Energy storage device and method of manufacturing the same

Abstract

The present invention provides an energy storage device and its manufacturing method that has a product form for connection to external devices, maintains the quality of the battery pack, and is compatible with battery packs without built-in contactors. The energy storage device (10) is divided into a battery container (20) and a backpack container (30). The battery container (20) has multiple high-voltage battery units (40) connected in parallel or in series / parallel in a matrix. The backpack container (30) includes a power conversion unit (32) and an energy management system (34). Each high-voltage battery unit (40) includes multiple low-voltage battery units (42) connected in series and a high-voltage control unit (44). Each low-voltage battery unit (42) and high-voltage control unit (44) have been used in an electric vehicle. Each high-voltage battery unit (40) or each low-voltage battery unit (42) has a housing that can be directly attached to an electric vehicle, and is a used battery pack that has been collected and remains undisassembled.

Description

[Technical Field]

[0001] The present invention relates to an energy storage device including a plurality of battery packs used primarily in an electric vehicle, and a method for manufacturing the same. [Background technology]

[0002] Conventionally, battery packs installed in electric vehicles and hybrid vehicles are assumed to be replaced with new battery packs when certain conditions are met. However, even used battery packs have sufficient performance for applications other than automobiles, and with the spread of electric vehicles and hybrid vehicles, a large amount of used battery packs is expected to be generated, so there is a desire to reuse them. On the other hand, energy storage devices installed in buildings are expensive and often have limited capacity, so there is a desire to reduce their prices and increase their capacity. In response to these needs, energy storage devices using used battery packs have been proposed.

[0003] US Patent No. 6,299,949 describes an integrated battery energy storage system that includes multiple second-life electric vehicle battery packs connected in a series / parallel configuration. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Table 2025-508433 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the storage system described in Patent Document 1 has the problem that while it takes into consideration the product form of the storage system itself, it does not consider the product form between the storage system and external devices such as a solar power generation unit or a power grid. Also, while it takes into consideration the reuse of electrochemical batteries from electric vehicles and their use for secondary or second-life stationary energy storage applications, it does not consider whether or not to disassemble the battery packs after recovery. Furthermore, it has the problem of not being able to accommodate low-voltage battery packs that do not have built-in contactors.

[0006] The present invention has been made in consideration of the above-mentioned problems of the prior art, and an object of the present invention is to provide an energy storage device and a manufacturing method thereof that has a product form for connection to an external device, maintains the quality of the battery pack by using it as is without disassembly after collection, and is also compatible with battery packs that do not have built-in contactors. In addition to the above object, another object of the present invention is to provide a large-capacity, low-cost energy storage device and a method for manufacturing the same. [Means for solving the problem]

[0007] As a result of extensive research conducted by the inventors in order to achieve the above-mentioned object, they discovered that by housing a power conversion unit and an energy management system in the housing of a backpack container, a product form suitable for connection to external devices can be obtained, and the quality of the battery pack can be maintained by using it as is without disassembly after collection, and that by connecting a contactor in series to multiple battery packs that do not have built-in contactors, it is possible to make the product compatible with battery packs that do not have built-in contactors.

[0008] The inventors have also discovered that energy storage devices can be made large-capacity and low-cost by manufacturing backpack containers in one location to reduce costs and by manufacturing battery containers at a collection site for used battery packs to minimize transportation costs for used battery packs, which led to the present invention.

[0009] That is, a first aspect of the present invention is a battery pack divided into a battery container having a plurality of high-voltage battery units connected in parallel or in series / parallel in a matrix, and a backpack container equipped with a power conversion unit and an energy management system, each high-voltage battery unit having a plurality of low-voltage battery units connected in series and a high-voltage control unit, each low-voltage battery unit and high-voltage control unit having been used primarily in an electric vehicle, each high-voltage battery unit or each low-voltage battery unit having a housing that can be directly attached to the electric vehicle, and being a used battery pack that has not been disassembled and has been collected, and the high-voltage control unit has a contactor connected in series to the plurality of low-voltage battery units and a battery management system, The contactor electrically connects or disconnects the plurality of low-voltage battery units and the power conversion unit, the battery management system has the function of collecting battery data output by each low-voltage battery unit and transmitting battery information including at least a portion of the battery data to the energy management system, the power conversion unit converts DC discharge power from the plurality of low-voltage battery units and outputs it to an external device, and converts power from the external device into DC charging power and outputs it to the plurality of low-voltage battery units, and the energy management system turns the contactors on and off to control charging and discharging of the plurality of low-voltage battery units and notifies the external device of battery information from the battery management system, thereby providing an energy storage device.

[0010] Here, in the first form of the present invention, it is preferable that the energy management system or battery management system further has a function of calculating the SOH value and the OCV value based on the battery data, and a function of adding the SOH value and the OCV value to the battery information. When charging or discharging the battery container, the energy management system preferably controls the contactor of the first high-voltage battery unit to open if the voltage of a first high-voltage battery unit among the multiple high-voltage battery units deviates from an operating voltage range previously specified for all the multiple high-voltage battery units, and controls the contactor of the second high-voltage battery unit to close when the relationship between the voltage difference ΔV between a second high-voltage battery unit among the multiple high-voltage battery units and a third high-voltage battery unit with its contactor closed, the maximum current Imax that the second high-voltage battery unit can pass, and the internal resistance R of the second high-voltage battery unit satisfies the following formula (1). 0 ≤ |ΔV| <Imax×R···(1) Preferably, the battery management system further has a function of transmitting only battery information required for maintenance work from among the battery data to the energy management system in order to reduce the amount of data transmitted to the energy management system.

[0011] Furthermore, in the first embodiment of the present invention, it is preferable that the weight of the entire contents contained in each housing of the backpack container is half or less of that of the battery container. The total weight of the contents contained in the battery container casing is preferably 500 to 6200 kg. The backpack container preferably has a volume of space containing all of the contents in each housing that is half or less of that of the battery container. The volume of the space that contains all the items stored inside the battery container is 12.0 to 76.0 m 3 It is preferable that: The weight of each battery pack is 50 to 250 kg, and the volume of the rectangular parallelepiped that contains each battery pack is 0.025 to 0.250 m 3 It is preferable that:

[0012] Furthermore, a second aspect of the present invention provides a method for manufacturing an energy storage device according to the first aspect of the present invention, wherein each low-voltage battery unit has a housing that can be directly attached to an electric vehicle and is a used battery pack that has not been disassembled and is in the collected state; the manufacturing process for each low-voltage battery unit that constitutes any one of the plurality of high-voltage battery units includes the steps of: a computer acquiring the OCV value and SOH value of each collected low-voltage battery unit; the computer classifying each low-voltage battery unit into a plurality of groups based on the magnitude of the SOH value of each low-voltage battery unit; the computer selecting a plurality of low-voltage battery units from those belonging to any one of the groups as a selected group; and a charging / discharging device adjusting the OCV value of each low-voltage battery unit so that the OCV value of each selected low-voltage battery unit is within ±0.3 V of a predetermined reference voltage.

[0013] Here, in the second embodiment of the present invention, it is preferable to further include a step of leaving each low-voltage battery unit connected in parallel with each other for at least 5 hours or more, so that the OCV values ​​of each low-voltage battery unit are equalized by each low-voltage battery unit itself. The selected group is preferably a group of low-voltage battery units selected by the computer from among those belonging to any one group to form any one high-voltage battery unit, and a group of low-voltage battery units selected by the computer from among those belonging to another group to form another high-voltage battery unit. [Effects of the Invention]

[0014] According to the present invention, a product form for connection to an external device is provided, the quality of the battery pack is maintained, and it is possible to make it possible to accommodate battery packs that do not have built-in contactors. Furthermore, in addition to the above effects, the present invention can achieve large capacity and low cost. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a block diagram illustrating an energy storage device of the present invention. [Figure 2] FIG. 10 is a block diagram showing a modified example of the energy storage device of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] The energy storage device of the present invention will be described in detail below based on preferred embodiments shown in the accompanying drawings. Fig. 1 is a block diagram showing the energy storage device of the present invention, specifically showing a case where each hatched high-voltage battery unit is a battery pack. Fig. 2 is a block diagram showing a modified example of the energy storage device of the present invention, specifically showing a case where each hatched low-voltage battery unit is a battery pack. Note that components with the same functions are given the same reference numerals.

[0017] The energy storage device 10 of the present invention is divided into a battery container 20 and a backpack container 30. The battery container 20 has multiple high-voltage battery units 40 connected in parallel or in series / parallel in a matrix. The backpack container 30 includes a power conversion unit 32 and an energy management system 34. Each high-voltage battery unit 40 includes multiple low-voltage battery units 42 connected in series and a high-voltage control unit 44. Each low-voltage battery unit 42 and high-voltage control unit 44 have been used in an electric vehicle. Either each high-voltage battery unit 40 or each low-voltage battery unit 42 is a used battery pack. The used battery pack has a housing that can be directly attached to an electric vehicle and is in its original, undisassembled state after collection. The high-voltage control unit 44 includes a contactor 46 connected in series to the multiple low-voltage battery units 42 and a battery management system 48.

[0018] The contactors 46 electrically connect or disconnect the plurality of low-voltage battery units 42 and the power conversion unit 32. The battery management system 48 has a function of collecting battery data output by each low-voltage battery unit 42 and transmitting battery information including at least a portion of the battery data to the energy management system 34. The power conversion unit 32 converts DC discharge power from the plurality of low-voltage battery units 42 and outputs it to an external device (not shown), and converts power from the external device into DC charging power and outputs it to the plurality of low-voltage battery units 42. The energy management system 34 turns the contactors 46 on and off to control the charging and discharging of the plurality of low-voltage battery units 42, and notifies the external device of the battery information from the battery management system 48.

[0019] Here, the relationship between the components of the battery container of the present invention and two typical product forms will be described. The first product form corresponds to a used battery pack that has been collected and not disassembled, in which the high-voltage battery unit 40 has a housing that can be directly attached to an electric vehicle, as shown in Figure 1. In this case, the low-voltage battery unit 42 and high-voltage control unit 44 have been used primarily in the electric vehicle, and while the high-voltage control unit 44 does not have a housing, the low-voltage battery unit 42 may have a housing as a battery module.

[0020] The second product form corresponds to a used battery pack that has been collected and not disassembled, in which the low-voltage battery unit 42 has a housing that can be directly attached to an electric vehicle, as shown in Figure 2. In this case, the low-voltage battery unit 42 and the high-voltage control unit 44 have been used initially in the electric vehicle, and while the high-voltage battery unit 40 does not have a housing, the high-voltage control unit 44 may have a housing that can be directly attached to the electric vehicle. The low-voltage battery unit 42 is sometimes called a battery module. Alternatively, the high-voltage battery unit 40 is configured by connecting multiple used low-voltage battery units 42 collected from an electric vehicle in series, connecting the contactors 46 of the high-voltage control unit 44 to the power cables of the multiple low-voltage battery units 42, and connecting the battery management system 48 of the high-voltage control unit 44 to the control cables of the multiple low-voltage battery units 42.

[0021] Next, common to the first and second product forms, multiple high-voltage battery units 40 are connected in parallel or in series-parallel in a matrix and housed in the housing of the battery container 20. The power conversion unit 32 is connected to the power cable between the contactor 46 and the external device, and the energy management system 34 is connected to the control cable between the battery management system 48 and the external device, and they are housed in the housing of the backpack container 30.

[0022] The housing of the battery container 20 may be a ready-made 10-foot, 20-foot, or 40-foot container. The power conversion unit 32 is a DC-DC converter when the input / output power of the external device is DC, and a power conditioner (hereinafter referred to as PCS) when the input / output power of the external device is AC, but if the input / output power of the external device is both AC and DC, both may be connected in parallel. The energy management system 34 and battery management system 48 are composed of electrical circuits and include a CPU as needed.

[0023] With this configuration, the energy storage device of the present invention has a product form for connection to an external device, maintains the quality of the battery pack, and can be used with battery packs that do not have built-in contactors. Furthermore, in addition to the above effects, the energy storage device of the present invention can be made large-capacity and low-cost.

[0024] Next, the SOH and OCV of each low-voltage battery unit constituting any one high-voltage battery unit will be described in detail. The energy management system 34 or the battery management system 48 preferably further has the following two functions: a function to calculate the SOH value and the OCV value based on the battery data, and a function to add the SOH value and the OCV value to the battery information.

[0025] Here, SOH refers to the battery capacity retention rate and indicates the battery's state of degradation. SOH can be calculated by using the voltage or coulomb counting method to determine the charge rate before and after charging, and then dividing the full charge capacity calculated from these charge rates and the charge at that time by the initial full charge capacity. SOH can also be calculated by applying two different current loads to a battery, calculating the internal resistance from the corresponding voltages and currents, and comparing this with a pre-existing internal resistance vs. SOH comparison table. OCV refers to the open-circuit voltage, i.e., the voltage when no current is flowing through the battery. Like internal resistance, OCV can be calculated from the corresponding voltages and currents when two different current loads are applied.

[0026] That is, the SOH value may be calculated by the energy management system 34 and added to the battery information, or the battery management system 48 may calculate it and add it to the battery information. Similarly, the OCV value may be calculated by the energy management system 34 and added to the battery information, or the battery management system 48 may calculate it and add it to the battery information.

[0027] With this configuration, the energy storage device of the present invention can contribute to the retention of a large capacity because the SOH value and the OCV value can be monitored by an external device.

[0028] Next, the opening and closing control of the contactors will be described in detail. When charging or discharging the battery container 20, the energy management system 34 preferably controls the contactor of the first high-voltage battery unit 40a to open if the voltage of the first high-voltage battery unit 40a among the multiple high-voltage battery units 40 deviates from a predetermined operating voltage range that is the same for all the multiple high-voltage battery units 40. Furthermore, when charging or discharging the battery container 20, the energy management system 34 preferably controls the contactor of the second high-voltage battery unit 40b to close when the relationship between the voltage difference ΔV between the second high-voltage battery unit 40b among the multiple high-voltage battery units 40 and the third high-voltage battery unit 40c with its contactor closed, the maximum current Imax that the second high-voltage battery unit 40b can pass, and the internal resistance R of the second high-voltage battery unit 40b satisfies the following formula (1): 0 ≤ |ΔV| <Imax×R···(1)

[0029] That is, when charging the battery container 20, if any high-voltage battery unit 40 has a voltage higher than an upper limit value of the operating voltage that has been specified in advance for the same high-voltage battery units 40, the energy management system 34 controls the contactor of that high-voltage battery unit 40 to open. Also, when discharging the battery container 20, if any high-voltage battery unit 40 has a voltage lower than a lower limit value of the operating voltage that has been specified in advance for the same high-voltage battery units 40, the energy management system 34 controls the contactor of that high-voltage battery unit 40 to open. Furthermore, when charging or discharging the battery container 20, if any high-voltage battery unit 40 has a voltage difference ΔV with the high-voltage battery unit in a contactor-closed state that is smaller than the product of the maximum current Imax and the internal resistance R, the energy management system 34 controls the contactor of that high-voltage battery unit 40 to close.

[0030] In the explanations in this document, Figure 1 shows six high-voltage battery units 40 as the multiple high-voltage battery units 40 and three low-voltage battery units 42 as the multiple low-voltage battery units 42, and Figure 2 shows three high-voltage battery units 40a, 40b, and 40c as the multiple high-voltage battery units 40 and nine low-voltage battery units 42a, 42b, and 42c as the multiple low-voltage battery units 42, but the number of parallel connections or series-parallel connections of high-voltage battery units 40 and the number of series connections of low-voltage battery units 42 are not restrictive.

[0031] With this configuration, the energy storage device of the present invention can extend its life by preventing overcharging, overdischarging, and overcurrent when the contactor is closed in the high-voltage battery section, thereby contributing to maintaining a large capacity.

[0032] Next, the data for each low-voltage battery unit required for maintenance work will be described in detail. Preferably, the battery management system 48 also has a function of transmitting only battery information required for maintenance work from among the battery data to the energy management system 34, in order to reduce the amount of data transmitted to the energy management system 34. The battery management system 48 is primarily used in electric vehicles, but if it is equipped with a CPU, its program can be modified with the manufacturer's permission.

[0033] For example, the battery data is composed of unique data and measurement data. The unique data includes the manufacturer name, model name, and serial number of each low-voltage battery unit 42, which is output at startup. The measurement data includes the cell voltage (the voltage of each battery cell in the low-voltage battery unit 42), module temperature (the temperature of each low-voltage battery unit 42), module voltage (the voltage of each low-voltage battery unit 42), and module current (the current of each low-voltage battery unit 42), which are output at set intervals. The battery information required for maintenance work is composed of the unique data, a portion of the measurement data extracted from the measurement data, and alarms. The portion of the measurement data and alarms are preferably classified into the following three categories: the first is measurement data and an alarm indicating that each value exceeds the allowable range, such as in the event of a malfunction; the second is measurement data and an alarm indicating that the difference between each cell voltage and each module voltage exceeds the allowable range, such as in the event of an imbalance; and the third is the SOH value and an alarm indicating that the SOH value exceeds a preset allowable range.

[0034] With this configuration, the energy storage device of the present invention does not require the connection of a new device for transmitting and receiving large amounts of data, which can contribute to lower prices.

[0035] Next, the weight of all the contents stored in the housing of each container and the volume of the space that contains all the contents will be described in detail. The backpack container 30 preferably has a total weight of the contents stored in each housing that is half or less of that of the battery container 20. Also, the backpack container 30 preferably has a volume of the space that contains all of the contents stored in each housing that is half or less of that of the battery container 20.

[0036] Specifically, the items housed within the housing of the battery container 20 include the low-voltage battery unit 42, high-voltage control unit 44, cooling fan, and cables connecting them. These items have high transport costs due to their large weight and volume, so by manufacturing them at a collection site for used battery packs, transport costs for used battery packs can be minimized. The items housed within the housing of the backpack container 30 include the power conversion unit 32, energy management system 34, air conditioner, control power supply, and cables connecting them. These items have low transport costs due to their small weight and volume, so by manufacturing them all at one location, costs can be reduced. The air conditioner and control power supply may also be installed within the housing of the backpack container 30 at the collection site for used battery packs.

[0037] With this configuration, the energy storage device of the present invention can minimize the transportation costs of used battery packs, thereby making it possible to reduce the price.

[0038] The weight of the entire contents contained within the housing of the battery container 20 is preferably 500 to 6200 kg (preferably 750 to 6100 kg, more preferably 1000 to 6000 kg). If the total weight of the contents inside the battery container 20 housing is less than 500 kg, the number of battery packs installed will be too small, resulting in insufficient battery capacity. If it exceeds 6,200 kg, the total weight will be heavy, resulting in increased work to consider laws and regulations regarding manufacturing, transportation, installation, and maintenance work.

[0039] The volume of the space that contains all the contents inside the battery container 20 is 12.0 to 76.0 m 3 (Preferably 13.0 to 67.0 m 3 , more preferably 14.0 to 33.0 m 3 ) is preferred. The volume of the space that contains all the contents inside the battery container 20 is 12.0 m 3 If the battery capacity is less than 76.0m, the number of battery packs installed will be too small, resulting in insufficient battery capacity. 3In the case of over 40 feet, the cost of manufacturing the enclosure will be high because it cannot be accommodated in a 40-foot (tall) container.

[0040] With this configuration, the energy storage device of the present invention can minimize the transportation costs of used battery packs, thereby making it possible to reduce the price.

[0041] Next, the weight of each battery pack and the volume of the rectangular parallelepiped that contains each battery pack will be described in detail. The weight of each battery pack is 50 to 250 kg (preferably 100 to 240 kg, more preferably 110 to 230 kg), and the volume of the rectangular parallelepiped containing each battery pack is 0.025 to 0.250 m 3 (Preferably 0.060 to 0.235 m 3 , more preferably 0.070 to 0.220 m 3 ) is preferred.

[0042] If the weight of each battery pack is less than 50 kg, the battery capacity will be insufficient, and if it exceeds 250 kg, it will be too heavy to be installed in an electric vehicle. 3 If it is less than 0.250m, the battery capacity will be insufficient. 3 If the battery pack exceeds this limit, it will be too large to be installed in an electric vehicle. If the battery pack uses lithium-ion batteries, the lithium-ion batteries themselves are vulnerable to impact, so the battery pack housing must be particularly sturdy when installed in an electric vehicle. This makes the battery pack heavy, weighing more than 100 kg for electric buses and electric trucks.

[0043] With this configuration, the energy storage device of the present invention can minimize the transportation costs of used battery packs, thereby making it possible to reduce the price. The energy storage device of the present invention is basically configured as described above.

[0044] Next, among the manufacturing methods for the energy storage device of the present invention, a detailed description will be given of the manufacturing process for each low-voltage battery unit 42 when the low-voltage battery unit 42 has a housing that can be directly attached to an electric vehicle and is a used battery pack that has not been disassembled after collection. The manufacturing process for each low-voltage battery unit 42a constituting any one high-voltage battery unit 40a among the plurality of high-voltage battery units 40 preferably includes the following steps: first, a computer (not shown) acquires the OCV and SOH values ​​of each collected low-voltage battery unit 42, then the computer classifies each low-voltage battery unit 42 into a plurality of groups (e.g., first, second, and third groups) based on the magnitude of the SOH value of each low-voltage battery unit 42, next, the computer selects a plurality of low-voltage battery units 42a from those belonging to the first group as a selected group, and then, a charging / discharging device (not shown) adjusts the OCV value of each selected low-voltage battery unit 42a so that the OCV value of each selected low-voltage battery unit 42a is within ±0.3V (preferably within ±0.2V, more preferably within ±0.1V) of a preset reference voltage.

[0045] The same applies to the manufacturing process of each low-voltage battery unit 42b that constitutes the high-voltage battery unit 40b among the multiple high-voltage battery units 40, and the manufacturing process of each low-voltage battery unit 42c that constitutes the high-voltage battery unit 40c.

[0046] For example, battery data is collected from each recovered low-voltage battery unit 42, and the SOH values ​​calculated based on the battery data are compared. The battery units with high SOH values ​​and large battery capacities are classified into the first group, those with slightly lower SOH values ​​and slightly lower battery capacities into the second group, and those with lower SOH values ​​and small battery capacities into the third group. A low-voltage battery unit 42 belonging to one of the first to third groups is then selected as the low-voltage battery unit 42a that constitutes the high-voltage battery unit 40a. The same applies to the low-voltage battery unit 42b that constitutes the high-voltage battery unit 40b and the low-voltage battery unit 42c that constitutes the high-voltage battery unit 40c. The computer is a general-purpose product used to manage the manufacturing process. The charging / discharging device is, for example, a Myway Plus regenerative DC power supply MWBFP3-1250-J02, which can be connected in series and parallel to support up to 1000V / 280A.

[0047] Next, the OCV value of each low-voltage battery unit 42a is compared with a preset reference voltage, and each low-voltage battery unit 42a is charged and discharged to adjust the OCV value to within ±0.3V of the reference voltage. Each low-voltage battery unit 42b and each low-voltage battery unit 42c are adjusted in the same way. If the difference between the OCV value of a low-voltage battery unit 42 and the reference voltage exceeds 0.3V, the battery capacity that cannot be charged or discharged increases, resulting in a decrease in the battery capacity of the high-voltage battery unit including that low-voltage battery unit. If the battery in the low-voltage battery unit 42 is an LFP lithium-ion battery, the reference voltage is preferably 88 to 91% of the fully charged voltage.

[0048] By adopting such a configuration, the manufacturing method of the energy storage device of the present invention can minimize the decrease in overall battery capacity due to variations in SOH and OCV, thereby contributing to an increase in capacity.

[0049] The manufacturing process for each low-voltage battery unit 42a constituting any one high-voltage battery unit 40a preferably further includes the following step: The low-voltage battery units 42a are connected in parallel and left for at least 5 hours (preferably 6 hours or more, and more preferably 7 hours or more) to equalize the OCV values ​​of the low-voltage battery units 42a themselves. The low-voltage battery units 42b and 42c are also equalized in the same manner.

[0050] In other words, even if the low-voltage battery units 42a are charged and discharged so that the OCV values ​​of the low-voltage battery units 42a are within ±0.3V of the reference voltage, the OCV values ​​of the low-voltage battery units 42a cannot be completely equalized, but if the low-voltage battery units 42a are left connected in parallel for at least five hours, the OCV values ​​of the low-voltage battery units 42a can be completely equalized. If the time left is less than five hours, the battery capacity that cannot be charged or discharged increases, and the battery capacity of the high-voltage battery units, including the low-voltage battery units that are not completely equalized, decreases.

[0051] By adopting such a configuration, the manufacturing method of the energy storage device of the present invention can minimize the decrease in the overall battery capacity due to variations in OCV, thereby contributing to an increase in capacity.

[0052] The selected battery group is preferably a combination of a plurality of low-voltage battery units 42a selected by the computer from among those belonging to one arbitrary group to form one arbitrary high-voltage battery unit 40a, and a plurality of low-voltage battery units 42b selected by the computer from among those belonging to another arbitrary group to form another arbitrary high-voltage battery unit 40b. The same applies when the combination is one arbitrary high-voltage battery unit 40a and one other arbitrary high-voltage battery unit 40c, and when the combination is one arbitrary high-voltage battery unit 40b and one other arbitrary high-voltage battery unit 40c.

[0053] For example, it is preferable to select low-voltage battery units 42 belonging to the first group as low-voltage battery units 42a constituting high-voltage battery unit 40a, select low-voltage battery units 42 belonging to the second group as low-voltage battery units 42b constituting high-voltage battery unit 40b, and select low-voltage battery units 42 belonging to the third group as low-voltage battery units 42c constituting high-voltage battery unit 40c.

[0054] By adopting this configuration, the manufacturing method of the energy storage device of the present invention does not install only low-voltage battery units with large SOH values ​​or only low-voltage battery units with small SOH values, thereby reducing variation in product lifespan. The method for manufacturing an energy storage device according to the present invention is basically configured as described above.

[0055] The energy storage device and its manufacturing method of the present invention have been described in detail above, but the present invention is not limited to the above description, and various improvements and modifications may be made without departing from the spirit and scope of the present invention. [Industrial Applicability]

[0056] The energy storage device and its manufacturing method of the present invention have the effect of providing a product form for connection to external devices, maintaining the quality of the battery pack, and being able to accommodate battery packs that do not have built-in contactors. In addition, they have the effect of being able to achieve large capacity and low price, making them industrially useful. [Explanation of symbols]

[0057] 10 Energy storage device 20 Battery Container 30 Backpack Container 32 Power conversion section 34 Energy Management System 40, 40a, 40b, 40c High voltage battery section 42, 42a, 42b, 42c Low voltage battery section 44 High voltage control section 46 Contactor 48 Battery Management System

Claims

1. a battery container having a plurality of high-voltage battery units connected in parallel or in series and parallel in a matrix; A backpack container equipped with a power conversion unit and an energy management system; Each high-voltage battery unit includes a plurality of low-voltage battery units and a high-voltage control unit connected in series with each other, Each low-voltage battery unit and the high-voltage control unit have been used primarily in an electric vehicle, each high-voltage battery unit or each low-voltage battery unit is a used battery pack that has a housing that can be directly attached to the electric vehicle and is in an undisassembled state after collection; the high voltage control unit includes a contactor connected in series to the plurality of low voltage battery units and a battery management system; the contactor electrically connects or disconnects the plurality of low-voltage battery units and the power conversion unit, the battery management system has a function of collecting battery data output from each low-voltage battery unit and transmitting battery information including at least a portion of the battery data to the energy management system; the power conversion unit converts DC discharge power from the plurality of low-voltage battery units and outputs the converted power to an external device, and converts power from the external device into DC charging power and outputs the DC charging power to the plurality of low-voltage battery units, The energy management system controls the charging and discharging of the plurality of low-voltage battery units by turning the contactors on and off, and notifies an external device of the battery information from the battery management system.

2. 2. The energy storage device of claim 1, wherein the energy management system or the battery management system further has a function of calculating a value of SOH and a value of OCV based on the battery data, and a function of adding the value of SOH and the value of OCV to the battery information.

3. 2. The energy storage device according to claim 1, wherein, when charging or discharging the battery container, if the voltage of a first high-voltage battery unit among the plurality of high-voltage battery units deviates from a predetermined operating voltage range that is identical for all the plurality of high-voltage battery units, the energy management system controls the contactor of the first high-voltage battery unit to open, and controls the contactor of the second high-voltage battery unit to close when a relationship between a voltage difference ΔV between a second high-voltage battery unit among the plurality of high-voltage battery units and a third high-voltage battery unit with its contactor closed, a maximum current Imax that the second high-voltage battery unit can pass, and an internal resistance R of the second high-voltage battery unit satisfies the following formula (1): 0≦|ΔV|<Imax×R...(1)

4. The energy storage device according to claim 1, wherein the battery management system further has a function of transmitting only battery information necessary for maintenance work from among the battery data to the energy management system in order to reduce the amount of data transmitted to the energy management system.

5. The energy storage device according to any one of claims 1 to 4, wherein the backpack container has a total weight of contents contained in each housing that is half or less of that of the battery container.

6. 6. The energy storage device according to claim 5, wherein the weight of the entire contents contained in the housing of the battery container is 500 to 6,200 kg.

7. 5. The energy storage device according to claim 1, wherein the backpack container has a spatial volume that encompasses all of the contents contained in each of the battery containers, the volume being half or less of the space that encompasses all of the contents contained in each of the battery containers.

8. The volume of the space that contains all the contents in the housing of the battery container is 12.0 to 76.0 m ３ 8. The energy storage device according to claim 7, wherein:

9. The weight of each battery pack is 50 to 250 kg, and the volume of the rectangular parallelepiped containing each battery pack is 0.025 to 0.250 m ３ The energy storage device according to any one of claims 1 to 4, wherein

10. 2. A method for manufacturing the energy storage device of claim 1, comprising: each low-voltage battery unit is a used battery pack that has a housing that can be directly attached to the electric vehicle and that has not been disassembled after collection; The manufacturing process of each low-voltage battery unit constituting any one of the plurality of high-voltage battery units includes the following steps: The computer acquires the OCV value and the SOH value of each of the collected low-voltage battery units, The computer classifies each low voltage battery unit into a plurality of groups based on the magnitude of the SOH value of each low voltage battery unit, The computer selects a plurality of low-voltage battery units from any one group as a selection group; A method for manufacturing an energy storage device, comprising a step of adjusting the OCV value of each selected low-voltage battery unit by a charging / discharging device so that the OCV value of each selected low-voltage battery unit is within ±0.3 V of a preset reference voltage.

11. The method for manufacturing an energy storage device according to claim 10, further comprising the step of leaving the low-voltage battery units connected in parallel with each other for at least five hours or more, thereby equalizing the OCV values ​​of the low-voltage battery units themselves.

12. 12. The method for manufacturing an energy storage device according to claim 10 or 11, wherein the selected group is a group of low-voltage battery units selected by the computer from among those belonging to any one group to form any one high-voltage battery unit, and a group of low-voltage battery units selected by the computer from among those belonging to another group to form another high-voltage battery unit.

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