JPH10126975A - Charging equipment for secondary battery provided with discharge function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a charger for a secondary battery provided with a discharge function capable of performing the complete discharge of the secondary battery without releasing for energy accumulated in the secondary battery by charge to outside, and also, shortening the charge and discharge time. SOLUTION: This charging equipment is equipped with a capacitor 13 for discharge and a charger 14 connected in series to a secondary battery mount 12, and a connection switching means 15 which switches these connection states, and this connection switching means connects only the capacitor for discharge to the secondary battery, bypassing the charger 14, at discharge, and also connects the capacitor for discharge and the charger to the secondary battery at initial stage of charge, and besides cuts off the capacitor for discharge from the secondary battery at the point of time when the voltage of the capacitor for discharge comes to zero after passage of specified time after start of charge.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a discharging function for discharging undischarged energy before charging a secondary battery having a memory effect such as a nickel-cadmium battery. The present invention relates to a secondary battery charger.

[0002]

2. Description of the Related Art A secondary battery such as a nickel-cadmium battery has a capacity of about 500 mAh and an operating voltage of 1.4.
V-1.0 V, and when the battery voltage drops due to power supply to the device, the voltage is recovered by charging and the battery is repeatedly used.

In the above-mentioned nickel-cadmium battery, if charge and discharge are repeatedly performed before reaching a final voltage of 1.0 V, which is a discharge lower limit voltage, a phenomenon that the discharge capacity gradually decreases (so-called memory effect). Is).

[0004] For example, when the battery is used in a device in which the end voltage or the remaining battery warning alarm operating voltage is set to 1.20 V, it is necessary to perform charging when the battery voltage drops to 1.2 V. In the initial stage where the number of discharges is small, the time required to reach the final voltage is about 55 min as shown by the solid line in FIG. Is greatly reduced to about 40 min as shown by a two-dot chain line in FIG.

[0005] Further, in FIG. 5, the one-dot chain line indicates that the cut-off voltage in use is set to 1.17 V, and the chain line indicates that the cut-off voltage in use is set to 1.13 V. FIG. 5 shows the tendency of the discharge time to decrease when the operation of starting charging is repeated 12 times. As is clear from this figure, when charging and discharging are repeated with a voltage equal to or higher than the discharge lower limit voltage 1.0 V of the nickel-cadmium battery as the end voltage, the memory effect is generated even though the degree is different.

Therefore, conventionally, as shown in FIG. 6, a battery mounting portion 2 to which a secondary battery 1 is detachably mounted is provided.
A charger 3 connected in series to the battery mounting portion 2; a discharging resistor 4 connected in series to the battery mounting portion 2; a voltage detector 5 for measuring the voltage of the secondary battery 1; Before the start of charging, the secondary battery 1 is charged with a discharge lower limit voltage by using a charging / discharging device 7 constituted by a changeover switch 6 for selectively connecting the mounting portion 2 to the charger 3 and the discharging resistor 4. The above-mentioned discharge is performed to reduce the above-mentioned memory effect.

That is, prior to the charging operation of the secondary battery 1, the changeover switch 6 is used to operate the battery mounting section 2.
And the discharging resistor 4 are connected in series, so that the secondary battery 1 is connected in series to the discharging resistor 4, and all of the energy of the secondary battery 1 is converted into heat energy in the discharging resistor 4 and externally. The discharge of the secondary battery 1 lowers the voltage of the secondary battery 1 to the discharge lower limit voltage to completely discharge the battery. The time when the discharge of the secondary battery 1 is completed is determined by the voltage detector 5 confirming that the voltage of the secondary battery 1 has reached the lower discharge limit voltage.

Then, after the secondary battery 1 is discharged until the voltage of the secondary battery 1 reaches the discharge lower limit voltage, the secondary battery 1 is connected to the charger 3 by the changeover switch 6 and the charger 3 When the battery 3 is operated, the charging of the secondary battery 1 is started, and the voltage detector 3 detects that the voltage of the secondary battery 1 reaches the maximum voltage corresponding to the fully charged state. At this point, the charging operation is stopped.

[0009]

However, according to such a conventional method of discharging the secondary battery 1, in order to reduce the memory effect, the residual energy of the secondary battery 1 is converted to the heat energy of the discharge resistor 4. There is a problem that energy is wasted because it is converted and discarded outside.

It is not only assumed that the heat generated by the discharge resistor 4 affects the components of the charging / discharging device 7, but also to suppress the above-mentioned thermal effects.
It is necessary to reduce the current flowing through the discharge resistor 4 to suppress the heat generation. However, if the discharge current is reduced, the discharge time of the secondary battery 1 is prolonged, and the discharge starts from the end of the charge. There is a problem that the time until the time is long.

For example, a trial calculation of the discharge time of the NiCd battery 1 shows that when the power of the resistor is 1/2 W, the derating is 50%, and the resistance value of the discharge resistor 4 is 5.6Ω, Has a discharge current of 200 mA,
A battery having a capacity of 500 mAh requires a discharge time of about 2.5 hours. Even if only the discharge time is taken, it becomes longer than a usable time in a state in which the battery is mounted on a device using a battery, and is difficult to use.

The present invention has been made in view of such a conventional problem, and completely discharges and recharges a secondary battery without discharging the energy stored in the secondary battery to the outside by charging. A primary object of the present invention is to provide a secondary battery charging device having a discharge function capable of performing a discharge function, and a secondary battery having a discharge function capable of shortening a time required from discharge to completion of charging. A second problem to be solved is to provide a charging device for a secondary battery.

[0013]

According to a first aspect of the present invention, there is provided a charging device for a secondary battery having a discharging function, in which the secondary battery is detachably mounted to solve the first problem. A secondary battery mounting portion to be mounted, a discharging capacitor and a charger connected in series to the secondary battery mounting portion, and connection switching means for switching a connection state between the secondary battery and the discharging capacitor and the charger. The connection switching means, when discharging the secondary battery, connects only the discharging capacitor to the secondary battery, bypassing the charger, and connects the secondary battery to the secondary battery in the initial stage of charging. The discharge capacitor and the charger are connected, and after a predetermined time has elapsed from the start of charging, when the voltage of the discharge capacitor (13) becomes zero, the discharge capacitor is discharged from the secondary battery. It is characterized in that made been in to decouple the Nsa.

According to a second aspect of the present invention, there is provided a charging device for a secondary battery having a discharging function according to the first aspect, wherein the charging device is connected in parallel with the discharging capacitor. A resistor is connected to the capacitor for discharging, and the resistor is connected to the discharging capacitor during charging.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, reference numeral 10 denotes a secondary battery charger having a discharging function according to a first embodiment of the present invention. A secondary battery mounting portion 12 to which the secondary battery 11 is detachably mounted, a discharging capacitor 13 and a charger 14 connected in series to the secondary battery mounting portion 12, the secondary battery 11 and a discharging capacitor 13 and a connection switching means 15 for switching a connection state between the charger 13 and the charger 14. The connection switching means 15 bypasses the charger 14 to the secondary battery 11 when the secondary battery 11 is discharged. While only the discharging capacitor 13 is connected, the discharging capacitor 13 and the charger 14 are connected to the secondary battery 11 in the initial stage of charging, and after a predetermined time has elapsed since the start of charging, Voltage discharge capacitor 13 becomes basic configuration as that of the secondary battery 11 has been made to decouple the discharge capacitor 13 when it becomes zero.

Next, these details will be described.
In the present embodiment, a nickel battery is used as the secondary battery 11, and the specifications of the nickel battery 11 are the same as those of the conventional nickel battery. The discharging capacitor 13 has a capacitance of 470F.
And a withstand voltage of 2.3 V are used. When the secondary battery 11 is connected, the discharging capacitor 13 is charged by discharging the secondary battery 11, and ideally, the voltage of both batteries is reduced by the secondary battery 11.
When the discharge lower limit voltage (final voltage) reaches 1 V, charging and discharging are balanced as shown by the solid line in FIG. 2 (in FIG. 2, curve A is the secondary battery voltage, and curve B is the discharging capacitor). As shown by the solid line in FIG. 3, the current from the secondary battery becomes zero, and the secondary battery 11 is completely discharged.

Assuming that charging and discharging are balanced under such ideal conditions, the discharging capacitor 13 is
Since it is charged from 0 V to 1 V, the capacitance 470
When a capacitor of F is used, its capacity is obtained by the following equation. Q = CV = 470F × (1V-0V) = 470A
Sec = 130 mAh Here, since the capacity of the secondary battery 11 is 500 mAh, the capacity of the discharge capacitor 13 is reduced by connecting the four capacitors of the above specifications in parallel to form the discharge capacitor 13. The capacity of the secondary battery 11 is balanced. With such a capacity balance, the secondary battery 11 and the discharging capacitor 13 can be controlled at the above-described discharge lower limit voltage of 1 V.
The charge and discharge between the batteries are balanced.

On the other hand, the charger 14 is provided between the discharging capacitor 13 and the negative electrode of the secondary battery 11, and is connected to the discharging capacitor 13 via the first diode 16 during charging. A voltage is applied, and a second diode 1 is connected to a terminal of the discharge capacitor 13 connected to the positive electrode of the secondary battery 11 between the first diode 16 and the first diode 16.
7 and a voltage is applied to the secondary battery 11 via the second diode 17 when the potential of the discharging capacitor 13 decreases during charging. I have.

A switch S1 is provided between the discharging capacitor 13 and the positive electrode of the secondary battery 11 for connecting and disconnecting the secondary battery 11 with the discharging capacitor 13 and the charger 14. Further, the capacitor 13 is connected to the negative electrode of the secondary battery 11 bypassing the charger 14,
A switch S2 for connecting and disconnecting the two is provided.

Therefore, in the present embodiment, the connection switching means 15 is constituted by the first and second diodes 16 and 17 and the switches S1 and S2.

Further, a voltage detector 18 is provided at a position where the voltage of the secondary battery 11 can always be detected.
This voltage detector 18 turns off the switch S2 when the voltage of the secondary battery 11 reaches the discharge lower limit voltage 1 V to stop the discharge when discharging the secondary battery 11, and charges the discharge completion signal. The battery is sent to the charger 14 to turn on the power of the charger 14 to start charging, and when it is detected that the rechargeable battery 11 is fully charged by continuing the charging, the switch is turned on. S1 is turned off to stop charging.

The reason why the discharge is stopped when the secondary battery 11 reaches the discharge lower limit voltage 1 V is as follows.

That is, normally, the electric capacity remaining in the secondary battery 11 at the time of starting discharging is not constant. For example, when discharging is started in a state close to full charge, or when the discharge reaches near the discharge lower limit voltage. In some cases, the discharge may be started from the state of the discharge.

Then, in order to start discharging in a state close to full charge, and to completely discharge the battery voltage of the secondary battery 11 close to the full charge state to a discharge lower limit voltage 1 V, the capacity of the discharging capacitor 13 is reduced. , Fully charged secondary battery 1
If the capacity of the discharging capacitor 13 is balanced so that the rechargeable battery 11 in a fully charged state or less is completely discharged, a larger capacity is left. Since the secondary battery 11 is no longer completely discharged, to completely discharge all the secondary batteries 11 having different remaining capacities, the capacity of the discharging capacitor 13 must be fully charged. It is necessary to balance the electric capacity of the secondary battery 11.

However, if the capacity of the discharging capacitor 13 is set to be balanced with the capacity of the fully charged secondary battery 11 in this way, the secondary battery 11 that is not fully charged can be discharged. When the battery is discharged until it equilibrates with the condenser 13, these equilibrium voltages are
As shown by the chain line, the discharge lower limit voltage of the secondary battery 11 becomes 1 V or less, resulting in overdischarge, which adversely affects the battery life of the secondary battery 11.

Therefore, by the above-described processing, the discharge of the secondary battery 11 is stopped when its voltage reaches the discharge lower limit voltage 1 V, thereby preventing overdischarge. Of course, if the remaining battery capacity at the time of discharging is constant, such processing can be omitted.

Next, the operation of the secondary battery charger 10 according to the present embodiment will be described. First, prior to charging the secondary battery 11 to be charged, the secondary battery charging device 10 is charged. A pair of switches S1 and S of the device 10
After turning ON the secondary battery 2, the secondary battery 11 is mounted on the secondary battery mounting portion 12 of the secondary battery charger 10. Alternatively, both switches S1 and S2 are turned ON after the secondary battery 11 is mounted on the secondary battery mounting section 12.

As a result, the secondary battery 11 and the discharging capacitor 13 are connected in series, so that the secondary battery 1
The energy of 1 flows into the discharging capacitor 13 to discharge the secondary battery 11 and charge the discharging capacitor 13.

Then, at the time of such a discharging operation,
The voltage of the secondary battery 11 is constantly monitored by the voltage detector 18. When the voltage of the secondary battery 11 reaches the lower discharge limit voltage 1V, the switch S2 is turned off, and the discharging operation is started. The operation is stopped, and the secondary battery 11 is completely discharged.

Next, when charging the completely discharged secondary battery 11, the switch S 1 is turned on and the switch S 2 is turned off. Then, the charger 14 is turned on.

By such an operation, a voltage is applied to the discharging capacitor 13 by the charger 14, and its potential is raised from the potential of the secondary battery 11 which has been completely discharged. The energy charged in the discharge capacitor 13 in the secondary battery 11
And charging of the secondary battery 11 is started.

Here, a voltage is also applied to the anode side of the second diode 17 by the charger 14, but the potential on the cathode side is higher by the potential of the discharging capacitor 13; No current flows through the diode 17.

When all of the energy charged in the discharging capacitor 13 is supplied to the secondary battery 11, the second diode 17 is turned on,
The charger 14 is connected to the secondary battery 11, whereby the secondary battery 11 is charged by the charger 14, and the secondary battery 1 is raised as the charging proceeds.
1 is detected by the voltage detector 18, and when this voltage reaches the full charge voltage, the switch S1 is turned off to complete the charging.

As described above, in the secondary battery power receiving device 10 according to the present embodiment, when the secondary battery 11 is completely discharged, the energy remaining in the secondary battery 11 is stored in the discharging capacitor 13. At the same time, this energy is returned to the secondary battery 11 at the time of charging, so that the energy can be used efficiently.

In addition, since the energy at the time of discharging the secondary battery 11 is stored in the discharging capacitor 13, heat generation at the time of discharging is suppressed, and the influence on the components of the charging device 10 for the secondary battery is reduced. And the secondary battery 11
The energy transfer between the capacitor and the discharge capacitor 13 is fast, which greatly reduces the discharge time and the time required for charging and discharging as a whole.

Next, a second embodiment of the present invention will be described with reference to FIG. The secondary battery charging device 20 according to the present embodiment discharges the energy collected at the time of discharging the secondary battery 11 in the first embodiment to the outside, and performs an external discharge operation and a charging operation of the energy. Are performed in parallel, thereby shortening the total required charging / discharging time.

That is, the secondary battery charger 20 according to the present embodiment connects the discharge resistor 21 in parallel to the discharge capacitor 13 of the secondary battery charger 10 in the first embodiment, and A switch S3 is provided between the discharging resistor 21 and the discharging capacitor 13 to connect the secondary battery 11 only during the charging operation.

In the secondary battery charger 20 according to the present embodiment, the discharging operation of the secondary battery 11 is performed in the same manner as in the first embodiment. Is recovered by the discharging capacitor 13.

At the time of charging the secondary battery 11,
When the switch S3 is turned on, the discharging capacitor 13 and the discharging resistor 21 are connected in series, so that the electricity collected by the discharging capacitor 13 flows to the discharging resistor 21, and this discharging is performed. Resistor 21
Is released to the outside by the heat generated by

With such a configuration, the energy discharged when the secondary battery 11 is discharged is recovered by the discharging capacitor 13 so that the secondary battery 11
Energy is quickly recovered, the secondary battery 11 is rapidly discharged, and the energy recovered by the discharging capacitor 13 is supplied to the discharging resistor 21 in accordance with the charging of the secondary battery 11 to the outside. As a result, the discharging operation and the charging operation of the secondary battery 11 are apparently performed in parallel.

Therefore, in the present embodiment, the charge / discharge time can be reduced although the residual capacity at the time of discharging the secondary battery 11 is wasted.

The above embodiments are merely examples, and various modifications can be made based on design requirements and the like. For example, the OFF operation of the switch S2 at the start of charging is performed by the charger 1
4 may be performed automatically in conjunction with the power ON, or may be performed manually.

Since the switch S2 is turned off when the discharge is completed, the power supply of the charger 14 is turned on based on the OFF signal of the switch S2, thereby discharging and charging the secondary battery 11. Can be automatically performed continuously.

[0044]

As described above, according to the first aspect of the present invention,
According to the charging device for a secondary battery having a discharging function according to the above, at the time of discharging the secondary battery, the energy remaining in the secondary battery is recovered by a discharging capacitor, and at the time of charging the secondary battery. In addition, the recovered energy can be returned to the secondary battery, thereby enabling efficient use of energy.

Further, by collecting the discharge energy of the secondary battery by the discharge capacitor, the energy transfer speed between the two is extremely high, so that the discharge time can be shortened and the discharge time of the secondary battery can be reduced. In this way, it is possible to prevent a problem such as heat generation from occurring in the device, thereby preventing the device from being thermally affected.

According to the charging device for a secondary battery having a discharging function according to the second aspect of the present invention, the discharging time of the secondary battery can be reduced by recovering the discharging energy of the secondary battery by the discharging capacitor. In addition, by discharging the recovered energy to the outside when the secondary battery is charged, it is possible to shorten the time required for charging and discharging as a whole, and to improve the usability.

[Brief description of the drawings]

FIG. 1 is an electric circuit diagram of a charging device for a secondary battery according to a first embodiment of the present invention.

FIG. 2 is a voltage change-time diagram of a secondary battery and a discharge capacitor for describing a discharging operation in the secondary battery charging device according to the first embodiment of the present invention.

FIG. 3 is a voltage change-time diagram of the secondary battery for describing a discharging operation in the secondary battery charging device according to the first embodiment of the present invention.

FIG. 4 is an electric circuit diagram of a charging device for a secondary battery according to a second embodiment of the present invention.

FIG. 5 is a change characteristic diagram of a discharge time for explaining a memory effect of a secondary battery.

FIG. 6 is an electric circuit diagram showing an example of a conventional charge / discharge device for a secondary battery.

[Explanation of symbols]

 10.20 Battery charger for secondary battery 11 Secondary battery 12 Secondary battery mounting part 13 Discharge capacitor 14 Charger 15 Connection switching means 18 Voltage detector

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shoichi Wakao 5-36-11 Shimbashi, Minato-ku, Tokyo Inside Fuji Electric Chemical Co., Ltd. (72) Koji Oishi 5-36-11 Shimbashi, Minato-ku, Tokyo Fuji Electric Chemical Co., Ltd.

Claims (2)

[Claims] A secondary battery mounting part (12) to which a secondary battery (11) is detachably mounted, and a secondary battery mounting part (1).
2) connection switching for switching the connection state between the discharge capacitor (13) and the charger (14) connected in series with the secondary battery (11) and the discharge capacitor (13) and the charger (14); Means (15), and the connection switching means (15) is provided with the secondary battery (11).
At the time of discharging, only the discharging capacitor (13) is connected to the secondary battery (11) bypassing the charger (14), and the discharging of the secondary battery (11) is performed at the initial stage of charging. The capacitor (13) and the charger (14) are connected, and after a lapse of a predetermined time from the start of charging, when the voltage of the capacitor (13) for discharging becomes zero, the secondary battery (11) A charging device for a secondary battery having a discharging function, characterized in that the discharging capacitor (13) is disconnected. 2. A resistor (21) is connected in parallel with the discharging capacitor (13), and the resistor (21) is connected to the discharging capacitor (13) during charging. The charging device for a secondary battery having a discharging function according to claim 1.