WO2013008396A1

WO2013008396A1 - Battery pack, charging control system and charging method

Info

Publication number: WO2013008396A1
Application number: PCT/JP2012/004149
Authority: WO
Inventors: 忠大吉田
Original assignee: Ｎｅｃエナジーデバイス株式会社
Priority date: 2011-07-08
Filing date: 2012-06-27
Publication date: 2013-01-17
Also published as: JPWO2013008396A1

Abstract

This battery pack (10) is provided with: battery cells (100); a temperature measurement means (a temperature sensor (210) and a temperature calculation unit (200)) for measuring the temperature of the battery cells (100); a termination current setting means (control unit (300)) for calculating a charging termination current value when the battery cells (100) are being charged; and a charging control means (control unit (300)) for terminating the charging of the battery cells (100). At a battery cell (100) temperature of at least 20°C to less than 45°C, the charging termination current value is altered on the basis of the temperature of the battery cells (100). The control unit (300) calculates, on the basis of the detection results of the temperature measurement means, the charging termination current value when the battery cells (100) are being charged. In addition, the control unit (300) terminates the charging of the battery cells (100) when the charging current of the battery cells (100) is less than or equal to the charging termination current value.

Description

Battery pack, charging control system, and charging method

The present invention relates to a battery pack, a charging control system, and a charging method.

A constant current and constant voltage charging method is used as a charging method for the lithium ion secondary battery. In the constant current / constant voltage charging method, charging is performed at a constant current until the battery voltage reaches a specific voltage (hereinafter referred to as a constant current mode), and after the specific voltage is reached, the applied voltage is constant. (Hereinafter referred to as a constant voltage mode) charging method.

In the constant current / constant voltage charging method, charging is terminated when the current value in the constant voltage mode becomes a sufficiently small value (hereinafter referred to as a charge termination current value).

On the other hand, when the lithium ion secondary battery is charged using the constant current and constant voltage charging method, the cycle performance of the battery may be deteriorated depending on the use environment and the charging condition of the battery.

Patent Document 1 (Japanese Patent Laid-Open No. 2005-294196) describes a charging method in which a charge termination rate is set to 0.2 ItA or higher for a battery whose temperature can be 45 ° C. or higher.
In a temperature environment of 45 ° C. or higher, it is described that a side reaction during charging accounts for a large percentage as a cause of reducing charge / discharge cycle performance, and the degree of the side reaction suddenly increases at 45 ° C. or higher. ing. In Patent Document 1, this side reaction is considered to be related to the potential applied in the constant voltage mode at the time of charging. By setting the charge termination rate to 0.2 ItA, the time of the constant voltage mode during charging is set. Is shortened. It is described that as a result of shortening the time in the constant voltage mode, the above side reaction is suppressed and the deterioration of the battery performance when the discharge cycle is repeated is suppressed.

JP 2005-294196 A

However, when such a charging method is used, a sufficient charging capacity cannot be obtained or an overcharged state may occur. In such a case, even if such a charging method is used, the cycle performance of the battery is deteriorated.

The present inventor has intensively investigated the mechanism of deterioration of the cycle performance of the battery, and it is not sufficient to switch the charge end current value at 45 ° C. or higher. I thought it was necessary to switch the current value.
It has been found that by setting the end-of-charge current value according to the temperature of the battery, overcharging can be prevented and close to full charging can be achieved.

According to the present invention,
A battery cell;
Temperature measuring means for measuring the temperature of the battery cell;
Based on the detection result of the temperature measuring means, an end current setting means for calculating a charge end current value when charging the battery cell;
Charging control means for terminating charging of the battery cell when the charging current of the battery cell becomes equal to or lower than the charge end current value;
With
When the temperature of the battery cell is at least 20 ° C. or more and less than 45 ° C.,
A battery pack is provided that changes the end-of-charge current value based on the temperature of the battery cell.

According to the present invention,
Temperature receiving means for receiving the temperature of the battery cell;
Based on the detection result of the temperature receiving means, an end current setting means for calculating a charge end current value when charging the battery cell;
Charging control means for terminating charging of the battery cell when the charging current of the battery cell becomes equal to or lower than the charge end current value;
With
When the temperature of the battery cell is at least 20 ° C. or more and less than 45 ° C.,
A charge control system is provided that changes the end-of-charge current value based on the temperature of the battery cell.

According to the present invention,
A charging start step for starting charging the battery cell and measuring the temperature of the battery cell being charged; and
An end current setting step for calculating a charge end current value when charging the battery cell based on the measured temperature;
A determination step for determining a condition that the charging current of the battery cell is equal to or lower than the charge end current value;
When the condition is not satisfied, the charging is continued, and when the condition is satisfied, the charging control step for terminating the charging of the battery cell;
With
When the temperature of the battery cell is at least 20 ° C. or more and less than 45 ° C.,
A charging method is provided that changes the end-of-charge current value based on the temperature of the battery cell.

The inventor considered the reason why the cycle performance of the battery deteriorated as follows.
The lithium ion secondary battery is activated as the temperature increases, and the direct current resistance decreases. For this reason, even if the charging conditions such as voltage, current, and time are the same, the higher the battery temperature, the easier the capacity is entered. Therefore, under the same charging conditions, the higher the battery temperature, the more overcharged, and the battery cycle performance tends to deteriorate. Under the same charging conditions, the full charge capacity cannot be obtained as the battery temperature decreases.
According to the present invention, the end-of-charge current value is set based on the temperature of the battery cell. By doing so, it is possible to suppress overcharging even when the temperature of the battery cell is high, and it is possible to approach the full charge capacity even when the temperature of the battery cell is low.

According to the present invention, the battery cell can be close to full charge without being overcharged.

The above-described object and other objects, features, and advantages will become more apparent from the preferred embodiments described below and the accompanying drawings.
It is a circuit diagram which shows the structure of the battery pack which concerns on 1st Embodiment. It is a flowchart which shows the charge method which concerns on 1st Embodiment. It is a flowchart which shows the charge method which concerns on 1st Embodiment. It is a figure for demonstrating the charge curve of the battery cell from which temperature differs. It is a circuit diagram which shows the structure of the battery pack which concerns on 2nd Embodiment. It is a flowchart which shows the charge method which concerns on 2nd Embodiment. It is a flowchart which shows the charge method which concerns on 2nd Embodiment. It is a circuit diagram which shows the structure of the battery pack and control circuit which concern on 3rd Embodiment. It is a circuit diagram which shows the structure of the battery pack and control circuit which concern on 4th Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same reference numerals are given to the same components, and the description will be omitted as appropriate.

As used herein, “battery pack 10” refers to an assembled battery having at least one battery unit. Further, the “battery unit” refers to one having at least one battery cell 100. Furthermore, the battery cell 100 included in the “battery unit” may include one or more single cells having a positive electrode, a negative electrode, and the like. Further, the plurality of “battery units” may have different numbers of battery cells 100. Hereinafter, a case will be described in which a plurality of battery cells 100 having two unit cells connected in parallel are connected in series.

(First embodiment)
The battery pack 10 according to the first embodiment will be described with reference to FIG. FIG. 1 is a circuit diagram showing a configuration of the battery pack 10 according to the first embodiment. The battery pack 10 includes a battery cell 100, temperature measuring means (temperature calculation unit 200 and temperature sensor 210) for measuring the temperature of the battery cell 100, and a termination for calculating a charge termination current value when the battery cell 100 is charged. Current setting means (control unit 300) and charge control means (control unit 300) for terminating the charging of the battery cell 100 are provided. Then, the control unit 300 changes the charge end current value based on the temperature of the battery cell 100 when the temperature of the battery cell 100 is at least 20 ° C. or higher and lower than 45 ° C.
The controller 300 calculates a charge termination current value when charging the battery cell 100 based on the detection result of the temperature measuring means. In addition, when the charging current of the battery cell 100 becomes equal to or lower than the charging end current value, the control unit 300 interrupts the charging current with the switch 500 or sends a signal from the external communication terminal 760 to the charger. 100 charge is terminated.

In the first embodiment, the battery pack 10 includes a plurality of battery cells 100. The plurality of battery cells 100 are connected in series. Further, as described above, the battery cell 100 has two single cells. Specifically, the battery cell 100 is a lithium ion secondary battery.

The battery pack 10 in the first embodiment has a control circuit 20 in addition to the battery cell 100. The control circuit 20 includes a temperature calculation unit 200, a control unit 300, a measurement unit 400, a current measurement unit 800, and a switch (SW) 500. Details will be described below.

The control circuit 20 in the first embodiment is connected to the battery cells 100 connected in series. The control circuit 20 has an internal positive terminal 620, an internal negative terminal 640, an external positive terminal 720, and an external negative terminal 740. The internal positive electrode terminal 620 is connected to the positive electrode of the battery cell 100 located closest to the positive electrode among the battery cells 100 connected in series. Moreover, the internal negative electrode terminal 640 is connected to the negative electrode of the battery cell 100 located closest to the negative electrode among the battery cells 100 connected in series.

The internal positive terminal 620 is connected to an external positive terminal 720 for connecting to an external device using the battery pack 10 via a wiring in the control circuit 20. Further, the internal negative terminal 640 is connected to an external negative terminal 740 for connecting to an external device using the battery pack 10 via a wiring in the control circuit 20.

A switch 500 for stopping charging or discharging is provided between the internal positive terminal 620 and the external positive terminal 720. For example, the switch 500 is provided between the internal positive terminal 620 and the external positive terminal 720 on the battery cell 100 side. In this case, the switch 500 is a P-channel MOSFET (Metal Oxide Semiconductor Field Effect Transistor), for example. In the switch 500, two P-channel MOSFETs are provided. Thereby, one MOSFET is used to control charging. On the other hand, the other MOSFET is used to control the discharge. Each MOSFET in the switch 500 is connected to the measurement unit 400.

If the switch 500 is an N-channel MOSFET, the switch 500 is disposed between the internal negative terminal 640 and the external negative terminal 740. In addition, the switch 500 may be an insulated gate bipolar transistor (Insulated Gate Bipolar Transistor, IGBT), a relay, or a breaker, for example.

The temperature measurement means in the first embodiment includes a temperature calculation unit 200 and a temperature sensor 210. The temperature sensor 210 is connected to the temperature calculation unit 200. The temperature sensor 210 is arrange | positioned at the center part (Cell3 of FIG. 1) in the some battery cell 100, for example. The temperature sensor 210 may be disposed in another place in the plurality of battery cells 100.
The temperature sensor 210 detects the temperature of the battery cell 100. The temperature calculation unit 200 calculates the temperature of the battery cell 100 using the signal output from the temperature sensor 210.

The end current setting means in the first embodiment includes a control unit 300. A temperature calculation unit 200 and a measurement unit 400 are connected to the control unit 300. The control unit 300 performs arithmetic processing based on the temperature of the battery cell 100 calculated by the temperature calculation unit 200. Specifically, the control unit 300 calculates a charge termination current value when charging the battery cell 100 based on the temperature of the battery cell 100 calculated by the temperature calculation unit 200.

The control unit 300 stores a full charge end current data indicating a relationship between a temperature of the battery cell 100 and a full charge end current value that is a charge end current value at the time of full charge, which will be described later (not shown). You may have.

The controller 300 is connected to an external communication terminal 760 for transmitting / receiving signals to / from an external device. The control unit 300 transmits a signal to an external device (not shown) via the external communication terminal 760. In addition, the control unit 300 receives a signal from an external device via the external communication terminal 760.

The battery pack 10 has a protection circuit in order to improve safety and charge / discharge cycle life. The protection circuit includes a control unit 300, a measurement unit 400, and a switch 500. The protection circuit has a function of forcibly terminating charging when the battery cell 100 is charged with a voltage exceeding the overcharge protection voltage.

Measurement unit 400 measures the voltage and current of battery cell 100. The control unit 300 is connected to the measurement unit 400. The controller 300 ends the charging of the battery cell 100 when the charging current value measured by the measuring unit 400 becomes equal to or less than the calculated charging end current value.

Thus, in the first embodiment, the battery pack 100 is packaged including the plurality of battery cells 100 and the control circuit 20.

Next, a method for charging the battery pack 10 according to the first embodiment will be described with reference to FIGS. 2 and 3. 2 and 3 are flowcharts for explaining the charging method according to the first embodiment. FIG. 3 is a modification of FIG.
The charging method according to the first embodiment includes the following steps. Charging of the battery cell 100 is started (S110). The temperature of the battery cell 100 is measured (S120). Based on the measured temperature, an end-of-charge current value for charging the battery cell 100 is calculated (S130). After the constant voltage mode is entered and the current starts to be reduced, a condition is determined that the charging current has become equal to or lower than the charge end current value (S140). When the condition is not satisfied (S140 No), the charging is continued. When the condition is satisfied (S140 Yes), the charging of the battery cell 100 is terminated (S150). Hereinafter, each step will be described in detail.

First, the external positive terminal 720 and the external negative terminal 740 are connected to the positive and negative electrodes of the power supply source. Thereby, charging of the battery cell 100 is started. At the same time, the measuring unit 400 measures the voltage of the battery cell 100, and the current measuring unit 800 measures the charging current of the battery cell 100 (S110).

Next, the temperature calculation unit 200 calculates the temperature of the battery cell 100 using the signal output from the temperature sensor 210 (S120).

Next, the control unit 300 receives the temperature result calculated from the temperature calculation unit 200, and calculates a charge termination current value when charging the battery cell 100 based on the temperature result (S130). Here, a method for calculating the charge end current value will be described below.

The charge end current value in the first embodiment is set to be higher as the temperature of the battery cell 100 becomes higher when the temperature of the battery cell 100 is at least 20 ° C. or higher and lower than 45 ° C.
The battery cell 100 is activated as the temperature increases, and the DC resistance decreases. The battery cell 100 has a higher DC resistance as the temperature is lower. For example, when the charging curve at 20 ° C. is V ₂₀ and the charging curve at 40 ° C. is V ₄₀ , the battery cell 100 at 40 ° C. has a smaller direct current resistance, and therefore the resistance difference × I in the constant current region. _The voltage drops by the amount corresponding to _RS (see FIG. 4A). Therefore, the battery cell 100 at 40 ° C. reaches the constant voltage mode voltage V ₁ slower by t ₂ −t _1, and the constant current mode continues longer by t ₂ −t ₁ . As a result, it reached earlier fully-charged capacity _{C 1} (see Figure 4 (b)). Therefore, if the charge end current value is set to the same Ia as 20 ° C., the battery is charged exceeding the full charge capacity.
Therefore, under the same charging conditions, the battery cell 100 becomes overcharged as the battery temperature increases, and the full charge capacity cannot be obtained as the battery temperature decreases.
In the first embodiment, the charging of the battery cell 100 is quickly completed by setting the charging end current value higher as the temperature of the battery cell 100 becomes higher. Therefore, the charging time of the battery cell 100 becomes shorter as the temperature becomes higher, and the battery cell 100 can be prevented from being overcharged. In addition, by setting the charge end current value to be lower as the temperature of the battery cell 100 becomes lower, the charging of the battery cell 100 ends late. Therefore, the charging time of the battery cell 100 becomes longer as the temperature becomes lower, and the battery cell 100 can be brought close to full charge.

Moreover, the calculation method of the charge end current value in 1st Embodiment is the charge end current used as the temperature of the battery cell 100 and the full charge capacity in each temperature, when the temperature of the battery cell 100 is at least 20 degreeC or more and less than 45 degreeC More preferably, it is performed based on the full charge end current data indicating the relationship with the value. Since the full charge end current data varies depending on the characteristics of the battery cell 100, it is preferable to acquire data in advance for each of the plurality of battery cells 100.
Here, the full charge capacity refers to a charge capacity when the battery pack 10 is charged under standard charge conditions at a reference temperature. For example, at 20 ° C., the charge voltage is 4.2 V, and the charge end current value is a capacity when charging is performed under the condition that the charge end rate is 0.05 ItA. The reference temperature is preferably room temperature.
The end-of-charge current value that is the full charge capacity at each temperature refers to the current value when the battery cell 100 reaches the full charge capacity at that temperature when the battery cell 100 is set to a certain temperature.
Full charge end current data indicating the relationship between the temperature of the battery cell 100 and the charge end current value at the full charge capacity at each temperature is created by measuring the charge end current value at the full charge capacity at each temperature. To do. The full charge end current data may be stored in a storage unit (not shown) of the control unit 300, or may be stored in an external device and received from the external communication terminal 760.

Thus, at each temperature, by calculating the charge end current value based on the full charge end current data indicating the relationship between the temperature of the battery cell 100 and the charge end current value that is the full charge capacity at each temperature. Without overcharging the battery cell 100, it can be performed more accurately to approach full charge.

Further, the end current setting means preferably corrects the end charge current value based on the ratio of the current full charge capacity to the initial capacity value that is the initial full charge capacity of the battery cell 100. Specifically, it is preferable to correct the charge end current value to be lower as the ratio of the current full charge capacity to the initial capacity value becomes smaller.
When the battery cell 100 is repeatedly used, the resistance gradually increases due to deterioration. Therefore, if the charge end current value calculated using the initial full charge capacity is fixed and used, the full charge capacity cannot be obtained as the deterioration proceeds.
Therefore, in the first embodiment, by correcting the charge end current value to be lower as the ratio of the current full charge capacity to the initial capacity value of the battery cell 100 becomes smaller, the battery without changing the charge end rate. The cell 100 can be brought close to full charge. For example, when charging the battery cell 100 whose full charge capacity is changed from 5 Ah to 4 Ah due to deterioration, the charge end current value is corrected from 250 mA to 200 mA. By doing so, it is possible to approach full charge without changing the charge end rate from 250 mA / 5 Ah = 0.05 ItA to 200 mA / 4 Ah = 0.05 ItA.
The current full charge capacity of the battery cell is measured by capacity measuring means. Specifically, the current can be calculated by measuring the current with the current measuring unit 800 and integrating the current value with the control unit 300.

Next, the control unit 300 receives the charging current of the battery cell 100 from the measurement unit 400, and determines a condition that the charging current is equal to or less than the calculated charge end current value (S140). When the condition is not satisfied, charging is continued (No in S140). At this time, as shown in FIG. 2, after the charging is continued, the temperature of the battery cell 100 may be measured again, and the charge end current value when the battery cell 100 is charged may be calculated again. Further, as shown in FIG. 3, after the charging is continued, the condition that the charging current becomes equal to or lower than the charging end current value may be determined without performing re-measurement of the temperature of the battery cell 100.

When the condition is satisfied (S140 Yes), a signal is transmitted from the external communication terminal 760 of the control unit 300 to the power supply source (not shown), and the charging of the battery cell 100 is terminated (S150). Alternatively, a signal is transmitted from the control unit 300 to the switch 500, and the charging current is interrupted by the switch 500, thereby terminating the charging of the battery cell 100 (S150).

As described above, charging of the battery pack 10 according to the first embodiment is controlled.

Next, the effect of the first embodiment will be described.
When the temperature of the battery cell 100 is at least 20 ° C. or higher and lower than 45 ° C., the battery cell 100 is activated as the temperature increases, and the direct current resistance decreases. Therefore, even if the charging conditions such as voltage, current, and time are the same, the capacity becomes easier as the battery temperature increases. Therefore, under the same charging conditions, the battery cell 100 becomes overcharged as the battery temperature increases, and the battery cell 100 cannot obtain a full charge capacity as the battery temperature decreases.
The battery pack 10 according to the first embodiment sets a charge termination current value based on the temperature of the battery cell 100. Specifically, when the temperature of the battery cell is at least 20 ° C. or more and less than 45 ° C., the charge end current value is set higher as the temperature of the battery cell 100 becomes higher. By carrying out like this, since the charge time of the battery cell 100 becomes short as the temperature of the battery cell 100 becomes high, it can suppress that the battery cell 100 becomes overcharged. Further, the end-of-charge current value is set lower as the temperature of the battery cell 100 becomes lower. By doing so, the charging time of the battery cell 100 becomes longer as the temperature of the battery cell 100 becomes lower, so that the battery cell 100 can be brought close to full charge.

As described above, according to the first embodiment, it is possible to prevent the battery pack 10 having the battery cells 100 from being overcharged, and to approach full charge.

(Second Embodiment)
A battery pack 10 according to the second embodiment will be described. The second embodiment is the same as the first embodiment except that each battery cell 100 includes a temperature sensor 210. Therefore, in the second embodiment, the description will focus on the parts that are different from the first embodiment.

FIG. 5 is a circuit diagram showing a configuration of the battery pack 10 according to the second embodiment.
The temperature measurement means in the second embodiment includes a temperature calculation unit 200 and a plurality of temperature sensors 210 provided for each battery cell 100. Each temperature sensor 210 is connected to the temperature calculation unit 200.
Each temperature sensor 210 detects the temperature of each battery cell 100. The temperature calculation unit 200 calculates the temperature of each of the plurality of battery cells 100 based on the detection result of each temperature sensor 210, and identifies the maximum temperature among the plurality of battery cells 100.

The end current setting means in the second embodiment calculates a charge end current value when charging the battery cell 100 based on the maximum temperature among the plurality of battery cells 100 specified by the temperature calculation unit 200.

Next, a method for charging the battery pack 10 according to the second embodiment will be described with reference to FIGS. 6 and 7. 6 and 7 are flowcharts for explaining the charging method according to the second embodiment. FIG. 7 is a modification of FIG.
The charging method according to the second embodiment includes the following steps. Charging of the battery cell 100 is started (S110). The temperatures of the plurality of battery cells 100 are measured (S122). The maximum temperature is specified among the plurality of battery cells 100 (S124). Based on the specified maximum temperature of the battery cell 100, a charge end current value when the battery cell 100 is charged is calculated (S132). After the constant voltage mode is entered and the current starts to be reduced, a condition is determined that the charging current has become equal to or lower than the charge end current value (S140). When the condition is not satisfied (S140 No), the charging is continued. When the condition is satisfied (S140 Yes), the charging of the battery cell 100 is terminated (S140). Hereinafter, each step will be described in detail.

Next, the temperature of each of the plurality of battery cells 100 is detected by the temperature sensor 210 (S122). The temperature calculation unit 200 receives the detection result of the temperature of each battery cell 100 from the temperature sensor 210, calculates the temperature of the battery cell 100 based on the detection result, and is the maximum among the plurality of battery cells 100. The temperature is specified (S124).

Next, the control unit 300 receives the maximum temperature result from the temperature calculation unit 200, and calculates a charge termination current value when charging the battery cell 100 based on the maximum temperature (S132).
The following steps are the same as those in the first embodiment except that the maximum temperature of the battery cell 100 is used.

Next, effects of the second embodiment will be described.
The plurality of battery cells 100 in the battery pack 10 may vary in temperature internally due to the arrangement of the battery cells 100. In particular, since the heat inside the battery cell 100 is less likely to diffuse toward the center, the temperature of the battery cell 100 (near Cell 3 in FIG. 5) tends to increase. As described above, the battery cell 100 is activated as the temperature increases, and the DC resistance decreases. Therefore, even if charging conditions such as voltage, current, and time are the same, the capacity of the battery cell 100 becomes easier as the battery temperature increases. Therefore, under the same charging condition, the battery cell 100 having a higher battery temperature becomes overcharged. In particular, when the battery cell 100 reaches a voltage exceeding the overcharge protection voltage, the charging is forcibly terminated by the protection circuit.
The battery pack 10 in the second embodiment sets a charge termination current value based on the maximum temperature in each battery cell 100. By doing so, since the battery cell 100 that reaches a voltage exceeding the overcharge protection voltage is suppressed, it is difficult for the protection circuit to forcibly terminate the charge.

As described above, according to the second embodiment, each of the plurality of battery cells 100 included in the battery pack 10 can be brought close to full charge while suppressing overcharging.

(Third embodiment)
FIG. 8 is a circuit diagram showing configurations of the battery pack 10 and the control circuit 20 according to the third embodiment. The third embodiment is the same as the first embodiment except that the control circuit 20 is provided outside the battery pack 10. Details will be described below.

As shown in FIG. 8, the control circuit 20 is provided outside the battery pack 10. The control circuit 20 is provided, for example, in a charging device (not shown) that is independent from the battery pack 10. Alternatively, the control circuit 20 may be provided in a device used when the battery pack 10 is discharged and used.

The battery pack 10 is provided with a positive terminal 820 and a negative terminal 840 for charging and discharging the battery pack 10.

The control circuit 20 includes a temperature calculation unit 200, a control unit 300, a measurement unit 400, and a switch (SW) 500. The positive terminal 920 of the control circuit 20 is provided at a position corresponding to the positive terminal 820 of the battery pack 10 on the battery pack 10 side of the control circuit 20. Further, the negative terminal 940 of the control circuit 20 is provided at a position corresponding to the negative terminal 840 of the battery pack 10. These terminals are connected to each other by wiring (not shown). As a result, charging power is supplied from the control circuit 20 to the battery pack 10.

According to the third embodiment, the control circuit 20 is provided outside the battery pack 10. The control circuit 20 is connected to the battery cell 100 via wiring. Thereby, the effect similar to 1st Embodiment can be acquired.

(Fourth embodiment)
FIG. 9 is a circuit diagram showing configurations of the battery pack 10 and the control circuit 20 according to the fourth embodiment. The fourth embodiment is the same as the third embodiment except that a plurality of temperature sensors 210 are provided for each battery cell 100.

The end current setting means in the fourth embodiment is charged when charging the battery cell 100 based on the maximum temperature in the battery cell 100 specified by the temperature calculation unit 200, as in the second embodiment. Calculate the end current value.

Therefore, according to the fourth embodiment, the same effect as that of the second embodiment can be obtained.

In the above third embodiment and fourth embodiment, the case where the control circuit 20 is provided outside the battery pack 10 has been described, but various other configurations are possible. For example, only the control unit 300 may be provided outside the battery pack 10.

In the above embodiment, a charging device including the above-described control circuit 20 is also disclosed.

As described above, the embodiments of the present invention have been described with reference to the drawings. However, these are exemplifications of the present invention, and various configurations other than the above can be adopted.

This application claims priority based on Japanese Patent Application No. 2011-152168 filed on July 8, 2011, the entire disclosure of which is incorporated herein.

Claims

A battery cell;
Temperature measuring means for measuring the temperature of the battery cell;
Based on the detection result of the temperature measuring means, an end current setting means for calculating a charge end current value when charging the battery cell;
Charging control means for terminating charging of the battery cell when the charging current of the battery cell becomes equal to or lower than the charge end current value;
With
When the temperature of the battery cell is at least 20 ° C. or more and less than 45 ° C.,
A battery pack that changes the end-of-charge current value based on a temperature of the battery cell.
The battery pack according to claim 1,
The termination current setting means is a battery pack that sets the charge termination current value higher as the temperature of the battery cell by the temperature measurement means becomes higher.
The battery pack according to claim 1,
Storage means for storing full charge end current data indicating a relationship between the temperature of the battery cell and a full charge end current value which is a charge end current value at the time of full charge;
The termination current setting means is a battery pack that sets the charge termination current value by using the full charge termination current data.
The battery pack according to any one of claims 1 to 3,
Capacity measuring means for measuring the current capacity of the battery cell;
The termination current setting means is a battery pack that corrects the charge termination current value based on a ratio of a measured value of the capacity measuring means to an initial capacity value of the battery cell.
The battery pack according to claim 4,
The battery pack which correct | amends the said charge end current value low as the ratio of the said measured value with respect to the said initial capacity value becomes small.
The battery pack according to any one of claims 1 to 5,
The temperature measuring means measures the temperature of each of the plurality of battery cells,
The termination current setting means is a battery pack that calculates the charge termination current value using a maximum temperature among the temperatures.
Temperature receiving means for receiving the temperature of the battery cell;
Based on the detection result of the temperature receiving means, an end current setting means for calculating a charge end current value when charging the battery cell;
Charging control means for terminating charging of the battery cell when the charging current of the battery cell becomes equal to or lower than the charge end current value;
With
When the temperature of the battery cell is at least 20 ° C. or more and less than 45 ° C.,
The charge control system which changes the said charge end current value based on the temperature of the said battery cell.
The charge control system according to claim 7,
The termination current setting means is a charge control system that sets the charge termination current value higher as the temperature by the temperature receiving means becomes higher.
The charge control system according to claim 7,
Storage means for storing full charge end current data indicating a relationship between the temperature of the battery cell and a full charge end current value which is a charge end current value at the time of full charge;
The termination current setting means is a charge control system that sets the charge termination current value using the full charge termination current data.
The charge control system according to any one of claims 7 to 9,
Capacity measuring means for measuring the current capacity of the battery cell;
The termination current setting means corrects the charge termination current value based on a ratio of a measured value of the capacity measuring means to an initial capacity value of the battery cell.
The charge control system according to claim 10,
The charge control system which correct | amends the said charge end current value low as the ratio of the said measured value with respect to the said initial capacity value becomes small.
The charge control system according to any one of claims 7 to 11,
The temperature receiving means receives the temperature of each of the plurality of battery cells,
The end current setting means is a charge control system for calculating the end charge current value using a maximum temperature among the temperatures.
A charging start step for starting charging the battery cell and measuring the temperature of the battery cell being charged; and
An end current setting step for calculating a charge end current value when charging the battery cell based on the measured temperature;
A determination step for determining a condition that the charging current of the battery cell is equal to or lower than the charge end current value;
When the condition is not satisfied, the charging is continued, and when the condition is satisfied, the charging control step for terminating the charging of the battery cell;
With
When the temperature of the battery cell is at least 20 ° C. or more and less than 45 ° C.,
The charging method which changes the said charge end current value based on the temperature of the said battery cell.
The charging method according to claim 13,
In the charging method, the end current setting step sets the charge end current value higher as the measured temperature becomes higher.
The charging method according to claim 13,
In the end current setting step, the charge end current value is set using full charge end current data indicating a relationship between a temperature of the battery cell and a full charge end current value that is a charge end current value at the time of full charge. Charging method.
The charging method according to any one of claims 13 to 15,
The end current setting step is a charging method in which the end current value is corrected based on a ratio of a current capacity value of the battery cell to an initial capacity value of the battery cell.
The charging method according to claim 16, wherein
A charging method for correcting the charge end current value to be lower as a ratio of the current capacity value to the initial capacity value becomes smaller.
The charging method according to any one of claims 13 to 17,
The charging start step measures the temperature of each of the plurality of battery cells,
In the charging method, the end current setting step calculates the charge end current value using a maximum temperature among the temperatures.