KR102180625B1 - Method for detecting state of health for secondary battery - Google Patents

Abstract

The present invention relates to a technology which determines a state of health (SOH) of a secondary battery based on the smaller SOH between the SOH in the current operation environment of the corresponding secondary battery and the SOH based on a usage time of the corresponding secondary battery up to now and correctly determines whether to replace the corresponding secondary battery based on the determined SOH thereof. According to the present invention, a method for detecting the SOH of the secondary battery of a battery management apparatus comprises: a first step of calculating a first SOH in an environment wherein charging/discharging is performed through a rectifier; a second step of calculating a second SOB corresponding to a usage time of the secondary battery up to now based on a predefined SOH characteristic table for each usage time; and a third step of determining the smaller SOH between the first and second SOHs as a current SOH, and determining that it is a replacement time of the secondary battery to generate a replacement alarm when the current SOH is equal to or less than a predetermined critical replacement value. In the first step, the first SOH is calculated by dividing the accumulated current amount for a predetermined time by a difference value between a full-charge discharge capacity and available discharge capacity of the secondary battery, wherein the accumulated current amount is calculated by accumulating the discharged current until the secondary battery becomes an operation voltage of a device from a state fully charged through a rectifier, and the available discharge capacity is set by a difference value between the full-charge capacity when the secondary battery is fully charged and the discharge capacity generated when power is supplied to the device.

Description

How to detect the life status of secondary battery {METHOD FOR DETECTING STATE OF HEALTH FOR SECONDARY BATTERY}

The present invention determines the remaining capacity state of the secondary battery based on the remaining capacity of the secondary battery based on the smaller value of the remaining capacity in the current operating environment and the remaining capacity based on the use time of the secondary battery up to the present time, and It relates to a technology that enables it to accurately determine whether to replace a secondary battery based on the remaining capacity of the secondary battery.

In general, equipment such as a communication base station has a battery of a large capacity to stably supply power, and a battery of a large capacity is often used by connecting a plurality of battery cells in series or parallel. Such a battery is a secondary battery and is composed of one or more electrochemical cells capable of charging and discharging.

In this case, as the charging and discharging is repeated while using the battery, the voltage difference between the battery cells increases and there is a tendency for unbalance to occur. In this case, due to some deteriorated battery cells, the life of the entire battery is shortened, and even the risk of fire or explosion increases.

Accordingly, in recent years, battery status is monitored using a battery management system (BMS).

The battery management system (BMS) is a system that receives battery information detected by a sensor, determines the situation, and controls it to maintain an appropriate battery state.Basically, it measures the charging capacity of each battery cell using various sensors and measurement methods. By discharging a cell that is charged higher than other cells through the measured SOC (Residual Capacity: State of Charge) data, it performs a cell balancing function that makes the charge capacity of the cells similar.

In particular, good management of the health of the battery is a problem that is directly related to the operation of the equipment, and it is helpful in cost reduction because it has a great influence on the timing of battery replacement.

Accordingly, the battery management system measures the remaining capacity (SOC) of the battery and performs the function of predicting the state of health (SOH) of the battery. In general, the internal resistance of the battery cell ( IR, Internal Resistance) is used to determine the remaining life of the cell, but since the SOH determination method using IR has low accuracy, there is a problem in that an error occurs in predicting battery life.

Accordingly, in order to ensure a more stable power supply to the equipment side from the viewpoint of reliability of equipment operation, maintenance, and stability, it is required to accurately predict the battery life and provide timely guidance on battery replacement time.

1. Domestic Registration Patent No. 10-1947490 (Name: Method for measuring remaining amount of battery status display) 2. Korean Patent Publication No. 10-2017-0085369 (Name: battery management device and method)

Accordingly, the present invention was created in view of the above circumstances, based on the remaining capacity of the smaller value of the remaining capacity in the current charging and discharging environment of the secondary battery and the remaining capacity based on the use time of the secondary battery to date. A method of detecting the life status of a secondary battery that determines the remaining capacity status of the corresponding secondary battery, accurately determines whether to replace the secondary battery based on the determined remaining capacity of the secondary battery, and informs timely when to replace the battery. To provide it has its technical purpose.

According to an aspect of the present invention for achieving the above object, in a method for detecting a life state of a secondary battery that is connected to an external device to perform charging and discharging, the battery management device is connected to an external device to perform charging and discharging. In the first step of calculating the first SOH, a second step of calculating a second SOH corresponding to the use time of the secondary battery up to the present based on a predefined SOH characteristic table for each use time, and the first SOH and the second step 2 The SOH of the smallest value among the SOH is determined as the current SOH, and when the current SOH value is less than a preset replacement threshold value, it is determined as the time to replace the secondary battery and a replacement alarm is generated, and the first In the step, the first SOH is calculated by dividing the accumulated current amount for a certain period of time by the difference between the discharge capacity and the dischargeable capacity when the secondary battery is fully charged, but the accumulated current amount is the power supply while the secondary battery is fully charged through an external device. It is calculated by integrating the discharge current until it drops to the driving voltage of the device to be supplied, and the dischargeable capacity is set as the difference value between the full capacity when the secondary battery is fully charged and the discharge capacity generated when power is supplied to the device. A method for detecting a life state of a secondary battery is provided.

In addition, the first step includes obtaining a first characteristic table consisting of SOC values for each voltage until the secondary battery is fully charged, and a second characteristic table consisting of a discharge capacity for each voltage from the secondary battery full voltage to the end voltage. And, in a state in which the secondary battery is set to a full charge state by using a first voltage applied from an external device based on the first characteristic table, extracting the full capacity at the full voltage from the second characteristic table, the external device The voltage of is set to a device driving voltage lower than the first voltage so that the secondary battery performs a discharging operation, and the accumulated current amount is calculated by integrating the amount of discharge current from the secondary battery to the device driving voltage from the full voltage state. Calculating the discharge capacity when the secondary battery is the driving voltage of the device based on the second characteristic table, and calculating the discharge capacity by calculating the difference from the full capacity to the discharge capacity, the accumulated current amount There is provided a method for detecting a life state of a secondary battery, comprising the step of calculating the first SOH by dividing by the dischargeable capacity.

In addition, in the first step, the battery management device monitors the state of charge until the secondary battery is fully charged through an external device to obtain a first characteristic table consisting of SOC values for each secondary battery voltage. A method of detecting the life status of a device is provided.

In addition, in the second characteristic table and the SOH characteristic table for each use time, each characteristic value for each voltage is set differently according to the secondary battery temperature, but the second characteristic value stored in the second characteristic table stops as the secondary battery temperature increases. The cumulative discharge capacity in voltage is set to be larger, and the SOH characteristic value for each usage time stored in the SOH characteristic table for each usage time is configured to be set to be smaller as the secondary battery temperature increases, and the battery management device is There is provided a method of detecting a life state of a secondary battery, characterized in that the first SOH and the second SOH are calculated by extracting the second characteristic value and the SOH characteristic value for each use time based on the temperature of the secondary battery.

In addition, in the second step, the use time of the secondary battery is calculated by counting "1" in units of preset reference days from the initial driving of the secondary battery, but when the secondary battery temperature is 0℃ or less, the counting reference days are increased. There is provided a method for detecting a life state of a secondary battery, comprising performing a deceleration count and performing an acceleration count by decreasing a reference number of days when the secondary battery temperature is 30°C or higher.

In addition, in the first step, when the device uses a secondary battery, the first SOH is calculated by integrating the secondary battery discharge current, and when the secondary battery is fully charged, a voltage environment for discharging to the device side at a preset period is set. Thus, there is provided a method for detecting a life state of a secondary battery, characterized in that the first SOH is calculated.

In addition, in the first step, the battery management apparatus learns the discharge frequency of the secondary battery, and sets a voltage environment for discharging to the device side during a time period when the frequency of use is low when the secondary battery is fully charged. A method of detecting the life status of a device is provided.

In addition, the secondary battery is composed of a battery pack in which a plurality of battery cells are connected in a series-parallel form, and in the first step, the battery management device calculates and stores SOH for each battery cell when calculating the first SOH before, Thereafter, based on the parallel connection, the first SOH in the current state is calculated by setting the discharge order in the order of the battery cells having the high SOH obtained during the calculation of the previous first SOH and the low battery cells. A detection method is provided.

According to the present invention, the remaining capacity state of the secondary battery is determined based on the remaining capacity of the secondary battery, which is the smaller of the remaining capacity in the current charging and discharging operation environment and the remaining capacity based on the use time of the secondary battery up to the present time. By determining and determining the life state of the secondary battery, it is possible to determine the replacement timing of the secondary battery more reliably than in the conventional configuration in which the life state of the secondary battery is determined using electronic elements around the secondary battery.

1 is a diagram showing a schematic configuration of a battery management system to which the present invention is applied.
FIG. 2 is a block diagram showing a functionally separated internal configuration of the battery management apparatus 100 shown in FIG. 1;
3 is a flowchart illustrating a method of detecting a life state of a secondary battery according to the present invention.
Figure 4 is a flow chart for explaining in more detail the process of calculating the first SOH shown in Figure 3;
5 to 7 are diagrams illustrating in graph form each characteristic table for calculating the first SOH and the second SOH.

Since the embodiments described in the present invention and the configurations shown in the drawings are only preferred embodiments of the present invention, and do not represent all the technical spirit of the present invention, the scope of the present invention is limited to the embodiments and drawings described in the text. Should not be construed as limited by That is, since the embodiments can be modified in various ways and have various forms, the scope of the present invention should be understood as including equivalents capable of realizing the technical idea. In addition, since the object or effect presented in the present invention does not mean that a specific embodiment should include all or only such effects, the scope of the present invention should not be understood as being limited thereby.

All terms used herein have the same meaning as commonly understood by one of ordinary skill in the field to which the present invention belongs, unless otherwise defined. Terms defined in a commonly used dictionary should be construed as having the meaning of the related technology in context, and cannot be interpreted as having an ideal or excessively formal meaning that is not clearly defined in the present invention.

1 is a diagram showing a schematic configuration of a battery management system to which the present invention is applied. In the present invention, the battery is a secondary battery composed of one or more electrochemical cells capable of charging and discharging.

Referring to FIG. 1, the battery management apparatus 100 according to the present invention is connected to the battery 200 to determine when to replace the battery 200 to generate an alarm. In this case, the battery management device 100 may be provided in a battery device in which the battery 200 is accommodated.

In addition, the battery 200 performs charging and discharging through an external device, such as a rectifier 300, and supplies driving power to the device 400, for example, a communication base station. In general, the rectifier 300 rectifies AC power applied from the outside to supply driving power of the device 400, and also charges the battery 200 by supplying a certain level of power to the battery 200. Here, the battery 200 may be formed of a battery pack in which a plurality of battery cells are arranged in series or parallel.

In addition, when AC power is not applied to the rectifier 300, power charged in the battery 200 is supplied to the device 400 through the rectifier 300 as the voltage level of the rectifier 300 is lowered.

FIG. 2 is a block diagram showing a functionally separated internal configuration of the battery management apparatus 100 shown in FIG. 1.

2, the battery management apparatus 100 includes a temperature sensor 110, a current/voltage measurement unit 120, a counter 130, a data memory 140, an alarm generator 150, and a control unit 160. Includes. In addition, the battery management apparatus 100 may be configured by additionally including a communication unit 170 for transmitting notification information of the battery replacement time to an external, for example, a manager terminal.

The temperature sensor 110 measures the ambient temperature of the battery. In this case, the temperature sensor 110 may measure the internal temperature of the battery device including the battery pack.

The current/voltage measuring unit 120 measures the output voltage and current of the battery 200.

The counter 130 is for calculating the battery usage time, and counts in units of a preset reference number of days. That is, when the number of days is 1, the battery usage time is counted by increasing "1" by 1 day. In this case, the reference days are counted from the initial driving of the battery, and the reference days for counting "1" are set differently according to the battery temperature.

The data memory 140 includes a first characteristic table consisting of SOC (Stage Of Charge) values for each battery voltage until the battery is fully charged, and a used discharge amount for each battery voltage up to the battery end voltage in which charging and discharging cannot be performed. Information for notification of various battery replacement times including a second characteristic table made of and an SOH characteristic table made of SOH (Stage Of Health) values for each battery use time is stored. At this time, the first and second characteristic tables and the SOH characteristic table are set to have different characteristic values according to temperature, and are made of characteristic values based on battery cells.

The alarm generator 150 displays battery replacement alarm information through an LED or outputs a voice. In this case, the alarm generator 150 may generate a warning signal indicating a specific battery cell that needs to be replaced among a plurality of battery cells constituting the battery 200. For example, an LED corresponding to the battery cell location may be flashed or battery replacement alarm information including a battery cell serial number may be voiced.

The control unit 160 calculates the first SOH in the rectifier-linked environment in which charging and discharging is performed through the rectifier 300, and calculates the second SOH corresponding to the use time of the battery up to the present time to calculate the first SOH and the second SOH. The SOH of the smallest value is determined as the current SOH for the corresponding battery, and when the determined SOH value is less than a preset replacement threshold value, it is determined as a battery replacement time, and replacement notification information is output through the notification generator 150. In this case, the controller 160 extracts the second characteristic value and the SOH characteristic value for each use time based on the battery temperature checked through the temperature sensor 120 to calculate the first SOH and the second SOH.

In addition, in calculating the first SOH, the controller 160 calculates the first SOH by integrating the discharge current of the battery 200 in a situation in which the device 400 uses the battery 200, but the device 400 In a situation in which) does not use the battery 200, the first SOH is calculated by arbitrarily setting a voltage environment for discharging to the device 400 in a state where the battery 200 is fully charged in a predetermined cycle unit. In this case, the controller 160 may learn the discharge frequency of the battery 200 and set a voltage environment for discharging to the device 400 during a time period when the battery 200 is fully charged and the frequency of use is low.

Next, a method of detecting a life state of a secondary battery according to the present invention will be described with reference to FIGS. 3 to 7. 3 is a flowchart illustrating a method of detecting a life state of a secondary battery according to the present invention, and FIG. 4 is a flowchart illustrating a process of calculating the first SOH shown in FIG. 3 in more detail, and FIGS. 5 to 5 7 is a diagram illustrating each characteristic table for calculating the first SOH and the second SOH.

First, a device 400 to be supplied with power, for example, a communication base station is connected to one end of the rectifier 300, and a battery 200 is connected to the other end of the rectifier 300.

Hereinafter, the use voltage of the communication base station 500 is 48V, the charging voltage from the rectifier 300 to the battery 200 is 53.3V, and the battery 200 full voltage is 52.5V, and the battery 200 is plural. The battery cells of, for example, 13 battery cells connected in series will be described as an example of a battery pack configured in a "13s11p" structure in which 11 are connected in parallel.

In addition, the operation for determining the battery replacement time as shown in FIG. 3 may be performed during a predetermined period, for example, at a preset time in units of one week, that is, a time period in which the device 400 is hardly used.

Referring to FIG. 3, the battery management apparatus 100 calculates a first SOH in an environment associated with a rectifier performing charging and discharging through the rectifier 300 (ST100). At this time, the battery management apparatus 100 calculates the first SOH by dividing the accumulated current amount for a predetermined time by a difference value between the discharge capacity and the dischargeable capacity when the battery is fully charged. Here, the accumulated current amount is calculated by integrating the discharge current until the battery 200 becomes the driving voltage of the device 400 in a fully charged state through the rectifier 300, and the dischargeable capacity is the battery 200 fully charged. It is set as a difference value between the discharge capacity generated when power is supplied to the device 400 from the full capacity at the time.

Referring to FIG. 4, the ST100 process includes a first characteristic table consisting of SOC values for each voltage from the battery management device 100 until the battery is fully charged, and a discharge capacity for each voltage from the battery full voltage to the end voltage. The resulting second characteristic table is acquired and stored (ST110). In this case, the first characteristic table may be obtained by monitoring the state of charge until the battery is fully charged through the rectifier 300 in the initial state in which the battery 200 is coupled to the rectifier 300 in the system of FIG. 1.

5 is a diagram showing a first characteristic table in graph form. The first characteristic table outputs a 53V voltage from the rectifier 300 to start charging the battery of the 13s11p battery pack structure, and the battery voltage from the battery management device 100 By monitoring the voltage until the voltage rises to 4.1V, which is the full charge voltage, the state of charge for each voltage, that is, the SOC value for each battery cell constituting the corresponding battery 200 is obtained. According to FIG. 5, it can be seen that when the battery cell voltage is 3.7V, the SOC value is 50%, that is, "0.5", and when the battery cell voltage is 4.1V, the SOC value is 95 to 100%, which is close to "1". .

Here, the battery management device 100 may generate each of the first characteristic tables according to the battery temperature while varying the battery temperature within an allowable range, for example, -30°C to 60°C. The first characteristic graph for each -10℃, 0℃, 10℃, 25℃, 45℃, 55℃ is shown. In this case, heating means and cooling means may be additionally provided in the battery device in which the battery is accommodated, and the temperature around the battery can be arbitrarily set by controlling the heating means and cooling means through the control unit 160.

And, according to FIG. 5, it can be seen that the first characteristic table shows a slight difference in the battery temperature.

In addition, the second characteristic table may be provided from the battery cell manufacturer, and FIG. 6 is a diagram showing the second characteristic table in the form of a graph.

Referring to FIG. 6, the second characteristic table is composed of a discharge capacity from a full voltage (4.15V) to an end voltage (2.5V) of a battery cell. In this case, the second characteristic table is configured to have different second characteristic values for each battery temperature. 6 shows the second characteristic graph for each -30℃, -20℃, -10℃, 0℃, 25℃, 45℃, and 60℃. Referring to FIG. 6, as the battery temperature increases, the amount of discharge to the end voltage is set larger as the second characteristic value, but it can be seen that the difference between the second characteristic values is insignificant under the temperature condition of 0°C or higher. For example, in Fig. 6, when the battery temperature is "-30°C", the amount of discharge to the end voltage is 3000mAh, and when the battery temperature is "25°C", "45°C", and "60°C", the use discharge to the end voltage. It can be seen that the amount is all 5000mAh.

Referring back to FIG. 4, while the first and second characteristic tables as described above are stored in the data memory 140, the battery management apparatus 100 is applied from the rectifier 300 based on the first characteristic table. The battery 200 is set to a full charge state by using the first voltage 53V, and in this state, the full charge capacity Ecap100 at the full charge voltage of the battery is obtained from the second characteristic table (ST120).

That is, the battery management device 100 is fully charged by the power supplied from the rectifier 300 so that the charging current and the discharging current are "0" A are maintained for 1 minute or more, and the full capacity (Ecap100) ) Is calculated. For example, the rectifier 300 supplies and charges the battery 200 with a power of 53V, and the battery 200 may be set to be fully charged at a battery voltage of 52.5V.

For example, when the SOC is 100% when the battery cell voltage is about 4.1V at full charge, the full charge capacity of the battery cell based on the battery temperature 25°C in the second characteristic graph shown in FIG. 6 is 5000mAh, and at this time, the battery pack is 11 Since it is a parallel circuit, the total capacity of the battery pack is calculated as 5000mAh × 11 = 55000mAh. That is, the full capacity Ecap100 of the battery 200 is 55Ah.

Subsequently, the battery management apparatus 100 sets the voltage of the rectifier 300 to a device driving voltage (48V) lower than the full charge voltage (53V) to set the battery 200 to a discharged state. That is, the battery 200 is set in a state in which power is supplied to the device 400 through the rectifier 300. In the above-described state, the battery management apparatus 100 accumulates the amount of discharge current from the voltage of the battery 200 to the full charge voltage (52.5V) to the driving voltage (48V) of the device 400, and the accumulated current amount (Ecap_c) Is calculated (ST130). At this time, the battery management device 100 calculates and stores the SOH for each battery cell when calculating the previous first SOH, and afterwards, the battery cell having a high SOH obtained at the time of calculating the previous first SOH based on a parallel connection By setting the discharge order in the order of, the first SOH in the current state can be calculated.

The accumulated current amount Ecap_c is an actual charge/discharge current amount until the battery voltage becomes from 52.5V to 48V, and is calculated as in Equation 1 below.

Here, i is the discharge current of the battery cell.

Further, the battery management apparatus 100 obtains the discharge capacity Ecap48 when the battery 200 is the device driving voltage 48V by using the second characteristic table (ST140). For example, the battery cell voltage when the battery voltage is 48V is 48V ÷ 13 = 3.7V because the series-connected battery cells constituting the corresponding battery 200 are 13, and the battery cell voltage in the first characteristic graph shown in FIG. This 3.7V SOC is 50%. In the second characteristic graph, the discharge capacity of the battery cell voltage of 3.7V is about 2500mAh based on the battery temperature of 25°C. Here, since the number of parallel-connected battery cells constituting the battery 200 is 11, the discharge capacity (Ecap48) of the battery pack is 2500mAh × 11 = 27500mAh, that is, 27.5Ah.

Subsequently, the battery management apparatus 100 calculates the dischargeable capacity of the corresponding battery 200 by performing a difference calculation (Ecap100-Ecap48) of the discharge capacity Ecap48 from the full capacity Ecap100 (ST150).

Then, the battery management apparatus 100 calculates the first SOH by dividing the accumulated current amount Ecap_c by the dischargeable capacity Ecap100-Ecap48 (ST160). That is, the first SOH (SOH1) calculation formula is shown in Equation 2 below.

For example, when the accumulated current amount (Ecap_c) calculated in step ST130 is 27500mAh, the first SOH becomes 27.5 ÷ (55-27.5) = "1", and when the accumulated current amount (Ecap_c) is 20000mAh, the first SOH Is 20 ÷ (55-27.5) = "0.72", and when the accumulated current amount (Ecap_c) is 10000mAh, the first SOH is calculated as 10 ÷ (55-27.5) = "0.36".

Meanwhile, in FIG. 3, the battery management apparatus 100 calculates the first SOH as described above, and calculates the second SOH corresponding to the current use time of the battery based on a predefined SOH characteristic table for each use time. Calculate (ST200).

That is, the battery management apparatus 100 obtains the current usage time of the corresponding battery 200 by counting "1" in units of a preset reference number of days from the initial driving of the battery. In this case, the battery usage time may be counted while setting the reference day unit differently according to the battery temperature. That is, when the battery temperature is 0°C or less, the deceleration count is performed by increasing the count reference days, and when the battery temperature is 30°C or higher, the acceleration count is performed by decreasing the count reference days to calculate the battery usage time. For example, if the battery temperature is set to "1" in the range of 0℃ ~ 30℃, and the battery temperature is -10℃, the number of days is increased to "2" and "1" every two days. Counting, and when the battery temperature is 45 ℃, it is possible to calculate the battery use time by decreasing the count reference days to 0.5" and counting "2" every day.

Subsequently, the battery management apparatus 100 extracts a second SOH value corresponding to the current use time of the battery from the SOH table. The SOH characteristic table for each use time can be provided from a corresponding battery cell manufacturer, and FIG. 7 is a diagram showing the SOH characteristic table for each use time in graph form.

In FIG. 7, the SOH characteristic value (Capacity), which is the usable discharge amount of the battery according to the use time of each battery temperature with a full charge voltage of 4.1V, is shown in a percentage form. At this time, the SOH graph is configured to have different use times for each battery temperature for the same usable discharge amount, and the higher the battery temperature, the smaller the SOH value for each use time is set. For example, in FIG. 7, when the SOH value is 80%, that is, "0.8", the battery temperature is "1460" in the condition of "45℃", and the battery temperature is "27℃" in the "4200" condition. You can see that it has.

In the ST200 step, when the battery temperature is 27°C in FIG. 7 and the current use time of the battery, that is, the count value is “3650”, the second SOH is calculated as “0.82” and the current use time is “5472” , The second SOH is calculated as "0.76".

Thereafter, the battery management apparatus 100 determines a smaller SOH of the first SOH calculated in the ST100 step and the second SOH calculated in the ST200 step as the current SOH (ST300). When the first SOH is "0.72" and the second SOH is "0.76", "0.72" is determined as the current SOH.

And, if the value determined as the current SOH is less than or equal to a preset replacement threshold, the battery management apparatus 100 determines that the battery is in a replacement state, and generates a replacement alarm (ST400). In this case, the replacement threshold is a value corresponding to a ratio corresponding to the current usage capacity relative to the total capacity of the battery and is set to a value less than or equal to "1", and may be set to, for example, "0.7". For example, in the ST300 step, if the current SOH is "0.72", it is determined that it is not yet the replacement time because it exceeds the replacement threshold "0.7", and if the current SOH is "0.65", it is considered that the replacement time is less than the replacement threshold. Judge.

100: battery management device, 200: battery,
300: rectifier, 400: device,
110: temperature sensor, 120: current/voltage measuring unit,
130: counter, 150: alarm generator,
160: control unit, 170: communication unit.

Claims (8)

In the method of detecting the life status of a secondary battery connected to an external device to perform charging and discharging,
The battery management device includes a first step of calculating the first SOH in an environment in which charging and discharging is performed by being connected to an external device,
A second step of calculating a second SOH corresponding to the use time of the secondary battery up to the present based on a predefined SOH characteristic table for each use time, and
Including the third step of determining the SOH of the smallest value among the first SOH and the second SOH as the current SOH, and when the current SOH value is less than a preset replacement threshold, it is determined as a secondary battery replacement time and a replacement alarm is generated. Become,
In the first step, the first SOH is calculated by dividing the accumulated current amount for a certain period of time by the difference between the discharge capacity and the dischargeable capacity when the secondary battery is fully charged, and the accumulated current amount is calculated by the secondary battery being fully charged through an external device. It is calculated by integrating the discharge current until it falls to the driving voltage of the device to be powered from in the state, and the dischargeable capacity is the difference between the full capacity when the secondary battery is fully charged and the discharge capacity generated when power is supplied to the device. A method for detecting a life state of a secondary battery, characterized in that it is set.
The method of claim 1,
The first step includes obtaining a first characteristic table consisting of SOC values for each voltage until the secondary battery is fully charged, and a second characteristic table consisting of discharge capacity for each voltage from the secondary battery full voltage to the end voltage,
Extracting the full capacity at the full voltage from the second characteristic table in a state in which the secondary battery is set to a fully charged state using a first voltage applied from an external device based on the first characteristic table,
By setting the voltage of the external device to a device driving voltage lower than the first voltage, allowing the secondary battery to perform a discharge operation, and accumulating the amount of discharge current from the secondary battery to the device driving voltage from the full voltage state Calculating the amount of current,
Obtaining the discharge capacity when the secondary battery is the driving voltage of the device based on the second characteristic table, and calculating the dischargeable capacity by calculating the difference between the discharge capacity from the full capacity,
And calculating the first SOH by dividing the accumulated current amount by the dischargeable capacity.
The method of claim 2,
In the first step, the battery management apparatus monitors the state of charge until the secondary battery is fully charged through an external device to obtain a first characteristic table consisting of SOC values for each secondary battery voltage. Status detection method.
The method according to claim 2 or 3,
In the second characteristic table and the SOH characteristic table for each use time, each characteristic value for each voltage is set differently according to the secondary battery temperature, and the second characteristic value stored in the second characteristic table is at the end voltage as the secondary battery temperature increases. The cumulative discharge capacity of is set to be larger, and the SOH characteristic value for each usage time stored in the SOH characteristic table for each usage time is configured so that the higher the secondary battery temperature, the smaller the SOH per usage time.
The battery management apparatus calculates the first SOH and the second SOH by extracting the second characteristic value and the SOH characteristic value for each use time based on the temperature of the secondary battery. "
The method of claim 1,
In the second step, the use time of the secondary battery is calculated by counting "1" by a preset reference number of days from the initial driving of the secondary battery,
When the secondary battery temperature is below 0℃, the deceleration count is performed by increasing the number of days based on the count, and when the secondary battery temperature is above 30℃, the number of days based on the count is decreased to perform an accelerated count. Status detection method.
The method of claim 1,
In the first step, when the device uses a secondary battery, the first SOH is calculated by integrating the discharge current of the secondary battery, and when the secondary battery is fully charged, a voltage environment for discharging to the device side at a preset period is set and 1 A method of detecting the life state of a secondary battery, characterized in that calculating SOH.
The method of claim 6,
In the first step, the battery management apparatus learns the discharge frequency of the secondary battery and sets a voltage environment for discharging to the device side during a time period when the secondary battery is fully charged and the frequency of use is low. Status detection method.
The method of claim 1,
The secondary battery is composed of a battery pack in which a plurality of battery cells are connected in series and parallel,
In the first step, the battery management device calculates and stores SOH for each battery cell when calculating the previous first SOH, and afterwards, battery cells having a high SOH obtained when calculating the previous first SOH based on a parallel connection A method for detecting a life state of a secondary battery, characterized in that by setting the discharge order in the order of to calculate the first SOH in the current state.

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