JPH06165400A - Charger for battery - Google Patents

Abstract

PURPOSE:To efficiently charge a battery to be used as a power source for an electric apparatus, etc., by providing a charging circuit and a discharging circuit in parallel, and so connecting both the circuits to batteries to be alternately switched via a changeover switch. CONSTITUTION:A discharging circuit 1 for discharging a consumed battery E up to a predetermined charge starting voltage, and a charging circuit 2 for charging the battery E in which discharge is completed are provided. The circuits 1 and 2 are alternately so connected in parallel as to be switched to the battery E via a changeover switch SW. On the other hand, after a power source is stepped down at a commercial power source AC100V to be connected via a plug provided at a charger BC at a transformer, a DC voltage converted by a bridge rectifier is applied to the circuit 2. Further, when a plurality of the batteries are simultaneously charged, the batteries are discharged to a predetermined level where charging is to start so as to make the residual voltages uniform, and then started to be charged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery charger for charging a battery used as a power source for electric equipment and the like.

[0002]

2. Description of the Related Art Conventionally, this type of charger has a commercial power supply AC1.
It is composed of a power supply circuit that steps down 00V and outputs a DC voltage by an AC-DC converter, and a charging circuit that applies a DC voltage to supply a charging current to the battery to charge the battery. Charging was started immediately when the charger was connected to the power source after being set in the charger, and the charging was performed only for a predetermined charging time regardless of the discharged state of the battery, that is, the residual voltage of the battery.

[0003]

Generally, a plurality of batteries are used as a power source for electric equipment, and the charging time of this type of battery is when the operation of the electric equipment is reduced or stopped when the battery is exhausted. Recognizing that, I was charging.

However, even in such a state, the residual voltage of each battery varies, and it cannot be said that the battery is necessarily in a state suitable for charging. That is, it is desirable to charge the battery after discharging it to an appropriate voltage according to its charge and discharge characteristics.
In such an intermediate discharge state, not only the charging efficiency is deteriorated, but also when charging is repeated in the intermediate discharge state, the charge / discharge cycle of the battery is shortened and the battery life is impaired.

When a plurality of batteries are charged at the same time, the residual voltage of each battery is non-uniform, so that the battery with a large residual voltage is overcharged, and the battery with a small residual voltage is insufficiently charged to improve the charging efficiency. It was getting worse.

[0006]

In order to solve the above problems, the present invention is designed to start charging after discharging a battery in an intermediate discharge state to a proper voltage. A configuration is provided in which a discharge circuit that discharges to a constant charge start voltage and a charge circuit that charges the discharge battery after the discharge is completed are provided in parallel, and both circuits are alternately and switchably connected to the battery via a changeover switch. It was done.

[0007]

According to the present invention, after the exhausted battery is connected to the discharging circuit and discharged up to the charging start voltage, the changeover switch is switched to the charging circuit to start charging, which is ideal for the charging / discharging characteristics of the battery. In addition, efficient charging can be performed.

Even when a plurality of batteries are charged at the same time, each battery is discharged to a constant charging start voltage to make the residual voltage of each battery uniform and start charging from an appropriate voltage. Extremely efficient charging can be achieved by eliminating variations such as overcharging and undercharging of each battery.

[0009]

Embodiments of the present invention will be described in detail below with reference to FIGS.

A discharging circuit 1 discharges a consumed battery E to a charge starting voltage (for example, a residual voltage of a battery at a chargeable limit ... A charging limit is about 0.8 V for a 1.2 V NiCd AA battery). Reference numeral 2 denotes a charging circuit for charging the battery E which has been completely discharged. As shown in FIG. 1, the discharging circuit 1 and the charging circuit 2 are connected in parallel to the battery E in a switchable manner via a changeover switch SW. .

On the other hand, the power supply circuit 3 includes a transformer T and a charger BC.
Commercial power supply AC10 connected by a plug 7 provided in
After reducing 0V, the DC voltage converted by the bridge rectifier VD is applied to the charging circuit 2.

FIG. 2 shows a circuit diagram of the charger BC, and the operation principle when the NiCd AA battery E is charged will be described based on the circuit diagram.

[0013] exhausted is set in the battery box 4 charger BC battery E, the battery E ⁺ → changeover switch SW → resistor R1 → cell E to cell E when switching the changeover switch SW from OFF to discharge circuit 1 as a power source ^- Then, the discharge current flows and the voltage of the battery E drops due to the resistance R1, and the discharge is continued until the residual voltage of the battery E reaches the charge start voltage, for example, 0.8V.

When a plurality of batteries E having different residual voltages are discharged at the same time, the batteries E are discharged to the charging start voltage, for example, 0.8 V, and the residual voltages of the batteries are made uniform.

When the battery E is discharged to a certain charge starting voltage, as a means for indicating that the discharge is completed, the discharge indicator lamp 8 (which turns on and off when the battery E is discharged and discharge is completed) The LED 1) is connected to the discharge indicator circuit 5 composed of the first transistor TR1 for controlling the switch of the discharge indicator lamp 8 (LED1). When the changeover switch SW is changed over to the discharge circuit 1 and the voltage higher than the charge start voltage is applied by the discharge of the battery E, the first transistor TR1 is turned on and the discharge indicator lamp 8 (LED1) is turned on in the indicator circuit 5 ( ON) to indicate that the discharge has started.

When the discharge further progresses and the residual voltage of the battery E reaches the charge start voltage, the first transistor TR1 is turned off to turn off the discharge indicating lamp 8 (LED1) to indicate that the discharge is completed.

When a plurality of batteries E discharged below the charge start voltage coexist when the plurality of batteries E are discharged, the above discharge is not performed, and therefore the discharge indicator lamp 8 (LED1) is in the off state. It can be confirmed that no discharge occurs.
In this case, each battery E is sequentially set in the battery box 4 and it is checked whether or not to discharge, and the battery E discharged below the charge start voltage is eliminated and then discharged again.

After confirming that the discharge is completed, the changeover switch SW is switched from the discharge circuit 1 to the charging circuit 2 to connect the battery E to the charging circuit 2, and the direct-current voltage V AC-DC converted by the power supply circuit 5 is connected. It is applied to the input end of the charging circuit 2.
The first diode D1 is connected to the output terminal of the charging circuit 2,
The reverse flow of the discharge current of the battery E is prevented.

The charging circuit 2 is provided with a voltage adjusting IC for obtaining a stable voltage required for charging, and a constant voltage corresponding to the input voltage is controlled by operating the resistor R2 to control the input voltage of the IC. The constant collector voltage is output to the base of the two-transistor TR2.

For example, when one NiCd AA battery E is charged, the charging start voltage is 0.8 V to the charging completion voltage 1.2.
The resistance R2 is set so that the battery E is charged with a voltage of 0.4 V in order to charge up to V (the rated output voltage of the NiCd AA battery).

When a plurality (for example, 6) of the batteries E are charged, the charging start voltage is 4.8 V (0.8 V × 6) to the charging completion voltage 7.2 V (1.2 V × 6). To do so, the resistor R2 is set so that the battery E is charged with a voltage of 2.4V.

Therefore, when a DC voltage V is applied to the charging circuit 2, a charging current flows as V ⁺ → second transistor TR2 → first diode D1 → switch SW → battery E → V ⁻ and the voltage of the battery E is charged. Charging is completed when the voltage is increased from the start voltage to the charge completion voltage.

As a means for indicating that the charging is completed, the charging indicator 2 (LED2) and the charging indicator 9 (LED2) which are turned on by the completion of charging of the battery E in the charging circuit 2 are switch-controlled. The charging indicator circuit 6 composed of the third and fourth transistors TR3, TR4, etc. is connected.

The charge indicating circuit 6 is the fourth transistor TR4.
Second diode D2 and resistor R3 for setting the operating voltage of
When the charging completion voltage is reached by the fourth transistor TR4
Is turned on, the third transistor TR3 is turned on, and the charging indicator lamp 9 (LED2) is turned on (on) to indicate that charging is completed.

Immediately after the completion of charging is confirmed, the changeover switch SW is turned off from the charging circuit 2 to end the charging.

[0026]

According to the present invention, a battery, which has been exhausted to a midway discharge state, is discharged to an appropriate charge start voltage by a discharge circuit and then the changeover switch is switched to the charge circuit to start charging. It is possible to perform ideal and efficient charging according to the characteristics, and even when charging multiple batteries at the same time, discharge the batteries with different residual voltages to the charge start voltage to make the voltage of each battery uniform. Since the charging is started from a proper voltage after charging, variations such as overcharging and undercharging of each battery after completion of charging can be eliminated and extremely efficient charging can be performed.

Therefore, it is possible to eliminate the problem of repetitive charging in a half-discharged state as in the prior art and solve the problem of impairing the battery life.

[Brief description of drawings]

FIG. 1 is a circuit block diagram of a battery charger showing an embodiment of the present invention.

FIG. 2 is a circuit diagram of the same.

FIG. 3 is a perspective view showing an appearance of the battery charger.

[Explanation of symbols]

 1 Discharge Circuit 2 Charging Circuit 3 Power Supply Circuit 5 Discharge Marking Circuit 6 Charging Marking Circuit 8 Discharge Marking Lamp 9 Charging Marking Lamp E Battery SW Switch Switch BC Charger

Claims (2)

[Claims] 1. A discharge circuit for discharging an exhausted battery to a constant charging start voltage, and a charging circuit for charging the discharge battery, wherein the discharge circuit and the charging circuit are alternately connected to the battery via a changeover switch. A battery charger characterized by being switchably connected. 2. When the battery is discharged to a charge starting voltage,
2. The battery charger according to claim 1, further comprising a means for indicating the completion of the discharge and a means for charging the discharge battery and indicating the completion of the charging.