JP2015070737A - Battery unit and control method therefor, and battery system and control method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a charge current at a low temperature.SOLUTION: A battery unit 10 includes a battery module 11 having at least one secondary battery connected in series. A load 14 is connected to the battery module 11. Further, the battery unit 10 includes a temperature sensor 15 for measuring a temperature of the battery module 11 or in the vicinity thereof, and a current sensor 16 for measuring a current flowing through the battery module 11. The measurement values of the temperature sensor 15 and the current sensor 16 are output to a control device 20. The control device 20 controls the load 14 when the temperature measured by the temperature sensor 15 is out of a preset temperature range and when a charge current of a predetermined value or greater is measured by the current sensor 16.

Description

  The present invention relates to a battery unit having a battery module in which at least one secondary battery is connected in series, a control method thereof, a battery system including the battery unit, and a control method thereof.

  It is known that, when the secondary battery is in a low temperature state, the ion transfer property and the reaction of the electrode active material are reduced, so that the internal resistance of the battery is increased and appropriate charging cannot be performed. For example, in a lithium ion secondary battery, when charged at a low temperature (for example, a temperature lower than 0 ° C.), lithium ions emitted from the positive electrode are not easily absorbed by the negative electrode, and lithium metal is liable to be deposited, leading to failure. There is a fear. Therefore, conventionally, a method has been proposed in which the temperature of a battery is detected, and when the temperature of the battery is equal to or lower than a predetermined set temperature, charging is stopped and heating means such as a heater is operated (for example, a patent) Reference 1).

JP 2011-238428 A

  By the way, when trying to apply control as disclosed in Patent Document 1 to a moving body such as a vehicle, it is necessary to perform heater control in consideration of the operating state of the moving body in addition to the battery temperature, There is a problem that the control becomes complicated.

  Further, for example, as shown in FIG. 7, when a battery system 50 in which a plurality of battery modules 51 and 52 are connected in parallel is used as a power source for a vehicle running motor 53, It is conceivable that the battery modules 51 and 52 are disconnected from each other and charging of the battery modules 51 and 52 due to the regenerative current of the traveling motor 53 is avoided. However, when the traveling motor 53 is a synchronous motor, it cannot be disconnected and is charged by a regenerative current. Even if charging by regenerative current is avoided, if there is a voltage difference between the battery modules 51 and 52, the battery module 51 (for example, the battery module 51) is returned to the battery module (for example, the battery module 52) having a higher voltage. Current flows. Therefore, in the battery system 50 in which a plurality of battery modules 51 and 52 are connected in parallel, the recirculation current flowing between the battery modules 51 and 52 is taken into consideration in addition to the regenerative current from the traveling motor 53. It was necessary to provide protection.

  This invention is made in view of such a situation, Comprising: It aims at providing the battery unit which can reduce the charging current at the time of low temperature, its control method, a battery system, and its control method. .

  According to a first aspect of the present invention, there is provided a battery module in which at least one secondary battery is connected in series, power consumption means connected to the battery module, and temperature measuring means for measuring the temperature of the battery module or the vicinity thereof. Current measuring means for measuring the current flowing through the battery module; and the temperature measured by the temperature measuring means is out of a preset temperature range, and the charging current greater than a predetermined value is measured by the current measuring means. And a control unit that controls the power consuming unit so that a charging current of the battery module is equal to or lower than a predetermined threshold when the battery module is charged.

  According to the above aspect, the battery module has a configuration in which the power consuming means is connected, the battery module or its surrounding temperature is out of the predetermined temperature range, and the charging current greater than the predetermined value is measured. The power consuming means is controlled by the control means so that the charging current of the battery module is equal to or less than a predetermined threshold value. By controlling the power consuming means, a current can flow through the power consuming means, so that the charging current of the battery module can be reduced. As a result, it is possible to avoid a charging current of a predetermined value or more flowing through the battery module at a low temperature, and to protect the battery module.

  In the battery unit, the power consuming means includes a load and a normally open type opening / closing means capable of connecting the load and the battery module, and the control means has a temperature measured by the temperature measuring means. The opening / closing means may be closed when the temperature is out of the preset temperature range and the current measuring means measures a charging current of a predetermined value or more.

  According to such a configuration, only simple control such as opening / closing control of the opening / closing means by the control means is performed when the battery module or its surrounding temperature is out of the predetermined temperature range and a charging current of a predetermined value or more is measured. Thus, it is possible to reduce the charging current of the battery module by flowing a current to the load side.

  In the battery unit, the power consuming means includes a load and a current control device disposed between the load and the battery module, and the control device has a temperature measured in advance by the temperature measuring means. The current flowing through the load is adjusted so that the charging current of the battery module falls below a predetermined threshold when the charging temperature exceeds a predetermined value when the current measuring means measures a charging current exceeding a predetermined temperature range. You may make it adjust with the said current control apparatus.

  According to such a configuration, when the battery module or its surrounding temperature is out of a predetermined temperature range and a charging current of a predetermined value or more is measured, the current flows to the load side under the control of the current control device by the control means. Since the amount of current can be adjusted, the charging current of the battery module can be accurately reduced.

In the battery unit, the power consuming means is a load having a variable resistance value, and the control means adjusts the resistance value of the load so that a charging current of the battery module is equal to or less than a predetermined threshold value. It is good as well.
In this case, the resistance value of the load is determined based on, for example, the voltage across the battery module and the current flowing into the battery unit.

  In the battery unit, the power consuming means may include a heater.

  According to such a configuration, heat can be generated by passing a current through the heater. As a result, the ambient temperature of the battery module can be increased, and the operating environment of the battery module can be improved.

  According to such a configuration, the charging current of the battery module can be made close to a predetermined threshold value, for example, close to zero.

A second aspect of the present invention is a battery system configured by connecting the plurality of battery units in parallel.
In the battery system, the control means may be shared among the plurality of battery units.
In the battery system, the power consuming unit may be shared among the plurality of battery units.
According to such a configuration, the number of parts can be reduced.

  A third aspect of the present invention is a battery system connected to an external load, in which at least one secondary battery is connected in series, a positive terminal of the first battery module, and the external A resistance element provided between the load, a second battery module connected in parallel to the first battery module via the resistance element, power consumption means connected to the second battery module, and A temperature measuring means for measuring the temperature of the second battery module or its vicinity, a current measuring means for measuring a current flowing through the second battery module, and a temperature range in which the temperature measured by the temperature measuring means is set in advance. And when the charging current greater than or equal to a predetermined value is measured by the current measuring means, the charging current of the battery module is less than or equal to a predetermined threshold value. A battery system and a control means for controlling the force dissipation means.

  According to such a battery system, at the time of discharging, a large amount of electric power is supplied from the second battery module to the external load by the resistance element provided between the positive terminal of the first battery module and the external load. The voltage across the first battery module can be maintained higher than the voltage across the second battery module. Thereby, the current flowing through the first battery module can be made smaller than the current flowing through the second battery module, and the direction in which the reflux current mainly flows can be specified in one direction. As a result, it is not necessary to connect a load for reducing the charging current to the first battery module, and the device configuration can be simplified.

  According to a fourth aspect of the present invention, the power consuming means is connected to a battery module in which at least one secondary battery is connected in series, and the temperature of the battery module or the vicinity thereof is out of a preset temperature range, and When the charging current of the battery module is equal to or higher than a predetermined value, the battery unit control method controls the power consuming means so that the charging current of the battery module is equal to or lower than a predetermined threshold value.

  According to a fifth aspect of the present invention, there is provided a control method for a battery system connected to an external load between the positive terminal of the first battery module in which at least one secondary battery is connected in series and the external load. And connecting the first battery module and the second battery module in parallel via the resistance element, connecting power consuming means to the second battery module, and connecting the second battery module or When the temperature in the vicinity is out of a preset temperature range and the charging current of the second battery module is equal to or higher than a predetermined value, the charging current of the battery module is equal to or lower than a predetermined threshold. A battery system control method for controlling power consumption means.

  According to the present invention, it is possible to reduce the charging current at a low temperature, and it is possible to contribute to battery protection.

It is the figure which showed schematic structure of the battery unit which concerns on one Embodiment of this invention. It is the flowchart which showed the process sequence of the control method of the battery unit which concerns on one Embodiment of this invention. It is a figure for demonstrating the resistance value of the load with which the battery unit which concerns on one Embodiment of this invention is provided. It is the figure which showed schematic structure of the battery system which concerns on 1st Embodiment of this invention. It is the figure which showed the other structural example of the battery system which concerns on 1st Embodiment of this invention. It is the figure which showed schematic structure of the battery system which concerns on 2nd Embodiment of this invention. It is the figure which showed one structural example of the conventional battery system.

Hereinafter, a battery unit and a control method thereof according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing a schematic configuration of a battery unit 10 according to an embodiment of the present invention. As shown in FIG. 1, the battery unit 10 according to this embodiment is connected to an external load 30 and supplies power to the external load 30. Further, when the external load 30 is a load capable of regenerative operation such as a motor, the external load 30 is charged by the regenerative current.

The battery unit 10 includes a battery module 11 in which a plurality of secondary batteries are connected in series. An example of the secondary battery is a lithium ion battery. In addition, the battery module 11 may be comprised with one secondary battery.
A load (power consuming means) 14 is connected to the battery module 11 in parallel. Further, a normally open type switch (opening / closing means) 13 is connected to the load 14 in series. In the present embodiment, the load 14 has a variable resistance value. In addition, as an example of the load 14, a heater is preferably used.

The battery unit 10 is provided with a temperature sensor (temperature measurement means) 15 that measures the temperature of the battery module 11 or the vicinity thereof, and a current sensor (current measurement means) 16 that measures the current flowing toward the battery module 11. ing. Measurement values of the temperature sensor 15 and the current sensor 16 are output to the control device 20. The position of the current sensor 16 is on the wiring between the positive side of the battery module 11 and the external load 30, and the external load 30 side as shown in FIG. 1 with reference to the connection point between the wiring and the load 14. Or may be provided on the battery module side with reference to the connection point of the load 14. The user can provide the current sensor 16 at an optimal position as appropriate according to the system.
The control device 20 is, for example, a microcomputer, and includes a main storage device such as a central processing unit (CPU) and a RAM (Random Access Memory), an auxiliary storage device, and the like. A series of processing steps for realizing various functions to be described later is recorded in the auxiliary storage device in the form of a program, and this program is read by the central processing unit to the main storage device to process and process information. By executing the above, various functions described later are realized.
FIG. 1 shows functional blocks of the control device 20. The control device 20 includes, for example, a sensor information acquisition unit 21, a determination unit 22, a switch control unit 23, and a resistance value adjustment unit 24.

In the battery unit 10 having such a configuration, the battery module 11 is charged / discharged in accordance with the operating state of the external load 30 and the processing shown in FIG. 2 is repeatedly executed at predetermined time intervals in the control device 20. .
First, the temperature measured by the temperature sensor 15 and the current value measured by the current sensor 16 are acquired by the sensor information acquisition unit 21 of the control device 20 (step S1 in FIG. 2). Next, it is determined by the determination part 22 whether the temperature acquired by the sensor information acquisition part 21 is outside the preset predetermined temperature range (step S2). Here, the predetermined temperature range is set in advance according to the temperature characteristics of the battery module, for example, and is stored in a predetermined storage area in the control device 20.

  As a result, if the temperature is not outside the predetermined temperature range (“NO” in step S2), the process ends, and if the temperature is outside the predetermined temperature range (“YES” in step S2), then, It is determined by the determination part 22 whether the charging current more than the predetermined value set beforehand is detected (step S3). Here, the “predetermined value” of the charging current is a current threshold that is set in advance according to the characteristics of the battery module 11, and is a temporary current threshold that is undesirable in a low temperature state. It is stored in a predetermined storage area.

  As a result, when a charging current of a predetermined value or more has not been detected (“NO” in step S3), the process ends, and when a charging current of a predetermined value or more is detected (“ YES ”), the switch 13 is closed by the switch controller 23 (step S4), and the resistance value of the load 14 is adjusted by the resistance value adjusting unit 24 so that the charging current of the battery module 11 becomes zero (step S4). Step S5). For example, the resistance value adjustment unit 24 performs feedback control of the resistance value so that the charging current of the battery module 11 becomes zero. Note that the charging current does not necessarily have to be zero. For example, the resistance value of the load 14 may be adjusted so that the charging current is equal to or less than a predetermined threshold set near zero. In addition, when the charging current is set to a predetermined threshold value or less, the discharge current flows from the battery module 11, and the resistance value of the load 14 may be adjusted by flowing the discharge current. If a heater is used as an example of the load 14, the resistance value of the load 14 can be adjusted by adjusting the amount of heat of the heater, for example. The predetermined threshold may be set to the same value as the above-mentioned “predetermined value” of the charging current, or set to a value smaller than the “predetermined value” of the charging current for protection of the secondary battery. May be. Further, the predetermined threshold value may be appropriately changed according to the temperature.

  As described above, according to the battery unit 10 and the control method thereof according to the present embodiment, the load 14 is connected in parallel to the battery module 11 and the switch 13 is connected in series with the load 14. The switch 13 is closed by the control device 20 when the battery module 11 or its surrounding temperature is out of a predetermined temperature range and a charging current of a predetermined value or more is measured. Since the current flows to the load 14 side by closing the switch 13, the charging current of the battery module 11 can be reduced. As a result, it is possible to prevent a charging current of a predetermined value or more from flowing through the battery module 11 at a low temperature, and to protect the battery module 11.

Further, when the switch 13 is closed, the resistance value of the load 14 is adjusted by the resistance adjusting unit 24 so that the charging current of the battery module 11 approaches zero, so that the current flowing through the battery module 11 is limited. It becomes possible to approach zero.
Further, by using a heater as the load 14, heat can be efficiently generated by the current flowing through the load 14. Thereby, it becomes possible to raise ambient temperature and the operating environment of the battery module 11 can be improved.

  In the present embodiment, the resistance value of the load 14 is variable, but the resistance value of the load 14 may be fixed. In this case, the resistance value of the load 14 is set so that the charging current of the battery module 11 becomes substantially zero when the switch 13 is closed. Hereinafter, the resistance value of the load 14 will be described.

As shown in FIG. 3, the sum of electromotive forces (hereinafter referred to as “first voltage”) of a plurality of secondary batteries constituting the battery module 11 is V, the internal resistance value of the battery module 11 is R ₀ , and the load 14. The resistance value is R, the charging current flowing through the battery module 11 is I _R0 , the current flowing through the load 14 is I _R , and the current flowing into the battery unit 10 is I. Although the electromotive force of the secondary battery is not illustrated, it is measured by a voltage sensor provided in each secondary battery, and information on the electromotive force is sent from the voltage sensor to the control device 20.
If the charging current I _R0 = 0 flowing in the battery module 11 when I ≠ 0, the following equation is established.

I _R = I (1)
V _R = V (2)

Since R = V _R / I _R , the following formula (3) is established by substituting the formulas (1) and (2) into this formula.

  R = V / I (3)

From the above, the resistance value R of the load 14 for setting the charging current I _R0 to 0 is set based on the first voltage V and the current I flowing into the battery unit 10. For example, a range that can be taken by the first voltage V and a range that can be taken by the current I flowing into the battery unit 10 are obtained in advance, and the resistance value R is set based on these pieces of information. Thereby, the charging current of the battery module 11 can be effectively reduced.

  In this embodiment, the resistance value of the load 14 is variable. However, the resistance value of the load 14 is fixed, a current control device is provided between the battery unit and the load 14, and the control device changes the current control device. You may make it control and control the electric current which flows into load.

Next, a battery system and a control method thereof according to the first embodiment of the present invention will be described with reference to the drawings.
FIG. 4 is a diagram schematically showing the battery system 1 according to the first embodiment of the present invention. As shown in FIG. 4, the battery system 1 has a configuration in which battery units 10a and 10b are connected in parallel. Here, each of the battery units 10a and 10b has the same configuration as the battery unit 10 described above. In FIG. 4, in order to distinguish between the configuration of the battery unit 10a and the configuration of the battery unit 10b, “a” is assigned to each symbol for the configuration provided in the battery unit 10a, and the configuration provided in the battery unit 10b. “B” is attached to each symbol. In FIG. 4, two battery units 10a and 10b are connected in parallel, but the number of units connected in parallel is not particularly limited. Further, the sum of electromotive forces of a plurality of secondary batteries constituting the battery module 11a is defined as a first voltage, and the sum of electromotive forces of the plurality of secondary batteries constituting the battery module 11b is defined as a second voltage.

  In the battery system 1 in which the plurality of battery units 10a and 10b are connected in parallel, the first voltage is applied when the connection with the external load 30 is interrupted in addition to the regenerative current from the external load 30 described above. When the voltage is higher than the second voltage, a reflux current may flow from the battery unit 10a to the battery unit 10b. Even in such a case, the battery temperature is outside the predetermined temperature range by individually executing the processing shown in FIG. 2 by the control devices 20a and 20b included in the battery units 10a and 10b, respectively. When the charging current is greater than or equal to the predetermined value, the switches 13a and 13b are closed, and the return current flows through the loads 14a and 14b. Thereby, the charging current of the battery modules 11a and 11b can be reduced.

As described above, according to the battery system 1 and the control method thereof according to the present embodiment, the charging current at a low temperature can be suppressed to a predetermined value or less.
Moreover, according to the battery system 1 according to the present embodiment, since the battery unit 10 is set as one unit and these are connected in parallel, the battery voltage of the battery system 1 can be easily changed by changing the number of parallel connections. Can be changed. Thereby, versatility can be improved.

As described above, instead of configuring the battery system 1 with the battery unit 10 as one unit, the load 14 and the temperature sensor 15 may be shared among the plurality of battery units 10a and 10b.
Further, the control device 20 may be shared among the plurality of battery units 10a and 10b as shown in FIG. For example, FIG. 5 shows a schematic configuration when the load 14 and the control device 20 ′ are shared among the plurality of battery units 10a and 10b. Here, in FIG. 5, as in FIG. 4, “a” is assigned to each symbol for the configuration provided in the battery unit 10 a, and “b” is assigned to each symbol for the configuration provided in the battery unit 10 b.
As shown in FIG. 5, when the control device 20 ′ is shared among a plurality of battery units 10a and 10b, the control device 20 ′ performs the processing shown in FIG. 2 for each battery unit 10a and 10b. Run each one.

In this way, by sharing the load 14, the control device 20 ', and the temperature sensor 15 among the plurality of battery units 10a and 10b, the number of components can be reduced, and cost reduction and downsizing of the device are expected. it can.
Note that the switch 13a of the battery system shown in FIG. 5 is omitted, and is based on the higher one of the measured values of the temperature sensors 15a and 15b or the larger one of the measured values of the current sensors 16a and 16b. Thus, the resistance value of the load 14 may be controlled. Even if it controls in this way, if wiring resistance is low enough, a return current will flow into the load 14, and the charging current of battery module 11a, 11b can be reduced.

Next, a battery system and a control method thereof according to the second embodiment of the present invention will be described with reference to the drawings.
FIG. 6 is a diagram schematically showing a battery system 1 ′ according to the second embodiment of the present invention. As shown in FIG. 6, the battery system 1 ′ is a battery system connected to an external load 30, and includes a first battery module 11c having at least one secondary battery connected in series, and a first module 11c. A resistance element 26 provided between the positive terminal and the external load 30 and a second battery module 11d connected in parallel to the first battery module 11c via the resistance element 26 are provided. Although FIG. 6 illustrates one second battery module 11d, the number of connections of the second battery module 11d is not limited.

A load 14d is connected in parallel to the second battery module 11d, and a normally open switch 13d is connected in series to the load 14d. Further, a temperature sensor 15d that measures the temperature of the second battery module 11d or its vicinity and a current sensor 16d that measures the current flowing through the second battery module 11d are provided.
Sensor measurement values measured by the temperature sensor 15d and the current sensor 16d are output to the control device 20d. The control device 20d has the same function as that of the control device 20 according to the first embodiment described above, the temperature measured by the temperature sensor 15d is outside the preset temperature range, and the current sensor 16d When a charging current of a predetermined value or more is measured, the switch 13d is closed and the charging current of the second battery module 11d is reduced.
At this time, the resistance value of the load 14d is variable, and the control device 20d feedback-controls the resistance value of the load 14d so that, for example, the charging current becomes zero.
Here, instead of the current value, it is also possible to control the charging current based on the sum of electromotive forces of a plurality of secondary batteries constituting the battery module. However, in addition to the sum of the electromotive forces of these secondary batteries, there are internal resistance values and wiring resistance values of each secondary battery, so it is better to control the charging current based on the current value that actually flows. It can be said that it is preferable in terms of control accuracy.

  Here, the resistance element 26 connected to the first battery module 11c is the sum of the electromotive forces of the plurality of secondary batteries constituting the first battery module 11c, and the plurality of secondary batteries constituting the second battery module 11d. Is a resistance element provided to maintain higher than the sum of the electromotive forces of the first battery module, absorbs the variation between the internal resistance value of the first battery module 11c and the internal resistance value of the second battery module 11d, and The resistance value of the arm on the module 11d side is set to a sufficient resistance value so that the resistance value is always larger than that of the arm on the first battery module 11c side.

  According to the battery system 1 ′ having such a configuration and the control method thereof, the resistance element 26 basically sets the current flowing through the second battery module 11d to a value larger than the current flowing through the first battery module 11c. can do. Therefore, it is not necessary to provide a current sensor, and the number of parts can be reduced.

While the embodiments of the present invention have been described above, the scope of the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the invention.
For example, in the above-described corner embodiment, the heater has been described as an example of the load 14. However, the present embodiment is not limited to this, and various kinds of lamps such as a lamp that can consume a reflux current are used together with or in place of the heater. A load may be used.

1, 1 'battery system 10, 10a, 10b battery unit 11, 11a, 11b battery module 11c first battery module 11d second battery module 13, 13a, 13b switch 14, 14a, 14b load 15, 15a, 15b temperature sensor 16 , 16a, 16b Current sensors 20, 20a, 20b Control device 21 Sensor information acquisition unit 22 Determination unit 23 Switch control unit 24 Resistance value adjustment unit 26 Resistance element 30 External load

Claims (12)

A battery module in which at least one secondary battery is connected in series;
Power consumption means connected to the battery module;
Temperature measuring means for measuring the temperature of the battery module or the vicinity thereof, and
Current measuring means for measuring a current flowing toward the battery module;
When the temperature measured by the temperature measuring means is out of a preset temperature range, and the charging current of a predetermined value or more is measured by the current measuring means, the charging current of the battery module is below a predetermined threshold value. A battery unit comprising control means for controlling the power consuming means. The power consuming means includes a load, and a normally open type opening / closing means capable of connecting the load and the battery module,
The control means closes the opening / closing means when the temperature measured by the temperature measuring means is out of a preset temperature range and when the charging current more than a predetermined value is measured by the current measuring means. The battery unit according to claim 1. The power consuming means includes a load and a current control device arranged between the load and the battery module,
When the temperature measured by the temperature measuring unit is out of a preset temperature range and the current measuring unit measures a charging current of a predetermined value or more, the control device is configured to charge the battery module. The battery unit according to claim 1, wherein the current flowing through the load is adjusted by the current control device so that the current becomes equal to or less than a predetermined threshold. The power consuming means is a load having a variable resistance value,
The battery unit according to claim 1, wherein the control unit adjusts a resistance value of the load so that a charging current of the battery module is equal to or less than a predetermined threshold.   The battery unit according to claim 4, wherein the resistance value of the load is determined based on a sum of electromotive forces of at least one secondary battery constituting the battery module and a current flowing into the battery module.   The battery unit according to any one of claims 1 to 5, wherein the power consuming means includes a heater.   The battery system comprised by connecting the some battery unit in any one of Claims 1-6 in parallel.   The battery system according to claim 7, wherein the control means is shared among a plurality of the battery modules. A battery system in which a plurality of battery units according to claim 1 are connected in parallel,
The battery system in which the power consuming means is shared among a plurality of the battery units. A battery system connected to an external load,
A first battery module in which at least one secondary battery is connected in series;
A resistance element provided between a positive terminal of the first battery module and the external load;
A second battery module connected in parallel to the first battery module via the resistance element;
Power consuming means connected to the second battery module;
Temperature measuring means for measuring the temperature of the second battery module or the vicinity thereof;
Current measuring means for measuring a current flowing through the second battery module;
When the temperature measured by the temperature measuring means is out of a preset temperature range, and the charging current of a predetermined value or more is measured by the current measuring means, the charging current of the battery module is below a predetermined threshold value. A battery system comprising control means for controlling the power consumption means. Connecting a power consuming means to a battery module in which at least one secondary battery is connected in series;
When the temperature of the battery module or the vicinity thereof is out of a preset temperature range, and the charging current of the battery module is equal to or higher than a predetermined value, the charging current of the battery module is equal to or lower than a predetermined threshold value. The battery unit control method for controlling the power consumption means. A control method for a battery system connected to an external load,
A resistance element is connected between a positive terminal of a first battery module in which at least one secondary battery is connected in series and the external load, and the first battery module and the second battery are connected via the resistance element. Connect the module in parallel,
Connecting power consuming means to the second battery module;
When the temperature of the second battery module or the vicinity thereof is out of a preset temperature range and the charging current of the second battery module is equal to or higher than a predetermined value, the charging current of the battery module is equal to or lower than a predetermined threshold value. A battery system control method for controlling the power consumption means.

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