KR20230084370A - Portable device for measuring capacity of battery and method thereof - Google Patents

Abstract

The present invention relates to a portable device for measuring a capacity of a battery and a method thereof, and particularly, to a portable device for measuring a capacity of a battery which can easily measure a capacity for each cell of a battery without disassembling the battery, and a method thereof. The portable device for measuring a capacity of a battery, according to one embodiment of the present invention, comprises: a discharging circuit for discharging battery cells; a charging circuit which supplies charging currents until voltages of each battery cell reach a preset end-of-charge voltage, when the discharging circuit is operated, and voltages of the battery cells reach a preset cut-off voltage; an FET control circuit which senses voltages of the battery cells to control cell resistance against currents flowing in each battery cell; and a cell-specific capacity producing unit which produces cell-specific capacity and stores the same based on time intervals required when the voltages of the battery cells reach to the end-of-charge voltage from the cut-off voltage, and a charging current intensity.

Description

Portable battery capacity measuring device and method {PORTABLE DEVICE FOR MEASURING CAPACITY OF BATTERY AND METHOD THEREOF}

The present invention relates to an apparatus and method for measuring capacity of a portable battery, and more particularly, to an apparatus and method for measuring capacity of a portable battery capable of easily measuring capacity of each cell of a battery without disassembling the battery.

When a battery is used, a deviation between cells of a battery configured in series occurs, and there is a limit to controlling such a deviation between cells to be reduced only by a battery management system (BMS) applied to the battery.

Existing battery balancing equipment manages batteries by applying a passive or active balancing circuit to the BMS.

In a normal operation state of the battery, the deviation between the cells of the battery does not occur significantly, and it is possible to respond by the BMS even with a small capacity design. However, when a battery ages or a large deviation occurs between cells of the battery, control by the BMS becomes difficult. In this case, it is necessary to go through cumbersome processes such as replacing the battery or recovering the battery and repairing the battery using charging/discharging equipment of the battery manufacturer.

Currently, charge/discharge equipment is expensive, and there is an inconvenience in that the battery must be disassembled, and balancing is performed by connecting cables for each cell to the charge/discharge equipment, and the battery must be reassembled after the balancing operation is completed.

Therefore, by applying a portable battery capacity measurement device to measure the state of each cell of the battery at a predetermined cycle according to the type of use, such as quarterly, semi-annually, or annually, in the field, there is a plan for controlling the deviation between cells of the battery. There is a need for research and development.

The present invention was created in view of the above circumstances, and an object of the present invention is to provide a portable battery capacity measuring device and method capable of calculating the capacity of each battery cell separately by a simple operation without disassembling the battery. will be.

In addition, an object of the present invention is to provide a portable battery capacity measuring device and method capable of precisely measuring the capacity of each battery cell without damaging the battery by setting the discharge end voltage and the charge end voltage of the battery in advance.

An apparatus for measuring capacity of a portable battery according to an embodiment of the present invention includes a discharge circuit for discharging battery cells, and when the discharge circuit operates so that the voltages of the battery cells reach a preset end-of-discharge voltage, each of the battery cells A charging circuit that supplies charging current until the voltage reaches a preset charging end voltage, a FET control circuit that detects voltages of the battery cells and controls cell resistance for current flowing through each of the battery cells, and the battery and a capacity calculation unit for each cell that calculates and stores the capacity of each cell based on the time interval from the discharge end voltage to the charge end voltage of the cells and the magnitude of the charging current.

In one embodiment, the discharge circuit includes a discharge connector for fully discharging the battery cells to a preset first discharge end voltage, and a discharge relay for controlling driving of the discharge connector, wherein the FET control circuit is configured to control the battery When the voltage of the cells reaches the first discharge end voltage, each cell resistor may be turned on to discharge each battery cell until the voltage reaches the second discharge end voltage.

In one embodiment, the charging circuit may include a charger that transfers current to the battery cells to charge them, and a charging relay that controls driving of the charger.

In one embodiment, the charger includes a first charger for supplying a first charging current, and a second charger for supplying a second charging current that is relatively smaller than the first charging current. When the voltage of a specific battery cell reaches the first charging end voltage by one charging current, charging of the battery cells by the second charging current of the second charger starts, and the FET control circuit determines that the voltage of each battery cell is When the second charging end voltage is reached, charging may be blocked by individually turning on the cell resistance.

In one embodiment, in an off state by the FET control circuit, the cell resistance may be designed so that the second charging current of the second charger bypasses and flows.

In one embodiment, the cell-by-cell capacity calculation unit, the time interval during which the first charger operates, the first charging current size of the first charger, the time interval required for the FET control circuit to turn on the cell resistance for each battery cell, and The capacity of each cell may be calculated from the magnitude of the second charging current of the second charger.

In one embodiment, the portable battery capacity measurement device includes a current sensor for detecting the amount of current flowing in the battery cells, and a fuse for cutting off the current when the amount of current sensed by the current sensor exceeds a preset threshold. can include more.

A method for measuring capacity of a portable battery according to an embodiment of the present invention includes the steps of turning on a discharge circuit to proceed with the entire discharge of battery cells, and when the voltage of a specific battery cell among the battery cells reaches a first discharge end voltage, discharging Turning off the circuit to stop discharging of all battery cells, Discharging until the voltage of each battery cell reaches the second discharge end voltage by individually turning on the cell resistance of the FET control circuit for the battery cells Step of operating the first charger to charge the battery cells and terminating the charging by the first charger when the voltage of the specific battery cell reaches the first charging end voltage, after the charging by the first charger is finished , operating the second charger, and when the voltage of each battery cell reaches the second charge end voltage, the FET control circuit turns on each cell resistance to cut off charging, and the time interval during which the first charger operates , calculating the capacity of each cell from the magnitude of the first charging current of the first charger, the time interval required for the FET control circuit to turn on the cell resistance for each battery cell, and the magnitude of the second charging current of the second charger. .

The apparatus and method for measuring capacity of a portable battery according to the present invention can easily and quickly measure the capacity of each cell without disassembling individual cells using cell cables of the battery, thereby improving the convenience of capacity measurement.

In addition, the apparatus and method for measuring capacity of a portable battery according to the present invention drops the voltage only to a predetermined discharge end voltage and performs charging to measure the capacity of each cell, so that charging can proceed in a stable state of the battery, There is an effect of efficiently performing capacity measurement.

1 is a block diagram showing the configuration of a portable battery capacity measurement device according to an embodiment of the present invention.
2 and 3 are block diagrams showing specific configurations of the portable battery capacity measuring device of FIG. 1 .
4 is a flowchart of a portable battery capacity measurement method according to an embodiment of the present invention.

Hereinafter, one embodiment of the present invention will be described in detail through exemplary drawings. In adding reference numerals to components of each drawing, it should be noted that the same components have the same numerals as much as possible even if they are displayed on different drawings. In addition, in describing the present invention, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present invention, the detailed description will be omitted.

1 is a block diagram showing the configuration of a portable battery capacity measurement device according to an embodiment of the present invention.

Referring to FIG. 1 , the portable battery capacity measurement device 100 of the present invention includes a discharge circuit 110, a charge circuit 120, a FET control circuit 130, a cell resistance 140, and a capacity calculation unit 150 for each cell. includes

The discharge circuit 110 is a circuit for discharging the battery cells 10, and the discharge circuit 110 operates to discharge the battery cells 10 so that the voltage of the battery cells 10 drops to a preset discharge end voltage.

The portable battery capacity measurement device 100 of the present invention is for measuring the capacity of a secondary battery capable of repeating charging and discharging, and when the secondary battery is discharged below a certain level of voltage, the active material of the electrode is It is difficult to recover to the state, which is undesirable for battery life.

Therefore, the battery is not discharged until the voltage of the battery is zero, and the discharge end voltage at which the discharge is stopped is set in advance, and the voltage is controlled so that the voltage does not drop below that level.

When the voltage of the battery cells 10 reaches the discharge end voltage due to the operation of the discharge circuit 110, the charging circuit 120 generates a charging current until the voltage of each cell 10 reaches a preset charge end voltage. supply

In the present invention, the cell-specific capacity of each battery cell 10 is calculated by checking the time taken to reach a preset charge end voltage in a state in which the voltage of each battery cell 10 is dropped to the discharge end voltage to generate the reference voltage. can do.

A field effect transistor (FET) control circuit 130 senses voltages of the battery cells 10 and controls cell resistance 140 for current flowing through each of the battery cells 10 .

The cell-by-cell capacity calculator 150 calculates and stores the cell-by-cell capacity based on the amount of charging current and the time interval from the discharge end voltage to the charge end voltage of each battery cell 10 .

2 and 3 are block diagrams showing specific configurations of the portable battery capacity measuring device of FIG. 1 .

Hereinafter, exemplary numerical values such as capacity of a battery cell, discharge end voltage, charge end voltage, charge current level, etc. are for explanation of the present invention, and may be arbitrarily changed within a range without departing from the spirit of the present invention. In particular, the first discharge end voltage and the second discharge end voltage may have a minute voltage difference or the same, and the first charge end voltage and the second charge end voltage may have a minute voltage difference or be the same. there is.

Referring to FIGS. 1 and 2 , the discharge circuit 110 may include a discharge relay 112 and a discharge connector 114 .

As the discharge relay 112 is turned on/off, driving of the discharge connector 114 is controlled. The discharge connector 114 fully discharges the battery cells 10 up to a preset first discharge end voltage. The discharge connector 114 may rapidly lower the voltage of the battery cells 10 to the first discharge end voltage by receiving power from the external power source 170 .

The first discharge end voltage is a voltage at which discharge is stopped, and may be previously set as a percentage value (%) with respect to the normal voltage, and may be, for example, 2.8V.

When the voltage of the battery cells 10 reaches the first discharge end voltage, the FET control circuit 130 turns on each cell resistor 140 so that the voltage of each cell 10 reaches the second discharge end voltage. discharge until

The second discharge end voltage is a voltage at which discharge is stopped, and may be previously set as a percentage value (%) with respect to the normal voltage, and may be, for example, 2.5V. Here, the second discharge end voltage may be set lower than the first discharge end voltage, and may be designed so that the battery cells 10 may be continuously discharged after the voltage reaches the first discharge end voltage.

That is, all of the battery cells 10 are collectively discharged until the voltage of the battery cells 10 reaches the first discharge end voltage, and each battery cell from the first discharge end voltage to the second discharge end voltage ( 10) may be individually discharged under the control of the FET control circuit 130.

When the voltage of a specific battery cell 10 reaches the second end-of-discharge voltage, the FET control circuit 130 sequentially turns off the cell resistance 140 so that the voltages of the other battery cells 10 reach the second end-of-discharge voltage. wait until it is reached.

The discharge relay 112 and the discharge connector 114 may be optionally added, and in another embodiment of the present invention, the discharge relay 112 and the discharge connector 114 may be omitted as shown in FIG. 3 .

In FIG. 3 , instead of operating the discharge relay 112 and the discharge connector 114, the switch 132 is turned on to discharge the battery cells 10 and the FET control circuit 130 operates to reduce the cell resistance 140. By turning on, the individual battery cells 10 can be discharged until the voltage reaches the second discharge end voltage.

When the voltages of all the battery cells 10 are lowered to the second discharge end voltage and the reference voltage is formed, the charging circuit 120 charges the battery cells 10 .

The charging circuit 120 may include charging relays 122 and 222 and chargers 124 and 224 . The charging relays 122 and 222 control driving of the chargers 124 and 224 while being turned on/off, and the chargers 124 and 224 transfer current to the battery cells 10 to charge them.

The chargers 124 and 224 may include a first charger 124 that supplies a first charging current and a second charger 224 that supplies a second charging current that is relatively smaller than the first charging current.

The first charger 124 may supply a first charging current of, for example, 20A, and the second charger 224 may supply a second charging current of, for example, 4A.

All of the battery cells 10 are charged by the first charging current of the first charger 124 until the voltage of the specific battery cell 10 reaches the first charging end voltage.

The cell-by-cell capacity calculation unit 150 checks the time taken until the first charger 124 is turned on and the voltage of the specific battery cell 10 reaches the first charge end voltage.

Thereafter, the first charging relay 122 is turned off and the operation of the first charger 124 is also turned off, and the second charging relay 222 is turned on to start charging by the second charging current of the second charger 224. do. The cell resistor 140 may be designed so that the second charging current of the second charger 224 bypasses and flows.

When the voltage of each of the battery cells 10 reaches the second charge end voltage, the FET control circuit 130 individually turns on the cell resistance 140 to block charging. At this time, the cell-by-cell capacity calculation unit 150 may check the time taken for each battery cell 10 to reach the second charge end voltage.

The cell capacity calculator 150 controls the time interval H1 during which the first charger 124 operates, the first charging current A1 of the first charger 124, and FET control for each battery cell 10 The capacity of each cell may be calculated from the time interval H2 taken for the circuit 130 to turn on the cell resistance 140 and the second charging current A2 of the second charger 224 .

It is calculated as charging capacity = current × time rate, and the capacity of each battery cell 10 can be calculated as follows.

Capacity of each battery cell 10 = A1 × H1 + A2 × H2

The present invention connects the cell resistance 140 to the cell cable of the battery cell 10 without disassembling the battery pack in order to measure the capacity of the individual battery cell 10, and controls the cell resistance 140 to individual battery cells. The capacity of (10) can be easily measured.

In one embodiment of the present invention, the portable battery capacity measuring device 10 may further include a current sensor 162 and a fuse 164 .

The current sensor 162 senses the amount of current flowing through the battery cells 10, and the fuse 164 blocks the current when the amount of current sensed by the current sensor 162 exceeds a preset threshold.

When the current sensor 162 and the fuse 164 are added, overcurrent flowing through the battery cells 10 can be blocked in advance, and thus damage to the battery cells 10 caused by the overcurrent can be prevented.

In FIGS. 2 and 3, in order to explain the function of each component, the FET control circuit 130, the cell resistance 140, and the capacity calculation unit 150 for each cell are shown separately, but integrally one chip or circuit may consist of

4 is a flowchart of a portable battery capacity measurement method according to an embodiment of the present invention.

Referring to FIG. 4 , first, the battery cells 10 connected to the outside are completely discharged by turning on the discharge circuit 110 (S100).

The discharge circuit 110 may include a discharge relay 112 and a discharge connector 114 . The discharge relay 112 is connected to the discharge connector 114, and when the discharge relay 112 is turned on, the discharge connector 114 operates to discharge all the battery cells 10.

Subsequently, it is determined whether the battery cells 10 have reached the first discharge end voltage (S200), and when the voltage of the specific battery cell 10 connected in series reaches the first discharge end voltage, the discharge circuit 110 or discharge By turning off the relay 112, discharging of all battery cells 10 is stopped (S300).

The first discharge end voltage is a voltage at which discharge is stopped, and may be previously set as a percentage value (%) with respect to the normal voltage, and may be, for example, 2.8V.

Subsequently, the FET control circuit 130 individually turns on the cell resistance 140 for each of the battery cells 10 to discharge each of the battery cells 10 (S400).

Subsequently, the FET control circuit 130 determines whether the voltage of each of the battery cells 10 has reached the second discharge end voltage (S500), and when the voltage of the specific battery cell 10 reaches the second discharge end voltage The cell resistance 140 of the corresponding battery cell 10 is switched to an off state to stop discharging, and when the voltages of all battery cells 10 reach the second discharging end voltage, discharging is terminated (S600).

The second discharge end voltage is a voltage at which discharge is stopped, and may be previously set as a percentage value (%) with respect to the normal voltage, and may be, for example, 2.5V. Here, the second discharge end voltage may be set lower than the first discharge end voltage.

When the voltages of all of the battery cells 10 reach the second discharge end voltage, the starting capacities for measuring the charging capacities of each of the battery cells 10 are equalized.

When the battery is fully discharged and then charged, it takes a predetermined time, approximately 20 to 30 minutes, for the battery to return to a stabilized voltage.

Since the present invention drops the voltage only up to the second discharge end voltage set in advance, and charging can be started in a state in which the battery is stabilized, stabilization of the battery during charging for measuring the capacity of each battery cell 10 is performed. can reduce the time wasted on

Since the stabilization condition of the battery is different depending on the type of battery, the magnitude of the discharge current, etc., the second discharge end voltage is a variable value.

Next, the first charging relay 122 is turned on and the first charger 124 is operated to charge all the battery cells 10 (S700). When the voltage of a specific battery cell 10 connected in series reaches the first charging end voltage (S800), the first charging relay 122 is turned off to terminate charging by the first charger 124 (S900).

The first charging end voltage is a voltage at which charging is stopped, and may be previously set as a percentage value (%) with respect to the normal voltage, and may be, for example, 3.6V.

Subsequently, the second charger 224 is operated by turning on the second charging relay 222 (S900).

The FET control circuit 130 determines whether the voltage of each of the battery cells 10 has reached the second charging end voltage by the second charging current of the second charger 224 (S1000), and each of the battery cells 10 When the voltage of ) reaches the second charging end voltage, charging is cut off by turning on each cell resistor 140 (S1100).

Here, the cell resistance 140 may be designed so that the second charging current of the second charger 224 bypasses and flows in an off state by the FET control circuit 130 .

In the present invention, a large charging current flows in the first charger 124 to rapidly charge up to a specific voltage, and a relatively small charging current flows in the second charger 224 so that the voltage of each battery cell 10 reaches the end of the charge. By allowing the voltage to reach, the charge capacity can be precisely measured.

When the FET control circuit 130 turns on the cell resistance 140 for all battery cells 10, the second charging relay 222 is turned off and charging is terminated.

The second charging end voltage is a voltage at which discharging is stopped, and may be preset as a percentage value (%) with respect to the normal voltage, and may be, for example, 3.65V. Here, the second charge end voltage may be set higher than the first charge end voltage.

Continuing, the cell-by-cell capacity calculation unit 150 determines the time interval H1 during which the first charger 124 operates, the first charging current size A1 of the first charger 124, and each battery cell 10 The capacity of each cell is calculated from the time interval H2 taken for each FET control circuit 130 to turn on the cell resistance 140 and the second charging current A2 of the second charger 224 (S1200).

It is calculated as charging capacity = current × time rate. For example, if a 20A charging current flows for 4 hours, it becomes 80Ah.

Hereinafter, an example will be described for understanding of the present invention, but the spirit of the present invention is not limited thereto.

It is assumed that the capacity of the first cell 10a is 100 Ah, the capacity of the second cell 10b is 101 Ah, and the capacity of the third cell 10c is 99 Ah. The first charging relay 122 is turned on to start charging with a charging current of 20A of the first charger 124 .

After 4 hours and 45 minutes, when the third cell 10c having the lowest capacity reaches the first charging end voltage (3.6V), the first charging relay 122 is turned off to block the charging current of 20A.

Next, the second charging relay 222 is turned on to start charging with the charging current of the second charger 224 of 4A. When a specific battery cell 10 reaches the second charging end voltage (3.65V) during the 4A charging process, the FET control circuit 130 turns on the cell resistance 140 for the cell 10 to block charging, , When all the cells 10 reach the second charging end voltage (3.65V), the second charging relay 222 is turned off and charging is terminated.

Here, the second charge end voltage is set to a slightly higher voltage than the first charge end voltage, but the second charge end voltage and the first charge end voltage may be identically configured.

When charging is performed with a charging current of 20A of the first charger 124, charging is stopped at the first charging end voltage (3.6V), and charging is performed with a charging current of 4A of the second charger 224, the size of the charging current decreases. Due to this, the voltage of the battery cell 10 may be temporarily lowered. Therefore, even if the second charging end voltage and the first charging end voltage are configured to be the same, charging can proceed with the charging current of 4A of the second charger 224 for the third cell 10c that has reached the first charging end voltage. there is.

The cell-specific capacity calculator 150 counts and stores the time interval required for the FET control circuit 130 to turn on the cell resistance 140 for each battery cell 10 after the second charging relay 222 is turned on. do.

When the first charging relay 122 is turned on, all the cells 10 are charged with a 20 A charging current for 4 hours and 45 minutes, so the charging capacity = 20 A × 4.75 h = 95 Ah.

Time taken for the FET control circuit 130 to turn on the cell resistor 140 for each cell 10 after the second charging relay 222 is turned on and charging is started with the charging current of 4A of the second charger 224 1 hour and 15 minutes for the first cell 10a, 1 hour and 30 minutes for the second cell 10b, and 1 hour for the third cell 10c.

The charging capacity by the charging current of 4A for each cell 10 is calculated as follows.

In the case of the first cell 10a, charge capacity = 4A × 1.25h = 5Ah

In the case of the second cell 10b, charge capacity = 4A × 1.5h = 6Ah

In the case of the third cell 10c, charge capacity = 4A × 1h = 4Ah

Therefore, the result of summing the charging capacities by the charging currents of 20A and 4A for each cell 10 is the initially assumed capacity of the first cell 10a of 100Ah, the capacity of the second cell 10b of 101Ah, and the capacity of the third cell ( 10c) with a capacity of 99 Ah.

The embodiments described above may be implemented as hardware components, software components, and/or a combination of hardware components and software components. For example, the devices, methods, and components described in the embodiments may include, for example, a processor, a controller, an arithmetic logic unit (ALU), a digital signal processor, a microcomputer, a field programmable gate (FPGA). array), programmable logic units (PLUs), microprocessors, or any other device capable of executing and responding to instructions. A processing device may run an operating system (OS) and one or more software applications running on the operating system. A processing device may also access, store, manipulate, process, and generate data in response to execution of software. For convenience of understanding, there are cases in which one processing device is used, but those skilled in the art will understand that the processing device includes a plurality of processing elements and/or a plurality of types of processing elements. It can be seen that it can include. For example, a processing device may include a plurality of processors or a processor and a controller. Also, other processing configurations are possible, such as parallel processors.

Although the present invention has been described in detail with reference to preferred embodiments, the present invention is not limited to the above embodiments, and the technical field to which the present invention belongs without departing from the gist of the present invention claimed in the following claims. Anyone skilled in the art will extend the technical spirit of the present invention to the extent that various variations or modifications are possible.

10: battery cell 100: portable battery capacity measuring device
110: discharge circuit 112: discharge relay
114: discharge connector 120: charging circuit
122: first charging relay 124: first charger
130: FET control circuit 132: switch
140: cell resistance 150: capacity calculation unit for each cell
162 current sensor 164 fuse
170: power 222: second charging relay
224: second charger

Claims (10)

a discharge circuit for discharging battery cells;
a charging circuit supplying charging current until the voltage of each battery cell reaches a preset end-of-charge voltage when the voltage of the battery cells reaches a preset end-of-discharge voltage when the discharge circuit operates;
a FET control circuit that senses voltages of the battery cells and controls cell resistance with respect to current flowing through each of the battery cells; and
and a capacity calculation unit for each cell that calculates and stores the capacity of each cell based on the amount of charging current and the time interval between the voltages of the battery cells from the discharge end voltage to the charge end voltage. measuring device. According to claim 1,
The discharge circuit,
a discharge connector for fully discharging the battery cells up to a preset first discharge end voltage; and
A discharge relay controlling the driving of the discharge connector; includes,
When the voltage of the battery cells reaches the first discharge end voltage, the FET control circuit turns on each cell resistance to discharge until the voltage of each battery cell reaches the second discharge end voltage. A portable battery capacity measuring device. According to claim 1,
The charging circuit,
a charger that transfers current to the battery cells to charge them; and
A portable battery capacity measuring device comprising a; charging relay for controlling driving of the charger. According to claim 3,
The charger,
a first charger supplying a first charging current; and
A second charger supplying a second charging current relatively smaller than the first charging current; includes,
When the voltage of a specific battery cell reaches the first charging end voltage by the first charging current of the first charger, charging of the battery cells by the second charging current of the second charger starts, and the FET control circuit A portable battery capacity measuring device characterized in that when the voltage of the battery cells of the second charge end voltage is turned on individually to block charging. According to claim 4,
In the off state by the FET control circuit, the cell resistance is designed so that the second charging current of the second charger bypasses and flows. According to claim 4,
The cell capacity calculation unit,
From the time interval during which the first charger operated, the size of the first charging current of the first charger, the time interval required for the FET control circuit to turn on the cell resistance for each battery cell, and the size of the second charging current of the second charger Portable battery capacity measuring device, characterized in that for calculating the capacity of each cell. According to claim 1,
a current sensor that senses the amount of current flowing through the battery cells; and
The portable battery capacity measuring device of claim 1, further comprising a fuse that cuts off the current when the magnitude of the current sensed by the current sensor exceeds a preset threshold. turning on a discharge circuit to perform full discharge of battery cells;
stopping discharging of all battery cells by turning off a discharge circuit when a voltage of a specific battery cell among the battery cells reaches a first discharge end voltage;
individually turning on cell resistances of the battery cells by a FET control circuit to discharge the battery cells until the voltage of each battery cell reaches a second discharge end voltage;
terminating charging by the first charger when a voltage of a specific battery cell reaches a first charging end voltage by operating a first charger to charge the battery cells;
After the charging by the first charger is finished, operating a second charger, and when the voltage of each battery cell reaches a second charging end voltage, a FET control circuit turning on each cell resistance to cut off charging; and
From the time interval during which the first charger operated, the size of the first charging current of the first charger, the time interval required for the FET control circuit to turn on the cell resistance for each battery cell, and the size of the second charging current of the second charger A portable battery capacity measurement method comprising the steps of calculating the capacity of each cell. According to claim 8,
The discharge circuit,
a discharge connector for fully discharging the battery cells up to a preset first discharge end voltage; and
A method for measuring capacity of a portable battery comprising: a discharge relay controlling driving of the discharge connector. According to claim 8,
In the off state by the FET control circuit, the cell resistance is designed so that the second charging current of the second charger bypasses and flows.

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