VL) between both inputs (VH, VL). The voltage Vd is sent to the comparison detection circuit 9 as an output signal. A comparison detection circuit 9 receiving the output signals of the memory circuit 5 and the differential amplifier circuit 8 is a comparator of the first and second discrimination circuits 9a and 9b receiving the output signal (VL) of the memory circuit 5. COMPl and COMP2 are the inputs (
L) are compared with reference voltages VLl and VL2, respectively, and when it is smaller than the reference voltage VLl, the comparator COMPl of the first discrimination circuit 9a sends an output of 1L11 level to the NOT circuit NOT4 and the AND circuit ANDl, and The received NOT circuit NOT4 sends a 1H8 level output to the relay X via the OR circuit 0R, which excites the relay
The output terminal of the operational amplifier circuit 11 connected in parallel with the output terminal of the operational amplifier circuit 11 is switched and connected to the display device 13, and the display device 13 is caused to respond to the output of the operational amplifier circuit 11 to display the remaining capacity CR of the storage battery 1. That is, as shown in FIG. 5, when the output signal (L) of the memory circuit 5 is smaller than the reference voltage L1, the first discrimination circuit 9a determines that the state of the storage battery 1 before measurement was in the discharging process. The output end of the operational amplifier circuit 11 for the discharge process is then connected to the display device 13. At this time, 11L of the comparator COMPl of the first discrimination circuit 9a
The AND circuit ANDl which receives the 11 level signal has the other input terminal connected to the 1H of the comparator COMP2 of the second discrimination circuit 9b.
Since it receives an output of 11 level (that is, the input is smaller than the reference voltage VL2), the output of the AND circuit AND becomes 1L1 level. Further, the comparator COIVl) 3 of the third discrimination circuit 9c also receives the output signal (Vd
), so when compared with the reference voltage Vdl, if it is higher than the reference voltage d1, 1L1! level output and both inputs of the AND circuit AND2 are at the 11L1W level, so the output is T2HF? Becomes a level OR circuit 0R
Relay X will be energized via 1, but since relay If the input (Vd) of the comparator COMP is smaller than the reference voltage Vdl, the output will be at the 1H11 level, so the output of the AND circuit AND2 will be at the 'L'1 level. This completes the discrimination when it is smaller than VLl in FIG. Also, the output signal (VL) of the memory circuit 5 is output from the comparator COMP.
When the voltage is higher than the reference voltage VLl due to l, the output is 1H.
Since the input to the OR circuit 0R1 received via the NOT circuit NOT4 is at the 11L1 level, the relay X is not excited. On the other hand, when it is smaller than the reference voltage VL2 of the comparator COMP2 of the second discrimination circuit 9b, the output of the comparator COMP2 becomes the WTHff level, and the AND circuit ANDl outputs 31L1! ' level output is sent to the AND circuit AND2, and when the input is small with respect to the reference voltage d1 of the comparator COMP3 of the third discrimination circuit 9c, it becomes the 11H11 level, so the AND circuit AND2
The output becomes 11H15 level and excites the relay X via the OR circuit 0R1 to actuate the changeover switch 10 and connect the output end of the operational amplifier circuit 11 to the display device 13.

At this time, when the comparator COMP3 receives the output signal (Vd) of the differential amplifier circuit 8 which is higher than the reference voltage D, its output becomes 1Lv1 level, so the output of the AND circuit AND2 is ! The level remains at 1L1 and relay X is not energized. That is, the output terminal of the operational amplifier circuit 12 for charging process is connected to the display device 13 via the changeover switch 10, and the display device 13 responds to the output of the operational amplifier circuit 12 and displays the remaining capacity CR. Furthermore, an input (L
) is received from the memory circuit 5, it becomes larger than the reference voltage L1 of the comparator COMPl of the first discrimination circuit 9a, so the output of the comparator COMPl is ! 1H1 level and the input of the OR circuit 0R1 via the NOT circuit NOT4 becomes t.
! Since it is at L1 level, relay X is not energized. On the other hand, since it is larger than the reference voltage L2 of the comparator COMP2, its output becomes the QlLl level, and the output of the AND circuit ANDl becomes 5L8, and the comparator COM of the third discrimination circuit 9c
The output of P3 is 1Hv1 when it is smaller than the reference voltage D.
The output of the AND circuit AND2 is at the 71L1 level, so the relay X is not energized. At this time, when the voltage is higher than the reference voltage Vdl, the output of the comparator COMP3 becomes the Q7Lll level, so the output of the AND circuit AND2 becomes the 8L11 level, and the relay X is not excited. That is, it is determined that the storage battery 1 before measurement was in the charging process. Simultaneously with the discrimination operation of the comparison detection circuit 9, the operational amplifier circuits 11 and 12 output the output signal (V
d), the operational amplifier circuit 11 receives the input (d) and calculates the difference from the reference voltage D52, and also sets the voltage according to the characteristics when the state before measurement is in the discharge process as shown in Fig. 4. On the other hand, the operational amplifier circuit 12 calculates the difference from the reference voltage D8l, and as described above, performs amplification according to the amplification degree set according to the characteristics of the charging process shown in FIG. By controlling the opening/closing of the changeover switch 10 by the switch 9, the display device 1 is changed depending on the state of the storage battery 1 before measurement.
An operational amplifier circuit 11 or 12 is selectively connected to 3, and the output thereof causes a display device 13 to respond, thereby displaying the remaining capacity CR of the storage battery 1. As described above, the present invention uses, as an output signal, the difference voltage between the terminal voltage of the storage battery that drops by discharging the storage battery at a constant current for a predetermined period of time and the terminal voltage that recovers after discharging is stopped, so that the storage battery can be charged or discharged before measurement. The output signal of the above-mentioned difference voltage is operationally amplified according to the charge/discharge process of the storage battery before measurement via a changeover switch that is controlled to open or close by a comparison detection circuit that discriminates which process the battery is in. The output terminals of two operational amplifier circuits with Since only a small current is required, heat generation due to discharge is suppressed, and it can be applied to large-capacity storage batteries.Furthermore, the remaining capacity is detected by the terminal voltage recovered after discharging has stopped, making it suitable for measurement. Errors due to lead wire resistance and contact resistance are of course reduced, and since correction is made according to the state of the storage battery before measurement, measurement errors are also reduced and accuracy can be improved. In addition, since the apparent internal resistance is measured, it can be closely related to the remaining capacity of the storage battery.Furthermore, the deterioration status of the storage battery can also be determined because it corresponds to the terminal voltage during the recovery process, and it is possible to determine the timing of measurement. Since it is not affected by differences, it has remarkable effects such as being able to further improve the reliability of measurement results.

[Brief explanation of the drawing]

Figure 1 is a constant current discharge characteristic diagram of the storage battery, Figure 2 is a characteristic diagram showing the recovery process of the terminal voltage of the storage battery after constant current discharge, and Figure 3 is a characteristic diagram showing the recovery process of the terminal voltage of the storage battery after constant current discharge.
The figure is a characteristic diagram showing the relationship between recovery voltage and time, Figure 4 is a characteristic diagram showing the relationship between recovery voltage and remaining capacity, and Figure 5 is a characteristic diagram showing the relationship between recovery voltage and terminal voltage of the storage battery when discharging is stopped. Characteristic diagram, Figure 6 is an explanatory diagram of the ion concentration distribution involved in the reaction,
FIG. 7 is a block diagram showing an embodiment of the present invention, FIG. 8 is a circuit diagram showing an embodiment of the time limit circuit of the present invention, and FIG. 9 is a circuit diagram showing an embodiment of the comparison detection circuit of the present invention. . 1: Storage battery, 2: Constant current discharge circuit, 3: Switching element, 5, 6: Memory circuit, 7: Time limit circuit, 8: Differential amplifier circuit, 9: Comparison detection circuit, 10: Changeover switch, 11, 1
2: operational amplifier circuit, 13: display device.

Claims (1)

[Claims] 1. A constant current circuit is connected between the terminals of the storage battery via a switching element, and one end of the storage battery is connected to the terminal voltage when the storage battery is discharged by the constant current discharging circuit, and the terminal voltage after a certain period of time after discharging is stopped. Two operational amplifier circuits having different amplification degrees are connected in parallel through a differential amplifier circuit that operationally amplifies the voltage difference between the terminal voltage and the terminal voltage. A display device is switchably connected to one end of the display device via a changeover switch controlled by a signal from a comparison and detection circuit connected to one end of the storage battery and configured to discriminate which stage of charging and discharging the storage battery is in;
A remaining capacity detection device for a storage battery, characterized in that the remaining capacity of the storage battery is detected based on the terminal voltage recovered after the storage battery discharges a constant current.