JP2005086867A - Charging control system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a charging control system which conducts a cell balance operation without heating or energy loss of a bypass circuit and at a low cost. <P>SOLUTION: The charging control system charges a capacitor 11 by turning ON any one of switches 7-1 to 7-4, connected to a single cell to be conducted at a voltage measuring time by a microcomputer 6, and allows to measure the voltage of the single cell to be measured by the microcomputer 6, by turning ON the switch 9 to connect the capacitor 11 with the microcomputer 6. At the charging time, a switch 8 is turned ON, the switch connected to the single cell to be charged of the switches 7-1 to 7-4 is controlled to be turned ON, and each single cell is charged to a constant voltage, by switching the same charging power supply 12. The voltage measurement and charging are conducted for 25 ms per single cell. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a charge control system, and more particularly to a charge control system that charges an assembled battery in which a plurality of secondary batteries are connected in series.

  Conventionally, in order to charge an assembled battery in which a plurality of secondary batteries are connected in series, a charge control system that measures the voltage of each secondary battery and charges the battery in a balanced manner has been used. In particular, in a lithium ion battery with high energy density and consideration for overcharge, voltage detection of each secondary battery is indispensable in order to ensure safety. In addition, since the lithium ion battery cannot balance the cells by overcharging like the nickel metal hydride battery, if the state of charge between the secondary batteries differs, the capacity that can be charged and discharged as an assembled battery decreases. As a result of the different deterioration states of the secondary batteries, the life of the assembled battery is also shortened. Therefore, a cell balance function for aligning the state of charge between the secondary batteries is indispensable.

  For this reason, in the charging of a lithium ion battery, a technique is known in which a bypass resistor is connected in parallel with a single cell to perform a bypass discharge to align the state of charge, that is, a cell balance operation is performed (see, for example, Patent Document 1). ). In this technique, for example, as shown in FIG. 5, a bypass state is performed by using four series batteries to perform a charge state, and a bypass resistor 2 and a switching element 3 are connected to the unit cell 1. The voltage of the unit cell 1 is converted into a voltage having the negative terminal of the assembled battery as the ground using the differential amplifier 4, and the converted output is connected to the A / D converter input of the microcomputer 6 through the multiplexer 5. The port output of the microcomputer 6 selects an input channel of the multiplexer, that is, a single cell, and also serves as a control output of the switching element 3. The microcomputer 6 switches the open voltage of the single cell 1 while controlling the multiplexer at the time of system start-up, measures it with an A / D converter, calculates the remaining capacity calculated from the open voltage of the single cell 1, and calculates four single cells. The switching element 3 is controlled only for the capacity that is the difference from the minimum remaining capacity, and the bypass discharge operation is performed.

  In the battery pack, since the cells are connected in series, the A / D converter can directly measure the single cell voltage with high accuracy unless the power supply of the A / D converter is isolated and the measurement input is switched. For this reason, a voltage detection circuit has been used in which the ground terminal of the A / D converter is connected to the minus terminal of the lowest unit cell of the assembled battery and the voltage of the unit cell is converted to the ground terminal level (for example, Patent Document 2). reference). In such a voltage detection circuit, a voltage dividing circuit and a differential amplifier circuit are combined.

JP 2000-92732 A JP 2001-231177 A

  However, in the technique of Patent Document 1, since the bypass discharge is performed, the charging energy is lost due to heat, and a relatively large current is caused to flow through the bypass resistor. There is a problem that it becomes complicated and expensive.

  In addition, the technique of Patent Document 2 requires a high-precision resistor and an operational amplifier with a low offset voltage in order to ensure a voltage detection accuracy of about ± 50 mV. It was.

  An object of the present invention is to provide a low-cost charge control system while performing a cell balance operation without heat generation and energy loss of the bypass circuit in view of the above-described case.

  In order to solve the above-described problem, a first aspect of the present invention is a charge control system for charging an assembled battery in which a plurality of secondary batteries are connected in series, wherein each secondary battery is assigned to each secondary battery. A first power source for constant voltage charging, a first switch element group having one end connected to the + terminal of each secondary battery and the other end connected to the + terminal of the first power source, and one end connected to each A second switch element group connected to the negative terminal of the secondary battery and having the other end connected to the negative terminal of the first power source; and each secondary battery as the first power source for each secondary battery to be charged. Control means for sequentially controlling one switch element of each of the first and second switch element groups so as to be connected and charged.

  In the first aspect, each of the secondary batteries is the same because the control device sequentially controls each one switch element connected to the secondary battery to be charged in the first and second switch element groups. Since the first power source is switched and charged at a constant voltage, cell balance can be achieved without performing bypass discharge. Therefore, a cell balance operation without heat generation and energy loss of the bypass circuit can be realized.

  In order to solve the above-mentioned problem, a second aspect of the present invention is a charge control system for charging an assembled battery in which a plurality of secondary batteries are connected in series, wherein each secondary battery is a secondary battery. A first power source for charging at a constant voltage every time, a capacitor for detecting the battery voltage of each secondary battery, a voltage measuring circuit for measuring the battery voltage of each secondary battery, A first switch element group connected to the + terminal of each secondary battery, the other end connected to one end of the capacitor, one end connected to the-terminal of each secondary battery, and the other end of the capacitor A second switch element group connected to one end, a switch element having one end connected to one end of the capacitor and the other end connected to the positive terminal of the charging power supply, and one end connected to the other end of the capacitor The end is connected to the negative terminal of the charging power source. A third switch element having a switch element; a switch element having one end connected to one end of the capacitor and the other end connected to one end of the voltage measuring circuit; and one end connected to the other end of the capacitor and the other end A fourth switch element having a switch element connected to the other end of the voltage measurement circuit; and when measuring the voltage of each secondary battery, the secondary battery to be measured in the first and second switch element groups After each of the connected switch elements is turned on and the capacitor is charged with the battery voltage of the secondary battery to be measured, the switch element is turned off and the fourth switch element is turned on. Allowing measurement of the battery voltage of each of the secondary batteries by a voltage measurement circuit, and turning on the third switch element when charging each of the secondary batteries, Control means for controlling one switch element of each of the first and second switch element groups to be in an ON state so that a secondary battery is charged by being connected to the first power source for each secondary battery to be charged; Is provided.

  In the second aspect, when the voltage is measured by the control means, the capacitor is charged by turning on each one switch element connected to the secondary battery to be measured in the first and second switch element groups. When the fourth switch element is turned on, the voltage measurement circuit and the capacitor are connected to allow the voltage measurement circuit to measure the battery voltage of each secondary battery. The battery voltage of each secondary battery can be measured with a single voltage measurement circuit and capacitor, and costly components such as multiplexers are not required, so the charge control system can be reduced in cost and charged. Sometimes, the third switch element is turned on, and one switch element connected to the secondary battery to be charged is controlled to be turned on in the first and second switch element groups. To be, since the secondary battery is a constant voltage is switched first power same charge can take cell balance without bypass discharge. At this time, the control means may sequentially charge each secondary battery by switching between voltage measurement and charging for each secondary battery.

  In the first and second aspects, the battery pack further includes a second power source for charging the assembled battery, and the control circuit is further fully charged with respect to the assembled battery charged to the end of charging or near the end of charging with the second power supply. Until each of the first and second switch element groups is controlled to be turned on so that each secondary battery is charged by being connected to the first power source for each secondary battery to be charged, Since the entire assembled battery can be charged simultaneously with two power sources, the charging time can be shortened, and the cell balance of each secondary battery can be obtained from the end of charging or near the end of charging to full charging. The capacity of the power source can be reduced and the cost can be reduced.

  According to the first aspect of the present invention, each of the switch elements connected to the secondary battery to be charged in the first and second switch element groups is sequentially controlled to be turned on by the control means. Since the secondary battery is charged at a constant voltage by switching the same first power supply, it is possible to obtain an effect that cell balance can be achieved without performing bypass discharge.

  According to the second aspect of the present invention, at the time of voltage measurement, one switching element connected to the secondary battery to be measured in the first and second switching element groups is turned on by the control means. Since the capacitor is charged and the fourth switch element is turned on, the voltage measurement circuit and the capacitor are connected, and the measurement of the battery voltage of each secondary battery by the voltage measurement circuit is allowed. The battery voltage of each secondary battery can be measured with a single voltage measurement circuit and capacitor with the-terminal of the ground as a capacitor, and costly components such as multiplexers are unnecessary, so the cost of the charge control system can be reduced. At the time of charging, the third switch element is turned on, and one switch element connected to the secondary battery to be charged is selected from the first and second switch element groups. Since each secondary battery is controlled at a constant voltage by switching the same first power source, the cell balance can be obtained without performing bypass discharge. .

(First embodiment)
Hereinafter, a first embodiment in which the present invention is applied to a charge / discharge control system will be described with reference to the drawings.

  As shown in FIG. 1, a charge / discharge control system 20 according to the present embodiment includes a microcomputer 6 (hereinafter referred to as a microcomputer) that controls the entire charge / discharge control system 20 and a battery pack 2 connected in series. A charging circuit 12 (first power supply) for charging the secondary batteries (hereinafter referred to as single cells) 1-1, 1-2, 1-3, and 1-4 at a constant voltage for each single cell, A capacitor 11 for detecting the battery voltage of the battery and a plurality of switch elements formed of FETs or the like are included.

  One end of the switch element is connected to the positive terminal of the unit cell 1-1, and the other end of the switch element is connected to one end of the capacitor 11. One end of another switch element is connected to the negative electrode terminal of the unit cell 1-1, and the other end of the switch element is connected to the other end of the capacitor 11. These two switch elements constitute a switch 7-1. Similarly, switches 7-2, 7-3, between the unit cell 1-2 and the capacitor 11, between the unit cell 1-3 and the capacitor 11, and between the unit cell 1-4 and the capacitor 11, respectively. 7-4 is connected. Each of the switches 7-1 to 7-4 has a switch element group (first switch element group) in which one end is connected to the positive terminal of each unit cell and the other end is connected to one end of the capacitor 11, and one end of each unit cell. And a switch element group (second switch element group) having the other end connected to the other end of the capacitor 11 and functions as a pair of interlocking switches corresponding to each unit cell.

  Further, one end of the capacitor 11 is connected to one end of a switch element whose other end is connected to the + terminal of the charging power source 12, and the other end of the capacitor 11 is connected to the − terminal of the charging power source 12. It is connected to one end of another switch element. These two switch elements constitute a pair of interlocking switches 8 (third switch elements).

  Further, one end of the capacitor 11 is connected to one end of a switch element whose other end is connected to the microcomputer 6, and the other end of the capacitor 11 is connected to the ground of the assembled battery 1 (the negative terminal of the unit cell 1-4). Is connected to one end of another switch element connected to. These two switch elements constitute a pair of interlocking switches 9 (fourth switch elements).

  The microcomputer 6 includes a CPU that performs arithmetic processing, a ROM that stores a control program and a table that will be described later, a RAM that functions as a work area of the CPU, and an A / D converter as a part of a voltage measurement circuit that converts an analog voltage into digital. It is comprised including. The other ends of the two switch elements constituting the switch 9 are connected to the A / D input and the ground which are the input sides of the A / D converter of the microcomputer 6, respectively. Further, the microcomputer 6 has an output port for outputting a high level signal to the switch elements constituting the above-described switches 7-1 to 7-4, 8, and 9 and turning on these switches.

  Each unit cell uses a lithium ion battery using an amorphous carbon material as a negative electrode active material and a manganese-containing complex oxide as a positive electrode active material. The rated voltage of each unit cell is 3.6 V, The rated capacity is 1000 mAh. The charging power supply 12 is limited to 4.2V, 4A.

  Next, the charging operation of the charge / discharge control system 20 of the present embodiment will be described with the CPU of the microcomputer 6 as a main component. In the initial state, all of the above-described switch elements are in an off state.

  The CPU outputs a high level signal to the output port connected to the switch 7-1 for a predetermined time (for example, 1 ms), turns on the switch 7-1, and then the output port connected to the switch 7-1. The output signal is set to low level and the switch 7-1 is turned off. Thereby, the battery voltage (open voltage) of the unit cell 1-1 is applied (charged) to the capacitor 11.

  Next, a high level signal is output to the output port connected to the switch 9 to turn on the switch 9, and the voltage across the capacitor 11 converted into a digital voltage by the A / D converter is used as the battery of the cell 1-1. The voltage is taken in, the output signal of the output port connected to the switch 9 is set to low level, and the switch 9 is turned off. In the initial state, the RAM has a relation table (or relational expression) between the open voltage (OCV) and the state of charge (SOC) of the unit cell, and calculates the state of charge of the unit cell 1-1 based on the acquired battery voltage. Then, it is determined whether or not the unit cell (unit cell 1-1) for voltage measurement is in a fully charged state. The operation time during this period is also set to 1 ms. Capacitor 11 is set to have a capacity so that the residual charge is reduced by the operation of the A / D converter.

  When the unit cell 1-1 is not fully charged, the switches 7-1 and 8 are turned on via the output port, and the unit cell 1-1 and the charging power source 12 are connected. Thereby, the unit cell 1-1 is charged at a constant voltage by the charging power source 12. The charging time is set to about 23 ms. When the charging time elapses, the switches 7-1 and 8 are turned off, the switch 9 is turned on, the charge charged in the capacitor 11 is released from the A / D input to the ground in the microcomputer 6, and the switch 9 is turned off. Similarly, voltage measurement and charging are performed on the unit cells 1-2, 1-3, and 1-4, and when the unit cell 1-4 is charged, the same operation is performed again from the unit cell 1-1. . Note that the CPU ends voltage measurement and charging for each unit cell in 25 ms, and performs voltage measurement and charging for the next (lower) unit cell.

  On the other hand, when the target cell (for example, the cell 1-1) is fully charged, the target cell is not charged in order to ensure safety against overcharging, and the next target cell (for example, Voltage measurement or charging is performed on the battery 1-2). The CPU ends the above charging routine when all the cells constituting the assembled battery 1 are fully charged. Table 1 below shows the operation of the switch controlled by the CPU.

  Next, the result of the charge test performed on the charge / discharge control system 20 of the present embodiment will be described. In this test, the battery pack 1 in which the charging capacities of the cells 1-1 to 1-4 were intentionally varied was prepared and the above-described charging routine was executed.

  FIG. 2 shows a characteristic diagram of the average voltage and average current of each unit cell during charging as a test result. As shown in FIG. 2, all the single cells were in a constant voltage state at the end of charging, and it was confirmed that charging was completed in a state where all voltages were aligned.

  As described above, in the charge / discharge control system 20 of the present embodiment, the switches 7-1 to 7- connected to the measurement target cell by the microcomputer 6 at the time of voltage measurement of the cells 1-1 to 1-4. 4 is turned on, the capacitor 11 is charged. When the switch 9 is turned on, the capacitor 11 and the microcomputer 6 are connected to allow the microcomputer 6 to measure the voltage of the unit cell to be measured. Is done. For this reason, the voltage of each single cell can be measured with one voltage measuring circuit in the microcomputer 6 and the capacitor 11 with the negative terminal of the assembled battery 1 as the ground, and costly parts such as a multiplexer are unnecessary. Cost reduction of the charge / discharge control system can be achieved.

  Further, in the charge / discharge control system 20 of the present embodiment, the switch 8 is turned on when the cells 1-1 to 1-4 are charged, and the unit to be charged among the switches 7-1 to 7-4 is charged. A switch connected to the battery is controlled to be in an ON state, and each cell is charged at a constant voltage by switching the same charging power source 12. For this reason, since the cell balance can be achieved without performing the bypass discharge as in the prior art, the bypass circuit becomes unnecessary, and the heat generation and energy loss of the bypass circuit do not occur. In addition, as shown in the test results (FIG. 3), the charging can be terminated in a state where all the voltages of all the single cells are prepared.

  Furthermore, in the charge / discharge control system 20 of this embodiment, voltage measurement and charging are performed in a short time of 25 ms per cell. For this reason, even if the assembled battery 1 is suddenly discharged, the voltages of the individual batteries are almost the same, which causes a problem of capacity reduction and deterioration of the entire assembled battery 1 due to different charging states between the single batteries. There is nothing.

(Second Embodiment)
Next, a second embodiment in which the present invention is applied to a charge / discharge control system will be described. In the following embodiments, the same components as those in the first embodiment are denoted by the same reference numerals, description thereof is omitted, and only different portions will be described.

  As shown in FIG. 3, in the charge / discharge control system of this embodiment, a switch 10 composed of an FET or the like is inserted between the + terminal of the battery pack 1 (the positive terminal of the cell 1-1) and the terminal A. Has been. The switch 10 is normally in an on state, and is in an off state when a high level signal is output from the output port of the microcomputer 6. An assembled battery charging power source (second power source) for charging the assembled battery 1 at a constant voltage is connected between the terminals A and B.

  In this embodiment, when an assembled battery charging power source is connected between the terminals A and B, the CPU supplies each unit cell constituting the assembled battery 1 with the assembled battery charging power source in the vicinity of the end of charging (for example, 4.0 V). ), The switch 10 is turned off, and thereafter, as described in the first embodiment, the voltage measurement and charging by the charging power source 12 are performed for each cell, and charging is performed until the battery is fully charged. The determination of whether or not the assembled battery 1 has been charged to the vicinity of the end of charging by the CPU is performed by, for example, calculating the charging state of each unit cell before connecting the assembled battery charging power source, and connecting the assembled battery charging power source. Sometimes, the estimated charging time until the end of charging of the assembled battery 1 is calculated according to the charging state of each unit cell, and the switch 10 may be turned on during that time, or the switch 10 may be turned off every predetermined time. As an alternative, the open voltage of each unit cell may be measured to determine the state of charge of the battery pack 1.

  In the charge / discharge control system of the present embodiment, in addition to the effects of the charge / discharge system 20 of the first embodiment described above, each unit cell constituting the assembled battery 1 is simultaneously charged to the vicinity of the end of charging by the assembled battery charging power source. Therefore, the charging time for the whole cell can be shortened. Moreover, in the charge / discharge control system of this embodiment, since the cell balance of each single battery should just be taken between the end of charge and a full charge, the capacity | capacitance of the power supply 12 for charge and cost reduction can be achieved.

(Third embodiment)
Next, a third embodiment in which the present invention is applied to a charge / discharge control system will be described. In addition, this embodiment is an example of a charging / discharging control system when the assembled battery 1 of 1st Embodiment is connected in series.

  As shown in FIG. 4, the charge / discharge control system of the present embodiment includes a plurality of charge / discharge control systems 20 and a host control unit 30 that controls each charge / discharge control system 20.

  The host control unit 30 includes a CPU that performs high-speed arithmetic processing, a ROM that stores control programs and tables, a RAM that serves as a work area for the CPU, and the microcomputer 6 and the communication line 33 of each charge / discharge control system 20. It has a communication port for sending and receiving information. Correspondingly, a communication port is also provided in the microcomputer 6 of each charge / discharge system 20.

  The + terminal of the uppermost assembled battery 1 is connected to one end of the Hall element 31 for detecting whether the entire assembled battery 1 is in a discharged state, a charged state, or a resting state. The other end of the switch is connected to one end of a switch 32 composed of an FET or the like. The output side of the hall element 31 is connected to the host control unit 30. The other end of the switch 32 is connected to a terminal A that is a positive terminal of the assembled battery 1. The switch 32 is connected to the output port of the host control unit 30 and is controlled to be turned on or off by the CPU of the host control unit 30. Note that the switch 32 is normally in an on state, and is in an off state by the output of a high level signal from the output port of the host control unit 30. Further, the minus terminal of the lowest assembled battery 1 is connected to a terminal B serving as a negative electrode terminal of the entire assembled battery 1.

  Unlike the first embodiment, the microcomputer 6 of each charge / discharge control system 20 measures and charges the voltage of each unit cell constituting the assembled battery 1, and calculates the charge state of each unit cell from the measured voltage. The voltage of each unit cell measured via the communication line 33 is notified to the host control unit 30, and the host control unit 30 calculates the charge state of each unit battery constituting each assembled battery 1. It has been.

  The host control unit 30 monitors the output of the Hall element 31, and when the charging power source for charging the entire assembled battery 1 is connected between the terminals A and B, the entire assembled battery 1 is in a charged state. And whether or not the assembled battery 1 is fully charged is determined. When the determination is affirmative, the switch 32 is turned off to prevent overcharging, and when the determination is negative, the switch 32 is maintained in the on state.

  As described above, the upper control unit 30 grasps the charging state of each unit cell constituting each assembled battery 1, so that the estimated charging time during which each assembled battery 1 is charged to the vicinity of the end of charging by the charging power source. When the time has elapsed, the switch 32 is turned off. Thereby, the whole assembled battery 1 will be in a charging / discharging rest state. The host control unit 30 instructs the microcomputer 6 of each charge / discharge control unit 20 to measure and charge the voltage of each unit cell via the communication line 33. Thereby, each cell which comprises each assembled battery 1 is charged to full charge similarly to 1st Embodiment.

  In addition, the charging / discharging control system of 3rd Embodiment has an effect similar to the charging / discharging control system of 2nd Embodiment mentioned above. Further, the determination as to whether or not the assembled battery 1 shown in the second embodiment is in the vicinity of the end of charging and the on / off control of the switch 10 are not necessarily performed by the microcomputer 6, and as shown in the third embodiment, the upper control It may be performed outside the microcomputer 6 such as the unit 30.

  Moreover, in the said embodiment, since CPU of the microcomputer 6 can acquire all the voltage of each single battery as a digital value, the microcomputer 6 or the high-order control unit 30 uses the voltage measurement result as an abnormality determination of each single battery, or an assembled battery. 1 may be used for determining whether to stop charging.

  Moreover, although the example which performs voltage measurement and charge continuously about each single cell was shown in the said embodiment, after measuring the voltage of all the single cells, you may make it charge for every single cell.

  Furthermore, in the above-described embodiment, a lithium ion battery that requires attention to overcharging as a single battery is illustrated, and an example in which the switches 8 and 9 and the capacitor 11 are provided in the charge / discharge control system 20 has been described. A secondary battery that is not required may be configured to lack the switches 8 and 9 and the capacitor 11.

  The charge control system of the present invention performs cell balance operation without heat generation and energy loss of the bypass circuit and contributes to manufacturing, sales, etc. because of low cost, and can be used industrially.

1 is a block circuit diagram of a charge / discharge control system according to a first embodiment to which the present invention is applicable. It is a characteristic diagram which shows transition of the average voltage and average current of each cell when it charges with the charge / discharge control system of 1st Embodiment. It is a block circuit diagram of the charging / discharging control system of 2nd Embodiment which can apply this invention. It is a block circuit diagram of the charging / discharging control system of 3rd Embodiment which can apply this invention. It is a block circuit diagram of the charging / discharging control system of a prior art.

Explanation of symbols

1 assembled battery 1-1, 1-2, 1-3, 1-4 cell (secondary battery)
6 Microcomputer (control means, voltage measurement circuit)
7-1, 7-2, 7-3, 7-4 switches (first switch group, second switch group)
8 switch (third switch element)
9 Switch (4th switch element)
11 Capacitor 12 Power supply for charging (first power supply)
20 Charge / Discharge Control System

Claims (4)

In a charge control system for charging an assembled battery in which a plurality of secondary batteries are connected in series,
A first power source for charging each secondary battery at a constant voltage for each secondary battery;
A first switch element group having one end connected to the + terminal of each secondary battery and the other end connected to the + terminal of the first power source;
A second switch element group having one end connected to the-terminal of each secondary battery and the other end connected to the-terminal of the first power source;
Control for sequentially controlling one switch element of each of the first and second switch element groups so as to charge each secondary battery connected to the first power source for each secondary battery to be charged. Means,
With charge control system. In a charge control system for charging an assembled battery in which a plurality of secondary batteries are connected in series,
A first power source for charging each secondary battery at a constant voltage for each secondary battery;
A capacitor for detecting a battery voltage of each of the secondary batteries;
A voltage measuring circuit for measuring a battery voltage of each of the secondary batteries;
A first switch element group having one end connected to the + terminal of each secondary battery and the other end connected to one end of the capacitor;
A second switch element group having one end connected to the-terminal of each secondary battery and the other end connected to the other end of the capacitor;
A switch element having one end connected to one end of the capacitor and the other end connected to the positive terminal of the charging power source, and one end connected to the other end of the capacitor and the other end connected to the negative terminal of the charging power source. A third switch element having a switch element;
A switching element having one end connected to one end of the capacitor and the other end connected to one end of the voltage measuring circuit, and one end connected to the other end of the capacitor and the other end connected to the other end of the voltage measuring circuit A fourth switch element having a switch element;
At the time of measuring the voltage of each of the secondary batteries, the battery voltage of the secondary battery to be measured is turned on by switching each one of the first and second switch element groups connected to the secondary battery to be measured. And after charging the capacitor, each of the one switch element is turned off and then the fourth switch element is turned on to allow the voltage measurement circuit to measure the battery voltage of each of the secondary batteries. When the battery is charged, the first switch and the second switch are set so that the third switch element is turned on, and the secondary batteries are connected to the first power source for each secondary battery to be charged. Control means for controlling one switch element of each element group to an ON state;
With charge control system.   The charging system according to claim 2, wherein the control unit sequentially charges each of the secondary batteries by switching between the voltage measurement and the charging for each secondary battery.   The secondary battery further includes a second power source for charging the assembled battery, and the control circuit further recharges each of the secondary batteries until the assembled battery charged to the end of charging or near the end of charging is further fully charged. 2. Each of the first and second switch element groups is controlled to be in an ON state so that each secondary battery to be charged is connected to the first power source for charging. The charge control system according to any one of claims 1 to 3.