JPH08149709A - Charger for secondary battery - Google Patents

Abstract

PURPOSE: To charge a nickel-cadmium battery and a nickel-hydrogen battery while suppressing the memory effect. CONSTITUTION: Sections where no current flow (pause sections) and pulse charging and discharging current sections are combined while setting the charging section t1 =7ms, the pause section t2 =2ms, the discharge section t3 =1ms and the charge/discharge current at 1.5A thus charging a nickel-hydrogen battery. Subsequent battery voltage variation amount is then detected based on the temperature, a temperature rise rate, a voltage and the maximum voltage of battery during the charging operation. Finally, a decision is made whether the charging operation is stopped or a transition is made to trickle charging based on the detected values.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging device for sealed secondary batteries such as nickel-cadmium batteries, nickel-hydrogen batteries and sealed lead-acid batteries.

[0002]

2. Description of the Related Art Secondary batteries mainly used as a power source for portable devices include nickel-cadmium batteries and sealed lead-acid batteries. Also, recently nickel-hydrogen batteries have been widely used. Among these, the nickel-cadmium battery and the nickel-hydrogen battery have a sharp drop in voltage at the initial stage of discharge when charging and discharging are repeated at a shallow depth of discharge (hereinafter, this phenomenon is referred to as "memory effect"). In this state, although electric energy actually remains inside the battery, it cannot be sufficiently extracted. In order to solve this, Japanese Patent Laid-Open No. 5-227671 proposes that the battery to be charged is completely discharged and then charged. As shown in the flowchart of FIG. 13, when the voltage of the battery to be charged is lower than the reference voltage A, the battery is charged immediately,
When it is higher than the reference voltage A, it is discharged by a discharge resistor and when it becomes lower than the reference voltage A, it is charged. Then, when the voltage becomes higher than the reference voltage B, the charging is terminated. Moreover, in order to charge these secondary batteries, they must be charged by a charging method suitable for each secondary battery. FIG. 11 shows the charging characteristics of the nickel-cadmium battery. Here, the charging current is controlled by the so-called −ΔV method, which utilizes the battery voltage drop characteristic occurring at the end of charging to detect the peak voltage and detect that the battery voltage has dropped by a predetermined value Vc. There is. Similarly, the -ΔV method is also used for nickel-hydrogen batteries, but the temperature of the nickel-hydrogen battery is monitored during charging because the temperature rises significantly during charging and there is a risk of leakage due to an increase in battery internal pressure due to heat generation. The mainstream is to stop charging when necessary. FIG. 12 shows the charging characteristics of the sealed lead-acid battery, in which the charging current is controlled when the battery voltage reaches a constant voltage.

[0003]

Even if the nickel-cadmium battery or the nickel-hydrogen battery having the above-mentioned memory effect is charged by the technique disclosed in the above-mentioned Japanese Patent Laid-Open No. 5-227671, the battery has the memory effect. Not fully recovered from the state of. Further, as described above, since the charging characteristics of the nickel-cadmium battery, the nickel-hydrogen battery, and the sealed lead-acid battery are different, it is difficult to properly charge each battery with one charging device. Also,
Nickel-cadmium batteries, the battery temperature in the nickel-hydrogen battery is conventional in a state of high compared with the normal temperature - when charged by the charging device of △ V system, the voltage drop V _c hardly appear. In addition, if the battery temperature is lower than that of the normal temperature, the internal impedance increases and the heat generation increases, and when the short-circuited battery is charged by the conventional −ΔV type charging device, the voltage changes naturally. not out voltage drop V _c for the battery temperature change does not occur, since the battery temperature does not become high temperature, the charging does not end even after forever. Moreover, long-term standing nickel-cadmium batteries, for nickel-hydrogen batteries having electrodes inactivate, the - △ if charged by the charging device of the V type not capable of sensing the voltage drop V _c overcharged Alternatively, a peak voltage appears immediately after the start of charging (within a few minutes), and it is erroneously determined that the voltage drop V _c has been detected, so that charging is stopped and necessary charging cannot be performed.

A first object of the present invention is to provide a charging device which reduces the memory effect in nickel-cadmium batteries and nickel-hydrogen batteries. Second of the present invention
The purpose of achieving the above-mentioned first purpose, and
It is an object of the present invention to provide a charging device that appropriately charges sealed secondary batteries such as cadmium batteries, nickel-hydrogen batteries, and sealed lead-acid batteries regardless of type. A third object of the present invention is to achieve the above first and second objects, and to provide a battery when the battery temperature before charging is higher or lower than room temperature, or when the battery is short-circuited. An object of the present invention is to provide a charging device having a protection function that prevents the battery from being charged. A fourth object of the present invention is to provide a charging device which achieves the above-mentioned first to third objects and is capable of performing appropriate charging even for a battery whose electrodes are inactivated by leaving it for a long time. Is to provide.

[0005]

In order to achieve the above first object, the charging device according to the present invention combines a charging current having a pulse waveform and a discharging current having a pulse waveform to obtain the charging electricity amount. It is characterized in that it is provided with a first charging means that is larger than the amount of discharged electricity. Here, the pulse waveform may include a section in which no current flows. Above to achieve the second object, during operation of the first charging means, means for detecting the increase rate [Delta] T ₀ means and T ₀ that detects a battery temperature T _0, the first charging means During operation, a means for detecting the battery voltage V _{off in a} section where no current flows, a means for detecting a variation ΔV of V _off during a predetermined time, and any one of the following (a) to (d): First
The second charging means is provided for performing trickle charging with a small current after stopping the charging means or after stopping the first charging means. (A) Battery voltage drop V _c after ΔV becomes negative
, V _c ≧ predetermined voltage amount V _a (b) T ₀ ≧ predetermined temperature T _c (c) ΔT ₀ ≧ predetermined value ΔT _a (d) | ΔV | ≦ predetermined set value V for a predetermined set time t
_d To achieve the third object, a means for detecting the battery voltage V and a means for detecting the battery temperature T before the operation of the first charging means, and one of the following (e) to (f): In this case, the first charging means is not operated. (E) V ≧ predetermined value _VL is not satisfied (f) Predetermined set temperature T _H ≧ T ≧ predetermined set temperature T _L (provided that _TH > T _L ) is not satisfied. In order to achieve the fourth object, a pulse is used. Means for detecting the battery voltage V _{on in a} section where a charging current having a waveform flows, means for calculating the internal impedance of the battery by the battery voltage V _on , the battery voltage V _off , and the charging current I having a pulse waveform, Means for changing the ratio of the charging current having the pulse waveform to the discharge current having the pulse waveform and / or the magnitude of the charging current having the pulse waveform and the discharging current having the pulse waveform according to the impedance value. And a means for relatively changing the height.

[0006]

In the present invention, charging is performed by the current having a pulse waveform. At this time, the charging can be advanced by increasing the charging amount of electricity with respect to the discharging amount of electricity in the pulse waveform.

An example of a current having a pulse waveform is shown in FIG.
In FIG. 1A, the charging section t ₁ and the discharging section t ₃ each have a value of a predetermined time, and are alternately and continuously repeated. In FIG. 1B, a charging section t ₁ , a section in which no current flows (hereinafter referred to as “pause section”) t ₂ , and a discharging section t ₃ each have a value of a predetermined time, and are repeated continuously in a cyclic manner. It is a thing. FIG. 1C shows a charging section t ₁ , a discharging section t ₃ ,
Each of the pause sections t ₂ has a value of a predetermined time, and is periodically repeated. In FIG. 1D, the charging section t ₁ , the rest section t ₂ , the discharging section t ₃ , and the rest section t ₂ each have a value of a predetermined time, and are cyclically and continuously repeated. According to the present invention, since the secondary battery is discharged during charging, a nickel-cadmium battery, a nickel-cadmium battery,
The memory effect in a hydrogen battery can be reduced. The reason for this is not clear, but the method of charging the secondary battery by repeating charging with a current having a pulse waveform and charging suspension as shown in JP-A-64-81628 does not show the above-mentioned reduction effect. From this, it is considered that discharging the secondary battery during charging has some effect.

[0008] Control of the charging of the charging device according to the invention, a nickel-cadmium batteries, in the case of such a nickel-hydrogen battery, a predetermined voltage drop V _c caused the end of charging in the condition judgment of Claim 3 wherein (a) Is detected to stop charging, or if the battery temperature during charging becomes too high or the battery temperature rises significantly according to the conditions (b) and (c), charging is stopped. In the case of a sealed lead-acid battery or the like, charging is stopped according to the condition judgment of (d). By doing so, the sealed secondary battery can be appropriately charged regardless of the type of the battery. It is preferable that the battery voltage detected during the charge control is performed in the rest period t ₂ .
One of the reasons is that it is difficult to accurately detect the battery voltage due to the influence of noise during charging or discharging with a current having a pulse waveform. Another reason is that the battery voltage is detected in a section in which no current flows, so that it is unlikely to be affected by the internal resistance of the battery and the contact resistance of the connection terminal connected to the battery.

Further, by providing a means for detecting the battery voltage before operating the first charging means, it is detected that the battery is short-circuited by the condition judgment of (e) of claim 5 and it is useless. You can avoid charging. Further, by providing a means for detecting the battery temperature before the start of charging, it is possible to avoid performing the charging by the first charging means under the temperature condition not suitable for the charging operation in the condition judgment of (f) according to claim 5. You can

A battery that has been left for a long time has a higher internal impedance than usual. Therefore, the internal impedance of the battery is measured immediately after the start of charging, and when the value is high, appropriate charging can be performed by increasing the ratio of the discharge time in one unit of pulse charging. The reason for this is not clear, but it is considered that the electrode plate that has been inactivated by being left for a long time is activated by increasing the ratio of the discharge time. Further, when the impedance value is high, the same effect as described above can be obtained by making the discharge current value of the pulse waveform larger than the charging current value of the pulse waveform. Further, the internal impedance of the battery is the battery voltage in the charging section t ₁ ,
It is performed by detecting the battery voltage in the pause section t ₂ and calculating the value of the battery voltage and the charging current I in the charging section t ₁ . Since the switch circuit of the control unit turns on and off the charge and turns on and off the discharge by the signal of the microcomputer, the change of the charge and discharge currents can be easily performed.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 5 is a block diagram showing a schematic configuration of a charging device according to an embodiment of the present invention. The battery temperature measuring unit 2 is a temperature detecting element such as a thermistor, and the battery temperature of the secondary battery 1 is measured by this. The microcomputer 3 includes a CPU (Central Processing Unit) 31, a memory 3
2. Built-in A / D converter (analog / digital converter) 34 for the output port 33 and the input port, and the like. Measured by the battery voltage measured by the battery voltage measuring unit 7 and the battery temperature measuring unit 2. The battery temperature signal thus generated is input to the A / D converter 34. This input is subjected to signal processing by the CPU 31 and the memory 32, and an output signal is generated from the output port 33. The control unit 4 controls whether to stop the first charging means in response to the output signal from the microcomputer 3 and controls switching between the charging section, the rest section, and the discharging section. The charging unit 5 supplies a charging current to the secondary battery 1. The discharging unit 6 is a discharging resistor for discharging the secondary battery 1.

Example 1 Corresponding to Claims 1 and 2 (Experiment 1) The effect of reducing the memory effect when a nickel-cadmium battery or a nickel-hydrogen battery is charged is shown. (Embodiment 1a) In this embodiment, the charging section t ₁ = 7 ms, the rest section t ₂ = 2 ms, and the discharging section t ₃ = 1 ms in the current having the pulse waveform shown in FIG. A nickel-hydrogen battery (nominal capacity: 1100 mAh) is charged with a discharge current of 1.5 A, and after the charging is stopped, discharging is performed at 1 C up to a final voltage of 1.0 V. This is done only in the first cycle. Then from the second cycle, 10
Up to the 0th cycle, charging was carried out under the same charging conditions as above, and discharging was repeated at 1 C and a final voltage of 1.2 V was repeated. After that, the 101st and 102nd cycles were charged and discharged in the same manner as the first cycle.

(Comparative Example 1) A charging period t ₁ = 7 ms and a rest period t ₂ = 3 ms of a current having a pulse waveform during charging are set,
No discharge section was inserted (t ₃ = 0). A charge / discharge cycle test was conducted under the same conditions as in Example 1a except for the above.

FIG. 6 shows a discharge curve when a charge / discharge cycle test was conducted under the above conditions. The number attached to the discharge curve in the figure indicates the number of charge / discharge cycles when the discharge is performed. Comparing the discharge capacities at the 100th cycle, Example 1a shows less decrease in capacity than Comparative Example 1. Therefore, it can be seen that the battery charged by the charging device according to the present invention has a clear reduction in the memory effect that appears when the discharge is repeated and the discharge is repeated at a shallow discharge.
In addition, the effect of clearly improving the battery voltage and the discharge capacity at the 102nd cycle after the deep discharge to the final voltage of 1.0V at the 101st cycle was found in Example 1a. This is considered to be because the temperature rise during charging was small in the case of the charging device of Example 1a, battery deterioration was suppressed, and electrode inactivation was suppressed. The above memory effect reduction effect is
Similar results were obtained when using a cadmium battery. Further, this effect was similarly obtained when the currents having the pulse waveforms of FIGS. 1 (a) (c) (d) were used.

Next, the effect of reducing the memory effect when the charging time and the discharging time are changed by the current having the pulse waveform is shown below. (Example 1b) Nickel-cadmium battery (nominal 700
mAh) was subjected to a charge / discharge cycle test using the charging device of Example 1a. The test conditions were exactly the same as in Example 1a.

(Example 1c) In Example 1b, t ₁
= 5 ms, t ₂ = 2 ms, t ₃ = 3 ms, and a charge / discharge cycle test was performed in the same manner as in Example 1b except for the above.

FIG. 7 shows a discharge curve when a charge / discharge cycle test was conducted under the above conditions. The number attached to the discharge curve in the figure indicates the number of charge / discharge cycles when the discharge is performed. As a result of repeating the shallow charge and discharge by the termination of 1.2 V, the discharge capacity of Example 1c in which the ratio of the discharge time was increased was larger than that of Example 1b, and the capacity decrease due to the cycle was less. It is considered that this is because the activation of the electrode is promoted by increasing the ratio of the discharge time. In this embodiment, the pulse charging / discharging time was changed, but the same result was obtained by increasing the discharging current. Therefore, it is considered that the above effect is promoted by increasing the amount of discharged electricity. This effect was similarly obtained when a nickel-hydrogen battery was used. Further, this effect was similarly obtained when the pulse waveforms of FIGS. 1A, 1C and 1D were used.

(Second Embodiment Corresponding to Claims 3 and 4) FIG. 2 is a flowchart showing a charge control algorithm of the present embodiment. In this example, the current having the pulse waveform shown in FIG. 1B was used. When the first charging means is operated,
The battery temperature T ₀ detected by the temperature measuring unit 2 is read by the microcomputer 3 in FIG. 5, and T ₀ ≧ T _c (T _c :
It is determined whether or not it is the upper limit value of the temperature limit). Next, the battery temperature T ₀ read by the microcomputer 3 and
The temperature increase rate ΔT ₀ is obtained from T ₀ read before that, and it is determined whether or not ΔT ₀ ≧ ΔT _a (ΔT _a : upper limit of temperature increase rate). Next, read the battery voltage V _off of the secondary battery of the microcomputer pause interval from V _off that are loaded in front loaded battery voltage V _off and obtains a battery voltage variation [Delta] V. It is determined whether or not ΔV becomes a battery voltage drop V _c ≧ V _a (V _a : a set battery voltage value) after the time when ΔV changes from a positive value to a negative value during the first charging operation. . Also, it is determined whether or not | ΔV | ≦ predetermined set value V _d during the predetermined time t. Here, the battery voltage V _off decays with time in one rest period,
As described above, since one pause section is on the msec level, it hardly changes. However, in this embodiment, the voltage was sampled four times in one rest period, and the average value was obtained. Next, the discharge section is started, and the secondary battery is discharged for a certain period of time. Then, the discharge section is returned to the charging section. Further, in this example, after the first charging means was started, T ₀ was measured once every 1000 times in the cycle of the flowchart of FIG. 2, and the rest was passed through. with this,
The judgment of T ₀ ≧ T _{c and} the judgment of ΔT ₀ ≧ ΔT _a were made. Also, FIG.
The measurement of V _off in
The measurement was performed once every 0 times, the rest was allowed to pass through, V _off was measured 4 times, and the average value of the 4 times was taken as the measured value. Such operation is repeated in the first charging, where the measured uptake maximum battery voltage value to the memory, V _c ≧ V _a by taking drop V _c voltage therefrom, | [Delta] V | ≦ predetermined The set value V _d (for a predetermined time t) was judged. Thus charged, pause, discharging repeating as one unit, in the _{meantime, T 0 ≧ T c, △} T 0 ≧ △ T a, V c ≧ V a, during the predetermined time period t | [Delta] V | of ≦ V _d Monitor whether the conditions are met.

The above condition judgment is performed, and in any of the following cases, the first charging means is stopped and the second charging means (trickle charging by a minute current) is started. When T ₀ ≧ T _c , the first charging means is stopped. Limit temperature upper limit value T
_In the case of the present example, since the chargeable temperature was 0 to 40 ° C., _c was set to 60 ° C., which was 20 ° C. higher than the chargeable upper limit temperature, in consideration of the temperature increase during charging. When ΔT ₀ ≧ ΔT _a , it is determined that charging is completed, and the first charging means is stopped.
In this embodiment, the value of the temperature increasing rate upper limit value △ T _a was 2 ℃ per minute. When V _c ≧ V _a is satisfied during the set time t, the first charging means is stopped. In other words, nickel
Performs -ΔV control for cadmium batteries and nickel-hydrogen batteries. The voltage setting value V _a is suitably 10 to 20 mV / cell when the ambient temperature is 20 ° C., and is 15 in this embodiment.
mV / cell. In addition, | ΔV | ≦ V during the predetermined time t
Even when the condition of _d is satisfied, the first charging means is stopped. That is, it is the control of stopping the first charging means when charging the small sealed lead acid battery. In this embodiment, the set time t
Was set to 10 minutes. In the case of the present embodiment, the second charging means is started after the first charging means is stopped, but the charging may be stopped as it is. By performing the above charging operation and control, nickel-cadmium battery, nickel-hydrogen battery,
It was possible to properly charge a sealed secondary battery such as a sealed lead acid battery.

Further, this result was similarly obtained when the pulse waveforms of FIGS. 1 (c) and 1 (d) were used.

Third Embodiment (corresponding to claim 5) FIG. 3 is a flow chart showing a charge control algorithm of the present embodiment. When the secondary battery 1 is connected and the charging device is started, the microcomputer 3 in FIG. 5 detects that the battery temperature T detected by the temperature sensor 2 attached to the secondary battery 1 is T before the first charging operation is started. It is determined whether or not _H ≧ T ≧ _TL ( _TH : chargeable upper limit temperature, T: battery temperature, _TL : chargeable lower limit temperature). If the condition of T _H ≧ T ≧ T _L is not satisfied, charging is not performed due to temperature abnormality. In this example, T _H = 40 ° C. and T _L = 0 ° C. In addition, the battery voltage V is measured before starting the first charging means, and V ≧ V
It is determined whether it is _L ( _VL : set voltage). V ≧ V
_{If L} is not satisfied, the battery is considered to be short-circuited, and the first charging means is not started. In this embodiment, V ≧
If V _L is not met, precharge (eg 10ms
If the set voltage is not exceeded even if the charging is performed and this is repeated several times (for example, three times), the first charging unit is not started. By providing the above control, it is possible to provide a charging device having a function of not starting the charging of the battery in a state not suitable for charging.

Fourth Embodiment (corresponding to claim 6) FIG. 4 is a flow chart showing a charge control algorithm of the present embodiment. Also in this case, the current having the pulse waveform shown in FIG. 1B was used. When the first charging means is operated, the second embodiment
In addition to the procedure described above, the process of reading and storing the battery voltage V _on in the charging section and V after the discharging section
_The process of calculating the impedance from _on , V _off , and the current I in the charging section and the determination as to whether or not to change the setting of the current forming the pulse waveform according to the process are added. The internal impedance Z is calculated by the above V _on , the above V _off , and the charging current I, and is obtained by the following equation (1). Z = (V _on −V _off ) / I (1) The interval between the charge, pause, and discharge sections of the pulse waveform is changed by the internal impedance of the secondary battery obtained by the equation (1). If the calculated internal impedance is large, reduce the ratio of the charging section to the discharging section,
On the contrary, if the impedance is small, the ratio of the charging section to the discharging section is increased. FIG. 8 shows an example of the impedance and the ratio of the discharge section to the charging section in the charging device of the present invention. The internal impedance of the nickel-metal hydride battery in the normal state used in this example is 20 to
It is about 40 mΩ. In this example, the ratio of the discharge section to the charge section (discharge / charge) was changed from 0.02 to 0.9 until the internal impedance was 90 mΩ, and
The value of mΩ or more was fixed at 0.9. Further, in this embodiment,
The total time of one cycle consisting of the charge, pause, and discharge sections was set to 10 ms, of which the rest section t ₂ = 2 ms was set constant.

(Experiment 2) Charging characteristics when a battery left for a long period of time is charged by the charging device of this embodiment will be described below. (Example 4a) In this example, a nickel-hydrogen battery having an internal impedance of 70 mΩ after being left for a long time was used. Therefore, at the start of the first charging means, the ratio of the discharging section to the charging section is 0.6 from FIG. 8, and the charging section t ₁
= 5 ms, rest period t ₂ = 2 ms, discharge period t ₃ = 3 ms
Will start charging. As the charging progressed and the internal impedance decreased, the ratio of the discharge section to the charging section was changed according to the relationship shown in FIG. 8 to perform charging.

(Embodiment 4b) The same battery as in Embodiment 4a is used for the charging section t ₁ = 7 ms, the rest section t ₂ = 2 ms, and the discharging section t.
_It was charged with a pulse waveform fixed at ₃ = 1 ms.

FIG. 9 shows changes with time in the battery voltage, the internal impedance, and the battery temperature rise amount when charging was performed at an ambient temperature of 20 ° C. in Example 4a. Since the impedance is 35 mΩ at the point (b) where the charging progresses and the impedance decreases, the charging section t ₁ = 7 ms, the rest section t ₂ = 2 ms, and the discharging section t ₃ = 1 ms. The amount of increase in battery temperature at that time was compared with Example 4b shown in FIG.
You can see that they are being suppressed. Although not shown in the figure,
A pulse waveform that does not include the conventional discharge section (charge section t ₁ =
When the battery was charged for 7 ms and the rest period t ₂ = 3 ms), the battery temperature rise amount exceeded 40 ° C. during the charging operation. When using nickel-cadmium batteries and sealed lead-acid batteries,
Although the remarkable effect as in this example was not observed, the temperature rise could be suppressed similarly. Since the charging pattern is changed according to the internal impedance of the battery as described above, sufficient charging can be performed without damaging the battery. Further, this effect was similarly obtained when the pulse waveforms of FIGS. 1C and 1D were used. In this embodiment, the ratio of the charge section and the discharge section of the current having the pulse waveform was changed, but the same result was obtained by changing the current of the discharge section. Therefore, it is considered that the above effect can be obtained by increasing the amount of discharged electricity. In the second embodiment, charging is not performed when the battery temperature is lower than 0 ° C. before starting the first charging means, but this is not always necessary, and when the internal impedance is high at such low temperature, It is considered that charging can be appropriately performed by the means according to the present embodiment.

[0026]

By using the charging device according to the first aspect of the present invention, the memory effect found in the nickel-cadmium battery and the nickel-hydrogen battery can be reduced. Further, by using the charging device according to the invention of claim 3, it was possible to appropriately charge regardless of the type of the sealed secondary battery such as a nickel-cadmium battery, a nickel-hydrogen battery, and a sealed lead acid battery. Further, by using the charging device according to the invention of claim 5, it is possible to provide a protection function that does not start charging depending on the state of the secondary battery to be charged. Further, by using the charging device according to the invention of claim 6, it was possible to perform appropriate charging even for a battery in which the battery was left for a long time and the electrodes were inactivated.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a current having a pulse waveform of a charging device according to the present invention.

FIG. 2 is a flowchart showing a charge control algorithm according to an embodiment of the present invention.

FIG. 3 is a flowchart showing a main part of a charge control algorithm according to an embodiment of the present invention.

FIG. 4 is a flowchart showing a charge control algorithm according to an embodiment of the present invention.

FIG. 5 is a block diagram of a charging device according to the present invention.

FIG. 6 is a diagram showing discharge characteristics of a nickel-hydrogen battery charged by a charging device according to an example of the present invention and a charging device of Comparative Example 1.

FIG. 7 is a diagram showing discharge characteristics of a nickel-cadmium battery charged by the charging device according to the example of the present invention.

FIG. 8 is a diagram showing an example of setting the ratio of the discharge section to the charge section with respect to the internal impedance of the battery in the charging device according to the embodiment of the present invention.

FIG. 9 is a diagram showing changes with time in battery voltage, battery internal impedance, and battery temperature when a nickel-hydrogen battery is charged by the charging device according to the embodiment of the present invention.

FIG. 10 is a diagram showing changes with time in battery voltage, battery internal impedance, and battery temperature when charged by the charging device according to the embodiment of the present invention.

FIG. 11 is a diagram showing general charging characteristics of a nickel-cadmium battery.

FIG. 12 is a diagram showing general charging characteristics of a sealed lead-acid battery.

FIG. 13 is a flowchart showing a charging operation of a conventional charging device.

[Explanation of symbols]

1 is a secondary battery, 2 is a battery temperature measuring unit, 3 is a microcomputer, 31 is a CPU, 32 is a memory, 33 is an output port, 34 is an A / D converter of an input port, 4 is a control unit,
5 is a charging unit, 6 is a discharging unit, 7 is a battery voltage measuring unit

Claims (6)

[Claims] 1. A secondary battery comprising a first charging means in which a charging current having a pulse waveform and a discharging current having a pulse waveform are combined to make the charged electricity amount larger than the discharged electricity amount. Charging device. 2. The first charging means is characterized in that a combination of a charging current having a pulse waveform and a discharging current having a pulse waveform includes a section in which no current flows. The rechargeable battery charging device described. 3. The battery temperature T ₀ during the operation of the first charging means.
Means for detecting the increase rate [Delta] T ₀ means and T ₀ for detecting, during the operation of the first charging means, V _off between means and a predetermined time to detect the battery voltage V _off in a section that does not carry current 3. The rechargeable battery according to claim 2, further comprising: a means for detecting the fluctuation ΔV of the above, and a means for stopping the first charging means in any of the following cases (a) to (d). Charging device. (A) Battery voltage drop V _c after ΔV becomes negative
, V _c ≧ predetermined voltage value V _a (b) T ₀ ≧ predetermined temperature T _c (c) ΔT ₀ ≧ predetermined value ΔT _a (d) | ΔV | ≦ predetermined set value V for a predetermined set time t
_d 4. The secondary battery according to claim 1, further comprising second charging means for performing trickle charging with a small current after stopping the first charging means. Charging device. 5. A means for detecting a battery voltage V and a battery temperature T before the operation of the first charging means, and a means for not operating the first charging means in any of the following cases (e) to (f): A means is provided.
The charging device for the secondary battery according to any one of 1 to 4. (E) V ≧ predetermined value _VL is not satisfied (f) Predetermined set temperature T _H ≧ T ≧ predetermined set temperature T _L (however, T _H > T _L ). 6. A means for detecting a battery voltage V _{on in a} section in which a charging current having a pulse waveform flows, and an internal impedance of the battery by the battery voltage V _on , the battery voltage V _off , and a charging current I having a pulse waveform. And means for changing the ratio of the time for flowing the charging current having the pulse waveform and the discharging current having the pulse waveform and / or the charging current having the pulse waveform and the pulse waveform according to the impedance value. 6. A charging device for a secondary battery according to claim 2, further comprising means for relatively changing the magnitude of the discharge current that forms