JPH0917454A - Charging method of secondary battery - Google Patents

Abstract

PURPOSE: To shorten charging time of a secondary battery without shortening its life by detecting the temperature of the secondary battery at the time of charging, selecting a charging mode corresponding to the temperature, and supplying current to the secondary battery. CONSTITUTION: A secondary battery B is connected with a charging apparatus A to start charging. Whether a cell 2 is connected or not is judged based on the voltage signal of a voltage detecting part 17. In the case the cell 2 is connected, the temperature signal detected by a temperature sensor 6 is decided and charging is not started until the temperature of the cell 2 becomes within a range from 0 to 40 deg.C, in which charging is possible. In the case the temperature of the cell 2 is within the range and not higher than 10 deg.C, a normal charging mode is started. In the normal charging mode, constant charging current about 0.3 times as large as the rated current value of the cell 2 is supplied to the cell. In the case the temperature of the cell 2 is higher than 10 deg.C, a quick charging mode is started. In the quick charging mode, constant charging current the same as the rated current value of the cell 2 is supplied to the cell 2. A control circuit 16 starts integration of the timer value Tn for the ordinal charging.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of charging a secondary battery suitable for use as a power source for an electric vehicle such as a bicycle with auxiliary power.

[0002]

2. Description of the Related Art For example, a secondary battery mounted on a bicycle with auxiliary power is adapted to be charged by a household power source, and a NiCd battery is known as such a secondary battery. It has been confirmed by various experiments that the charging of the NiCd battery has a bad influence on the cycle life of the secondary battery when the charging is performed at a high temperature. On the other hand, for example, 1
Even when quick charging is performed at a low temperature of 0 ° C. or less, the charging efficiency is extremely reduced, and the charging tends to be insufficient.
The electrolyte solution inside the iCd battery becomes a gas and the life is extremely reduced.

[0003]

However, even at the above-mentioned low temperature, at a certain temperature, for example, 0 ° C. or higher, it is possible to perform charging with a reduced charging current value. And if you limit charging to 10 ℃ or more, when using the secondary battery in winter or cold regions, the secondary battery or auxiliary power equipped with the secondary battery in warm indoors. Move the attached bicycle etc. to 2
Only after waiting for the temperature of the next battery to rise, can the battery be charged. Therefore, there is a problem that time is wasted by waiting for the temperature to rise.

At the beginning of charging, even if the secondary battery has to be charged by lowering the charging current value due to the low temperature, if the temperature of the secondary battery rises after the start of charging, the secondary battery is charged. The current value is raised to enable quick charging. In such a case, it is not efficient to continue charging with a low current value.

The present invention has been made in consideration of the above circumstances, and by performing an appropriate treatment corresponding to the battery temperature, the charging time is shortened without impairing the life of the secondary battery. It is an object of the present invention to provide a secondary battery charging method capable of charging the secondary battery.

[0006]

In order to solve the above-mentioned problems, in the method of charging a secondary battery according to claim 1,
In a method of charging a secondary battery in which current is supplied to the secondary battery from a charging means, a process of measuring a temperature of the secondary battery and a process of selecting a charging mode corresponding to the temperature of the secondary battery are selected. It is characterized in that the process of supplying a current to the secondary battery in a charging mode is repeated.

According to a second aspect of the present invention, there is provided a method for charging a secondary battery according to the first aspect, wherein A: when the voltage of the secondary battery takes a peak value and then drops by a predetermined voltage, B: When the temperature of the secondary battery exceeds the first predetermined temperature, and when any one of the following conditions is satisfied, the charging is terminated, and the temperature of the secondary battery is currently in progress. Even when the value becomes appropriate for selecting a charging mode different from the charging mode, C: charging of the secondary battery is started, the first predetermined time has elapsed, and the voltage of the secondary battery reaches the peak value. After that, D: the temperature of the secondary battery is lower than the first predetermined temperature
After the temperature exceeds the predetermined temperature of E, before the second predetermined time elapses after the current charging mode is selected, the current charging mode should be continued. It has a feature.

[0008]

According to the rechargeable battery charging method of claim 1, first, the temperature of the rechargeable battery is measured, and the charge mode corresponding to the temperature of the rechargeable battery is selected. Supply current to the secondary battery. Then, the temperature of the secondary battery is further measured, the charging mode corresponding to the temperature of the secondary battery at that time is selected, and the current is supplied to the secondary battery. As a result, even after the charging is once started, it is possible to switch the charging mode when the temperature of the secondary battery changes and the charging mode that has continued until then becomes inappropriate. . Therefore, it is possible to reduce the charging current value when the temperature of the battery is lowered, prevent the life of the secondary battery from being impaired, and increase the charging current value when the temperature is raised to shorten the charging time.

According to the secondary battery charging method of the second aspect, A: When the voltage of the secondary battery drops to a predetermined voltage after the secondary battery takes a peak value, B: the temperature of the secondary battery becomes the first When the temperature exceeds the predetermined temperature, the charging is terminated when any one of the conditions is satisfied. Here, if the charging current value is changed after the voltage of the secondary battery reaches the peak value, the battery voltage may be changed, and the determination of the voltage drop of condition A may be erroneous. In addition, the battery voltage may drop for a while after starting charging or shifting to another charging mode, and the determination of the condition A may be erroneous. Further, if the charging current value is changed when the temperature of the secondary battery rises, the battery temperature may be changed and the condition B may be erroneously determined. Therefore, even when the temperature of the secondary battery reaches an appropriate value for selecting a charging mode different from the charging mode currently in progress, C: charging of the secondary battery is started and the first predetermined time has elapsed. After the voltage of the secondary battery reaches the peak value, D:
Either after the temperature of the secondary battery exceeds a second predetermined temperature lower than the first predetermined temperature, E: before the second predetermined time elapses after the charging mode currently in progress is selected. In the case of, the charging mode in progress is continued. As a result, it is possible to appropriately determine the completion of charging, and it is possible to perform charging without excess or deficiency.

[0010]

【Example】

A. Configuration of Embodiment One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a connection between a charger A and a secondary battery B for carrying out the secondary battery charging method according to the embodiment. First, the structure of the secondary battery B will be described. In the figure, reference numeral 2 indicates a plurality of single cells (cells) that are NiCd batteries.
It is. The unit cells 2 are connected to each other in series and arranged in one battery case (not shown). Single battery 2
Both electrodes are connected to the contacts 4a and 4b of the connector. Further, a temperature sensor 6 such as a thermistor is arranged inside the battery case, and the temperature sensor 6 is brought into contact with any one of the cells 2 to detect the temperature thereof. The temperature sensor 6 is a contact point 8 of the connector.
It is connected to a and 8b.

Next, the structure of the charger A will be described.
Reference numeral 10 in the figure indicates a socket connected to a household power supply. The socket 10 is connected to the rectifier circuit 11,
The AC current from the household power supply is converted into DC current by the rectifier circuit 11. A control circuit 12 is connected to the rectifier circuit 11, and a direct current is supplied from the rectifier circuit 11 to the control circuit 12.

The control circuit 12 has a built-in FET and converts the supplied DC current into two periodic currents. One of the periodic currents is supplied to the primary coil of the transformer unit 13, the voltage of which is adjusted and supplied to the rectifier circuit 14. The current converted into direct current by the rectifier circuit 14 is supplied to the secondary battery B via the transistor 15. In this case, the other control circuit 16 outputs a control signal to the base of the transistor 15 to control the current value supplied to the secondary battery B.

Next, the other periodic current converted by the control circuit 12 is supplied to the other primary coil of the transformer section 13, the voltage of which is adjusted and supplied to the rectifier circuit 19. The current converted into direct current by the rectifier circuit 19 is used as a power source for driving the control circuit 16.

Now, the current value of the charging current is calculated by the current detection unit 1
8, the current detection unit 18 outputs a voltage corresponding to the detected current value to the control circuit 16. Also, 2
The voltage of the secondary battery B is detected by the voltage detector 17,
The voltage detection unit 17 outputs a voltage corresponding to the detected voltage to the control circuit 16. Furthermore, the temperature signal from the temperature sensor 6 is input to the control circuit 16 via the contacts 8a and 8b of the connector.

The control circuit 16 includes a current detector 18
A control signal is output to the base of the transistor 15 on the basis of the current signal from, and thereby the current supplied to the secondary battery B is feedback controlled to perform constant current charging described later. The control circuit 16 also performs various controls such as termination of the charging mode based on the voltage signal input from the voltage detection unit 17.

Further, the control circuit 16 is adapted to conduct / shut off the control circuit 12 through the insulating circuit 20. This controls the output voltage of the rectifier circuits 14 and 19.

B. Operation of Embodiment Next, a method of charging the secondary battery having the above-described configuration will be described with reference to the flowcharts of FIGS. 2 to 6. B-1. Determination of Charge Appropriateness First, the secondary battery B is connected to the charger A through the connector, the socket 10 is connected to the household AC power supply, and the charging operation is started (FIG. 2). Then, it is determined whether or not the unit cell 2 is connected based on the voltage signal of the voltage detection unit 17 (step S1). Then, if the unit cell 2 is connected, the process proceeds to step 2, the temperature signal detected by the temperature sensor 6 is determined, and the temperature of the unit cell 2 becomes 0 when the unit can be charged.
If not in the range of 40 ° C to 40 ° C, wait until the proper temperature is reached.

B-2. Normal charging mode If the temperature of the unit cell 2 is within the above range in step 2, the process proceeds to step 3 and it is determined whether the temperature is 10 ° C. or lower. When the temperature of the unit cell 2 is 10 ° C. or lower, the determination result of step 3 is YES, and the process proceeds to step 4 to start the normal charging mode. In the normal charging mode, a constant charging current having a value 0.3 times the rated current value of the unit cell 2 is applied to the unit cell 2. In this embodiment, the rated current value of the unit cell 2 is 5A and the charging current value in the normal charging mode is 1.5A.
This normal charging mode is suitable for charging that does not reduce the life of the battery at 10 ° C. or lower in winter or cold regions.

On the other hand, when the temperature of the unit cell 2 is higher than 10 ° C., the rapid charge mode described later is started (FIG. 4). In the rapid charging mode, a constant charging current equal to the rated current value of the unit cell 2 is given to the unit cell 2. In this embodiment, the charging current value in the rapid charging mode is 5A. As described above, in the present embodiment, two kinds of charging modes, that is, the normal charging mode and the quick charging mode are prepared, and one of the appropriate charging modes is selected according to the temperature of the cell 2 at the start of charging. It is supposed to do.

In the normal charging mode of FIG. 2, charging is started at the same time when the control circuit 16 starts the integration of the timer value Tn for normal charging (step S4).
Then, as shown in step S5, when the timer value Tn reaches a predetermined timer end value Tne, it is considered that charging of the unit cell 2 is completed, and the charging is ended. Even if the timer value Tn does not reach the timer end value Tne, when the temperature of the unit cell 2 is lower than 0 ° C. as shown in step S6, it is unsuitable for charging, so charging is forced. To end.

When the timer value Tn does not reach the timer end value Tne and the temperature of the unit cell 2 is 0 ° C. or higher, the temperature of the unit cell 2 does not reach 13 ° C. or higher, and 45
The normal charging mode is continued unless the temperature exceeds C (steps S7 to S8). If it is determined in step S8 that the temperature of the unit cell 2 exceeds 45 ° C., it is considered that normal charging is completed, the normal charging mode is ended, and the process proceeds to step S10. This will be described with reference to FIG. 7. When charging a NiCd battery with a constant current,
The battery temperature tends to rise gradually just before charging is completed, regardless of the amount of discharge and the ambient temperature of the battery. This temperature rise characteristic is effective for detecting the completion of charging. Generally, NiC
Since the charging efficiency of the d battery at a high temperature is poor and affects the life of the battery, in the present embodiment, it is considered that the normal charging is completed when the temperature of the single battery 2 is 45 ° C. As described above, in the present embodiment, the battery temperature is taken into consideration and the normal charging is ended, so that the unit cell 2 is prevented from being damaged.

Further, when the temperature of the unit cell 2 is 45 ° C. or lower and the normal charging is continued, it is determined whether or not the voltage drop is detected (step S9). This drop voltage is shown in FIG.
In the case of charging a NiCd battery with a constant current, the battery voltage rises as the charging progresses, reaches a peak value immediately before completion of charging, and then drops slightly thereafter. In FIG. 7, this dropped voltage is shown as −ΔV. This voltage drop characteristic is effective for detecting the completion of charging. Therefore, when the drop voltage is detected in step S9, it is considered that the charging is completed, the normal charging mode is ended, and the process proceeds to step S10.

On the other hand, the temperature of the unit cell 2 does not exceed 13 ° C.,
If the temperature does not exceed 45 ° C and the voltage drop is not detected, it is determined that the normal charge mode should be continued (step S
9), returning to step S5, the above steps S5 to S9.
Repeat the process of.

B-3. Follow-up charging mode In step S10, a constant charging current having a current value lower than that in the normal charging mode, for example, 0.1 times the rated current value of the single battery 2 is applied to the single battery 2. In this embodiment,
The charging current value to be given here is 0.5A. Less than,
This charging is called "additional charging". That is, in the normal charging mode, when the temperature exceeds 45 ° C, or (-Δ
When the voltage drop of V) is detected, not all the single cells 2 are in the fully charged state. However, if the normal charging is continued after this, there is a risk of overcharging and damage to the unit cell 2. Therefore, in the present embodiment, by performing the final charging with a low current value, it is possible to perform sufficient charging.

In the additional charge mode, the additional charge is started, and at the same time, the control circuit 16 starts the integration of the timer value Tc for normal charge (step S10). Then, as long as the temperature of the unit cell 2 does not deviate from the range of 0 ° C. to 45 ° C. (step S11), the additional charging is continued until the timer value Tc reaches the timer end value Tce.
When the timer value Tc reaches the timer end value Tce, it is considered that the unit cell 2 is fully charged or is in a state close to the full charge, and the charging is ended.

In step S11, the unit cell 2
If the temperature is deviated from the appropriate temperature of 0 ° C. to 45 ° C., the appropriate temperature waiting process R1 is performed. Referring to FIG.
The appropriate temperature waiting process R1 will be described. First, if the temperature of the unit cell 2 deviates from the proper temperature, step S
As shown in 13, the additional charging current is stopped. Even in this case, the integration of the timer value Tc continues. Then, it waits until the unit cell 2 reaches the proper temperature, and when it reaches the proper temperature, the additional charging is restarted (steps S14 to S16), and the process returns to step S11. During this time, the timer value Tc
Is continuously accumulated (step S16).

In the appropriate temperature waiting process R1, if the timer value Tc reaches the timer end value Tce (steps S14 and S15) without the temperature of the unit cell 2 becoming proper, the charging is forcibly performed. To finish. This is because the normal charging is already completed and the additional charging is performed even temporarily, so it is considered that the unit cell 2 is in a state close to the full charging state even if the unit cell 2 is not in the full charging state. It is not efficient to wait any longer until the temperature is reached.

B-4. Rapid Charge Mode On the other hand, if it is determined in step S3 that the temperature of the unit cell 2 exceeds 10 ° C., the rapid charge mode shown in FIG. 4 is started (step S17). In the rapid charging mode, a constant charging current equal to the rated current value of the unit cell 2, that is, a charging current of 5 A in this embodiment is applied to the unit cell 2. This rapid charging mode is suitable for short-time charging at a temperature exceeding 10 ° C.

In the rapid charging mode, at the same time when charging is started, the control circuit 16 starts integrating the timer value Tq for rapid charging (step S17). Then, as shown in step S18, when the timer value Tq reaches the predetermined timer end value Tqe, it is considered that charging of the unit cell 2 is completed, and the charging is ended. Even if the timer value Tq does not reach the timer end value Tqe, as shown in step S19, when the temperature of the unit cell 2 is lower than 0 ° C., it is unsuitable for charging, and therefore charging is forced. To end.

When the timer value Tq does not reach the timer end value Tqe and the temperature of the unit cell 2 is 0 ° C. or higher, the temperature of the unit cell 2 is 10 ° C. or higher, and 45
The rapid charge mode is continued unless the temperature exceeds C (steps S20 to S21). Also, in step S21,
If it is determined that the temperature of the unit cell 2 exceeds 45 ° C., it is considered that the quick charging is completed, the quick charging mode is ended, and the process proceeds to step S10. That is, the additional charging mode similar to the above is entered.

Further, when the temperature of the unit cell 2 is 45 ° C. or lower and the rapid charging is continued, it is determined whether or not the voltage drop −ΔV is detected, as in step S9 of the normal charging mode (step S22). . Then, in step S22, when the voltage drop is detected, it is considered that the charging is completed, the quick charging mode is ended, and the process proceeds to step S10.
Transition to additional charge mode. Thus, even after the end of the quick charge mode, in order to perform charging without excess or deficiency, the auxiliary charge mode is entered and the final charge is performed with a low current value.

On the other hand, when the temperature of the unit cell 2 does not fall below 10 ° C., does not exceed 45 ° C., and the drop voltage is not detected, it is judged that the rapid charging mode should be continued (step S22), Returning to S17, the above step S1
The process of 7 to S22 is repeated.

B-5. Transition from Normal Charge Mode to Quick Charge Mode As described above, in the present embodiment, either the normal charge mode or the quick charge mode is selected according to the temperature of the unit cell 2 at the start of charging. (Step S3). Further, in this embodiment, even after one of the charging modes is started once, the charging mode is shifted to a more appropriate charging mode according to the temperature of the unit cell 2. Hereinafter, this will be described.

First, even after the normal charging mode is selected, if the temperature of the unit cell 2 rises to some extent, rapid charging becomes possible, and normal charging with a low charging current value is continued. Is not efficient. Therefore, step S7
In FIG. 2, when the battery temperature exceeds 13 ° C., the process proceeds to step S23. Then, it is determined here whether or not the following three determination conditions are met. A predetermined time after starting charging (10 minutes in this embodiment)
Has passed, and the voltage of the unit cell 2 has reached the voltage drop time at the end of charging. That is, after taking the peak value shown in FIG. After the unit cell 2 has reached the temperature rising time at the end of charging. That is, a predetermined temperature (40 ° C. in this embodiment)
After crossing. The predetermined time (10 minutes in this embodiment) has not elapsed since the start or transition of normal charging. That is, the timer value Tn is less than the predetermined value.

Here, the condition is provided because if the voltage drop time is reached, the normal charging mode will be ended soon, and there is no need to shift to the quick charging mode. Further, if the charging current value is changed at the time of the voltage drop, the battery voltage is changed, and the detection of the drop voltage -ΔV in step S9 (or step S22 when assuming that the quick charge mode is entered) is erroneous. Because there is a possibility.

The condition is set so that if the temperature rise time is reached, the normal charge mode will be ended soon, so that there is no need to shift to the quick charge mode, and the charge current value is not reached during the temperature rise time. This is because there is a possibility that the battery temperature may be fluctuated and the battery temperature determination in step S8 (or step S21 when it is assumed that the quick charging mode has been entered) may be erroneous. Further, the condition is provided because the voltage may drop for a while after the start or transition of normal charging, and the condition may be erroneously determined.

Then, in step S23, if any of the above three conditions is satisfied, the process proceeds to step S8, and the normal charging mode is continued. On the other hand, if none of the above three conditions is met, the process proceeds to the rapid charging mode transition process R2.

In this way, in this embodiment, even if the temperature of the unit cell 2 exceeds 13 ° C. and it is appropriate to shift to the quick charge mode, if the shift to the quick charge mode is made, If it becomes difficult to judge the charging completion of the
The normal charging mode is continued. As a result, it is possible to appropriately determine the completion of charging, and it is possible to perform charging without excess or deficiency.

Referring to FIG. 5, rapid charging mode transition processing R
2 will be described. Here, first, the total charge amount Ct up to the present is calculated by the equation 1 (step S24). Ct = 0.3C * Tn + 1C * Tq (Formula 1) Here, C shows the rated current value of the cell 2. Therefore, as is clear from the above description, 0.3C indicates the charging current value in the normal charging mode (1.5A in this embodiment), and 1C indicates the charging current value in the rapid charging mode (in this embodiment, 5A). Further, Tn represents the timer value integrated in the normal charging mode as described above, and Tq represents the timer value integrated in the quick charging mode. The second term of Equation 1 is
Add only when the quick charge mode has already transitioned to the normal charge mode.

Next, according to equation 2, the remaining required charge amount Cr
Is calculated (step S25). Cr = Cl-Ct (Equation 2) where Cl is the finally required charge amount,
It is a value that is known in advance.

Further, the timer end value Tqe in the quick charge mode is calculated by the equation 3 (step S26). Tqe = Cr / 1C (Equation 3) Then, the timer end value Tqe in the rapid charging mode performed thereafter is set to the value calculated by Equation 3 (step S2
7) and shifts to the quick charge mode shown in FIG. At the time of this transition, integration of the timer value Tq in the quick charge mode is started.

As described above, the quick charge mode shown in FIG. 4 is newly started. Thus, in this embodiment,
Even after the normal charging mode is selected, if the temperature of the unit cell 2 exceeds 13 ° C. and none of the predetermined conditions is met, the charging time is changed by shifting to the quick charging mode. It is being shortened.

B-6. Transition from the quick charge mode to the normal charge mode On the other hand, even after the quick charge mode is selected, depending on the ambient temperature, the temperature of the unit cell 2 may be lowered and the rapid charge may be inappropriate. There is. That is, the unit cell 2
If the temperature is lower than a certain temperature (for example, 10 ° C.), the charging efficiency is extremely lowered, so that the charging is likely to be insufficient, and further, the electrolyte solution inside the NiCd battery becomes a gas and the life is extremely shortened. Therefore, step S20
In FIG. 4, when the battery temperature is lower than 10 ° C., the process proceeds to step S28. Then, similarly to the above, it is determined whether or not the following three determination conditions are satisfied. A predetermined time after starting charging (10 minutes in this embodiment)
Has passed, and the voltage of the unit cell 2 has reached the voltage drop time at the end of charging. That is, after taking the peak value shown in FIG. After the unit cell 2 has reached the temperature rising time at the end of charging. That is, a predetermined temperature (40 ° C. in this embodiment)
After crossing. A predetermined time (10 minutes in this embodiment) has not elapsed since the start or transition of the quick charge. That is, the timer value Tn is less than the predetermined value. The reason why these three determination conditions are provided is for the same reason as described above.

Then, in step S28, if any of the above three conditions is satisfied, the process proceeds to step S21, and the quick charging mode is continued. On the other hand, if none of the above three conditions is satisfied, the routine proceeds to normal charge mode transition processing R3.

In this way, the temperature of the unit cell 2 is 10 ° C.
Even when it is appropriate to shift to the normal charge mode, if the shift to the normal charge mode is made and it becomes difficult to determine the completion of charging thereafter, continue the quick charge mode. I have to. As a result, it is possible to appropriately determine the completion of charging, and it is possible to perform charging without excess or deficiency.

Referring to FIG. 6, normal charge mode transition processing R
3 will be described. Here, first, as in the case of
Thus, the total charge amount Ct up to the present is calculated (step S29). Ct = 0.3C × Tn + 1C × Tq (Equation 1) The first term of Equation 1 is added only when the normal charge mode has already transitioned to the quick charge mode. next,
The remaining required charge amount Cr is calculated by the equation 2 (step S30). Cr = Cl-Ct (Equation 2)

Further, the timer end value Tne in the normal charging mode is calculated by the equation 4 (step S31). Tne = Cr / 0.3C (Equation 4) Then, the timer end value Tne in the normal charging mode performed thereafter is set to the value calculated by Equation 4 (step S3).
2), shift to the normal charging mode shown in FIG. At the time of this transition, the accumulation of the timer value Tn in the normal charging mode is started.

As described above, the normal charging mode shown in FIG. 2 is newly started. Thus, in this embodiment,
Even after the quick charging mode is selected, if the temperature of the unit cell 2 is lower than 10 ° C. and none of the predetermined conditions is met, the unit cell is switched to the normal charging mode, thereby 2 is intended to prevent a decrease in life.

It should be noted that, when the normal charge mode is changed to the quick charge mode, the condition is that the battery temperature exceeds 13 ° C. (step S7 in FIG. 2), while the quick charge mode is changed to the normal charge mode. When the battery temperature shifts to 1
The condition is that the temperature is below 0 ° C. (step S in FIG. 4).
20) is to shift to another charging mode only when the state to shift to another charging mode continues,
This is to prevent a transition to another charging mode due to an instantaneous fluctuation of the battery temperature.

C. Modifications The present invention is not limited to the above embodiments, but various modifications such as the following are possible. The current value and various temperature settings in the normal charge mode, the quick charge mode, and the additional charge mode are not limited to the values in the above-mentioned embodiment, and can be set arbitrarily. In the above-mentioned embodiment, two kinds of charging modes, that is, the normal charging mode and the quick charging mode, are prepared. The most appropriate charging mode may be selected accordingly.

[0051]

As described above, according to the present invention, the temperature of the secondary battery changes even after the charging is started once, and the charging mode which has been continued until then is inappropriate. It becomes possible to switch the charging mode. Therefore, it is possible to reduce the charging current value when the temperature of the battery is lowered, prevent the life of the secondary battery from being impaired, and increase the charging current value when the temperature is raised to shorten the charging time.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a connection between a charger A and a secondary battery B for implementing a secondary battery charging method according to an embodiment of the present invention.

FIG. 2 is a flow chart showing the operation of the embodiment.

FIG. 3 is a flowchart showing the operation of the embodiment.

FIG. 4 is a flowchart showing the operation of the embodiment.

FIG. 5 is a flowchart showing the operation of the embodiment.

FIG. 6 is a flowchart showing the operation of the embodiment.

FIG. 7 is a graph showing temporal changes in battery voltage and battery temperature in general constant current charging.

[Explanation of symbols]

 A charger, B secondary battery, 2 unit cells, 4a, 4b connector contacts, 6 temperature sensor, 8a, 8b connector contacts, 10 sockets, 11 rectifier circuit, 12 control circuit, 13 transformer section, 14 rectifier circuit, 15 FETs, 16 control circuit, 17 voltage detection unit, 18 current detection unit, 19 rectifier circuit, 20 insulation circuit

Claims (2)

[Claims] 1. A method of charging a secondary battery, wherein a current is supplied from a charging means to the secondary battery, the step of measuring the temperature of the secondary battery, and the step of selecting a charging mode corresponding to the temperature of the secondary battery. And a process of supplying a current to the secondary battery according to the selected charging mode, are repeated. 2. Any one of the following conditions: A: When the voltage of the secondary battery takes a peak value and then drops by a predetermined voltage, and B: When the temperature of the secondary battery exceeds a first predetermined temperature. When the temperature of the secondary battery reaches an appropriate value for selecting a charging mode different from the charging mode currently in progress, C: secondary charging is performed. After the first predetermined time has elapsed since the battery was charged and the voltage of the secondary battery reached a peak value, D: the temperature of the secondary battery was lower than the first predetermined temperature.
After the temperature exceeds the predetermined temperature of E, before the second predetermined time elapses after the selection of the current charging mode, the current charging mode should be continued. The method for charging a secondary battery according to claim 1, which is characterized in that.