JP5553622B2 - Secondary battery system and management method thereof - Google Patents

Description

  The present invention relates to a secondary battery system that can easily determine the presence or absence of abnormality such as an assembled battery or a discharge circuit, and a management method thereof.

In general, lead-acid batteries are used as backup batteries for communication power supplies. However, since lead-acid batteries have low volume and weight energy density, the capacity of storage battery equipment required to extract a certain amount of electricity is low. Not only does it require a large installation space, it also increases the weight. Thus, lithium ion secondary batteries with high energy density have been adopted as backups for communication power supplies as an alternative to lead storage batteries. Lithium-ion secondary batteries have high energy density and low self-discharge, and can be charged at the same constant current and constant voltage as conventional lead-acid batteries. Is suitable. And about the lithium ion secondary battery used for the power supply for communication, the management system which prevented damage to the wiring by an excessive electric current is known (for example, refer patent document 1).
In addition, since the DC power supply for power failure compensation requires high reliability to continuously supply stable power, the assembled battery used in such applications is periodically deteriorated. (Capacity) is confirmed, and when the capacity is reduced to a predetermined level, renewal is performed. As an example of the capacity test of such a backup battery pack, a battery deterioration determination method for a power failure backup power supply is known (see, for example, Patent Document 2). In this battery deterioration determination method, an arbitrary assembled battery is selected, and the selected assembled battery is directly discharged to check the capacity.

JP 2009-22999 A Japanese Patent Laid-Open No. 10-2943

The lithium ion secondary battery is suitable for use as a battery pack for backup such as a communication power source, but in this case, it is required to function reliably during a power failure. For example, if there is an abnormality such as a capacity drop in some battery packs composed of lithium ion secondary batteries, or if there is an abnormality in the discharge circuit of the battery pack, a direct current load will occur if a power failure occurs. There is a problem that the equipment cannot be reliably backed up. In order to check the capacity of the storage battery, a capacity test for each assembled battery is performed by a discharge test. In the discharge test, it is necessary to discharge the battery to the end-of-discharge voltage, and in preparation for a power failure during the test. It is necessary to connect an alternative storage battery to the test target battery, which requires a great deal of cost. Such a problem is not limited to lithium ion secondary batteries, but also exists in lead-acid batteries and other secondary batteries. Therefore, it is convenient and can contribute to cost reduction if it is possible to easily determine abnormality of the assembled battery constituted by the secondary battery, abnormality of the discharge circuit, and the like.
Further, in the battery deterioration determination method of Patent Document 2, since the assembled battery to be tested is completely discharged at the end of the test discharge, the capacity of the assembled battery system is insufficient, and a power failure occurs immediately after the end of the test. In such a case, there is a problem that sufficient backup cannot be performed and reliability is insufficient.

  Accordingly, an object of the present invention is to provide a secondary battery system and a management method that can easily determine the presence or absence of an abnormality in an assembled battery or a discharge circuit and that do not impair the reliability against a power failure immediately after the end of the test. To do.

In order to achieve the above object, the invention according to claim 1 is a battery pack group in which a plurality of battery packs configured by connecting a number of secondary batteries in series are connected in parallel; and the plurality of battery packs; A secondary battery system comprising: a DC load facility connected in parallel; and a DC power supply source that charges the plurality of assembled batteries and supplies DC power to the DC load facility, the secondary battery system comprising: Discharge command means for temporarily controlling the output voltage to be lower than the open voltage of the assembled battery, forcibly discharging the plurality of assembled batteries, and the discharge command of the plurality of assembled batteries , respectively, Current measuring means for measuring a discharge current flowing from the assembled battery to the DC load facility due to a temporary drop in the output voltage of the DC power supply source by the means below the open voltage of the assembled battery; and each current measurement To the means Comprising determining means for determining whether there is an abnormality in the system including the battery pack based on the discharge current measured respectively, the I, the determination means, the DC power supply by the discharge command signal from the discharge command means Compare the discharge current at the beginning of discharge of each assembled battery with a temporary decrease in the output voltage of the source and a preset reference current value to determine whether the discharge current from each assembled battery is normal. The assembled battery supplies DC power to the DC load facility even if the power supply from the DC power supply source is stopped immediately after the discharge is completed, based on the determination based on the discharge current at the initial stage of discharge by the determination means. so as to have sufficient capacity to supply the discharge command means and said current measuring means and managed by the assembled battery state monitoring device and a said determination means, a secondary battery cis, characterized in that It is a non.

  According to this invention, when the power supply from the DC power supply source is stopped, the power is supplied from the plurality of assembled batteries to the DC load equipment, and the discharge current flows from each assembled battery to the DC load equipment by the current measuring means. Is measured. Here, if the battery capacity of each assembled battery is equal, the discharge current at the initial stage of discharge shared by each assembled battery will be the same value, but if there is an abnormality in the assembled battery or the discharge circuit, the DC load equipment from each assembled battery Since the discharge current value at the initial stage of discharge flowing into the battery is greatly different, it is possible to easily determine an abnormality in the system such as an abnormality in the battery or the discharge circuit.

The invention described in claim 2 is the secondary battery system according to claim 1, in the determination means is characterized in that the determination result displaying means for displaying the presence or absence of an abnormality in the system is connected .

According to a third aspect of the present invention, in the secondary battery system according to the first or second aspect, the secondary battery is composed of a lithium ion secondary battery.

According to a fourth aspect of the present invention, there is provided an assembled battery group in which a plurality of assembled batteries configured by connecting a large number of secondary batteries in series are connected in parallel, and a DC load connected in parallel with the plurality of assembled batteries. A method for managing a secondary battery system comprising: a facility; and a DC power supply source that charges the plurality of assembled batteries and supplies DC power to the DC load facility, wherein the output voltage of the DC power supply source is discharged The plurality of assembled batteries are forcibly discharged by controlling temporarily lower than the open voltage of the assembled battery by command means, and the temporary set of the output voltage of the DC power supply source by the discharge command means the discharge current by the decrease in the battery to the open-circuit voltage below flows into the DC load equipment from each assembled battery measured by the respective current measuring means, based on said discharge current measured respectively by the individual current measuring means Determined by the determining means whether there is an abnormality in the system including a battery, said determining means of each set cell with a temporary reduction in the output voltage of the DC power supply by the discharge command signal from the discharge command means A comparison is made between the discharge current at the initial stage of discharge and a preset reference current value to determine whether or not the discharge current from each battery pack is normal, and the battery pack is discharged at the initial stage of discharge by the determining means. According to the determination based on the current, even if the power supply from the DC power supply source is stopped immediately after the end of the discharge, the current measurement is performed so as to have a sufficient capacity for supplying DC power to the DC load facility. The secondary battery system management method is characterized by being managed by an assembled battery state monitoring device having a means and a determination means .

According to the first and fourth aspects of the present invention, it is possible to easily determine an abnormality in the system such as an abnormality in an assembled battery or a discharge circuit, so that a long-time discharge test is not required. In addition, the cost for grasping the abnormality can be significantly reduced. In addition, since the presence or absence of abnormality is determined based on the discharge current at the beginning of discharge, the assembled battery has sufficient capacity at the end of discharge, and DC power is reliably supplied to the DC load facility even if a power failure occurs immediately after the end of discharge. The reliability against power failure can be maintained.

According to the first aspect of the present invention, since the plurality of assembled batteries can be forcibly discharged by the discharge command means, it is possible to periodically grasp the presence or absence of abnormality in the assembled battery or the discharge circuit. It is possible to always maintain the battery and the discharge circuit in the best state. Thereby, even when a power failure occurs, the DC load facility can be reliably backed up, and the reliability of the system can be maintained.

According to the second aspect of the present invention, since the determination means is connected to the determination result display means for displaying the presence / absence of the system abnormality, it is possible to quickly grasp the system abnormality and take quick measures. It becomes possible.

According to the invention described in claim 3 , since the secondary battery is composed of a lithium ion secondary battery having a high energy density, the volume can be made smaller than that of other secondary batteries. The system can be made compact.

It is a block diagram which shows schematic structure of the secondary battery system which concerns on embodiment of this invention. It is a circuit diagram which shows the connection relation of the assembled battery and each apparatus in the secondary battery system of FIG. It is a block diagram which shows schematic structure of the assembled battery state monitoring apparatus of FIG. It is a flowchart which shows the procedure of the management method in the secondary battery system of FIG. It is a characteristic view which shows the change of the discharge voltage in the initial stage of discharge when each assembled battery of FIG. 1 has not deteriorated. It is a characteristic view which shows the change of the discharge voltage and the discharge current in the early stage of discharge when deterioration has arisen in some assembled batteries of FIG. FIG. 2 is a characteristic diagram showing the relationship between the period of use and discharge current of each assembled battery in FIG. 1 and showing the same value for the discharge current of each assembled battery (number of battery packs connected in parallel: 3 with the same rated capacity). is there. FIG. 2 is a characteristic diagram showing the relationship between the period of use and discharge current of each assembled battery in FIG. 1 and showing the values of different discharge currents for each assembled battery (number of assembled battery parallel connections: 3; rated capacity is the same). is there. It is a characteristic view which shows the relationship between a use period and a capacity | capacitance in the assembled battery of FIG. It is a characteristic view which shows the relationship between the use period and internal resistance in the assembled battery of FIG. It is a characteristic view which shows the relationship between internal resistance and battery capacity in the assembled battery of FIG.

  The present invention will be described below based on the illustrated embodiments.

  1 to 11 show an embodiment of the present invention. In FIG. 2, the secondary battery system 1 includes an assembled battery 3 in which a plurality of lithium ion cells (lithium ion secondary batteries) 2 that are unit cells are connected in series. A battery monitoring controller 4 as a cell controller is connected to the assembled battery 3. The battery monitoring controller 4 measures the voltage of each cell 2 via the cell voltage measurement wiring 4a, and measures the voltage of the entire assembled battery 3 via the assembled battery voltage measurement wiring 4b. . The battery monitoring control unit 4 has a function of measuring and monitoring the cell state such as the voltage and temperature of each lithium ion cell 2 and adjusting the charging voltage of each lithium ion cell 2 to be within a predetermined value. Yes. The assembled battery 3 and the battery monitoring control unit 4 are combined as one assembled battery management unit 5.

  In this embodiment, the secondary battery system 1 includes an assembled battery group including, for example, three assembled batteries 3 (assembled batteries A to C) as shown in FIGS. 1 and 2. Each assembled battery 3 is connected in parallel. The three assembled batteries 3 are connected in parallel to a rectifier 101 as a DC power supply source and a DC load facility 102 as a communication facility. The rectifier 101 has a function of converting commercial power supply 100 that is AC power into DC power, float-charging the assembled battery 3, and supplying DC power to the DC load equipment 102. That is, the secondary battery system 1 normally floats each assembled battery 3 by the rectifier 101 and supplies DC power to the DC load facility 102. DC power is supplied from the assembled battery 3 to the DC load facility 102.

  Each assembled battery 3 is monitored for abnormality by the assembled battery state monitoring device 10. As shown in FIG. 1, the assembled battery state monitoring device 10 includes a determination unit 12, a determination result display unit 17, a discharge command unit 18, and a current measurement unit 19. As shown in FIG. 1, the current measuring means 19 is provided in each of the discharge circuits of the three assembled batteries 3 and has a function of measuring the discharge current flowing from each assembled battery 3 toward the DC load equipment 102. ing. In this embodiment, the current measuring means 19 is provided in each assembled battery management unit 5. The current measuring means 19 may be of any type as long as it can measure a direct current, but is preferably of a type that can suppress heat generation due to the discharge current as much as possible.

As shown in FIG. 3, the assembled battery state monitoring device 10 includes a power supply unit 11 that converts power from the commercial power supply 100 into power necessary for control. A determination unit 12 is connected to the power supply unit 11. The determination unit 12 includes a measurement condition set value input unit 13, an assembled battery information storage unit 14, a calculation unit 15, and a data input unit 16. The measurement condition set value input unit 13 is a part for inputting measurement conditions for increasing the determination accuracy, and is composed of, for example, a computer keyboard. The assembled battery information storage unit 14 has a function of storing, for example, initial discharge characteristics of single cells constituting the assembled battery. The calculation unit 15 is based on the information from the assembled battery information storage unit 14 and the information on the discharge currents I ₁ , I ₂ , and I _{3 at} the initial discharge of each assembled battery 3 input via the data input unit 16. It has a function of determining the deterioration state of each assembled battery 3.

  As shown in FIG. 1, the discharge command means 18 is connected to a control circuit (not shown) of the rectifier 101. The discharge command means 18 is configured to periodically output a discharge command signal K1 to the rectifier 101 based on, for example, a preset program. The rectifier 101 has a function of temporarily discharging the assembled battery 3 by controlling the output voltage to decrease with respect to the normal time by the discharge command signal K1 from the discharge command means 18. That is, the discharge command means 18 has a function of forcibly discharging the assembled battery 3 by temporarily reducing the output power from the rectifier 101 below the open voltage of the assembled battery 3 by the discharge command signal K1.

As shown in FIG. 1, the determination unit 12 measures the measured values of the discharge currents I ₁ , I ₂ , and I _{3 at} the initial stage of the discharge measured by the current measurement unit 19 based on the command signal K2 from the discharge command unit 18. receiving signals K3a, K3b, as k3c, the measurement signal K3a, K3b, by comparing the discharge current _{I 1,} I 2, _{I 3} with a preset reference current value Ic corresponding to k3c, at least the battery pack 3 The system has a function of determining whether there is an abnormality in the system including abnormalities (abnormalities such as capacity reduction due to aging) and abnormalities in the discharge circuit of the assembled battery 3. That is, the determination means 12 includes a current value (reference current value Ic) in a normal range predicted in advance when the battery pack 3 is discharged, and discharge currents I ₁ , I ₂ , I _{3 at the} initial stage of the actual measurement. By comparing these, abnormalities in the system such as abnormalities in the assembled battery 3 and the discharge circuit are determined.

The discharge currents I ₁ , I ₂ , and I ₃ measured by the current measuring means 19 are equal to each other when the battery capacity of each assembled battery 3 is equal and the discharge circuit is normal. 1: 1: 1, but if there is an abnormality in each assembled battery 3 or the discharge circuit, the discharge current of each assembled battery 3 depends on the parallel number, for example 1: 0.5: 1.5. It will not be the discharge current value. In this embodiment, the reference current value Ic determined to be abnormal is set to ± 50%, for example, with respect to the ideal value. This reference current value Ic is set to a level depending on the age of the assembled battery 3. It is desirable to change.

  A determination result display means 17 is connected to the determination means 12. The determination unit 12 outputs a determination signal K4 to the determination result display unit 17. The determination result display means 17 outputs an abnormality alarm when the determination means 12 determines that the assembled battery 3 is deteriorated or the discharge circuit in the system is abnormal, for example. The determination result display means 17 is composed of, for example, an LED lamp or an alarm buzzer. The determination result display means 17 may be installed in the vicinity of the assembled battery 3 or may be installed in a place far away from the installation location of the assembled battery 3.

  Next, the operation and management method of the secondary battery system 1 will be described.

  FIG. 4 shows a procedure for determining the deterioration degree of the assembled battery 3 and the abnormality of the discharge circuit in the secondary battery system 1. In step S1 of FIG. 3, the discharge command signal K1 is output from the discharge command means 18, and thereby the output voltage from the rectifier 101 is lowered from the normal time. That is, the output voltage of the rectifier 101 is controlled to be lower than the open voltage of the assembled battery 3 based on the discharge command signal K1 from the discharge command means 18. As a result, DC power is supplied from each assembled battery 3 to the DC load facility 102. Here, even when the rectifier 101 receives the discharge command signal K1 from the discharge command means 18, the output voltage is maintained within the allowable voltage range. For example, the power supply from the storage battery 3 is stopped during the determination operation. Even in this case, the DC load facility 102 can be operated.

Next, as shown in step S <b> 2 of FIG. 4, the discharge currents I ₁ , I ₂ , and I ₃ flowing from the assembled battery 3 to the DC load facility 102 are measured by the current measuring means 19 provided in each assembled battery management unit 5. Is done. In step S3, the measured discharge currents I ₁ , I ₂ , I ₃ are compared with the reference current value Ic to determine whether the discharge currents I ₁ , I ₂ , I ₃ are normal. To be judged. In this case, “normal state” means that the discharge current from each assembled battery has a value that is 1/3 of the power consumption of the load. Here, when it is determined that the discharge currents I ₁ , I ₂ , and I ₃ are normal, the process proceeds to step S 4, the storage battery discharge command by the discharge command means 18 is canceled, and the rectifier 101 returns to the DC load facility 102 again. Power supply and float charging of the three assembled batteries 3 by the rectifier 101 are resumed.

As described above, at the time of discharging each assembled battery 3 due to the output voltage drop of the rectifier 101, if the battery capacity of the assembled battery A to the assembled battery C is equal, the discharge current I shared by the assembled battery A to the assembled battery C is as follows. ₁ , I ₂ , and I ₃ are values obtained by dividing the total discharge current flowing into the DC load facility 102 by 3, but in parallel when the degree of deterioration of each assembled battery 3 is different or the discharge circuit is abnormal. The discharge current value does not correspond to the number. Therefore, when the discharge currents I ₁ , I ₂ , and I ₃ do not become the discharge current values corresponding to the number of parallel connections, the discharge current values greatly deviate from the reference current value I _{0. In} step S 3, the assembled battery 3 itself Or the discharge circuit of the assembled battery 3 is determined to be abnormal.

Next, the relationship between battery deterioration and discharge current will be specifically shown. FIG. 5 shows changes in discharge voltage and discharge current at the initial stage of discharge when the rated capacities of the assembled batteries 3 are equal and not deteriorated. As shown in FIG. 5, when each assembled battery 3 is not deteriorated, the discharge currents I ₁ , I ₂ , and I ₃ are equal in each assembled battery 3 and become 1/3 of the load current. On the other hand, FIG. 6 shows changes in the discharge voltage and discharge current in the initial stage of discharge when some of the assembled batteries 3 are deteriorated. Even if the rated capacity of each set is equal, when some of the assembled batteries 3 are deteriorated, the discharge currents I ₁ , I ₂ , and I ₃ are different for each assembled battery 3. FIG. 7 shows the relationship between the period of use of each assembled battery 3 and the discharge current. When each assembled battery 3 is not deteriorated, the discharge currents I ₁ , I ₂ , I ₃ of each assembled battery ₃ are Both show equal values of 1/3 of the load current. However, when some of the assembled batteries 3 are deteriorated, as shown in FIG. 8, the relationship between the use period of each assembled battery 3 and the discharge current is the discharge current I _{1 of} each assembled battery 3 over time. , I ₂ and I ₃ gradually increase. The vertical axis 1 / n in FIGS. 7 and 8 indicates that when the number of the assembled batteries 3 is n, the discharge current flowing through each assembled battery 3 becomes 1 / n of the load current. In this embodiment, since the number of the assembled batteries 3 is 3, the discharge current of each assembled battery 3 is 1/3 of the load current as described above.

FIG. 9 shows a capacity change due to normal deterioration and a capacity change due to abnormal deterioration in the assembled battery 3. As shown in FIG. 9, in the case of abnormal deterioration, it can be seen that the capacity of the assembled battery 3 is significantly reduced in a shorter use period than in the normal case. FIG. 10 shows changes in internal resistance due to normal deterioration in the assembled battery 3 and changes in internal resistance due to abnormal deterioration. As shown in FIG. 10, in the case of abnormal deterioration, it can be seen that the internal resistance of the assembled battery 3 significantly increases in a shorter use period than in the normal case. FIG. 11 shows the relationship between the internal resistance and the battery capacity in the assembled battery 3. As shown in FIG. 11, it can be seen that the battery capacity decreases as the internal resistance increases. Thus, since the deterioration of the assembled battery 3 appears in the capacity and the internal resistance, whether or not the assembled battery 3 is deteriorated by measuring the discharge currents I ₁ , I ₂ , and I ₃ related to the capacity and the internal resistance. It becomes possible to determine.

As shown in FIG. 8, the discharge current I ₁ and the assembled battery discharge current I ₂ of the B of the battery pack A, while indicating a value exceeding the reference current value Ic, the discharge current I ₃ of the battery pack C, the reference It is below the current value Ic. Here, the reference current Ic, since a threshold of quality determination, for the battery pack C corresponding to the discharge current I ₃ falls below the reference current value Ic, or capacity is lowered, or the assembled battery C It is determined that there is an abnormality in the discharge circuit (such as a loose connection terminal screw or disconnection in the discharge circuit).

In step S3 of FIG. 4, if the measured value of the discharge current I ₃ of the battery pack C is determined not to be normal, the process proceeds to step S5, the determination signal K4 to the effect that the abnormality judging means 12 is outputted, the determination result An alarm is issued by the display means 17. Thereafter, the process proceeds to step S4, where the storage battery discharge command by the discharge command means 18 is canceled, and the power supply to the DC load facility 102 by the rectifier 101 and the float charging of the three assembled batteries 3 by the rectifier 101 are resumed.

  As described above, the determination unit 12 can easily determine whether the assembled battery 3 itself or the discharge circuit of the assembled battery 3 is abnormal. The cost for grasping the abnormality of the battery system 1 can be significantly reduced. Further, since the discharge command means 18 can periodically grasp the deterioration of the assembled battery 3 and the abnormality of the discharge circuit, it is possible to always maintain the assembled battery 3 and the discharge circuit in the best state. Become. As a result, even when the commercial power supply 100 fails due to a lightning strike or the like, the DC load facility 102 can be reliably backed up by the assembled battery 3 and the reliability of the secondary battery system 1 can be maintained. Furthermore, since the determination result display means 17 is connected to the determination means 12, it is possible to quickly grasp the abnormality in the secondary battery system 1 and to take quick measures.

Moreover, since the presence or absence of abnormality is determined based on the discharge currents I ₁ , I ₂ , and I ₃ at the initial stage of discharge, the assembled battery 3 has a sufficient capacity at the time when the discharge test is completed, and a power failure occurs immediately after the end of the discharge. Even if this occurs, DC power can be reliably supplied to the DC load facility 102, and reliability against power failure can be maintained. Furthermore, in this embodiment, the output voltage of the rectifier 101 is temporarily lowered from the open voltage of the assembled battery 3 to forcibly discharge the assembled battery 3, so that, for example, when the battery is determined to be abnormal, the storage battery Even when the power supply by 3 is stopped, the operation of the DC load facility 102 can be continued by the rectifier 101. Therefore, the reliability of power supply to the DC load facility 102 can be maintained as compared with the case where the output of the rectifier 101 is completely stopped to determine whether or not there is an abnormality.

Although the embodiment of the present invention has been described above, the specific configuration is not limited to the above embodiment, and even if there is a design change or the like without departing from the gist of the present invention, Included in the invention. For example, in the above embodiment, the case where the secondary battery system 1 is applied to the DC load equipment 102 such as communication equipment has been described. However, an uninterruptible power supply (UPS) that uses DC power as an input, It can also be applied to other equipment. The discharge command means 7 has a function of discharging the plurality of assembled batteries 3 by temporarily reducing the output voltage of the rectifier 101 by the discharge command signal K1, but the output power from the rectifier 101 is temporarily reduced. It is good also as a structure which discharges the some assembled battery 3 by making it stop completely and causing a pseudo power failure. Furthermore, the measurement of the discharge currents I ₁ , I ₂ , and I _{3 at} the initial stage of discharge is possible even when the power supply from the commercial power supply 100 is stopped due to an actual power failure. In this case, the discharge currents I ₁ , The presence or absence of abnormality of the assembled battery 3 can be determined based on I ₂ and I ₃ .

  In the above embodiment, a lithium ion secondary battery is used as a secondary battery. However, the secondary battery is not limited to a lithium ion secondary battery, and may be a lead storage battery. Other types of secondary batteries may be used. The discharge command means 18 is configured to periodically output the discharge command signal K1 to the rectifier 101 based on a preset program, but outputs the discharge command force signal K1 to the rectifier 101 by remote operation. It is good also as a structure. Furthermore, it is desirable that the discharge time of the assembled battery 3 when determining the presence or absence of abnormality is as short as possible in consideration of the capacity of the assembled battery 3, the capacity of the DC load equipment 102, the determination accuracy, and the like.

1 Secondary battery system 2 Lithium ion cell (secondary battery)
DESCRIPTION OF SYMBOLS 3 Assembly battery 4 Battery monitoring control part 5 Assembly battery management unit 10 Assembly battery state monitoring apparatus 12 Judgment means 17 Judgment result display means 18 Discharge command means 19 Current measurement means 100 Commercial power supply 101 Rectifier (DC power supply source)
102 DC load equipment

Claims (4)

An assembled battery group in which a plurality of assembled batteries configured by connecting a large number of secondary batteries in series are connected in parallel; a DC load facility connected in parallel with the plurality of assembled batteries; and the plurality of assembled batteries. A secondary battery system having a DC power supply source for charging and supplying DC power to the DC load equipment, wherein the output voltage of the DC power supply source is temporarily controlled to be lower than the open voltage of the assembled battery A discharge command means for forcibly discharging the plurality of assembled batteries, and a discharge circuit of the plurality of assembled batteries , respectively, for temporarily outputting the output voltage of the DC power supply source by the discharge command means. and current measuring means for measuring a discharge current flowing to the DC load equipment from the battery pack by drop to the open-circuit voltage below the battery pack, the assembled collector on the basis of the discharge current measured respectively by each current measuring means And a determining means for determining whether there is an abnormality in the system including the determination means, each set associated with a temporary reduction in the output voltage of the DC power supply by the discharge command signal from the discharge command means A discharge current at the initial stage of battery discharge is compared with a preset reference current value to determine whether or not the discharge current from each assembled battery is normal. According to the determination based on the discharge current, even if the power supply from the DC power supply source is stopped immediately after the end of the discharge, the DC load equipment has a sufficient capacity to supply DC power even if the power supply is stopped. A secondary battery system managed by an assembled battery state monitoring device having a discharge command means, the current measurement means, and the determination means .   The secondary battery system according to claim 1, wherein the determination unit is connected to a determination result display unit that displays presence / absence of abnormality in the system.   The secondary battery system according to claim 1, wherein the secondary battery includes a lithium ion secondary battery. An assembled battery group in which a plurality of assembled batteries configured by connecting a large number of secondary batteries in series are connected in parallel; a DC load facility connected in parallel with the plurality of assembled batteries; and the plurality of assembled batteries. A method for managing a secondary battery system comprising a DC power supply source for charging and supplying DC power to the DC load equipment , wherein the assembled battery is temporarily supplied with an output voltage of the DC power supply source by a discharge command means. The plurality of assembled batteries are forcibly discharged by controlling the voltage to be lower than the open circuit voltage of the battery, and the output voltage of the DC power supply source by the discharge command means is temporarily reduced below the open voltage of the assembled battery. the measured respectively by the current measurement means discharge current flowing to the DC load equipment from the assembled battery, in a system including the battery pack based on the discharge current measured respectively by the individual current measuring means The presence or absence of atmospheric determined by the determining means, said determining means, the discharge initial discharge current temporary respective cell packs with decreasing output voltage of the DC power supply by the discharge command signal from the discharge command means and It is determined whether or not the discharge current from each assembled battery is normal by comparing with a preset reference current value, and the assembled battery is determined based on the discharge current at the initial stage of discharge by the determination means, Even if the power supply from the DC power supply source stops immediately after the end of the discharge, the current measuring means and the determining means have a sufficient capacity to supply DC power to the DC load equipment. A management method for a secondary battery system, characterized in that the secondary battery system is managed by an assembled battery state monitoring device .

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