JPH06113473A - Control circuit of charge type battery - Google Patents

Abstract

PURPOSE:To prevent a virtual capacity drop due to memory effect by measuring a time period after the discharge of a charge-type battery and by discharging the charge-type battery when this time period reaches a predetermined value. CONSTITUTION:A charge voltage detector 51 detects the output of the charge voltage of a charger 2, and a charge voltage detection signal is sent out to a timer 52. Next, a flip-flop 53 sends out a signal to switching means 4 by an output signal from the timer 52 and an output signal from the charge voltage detector 51, thereby connecting the charge-type battery 1 to discharge means 3. Then, a discharge voltage monitor circuit 54 monitors the discharge voltage of the charge-type battery 1, sends out a signal to the flip-flop 53 for resetting when said discharge voltage has reached the set point, and sends out a signal to switching means 4 and isolates the charge-type battery 1 from the discharge means 3. By doing this, a temporary drop in the virtual capacity due to memory effect can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control circuit for a rechargeable battery, and more specifically, the capacity of a rechargeable battery such as a nickel-cadmium battery or a nickel-hydrogen battery is apparently temporarily reduced. The present invention relates to a control circuit that eliminates a phenomenon (memory effect).

[0002]

2. Description of the Related Art The memory effect of a rechargeable battery is caused by repeating charging / discharging only a part of the total discharge capacity or continuing trickle charging at high temperature. It is known that it is possible to charge the battery again after charging.

As a means for eliminating such a memory effect, there is a discharger which discharges a rechargeable battery according to a user's arbitrary intention and is commercially available.

[0004]

The apparent capacity decrease due to the memory effect described above is often judged by the user to be the end of life due to the passage of charge / discharge cycles, which is a cause of waste of the rechargeable battery. .

Further, since the commercially available discharger is used by the user's arbitrary intention, it has not been possible to prevent the waste of the rechargeable battery as described above.

[0006]

In order to solve the above problems, the present invention comprises a discharging means for discharging a rechargeable battery and a switching means for connecting the rechargeable battery to the discharging means, The time after discharge of the rechargeable battery is measured, and when the time reaches a predetermined value, the switching means is operated to control the discharge of the rechargeable battery, and the discharge voltage of the rechargeable battery is monitored. When the discharge voltage reaches a set value, the switching means is operated to control so as to stop the discharge of the rechargeable battery.

[0007]

[Operation] Therefore, according to the present invention, the time after discharge of the rechargeable battery is measured, and the rechargeable battery is discharged when this time reaches a predetermined value. The decrease can be prevented.

[0008]

1 is a block diagram of a control circuit for a rechargeable battery according to the present invention.

In FIG. 1, reference numeral 1 is a rechargeable battery, and a switching means 4 for connecting to a charger 2 or a discharging means 3 is connected to the rechargeable battery 1. Normally, the rechargeable battery is operated by the switching means 4. 1 is configured to be connected to the charger 2 for trickle charging, and the charging time by the charger 2 by the control means 5, that is, the discharging means 3
It is configured to measure the time from when the battery is switched to the charger 2.

The control means 5 detects the output of the charging voltage of the charger 2 and outputs a charging voltage detection signal to the timer 52, an output signal from the timer 52 and the charging voltage detection signal. A signal is sent to the switching means 4 according to the output signal from the device 51, a flip-flop 53 for connecting the rechargeable battery 1 to the discharging means, and the discharge voltage of the rechargeable battery 1 are monitored. Of the discharge voltage monitoring circuit 54 for sending a signal when the voltage reaches a set value, the flip-flop 53 is reset by the output signal from the discharge voltage monitoring circuit 54, and a signal is sent to the switching means 4 for charging. The formula battery 1 is configured to be separated from the discharging means 3.

FIG. 2 is a circuit diagram of the control means 5.

In FIG. 2, a charging voltage detector 51 includes resistors R1 and R2 for dividing the output voltage of the charger, a transistor Q3 to which the divided output is input, and an oscillator circuit IC2.
-1, and when the output of the charging voltage is detected, the collector potential of the transistor Q3 becomes L level, and the oscillator circuit IC2-1 that oscillates a pulse determined by the resistor RC and the capacitor CC operates. Has been done.

The timer 52 is a counter circuit I.
The oscillator circuit I comprises a C3 and an inverting circuit IC2-3.
The pulse output from C2-1 is input as a clock pulse, the period of the pulse is expanded 16384 times and output, and the phase is inverted by the inverting circuit IC2-3.

The signal from the inverting circuit IC2-3 and the pulse from the oscillating circuit IC2-1 are supplied to the inverting circuit IC2-.
The signal whose phase has been inverted by 2 is input to the C terminal and D terminal of the flip-flop 53, respectively, and the signal is sent from the inverted Q output of the flip-flop 53 to the switching means 4.

The switching means 4 comprises a transistor Q2 and a resistor R3, and the discharging means 3 comprises a field effect transistor FET1, a resistor R and a light emitting diode LED1. When the signal from the inverted Q output becomes L level, The transistor Q2 is off and the field effect transistor FE
When T1 is turned on, the rechargeable battery 1 is discharged through the resistor R. At this time, when the output of the charger is stopped, the collector potential of the transistor Q3 becomes H level.

The discharge voltage of the rechargeable battery 1 is monitored by a discharge voltage monitoring circuit 54 composed of a voltage detection circuit IC1 and transistors Q1 and Q4, until the discharge voltage of the rechargeable battery 1 reaches a set value. An H level signal is sent from the voltage detection circuit IC1 and the transistor Q
1 is on, transistor Q4 is off, and AND circuit IC
When one of the input terminals 2-4 is at the H level, the flip-flop 53 is reset. Then, when the discharge voltage reaches the set voltage, an L level signal is sent from the voltage detection circuit IC1 and one input terminal of the AND circuit IC2-4 becomes L level. At this time, since the collector potential of the transistor Q3 in the charging voltage detector 51 is at H level, the other input terminal of the AND circuit IC2-4 is also at H level. Therefore, the output of the AND circuit IC2-4 becomes H level, and the inverted Q of the flip-flop 53.
The output becomes H level and the rechargeable battery 1 is disconnected from the discharging means 3.

In FIG. 2, IC4 is a power supply circuit, SW1 is for manually setting the flip-flop 53 to connect the rechargeable battery 1 to the discharging means 3, and a memory effect can be obtained by a single discharge. Used when it cannot be removed.

In the above embodiment, the time after discharging the rechargeable battery 1 was measured, but it goes without saying that the number of times of charging after discharging may be counted.

If an enameled resistor is used as the resistor R,
Since the surface temperature becomes high during discharge, the time required for discharge takes 5 hours or more, but if a sheet heating element is used for the resistor R,
The rise in the surface temperature can be reduced, and the required discharge time can be set to about 2 hours.

[0020]

As described above, according to the present invention, since the rechargeable battery can be discharged periodically, it is possible to prevent the apparent capacity from temporarily decreasing due to the memory effect.

[Brief description of drawings]

FIG. 1 is a block diagram of a control circuit for a rechargeable battery according to the present invention.

FIG. 2 is a circuit diagram of control means in the control circuit of FIG.

[Explanation of symbols]

 1 Rechargeable Battery 2 Charger 3 Discharging Means 4 Switching Means 5 Control Means

Claims (3)

[Claims] 1. A discharge means for discharging a rechargeable battery, and a switching means for connecting the rechargeable battery to the discharge means, and the time after discharging the rechargeable battery is measured. When the value reaches a value, the switching means is operated to control so as to discharge the rechargeable battery, the discharge voltage of the rechargeable battery is monitored, and the switching means is activated when the discharge voltage reaches a set value. A control circuit for a rechargeable battery, comprising control means for operating the control device to stop the discharge of the rechargeable battery. 2. The control circuit for a rechargeable battery according to claim 1, wherein the time after discharging the rechargeable battery is measured by counting the number of times of charging. 3. The control circuit for the rechargeable battery according to claim 1, wherein the discharging means for discharging the rechargeable battery is a planar heating element.