KR20230107023A - Method for detecting a low voltage of secondary battery and system for detecting a low voltage - Google Patents

Abstract

The disclosed invention relates to a method for detecting a low voltage defect of a battery cell, which includes charging the battery cell, performing constant voltage (CV) charging before the battery cell is fully charged, and constant voltage (CV) charging. Measuring the constant voltage (CV) charging time required from start to full charge, comparing the measured constant voltage (CV) charging time with a preset reference constant voltage (CV) charging time, and the measured constant voltage (CV) charging time and determining the battery cell as a low voltage defect when the positive error range is greater than the reference constant voltage (CV) charging time.

Description

Low voltage defect detection method and low voltage defect detection system according to the method

The present invention relates to a low voltage defect detection method.

More specifically, the present invention relates to a low voltage defect detection method capable of detecting a low voltage defect through a constant voltage (CV) charging time of a secondary battery.

In addition, the present invention relates to a low voltage defect detection system.

Recently, secondary batteries capable of charging and discharging have been widely used as energy sources for wireless mobile devices.

In addition, secondary batteries are electric vehicles and hybrid electric vehicles, which are being proposed as a solution to air pollution from conventional gasoline vehicles and diesel vehicles that use fossil fuels, as well as portable devices such as cell phones, laptops, and camcorders. It is also attracting attention as an energy source.

Therefore, the types of applications using secondary batteries are diversifying due to the advantages of secondary batteries, and it is expected that secondary batteries will be applied to more fields and products than now.

These secondary batteries are classified into lithium ion batteries, lithium ion polymer batteries, lithium polymer batteries, etc. according to the composition of electrodes and electrolytes, and the use of lithium ion polymer batteries, which are less likely to leak electrolyte and are easy to manufacture, is increasing.

In general, secondary batteries are classified into cylindrical batteries and prismatic batteries in which electrode assemblies are embedded in cylindrical and prismatic metal cans, and pouch-type batteries in which electrode assemblies are embedded in pouch-type cases of aluminum laminate sheets, depending on the shape of the battery case. .

In addition, the electrode assembly embedded in the battery case is a power generating device capable of charging and discharging, consisting of a structure in which a positive electrode, a negative electrode, and a separator are interposed between the positive electrode and the negative electrode. It is classified into a rolled jelly roll type and a stack type in which a plurality of positive and negative electrodes formed in a predetermined size are sequentially stacked with a separator interposed therebetween.

Here, since electric vehicles and the like use high-output electric energy, a plurality of battery modules are required, and a plurality of battery cells are connected in series or parallel to the inside of the battery module.

On the other hand, secondary batteries are manufactured by embedding an electrode assembly composed of a positive electrode, a negative electrode, and a separator in a pouch-type case and injecting an electrolyte into the pouch-type case, and then going through a conversion process that activates the manufactured secondary battery to be shipped as a product.

The conversion process for activating the secondary battery includes a formation process, an aging process, and a defect selection process, and the secondary battery is shipped only after passing through all conversion processes and not being classified as defective.

Here, the formation process activates the battery by repeatedly performing predetermined charging and discharging, and the aging process is a maturation process in which time is provided so that the electrolyte enters the empty space of the electrode to form a stable electrolyte channel.

On the other hand, secondary batteries are manufactured to prevent short circuits by preventing contact between the positive and negative electrodes by a porous separator, but insulation may not be properly maintained due to various causes during the battery manufacturing process, and thus short circuits inside the battery. this may occur.

In this way, lithium ion batteries can be connected to ignition and explosion if a short circuit occurs between the positive and negative electrodes, and ions move and current flows even when there is a very small short circuit. This condition is often referred to as a soft short or micro short.

A low voltage defect is induced by a soft short. Soft short batteries often take a relatively long time for low voltage defects to occur compared to hard short batteries. I should too

In addition, as shown in FIG. 1 , the secondary battery may be mixed with metal foreign substances including copper or iron from the outside.

These metal foreign substances are dissolved in the electrolyte and grow on the negative electrode in the form of needles to form dendrites, and the dendrites break through the separator to reach the positive electrode, causing a short circuit.

In this way, there is a problem that metal foreign substances mixed into the secondary battery cause low voltage defects of the secondary battery by freely participating in the electrochemical reaction within the battery.

Therefore, in order to select defects of the secondary battery, low-voltage defects of the secondary battery are determined through leakage current due to dendrite growth during an activation process.

That is, as shown in FIG. 2, after measuring the OCV (Open Circuit Voltage) value of the secondary battery before and after the aging process to secure the time necessary for dendrite growth, the low voltage defect is determined by comparing the measured OCV value. determined.

Here, although it is judged to be normal during the activation process, after the activation process is finished, defects in the secondary battery may additionally occur through a storage period from the time the secondary battery is put into the battery pack.

In addition, in order to determine a defect after measuring the OCV value before and after the aging process, it is necessary to wait for a period of time during which dendrites can grow in the secondary battery, so it may take a long time of 5 days or more to determine a defect.

In this way, since the low voltage defect is left to develop through self-discharge and a waiting time of several days or more is required during the long-term aging process until the low voltage defect appears, there is a problem in that overall productivity is lowered.

Republic of Korea Patent Publication No. 10-2014-0141289

The present invention has been made to solve the above problems, and a low voltage defect detection method capable of quickly sorting out low voltage defective secondary batteries without waiting for a long time through the charging time during constant voltage (CV) charging of the secondary batteries. And to provide a low voltage defect detection system accordingly.

In addition, an object of the present invention is to provide a low voltage defect detection method and a low voltage defect detection system that can select a low voltage by utilizing a charging current profile generated during charging during constant voltage (CV) charging of a secondary battery and a low voltage defect detection system accordingly.

In order to realize the above object, the present invention provides a method for detecting a low voltage defect of a battery cell, comprising: charging the battery cell; Performing constant voltage (CV) charging before fully charging the battery cell; Measuring a constant voltage (CV) charging time required from the start of constant voltage (CV) charging to fully charged; comparing the measured constant voltage (CV) charging time with a preset reference constant voltage (CV) charging time; and determining the battery cell as a low voltage defect when the measured constant voltage (CV) charging time exceeds a positive error range than the reference constant voltage (CV) charging time. It is characterized in that it includes.

As a specific example, constant current (CC) charging is performed on the battery cells before constant voltage (CV) charging.

As another specific example, the constant voltage (CV) charging is performed until the constant voltage (CV) charging current reaches a preset lower limit value.

As another specific example, the positive error range for the reference constant voltage (CV) charging time is +5% to +10%.

As an example, a method for detecting a low voltage defect of a battery cell, comprising: charging the battery cell; Performing constant voltage (CV) charging before fully charging the battery cell; measuring a rate of change of constant voltage (CV) charging current from the start of constant voltage (CV) charging to a predetermined time before being fully charged; comparing the measured constant voltage (CV) charging current rate of change with a preset reference constant voltage (CV) charging current rate of change; and determining the battery cell as a low voltage defect when an absolute value of the measured constant voltage (CV) charging current rate of change is less than a negative error range than an absolute value of the reference constant voltage (CV) charging current rate of change. includes

As a specific example, constant current (CC) charging is performed on the battery cells before constant voltage (CV) charging.

As another specific example, the constant voltage (CV) charging is terminated before the constant current charging current reaches a preset lower limit value.

As another specific example, the negative error range for the standard constant voltage (CV) charging current change rate is -5% to -10%.

As another example, in the detection system for detecting a low voltage defect of a battery cell, the charger device for charging the battery cell; An ammeter measuring the charging time of the battery cell charged through the charger in units of time; a storage unit for storing in real time the charging time of the battery cell and the change rate of the charging current measured by the ampere meter; and a control unit for controlling a charging device and receiving a charging time and a change rate of a charging current of the battery cells stored in the storage unit. Including, the control unit controls the charging device to perform constant voltage (CV) charging before charging of the battery cell, and the constant voltage (CV) charging time required from the start of constant voltage (CV) charging to full charging is a preset reference constant voltage ( CV) exceeds the positive error range than the charging time, or the absolute value of the rate of change of the constant voltage (CV) charging current from the start of charging the constant voltage (CV) to the predetermined time before being fully charged is the preset reference constant voltage ( If CV) is less than the negative error range than the absolute value of the charging current change rate, the battery cell is determined as a low voltage defect.

As a specific example, the control unit controls the charger to perform constant current (CC) charging on the battery cells before constant voltage (CV) charging.

According to the present invention, when charging a secondary battery with a constant voltage (CV), it is possible to quickly select a low voltage defect by checking the CV charging delay time affected by the leakage current of the low voltage defect.

In addition, when charging the secondary battery with constant voltage (CV), it is possible to select low-voltage defects by utilizing the charging current profile generated during charging, thereby shortening the time for sorting low-voltage defects and reducing the aging process time to improve productivity and secondary batteries. of shipment responsiveness can be secured.

In addition, it is possible to reduce the construction cost of the aging rack in the aging process, thereby reducing the facility cost and the site cost, and preventing the external shipment of defective batteries by increasing the defect detection rate.

1 is a schematic diagram schematically showing current flow during charging of a battery cell.
2 is a conceptual diagram schematically illustrating a process of selecting low voltage defects according to the prior art.
3 is a flowchart schematically illustrating a method of detecting a low voltage defect of a battery cell according to an embodiment of the present invention.
4 is a diagram showing a charging profile of a battery cell for detecting a low voltage defect according to an embodiment of the present invention.
5 is a conceptual diagram schematically illustrating a process of selecting low voltage defects according to the present invention.
6 is a configuration diagram conceptually illustrating a low voltage defect detection system according to an embodiment of the present invention.
7 is a configuration diagram schematically illustrating a control unit of a low voltage defect detection system according to an embodiment of the present invention.
8 is a flowchart schematically illustrating a method of detecting a low voltage defect of a battery cell according to another embodiment of the present invention.

Hereinafter, the present invention will be described in detail. Prior to this, terms or words used in this specification and claims should not be construed as being limited to ordinary or dictionary meanings, and the inventor appropriately uses the concept of terms in order to describe his/her invention in the best way. It should be interpreted as a meaning and concept consistent with the technical spirit of the present invention based on the principle that it can be defined in the following way.

Terms such as "include" or "have" used throughout the specification of the present invention are intended to designate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, but one or other features, numbers, steps, operations, components, parts, or combinations thereof, are not precluded from being excluded in advance.

In addition, when a part such as a layer, film, region, plate, etc. is said to be "on" another part, this includes not only the case where it is "directly on" the other part, but also the case where another part is present in the middle. Conversely, when a part such as a layer, film, region, plate, etc. is said to be "under" another part, this includes not only the case where it is "directly under" the other part, but also the case where there is another part in between. In addition, in the specification of the present invention, being disposed "on" may include the case of being disposed at the bottom as well as at the top.

In addition, when a part such as a layer, film, region, plate, etc. is said to be "on" another part, this includes not only the case where it is "directly on" the other part, but also the case where another part is present in the middle. Conversely, when a part such as a layer, film, region, plate, etc. is said to be "under" another part, this includes not only the case where it is "directly under" the other part, but also the case where there is another part in between. In addition, in the present application, being disposed "on" may include the case of being disposed at the bottom as well as at the top.

(First Embodiment)

3 is a flowchart schematically illustrating a method of detecting a low voltage defect of a battery cell according to an embodiment of the present invention. 4 is a diagram showing a charging profile of a battery cell for detecting a low voltage defect according to an embodiment of the present invention. 5 is a conceptual diagram schematically illustrating a process of selecting low voltage defects according to the present invention. 6 is a configuration diagram conceptually illustrating a low voltage defect detection system according to an embodiment of the present invention. 7 is a configuration diagram schematically illustrating a control unit of a low voltage defect detection system according to an embodiment of the present invention.

As shown in FIG. 3, the low voltage defect detection method according to an embodiment of the present invention includes the step of charging the battery cell (S10), and the constant voltage (CV) before the battery cell is fully charged. The step of performing charging (S20), the step of measuring the constant voltage (CV) charging time required from the start of the constant voltage (CV) charging to full charge (S30), and the measured constant voltage (CV) charging time based on a preset standard. Comparing the constant voltage (CV) charging time (S40), and determining the battery cell as a low voltage defect when the measured constant voltage (CV) charging time exceeds a positive error range than the reference constant voltage (CV) charging time. (S50) is included.

Specifically, the present invention is an invention for quickly determining whether a low voltage battery cell is defective due to a leakage current generated by the growth of dendrites in the battery cell, and charging the battery cell manufactured first Do (S10).

As shown in FIG. 4, in order to detect the low voltage defect of the battery cell, constant voltage (CV) charging is performed before the battery cell is fully charged (S20).

In constant voltage (CV) charging, the charging voltage is constant, but the charging current gradually drops as it progresses to full charge.

Here, in the prior art, the aging process takes about 5 days to grow dendrites, but in the present invention, as shown in FIG. 5, the battery cell is charged after the aging process and before product shipment, At this time, the aging process time can be shortened by charging the battery cell with a charging time of about 10 minutes.

In the present embodiment, constant voltage (CV) charging is performed after the battery cell aging process and before product shipment, and low voltage defects are determined through this, but low voltage defects are caused by charging the battery cells in the manufacturing step or activation step It may be made to determine.

Meanwhile, before the constant voltage (CV) charging, constant current (CC) charging is performed on the battery cell.

Since constant current (CC) charging with a constant charging current can quickly increase the charging rate, it is preferable that constant current (CC) charging be preceded to a certain extent before fully charged.

In this way, by performing constant current (CC) charging in which current is constantly applied to the battery cell, electric energy is quickly charged to the battery cell, and at this time, the voltage of the battery cell rises due to the progress of constant current (CC) charging, When the voltage value of the cell reaches a preset voltage value, constant current (CC) charging is switched to constant voltage (CV) charging so that charging proceeds.

Then, when the constant voltage (CV) charging is switched, the constant voltage (CV) charging time required from the start of the constant voltage (CV) charging to full charge is measured (S30).

Specifically, the constant voltage from the point of conversion from constant current (CC) charging to constant voltage (CV) charging to the point of full charge, not the total charging time of the battery cell, which is the combination of constant current (CC) charging and constant voltage (CV) charging. (CV) Measure the time spent in the charging section.

Here, the constant voltage (CV) charging is performed until the constant voltage (CV) charging current reaches a preset lower limit value. That is, the lower limit of the constant voltage (CV) charging current is set as the reference value for full charge.

For example, as shown in FIG. 4, a constant current (CC) charge is performed by constantly applying a current of 50 [mA] to the battery cell, and as the charging progresses, the voltage of the battery cell rises to a preset voltage. When the value is reached, it is converted to constant voltage (CV) charging and charged while maintaining the set voltage value. At this time, the charging of the battery cell is performed until the constant voltage (CV) charging current reaches the preset lower limit of 20 [mA].

Next, the measured constant voltage (CV) charging time required from the start of the constant voltage (CV) charging to full charge is compared with a preset reference constant voltage (CV) charging time (S40).

Here, the reference constant voltage (CV) charging time is determined by inspecting a plurality of battery cells for low voltage defects, measuring the constant voltage (CV) charging time, and calculating the constant voltage (CV) for a group of battery cells determined to be good as a result of the inspection. ) can be set as the average value of charging time.

For this reason, as shown in FIG. 4 , it appears that the constant voltage (CV) charging time of the battery cell determined to be low voltage defective takes a longer time than the reference constant voltage (CV) charging time set as described above.

Therefore, when the constant voltage (CV) charging time measured for the current battery cell for which the low voltage defect is determined exceeds the preset reference constant voltage (CV) charging time, it is possible to determine the battery cell as the low voltage defect.

That is, if the measured constant voltage (CV) charging time exceeds the positive error range of the reference constant voltage (CV) charging time, in other words, if it is measured as a longer constant voltage (CV) charging time exceeding the error range, the corresponding battery The cell is determined as a low voltage defect (S50).

Here, the positive error range for the preset reference constant voltage (CV) charging time may be set in the range of +5% to +10%.

In this way, if it is determined that the constant voltage (CV) charging time is less than the positive error range with respect to the reference constant voltage (CV) charging time, it can be determined as a normal battery cell, and conversely, the constant voltage (CV) charging time is the reference constant voltage charging When it is determined that the positive error range is exceeded with respect to time, it can be determined as a low-voltage defective battery cell.

On the other hand, as shown in FIG. 6, the low voltage defect detection system 1 for detecting the low voltage defect according to an embodiment of the present invention includes a charger device 10, a current meter 20, and a storage unit 30 and a control unit 40.

The charger 10 is a device for charging a battery cell, and is preferably a charger that supports both constant current (CC) charging and constant voltage (CV) charging and can easily switch between them.

At this time, the charger device 10 maintains a constant voltage value in the constant voltage (CV) charging section, while constantly reducing the current, and when the current value reaches the set current value, it is determined as fully charged and automatically terminates charging.

In addition, the ampere meter 20 is for measuring the charging time of the battery cell charged through the charger 10, and the ampere meter 20 may further include a display unit, and the battery measured through this The charging time of the cell may be counted in real time and displayed.

The storage unit 30 stores the charging time of the battery cell measured by the current meter 20 in real time.

Here, the storage unit 30 is a storage medium for storing data such as the charging time of a battery cell, and includes information such as a flash memory, a compact flash card (CF card), and a secure digital card (SD card). It includes a module capable of input/output, and may be provided inside the device or may be provided in a separate device.

The control unit 40 controls the charging device 10 and receives the charging time of the battery cells stored in the storage unit 30 .

Here, the control unit 40, as shown in Figure 7, the charge control unit 41 for controlling the charger 10 to perform constant voltage (CV) charging, constant voltage (CV) charging time and reference It includes a time comparison unit 42 that compares set constant voltage (CV) charging times, and a determination unit 43 that determines low voltage defects through the charging times compared through the time comparison unit 42 .

The charge control unit 41 controls the charging device 10 to perform constant voltage (CV) charging before charging the battery cells.

The time comparator 42 compares the constant voltage (CV) charging time required from the start of the constant voltage (CV) charging to full charge with a preset reference constant voltage (CV) charging time.

When the constant voltage (CV) charging time required from the start of the constant voltage (CV) charging to full charge exceeds a positive error range than the preset reference constant voltage (CV) charging time, the determination unit 43 determines the battery cell as low voltage defective. judged by

Meanwhile, the charge control unit 41 controls the charger 10 to perform constant current (CC) charging of the battery cell before the constant voltage (CV) charging.

With the structure as described above, the charge control unit 41 controls the charger 10 to perform constant current (CC) charging by constantly applying a current to the battery cell, and as the charging progresses, the battery cell When the voltage of reaches the preset voltage value, the charge control unit 41 controls the charger 10 to perform constant voltage (CV) charging, and the constant voltage (CV) charging time compared by the time comparison unit 42. Based on the result of the above, the determining unit 43 determines whether or not the battery cell has a low voltage defect.

(Second Embodiment)

8 is a flowchart schematically illustrating a method of detecting a low voltage defect of a battery cell according to another embodiment of the present invention.

As shown in FIG. 8, a method for detecting a low voltage defect of a battery cell according to another embodiment of the present invention includes the step of charging the battery cell (S10'), and the constant voltage before the battery cell is fully charged. (CV) performing charging (S20'), measuring a constant voltage (CV) charging current change rate from the start of the constant voltage (CV) charging to a predetermined time before being fully charged (S30'), and measuring Comparing the constant voltage (CV) charging current rate of change with a preset reference constant voltage (CV) charging current rate of change (S40′), and the absolute value of the measured constant voltage (CV) charging current rate of change is the standard constant voltage (CV) charging current rate of change and determining the battery cell as a low voltage defect when the absolute value of is less than a negative error range (S50′).

Here, the step of charging the battery cell (S10') and the step of performing constant voltage (CV) charging before the full charge of the battery cell (S20') are the same as those of the first embodiment, and will be described in detail below. will be omitted.

Also, in the step of performing constant voltage (CV) charging before the battery cells are fully charged (S20), constant voltage (CV) charging in which voltage is constantly applied is performed before the battery cells are fully charged, and the constant voltage (CV) charging is performed. Previously, it is switched to performing constant current (CC) charging on the battery cell.

On the other hand, in the second embodiment of the present invention, from the start of the constant voltage (CV) charging, which is shifted from the constant current (CC) charging to the constant voltage (CV) charging after performing the constant voltage (CV) charging before the full charge of the battery cell. A constant voltage (CV) charging current change rate for a predetermined time before being fully charged is measured (S30').

Here, the constant voltage (CV) charging is terminated before the constant current (CC) charging current reaches a preset lower limit value, which is a difference between the present embodiment and the first embodiment.

Then, the constant voltage (CV) charging current change rate measured for a predetermined time from the start of the constant voltage (CV) charging until fully charged is compared with a preset reference constant voltage (CV) charging current change rate (S40′).

Here, the rate of change of the standard constant voltage (CV) charging current is similar to the setting of the aforementioned standard constant voltage (CV) charging time, and a plurality of battery cells are inspected for low voltage defects, and the rate of change of the constant voltage (CV) charging current is measured. After the inspection, it can be set as the average value of the constant voltage (CV) charging current change rate calculated for the battery cell group determined to be good as a result of the inspection.

Specifically, when the absolute value of the constant voltage (CV) charging current rate of change required for a predetermined time from the start of the compared constant voltage (CV) charging until fully charged is less than the absolute value of the preset reference constant voltage (CV) charging current rate of change, The battery cell is determined as a low voltage defect.

That is, a case in which the steepness is gentle compared to the slope of the reference constant voltage (CV) charging current change rate is determined as a low voltage defect, which is in line with the increase in the reference constant voltage (CV) charging time in the case of a low voltage defect.

However, in the present embodiment, even before reaching a full charge state for determining the constant voltage (CV) charging time, it is possible to more quickly determine whether or not the battery cell has a low voltage defect by using the constant voltage (CV) charging current rate of change. can be said to be advantageous.

As a result, when the absolute value of the measured constant voltage (CV) charging current rate of change is less than a negative error range than the absolute value of the reference constant voltage (CV) charging current rate of change, the battery cell may be determined as a low voltage defect (S50').

As an example, the negative error range for the preset reference constant voltage (CV) charging current change rate may be set to a range of -5% to -10%.

In this way, when the rate of change of the constant voltage (CV) charging current is determined to be less than the negative error range with respect to the rate of change of the reference constant voltage (CV) charging current, the battery cell is determined to be a low voltage defective battery cell, and conversely, the rate of change of the constant voltage (CV) charging current is the standard. If it is determined that the change rate of the constant voltage (CV) charging current exceeds the negative error range, it can be determined as a normal battery cell.

To this end, the storage unit 30 may store the change rate of the constant voltage (CV) charging current of the battery cell measured by the ampere meter 20 in real time.

In addition, the control unit 40 may receive the constant voltage (CV) charging current change rate of the battery cell stored in the storage unit 30, and determine the low voltage defective battery cell through the received constant voltage (CV) charging current change rate. there is.

In addition, the control unit 40 may further include a change rate comparator 44 that compares the rate of change of the constant voltage (CV) charging current when charging the battery cell with the rate of change of the constant voltage (CV) charging current set as a reference.

Further, the rate of change comparator 44 compares the rate of change of the constant voltage (CV) charging current from the start of charging the constant voltage (CV) to a predetermined time before being fully charged and the rate of change of the predetermined reference constant voltage (CV) charging current.

Preferably, the change rate comparator 44 may compare an absolute value of a rate of change of the constant voltage (CV) charging current with an absolute value of a rate of change of the predetermined reference constant voltage (CV) charging current.

Also, the determination unit 43 may determine whether the low voltage is defective through the result value compared through the change rate comparison unit 44 .

That is, the determination unit 43 determines that the absolute value of the constant voltage (CV) charging current change rate from the start of constant voltage (CV) charging to the predetermined time before being fully charged is the absolute value of the preset reference constant voltage (CV) charging current change rate. In the case of less than a more negative error range, the battery cell may be determined as a low voltage defect.

In the above, the present invention has been shown and described in relation to specific embodiments, but it is common knowledge in the art that various modifications and changes are possible within the limit that does not depart from the spirit and scope of the invention shown in the appended claims. Anyone who has it will be able to easily understand.

1: Low voltage defect detection system
10: charger
20: amperage meter
30: storage unit
40: control unit
41: charging control unit
42: time comparison unit
43: Judgment
44: change rate comparison unit

Claims (10)

In the method for detecting a low voltage defect of a battery cell,
charging the battery cell;
Performing constant voltage (CV) charging before fully charging the battery cell;
measuring a constant voltage (CV) charging time required from the start of the constant voltage (CV) charging to fully charged;
comparing the measured constant voltage (CV) charging time with a preset reference constant voltage (CV) charging time; and
determining the battery cell as a low voltage defect when the measured constant voltage (CV) charging time exceeds a positive error range than the reference constant voltage (CV) charging time;
Low voltage defect detection method comprising a.
According to claim 1,
Low voltage defect detection method, characterized in that for performing a constant current (CC) charging of the battery cell before the constant voltage (CV) charging.
According to claim 1,
The low voltage defect detection method, characterized in that the constant voltage (CV) charging is performed until the constant voltage (CV) charging current reaches a preset lower limit value.
According to claim 1,
The low voltage defect detection method, characterized in that the positive error range for the reference constant voltage (CV) charging time is +5% to +10%.
In the method for detecting a low voltage defect of a battery cell,
charging the battery cell;
Performing constant voltage (CV) charging before fully charging the battery cell;
measuring a constant voltage (CV) charging current change rate from the start of the constant voltage (CV) charging to a predetermined time before being fully charged;
comparing the measured constant voltage (CV) charging current rate of change with a preset reference constant voltage (CV) charging current rate of change; and
Determining the battery cell as a low voltage defect when an absolute value of the measured constant voltage (CV) charging current rate of change is less than a negative error range than an absolute value of the reference constant voltage (CV) charging current rate of change;
Low voltage defect detection method comprising a.
According to claim 5,
Low voltage defect detection method, characterized in that for performing a constant current (CC) charging of the battery cell before the constant voltage (CV) charging.
According to claim 5,
The low voltage defect detection method, characterized in that the constant voltage (CV) charging is terminated before the constant current (CC) charging current reaches a preset lower limit value.
According to claim 5,
The low voltage defect detection method, characterized in that the negative error range for the reference constant voltage (CV) charging current change rate is -5% to -10%.
In the detection system for detecting a low voltage defect of a battery cell,
a charger for charging a battery cell;
a current meter measuring the charging time of the battery cell charged through the charger in units of time;
a storage unit for storing in real time the rate of change of the charging time and charging current of the battery cells measured by the ampere meter; and
a control unit that controls the charging device and receives the charging time and rate of change of the charging current of the battery cells stored in the storage unit;
including,
The control unit,
Control the charging device to perform constant voltage (CV) charging before charging the battery cell,
The constant voltage (CV) charging time required from the start of CV charging to full charge exceeds the positive error range of the preset reference constant voltage (CV) charging time, or When the absolute value of the rate of change of the constant voltage (CV) charging current for a predetermined period of time is less than the negative error range than the absolute value of the rate of change of the predetermined standard constant voltage (CV) charging current, the battery cell is judged as a low voltage defect Low voltage characterized in that defect detection system.
According to claim 9,
The control unit,
The low voltage defect detection system, characterized in that for controlling the charger to perform constant current (CC) charging of the battery cell before the constant voltage (CV) charging.

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