JPH05166541A - Discharge device - Google Patents

Abstract

PURPOSE:To prevent the storage capacity of a nickel-cadmium secondary battery from being decreased by the memory effect of the battery caused by repeating charging of the battery. CONSTITUTION:Means 10 for storing the number of times of charging are provided inside a discharge device or a battery main body and a CPU 9 checks the number of times of charging, and when a preset number of times is reached, complete discharging of the battery is forcibly done by a discharge circuit 6 prior to charging. Complete discharging of the battery is thus periodically performed so as to prevent the storage capacity of the battery from being decreased by memory effect.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge device having a function of detecting the number of times a nickel-cadmium secondary battery has been charged and forcibly performing a complete discharge every predetermined number of times of charging.

[0002]

2. Description of the Related Art Conventionally, there is a device having a function of sounding an alarm or displaying the remaining capacity when it detects that the remaining capacity of the battery is low due to the main body of the device using the nickel-cadmium secondary battery. In this way, when the user of the device is informed that the battery needs to be charged, the device user generally charges the battery by himself. As a charging method, constant current charging in which a constant current is charged for a prescribed time, charging-ΔV detection method in which a change in voltage appearing immediately before the completion of charging is detected to terminate charging, or a small charging current is always used. A trickle charging system that is kept flowing is typically known.

Upon charging, the user of the apparatus generally performs a charging start operation procedure to charge the nickel-cadmium secondary battery at any time regardless of the remaining amount of the battery. .

However, in general, in the case of nickel-cadmium secondary batteries, if the usage cycle of charging 100% of the storage capacity without being used up (without complete discharge) is repeated many times, the initial storage capacity will be reduced. It is known that there is a so-called memory effect of gradually decreasing. In this case, in order to restore the initial storage capacity from the state where the memory effect occurs, it is necessary to perform complete discharge once. Normally, in the case of nickel-cadmium secondary batteries, the electromotive voltage per cell is 1.2 V.
Voltage of about 1.0 V per cell (fully discharged)
Is required to be discharged.

[0005]

However, due to the characteristics of the device using the nickel-cadmium secondary battery, there are cases where discharge to the final voltage is impossible. For example, when a RAM is used in the device, if the operation stops during use, there is a risk that the information in the RAM will be lost. Often designed to sound an alarm that requires charging.

Further, for example, in the case of a device having an operating voltage of 12 V, it is possible to use 10 cells of nickel-cadmium secondary batteries connected in series. In this case, 1
When the final voltage per cell is set to 1.0 volt, the total electromotive voltage at the final voltage is 10 volt. In this case, if the device cannot be guaranteed to operate at 10 volts, it will not be able to discharge to the final voltage.

Generally, even in a device capable of discharging up to the final voltage, it is rare that the device cannot be charged until the final voltage is discharged, and the charging operation is based on the intention of the user. At that time, nickel-cadmium The remaining capacity of the secondary battery is unpredictable. Therefore, for the reasons described above, the conventional nickel-cadmium secondary battery charging circuit (or charging system) always causes a memory effect and has a risk of reducing the storage capacity. was there.

[0008]

According to the present invention, the device body or the nickel-cadmium secondary battery itself is provided with a charging frequency storage means to check whether the charging frequency has reached a preset number of times. If it is determined that the number of times is reached, the memory effect of the nickel-cadmium secondary battery is prevented by forcibly performing a complete discharge before charging,
This allows repeated use without discharging to the final voltage.

[0009]

FIG. 1 is a circuit diagram showing an embodiment of the present invention,
FIG. 2 is a flowchart thereof. In FIG. 1, 1 is a constant voltage charging circuit, 2 is a current limiting resistor for charging, 3 is a charging transistor for starting or stopping charging,
4 is a diode for preventing the reverse flow of current from the nickel-cadmium secondary battery, 5 is a nickel-cadmium secondary battery, 6 is a discharge circuit for forced discharge, 7 is the start or stop of discharge in the discharge circuit A discharging transistor 8 for discharging is a discharging resistor for limiting a discharging current. 9 is a CPU (central processing unit), and 1
0 is a RAM that stores the number of times of charging. And CPU
Reference numeral 9 retrieves data on the number of times of charging from the RAM 10, determines whether or not a predetermined number of times of programming has been reached, and controls the discharging transistor 7 and the charging transistor 3 according to the information. Reference numeral 11 is a battery for holding the contents of the RAM 10 even when the power source of the apparatus is OFFN.

Next, a series of operations in this embodiment will be described with reference to FIGS. First, when charging, FIG.
When a charge start signal is input to the CPU 9 from the outside in step S1 of, the CPU 9 accesses the RAM 10 in step S2 to check how many times the current charging is. Here, the predetermined number of times may be arbitrary, but depending on the characteristics of the nickel-cadmium secondary battery 5 and the usage pattern of the apparatus body, it is necessary to set the number of times so as not to cause the memory effect. When the number of times of charging does not reach the predetermined number of times, the CPU 9 proceeds from step S3 to step S6, operates the charging transistor 3 for a predetermined time, and
Charge the cadmium secondary battery 5 until it is fully charged,
Charging ends in step S7. Then, step S8
The RAM 10 is updated with the number of times of charging.

On the other hand, if the number of times of charging reaches the predetermined number of times in step S3, the discharging transistor 7 is operated for a certain period of time, and in step S4 the nickel-cadmium secondary battery 5 is forcibly discharged. After that, the forced discharge by the discharging transistor 7 is stopped and finished in step S5. Then, in step S6, the charging transistor 3 is operated to start charging. When the charging is completed, the operation of the charging transistor 3 is stopped in step S7, and the number of times of charging "1" is recorded in the RAM 10 in step S8.

Here, the nickel-cadmium secondary battery 5
In the case where the battery is discharged for a certain period of time, if it takes too long to complete the charging, the voltage of the nickel-cadmium secondary battery 5 is input to the A / D input section of the CPU 9, and the cut-off voltage is reached. You may employ the method of discharging until it becomes.

FIG. 3 shows another embodiment of the present invention.

In FIG. 3, reference numerals 1 to 9 and 12 are the same as in FIG. Reference numeral 13 is a recording medium attached to the nickel-cadmium secondary battery 5, and 14 is an element for performing recording, reading and the like on the recording medium 13. As a recording method, for example, a material such as a magnetic film as a recording medium may be attached to a secondary battery and recording and reading may be performed by a magnetic head, but other methods may be used.

When the nickel-cadmium secondary battery is incorporated in the device body and cannot be removed, the embodiment shown in FIGS. 1 and 2 is effective. However, the secondary battery can be removed from the device body, For those in which the charging history up to which the charging history is unknown may be attached, the present embodiment in which the charging history is recorded in the secondary battery body is effective. The operation of this embodiment will be described. First, when the charge start signal from the outside is C
Upon entering the PU 9, the CPU 9 reads the number of times of charging recorded in the recording medium 13 of the nickel-cadmium secondary battery 5 by the recording / reading element 14. A method is conceivable in which recording and reading of the number of times of charging is performed by magnetic recording and reading by the recording medium 13, and the number of times of charging is determined by, for example, its magnetization intensity.

The CPU 9 indicates that the number of times of charging read is CP
It is determined whether or not the set number of times set in U9 has been reached, and as a result, if not reached, the charging transistor 12 is driven to start charging. If the number of times of charging reaches the set number of times, the discharging transistor 7 is driven to enter the discharging mode. Then, after the discharge is completed, the mode shifts to the charging mode. When charging is complete, CPU
The recording element 9 updates the number of times of charging the recording medium 13 by the recording element 14 and ends the charging operation.

[0017]

As described above, in the discharging device of the present invention, in the device using the nickel-cadmium secondary battery, the charging frequency storage means is provided in the device body or in the battery itself to perform discharging periodically. . Therefore, even when it is impossible to discharge to the final voltage due to device restrictions, or when charging is repeated before it reaches the fully discharged state, the effect of preventing the decrease in the storage capacity due to the memory effect of the nickel-cadmium secondary battery is prevented. There is. Then, the battery can be used with peace of mind without worrying about the remaining battery level.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram of an embodiment according to the present invention in which a storage unit is provided in a device body.

FIG. 2 is a flowchart illustrating the operation of the circuit shown in FIG.

FIG. 3 is a circuit configuration diagram showing another embodiment according to the present invention.

[Explanation of symbols]

 1 Constant Voltage Charging Circuit 5 Nickel Cadmium Secondary Battery 6 Discharging Circuit 9 CPU 10 RAM 13 Recording Medium 14 Recording / Reading Element

Claims (1)

[Claims] 1. A discharge device using a nickel-cadmium secondary battery, for storing the number of times of charging in the main body of the device using the nickel-cadmium secondary battery or in the nickel-cadmium secondary battery itself. A charge number storage means, a determination means for determining whether or not the number of times of charging has reached a preset number of times, and when the number of times of charging determined by the determination means reaches a predetermined number, it is forcibly forced before charging. A discharge device comprising means for performing a complete discharge.