JPH04325836A - Battery charger - Google Patents

Abstract

PURPOSE:To obtain a battery charger comprising a downsized discharging means for eliminating the memory effect and suppressing production of heat and charging means in which charging time is shortened through combination of V, detection of battery temperature and detection of ambient temperature. CONSTITUTION:The battery charger comprises means 3 for discharging a secondary battery 2, charging means 4 for switching the charging current, a battery voltage detecting means 5, a battery temperature detecting means 6, a time measuring means 7, an ambient temperature detecting means 8, and a control means 6 wherein the control means controls the charging characteristics of the charging means based on the ambient temperature detected through the ambient temperature detecting means.

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 charging secondary batteries such as nickel-cadmium batteries (nickel-cadmium batteries).

0002

2. Description of the Related Art In recent years, NiCd batteries have come into widespread use as secondary batteries for small portable electronic devices. A characteristic of NiCd batteries is a phenomenon called memory effect, which causes problems when using NiCd batteries on a daily basis. Currently available commercially available devices for charging NiCd batteries include a discharging device consisting of a resistor and a charging device, but this charging device controls the charging time using ΔV detection and a timer.

[0003] The discharge device has the disadvantage that it is large in size due to the heat it generates, and the above-mentioned charging device has the disadvantage that there is a limit to shortening the charging time. That is, it takes about 1 hour to charge 1Ah.

0004

SUMMARY OF THE INVENTION The present invention has been made to solve the drawbacks of such conventional discharging devices and charging devices, and relates to a battery charging device equipped with a discharging means. , the memory effect can be eliminated, and the device can be made smaller and generate less heat. Another object of the present invention is to provide a battery charging device that uses ΔV, battery temperature detection, and ambient temperature detection in combination to shorten charging time.

[0005]

[Means for Solving the Problems] A battery charging device of the present invention is connected to a secondary battery and includes a discharging means for discharging the secondary battery, and a discharging means connected to the secondary battery and comprising:
a charging means for charging the secondary battery by switching the magnitude of the charging current flowing through the secondary battery; a voltage detecting means for detecting the voltage of the secondary battery; a battery temperature detecting means for detecting the temperature of the secondary battery; a time measuring means for measuring the time during which the discharging means is connected to the secondary battery; an ambient temperature detecting means for detecting the temperature around the secondary battery; and a time measuring means for measuring the time during which the discharging means is connected to the secondary battery; state, the connection with the secondary battery is switched from the discharging means according to the outputs of the voltage detecting means and the time measuring means, and the charging means is switched from the discharging means to the secondary battery.
After switching the charging current of the charging means according to the output of the voltage detecting means while connected to the secondary battery, the charging means is connected to the secondary battery according to the output of the battery temperature detecting means. and a control means configured to open the charging means, and the charging characteristic of the charging means is controlled by the control means based on the ambient temperature detected by the ambient temperature detection means.

[0006]

[Operation] In this way, in addition to the secondary battery voltage detection means and the battery temperature detection means, the ambient temperature detection means detects the ambient temperature of the secondary battery and controls the charging characteristics, thereby increasing the charging time. Shorten.

[0007]

[Embodiment] FIG. 1 shows a block diagram of an embodiment of the battery charging device of the present invention, and FIG. 2 shows a flow diagram of the control of this battery charging device, and this embodiment will be explained with reference to these figures. However, before that, the charging characteristics of the battery will be explained using FIG. 3, and the discharging characteristics of the battery will be explained using FIG. 4.

In FIG. 3, the battery voltage gradually increases while the amount of charge is small, increases rapidly when the amount of charge approaches 100%, and then decreases after reaching a peak. This sudden increase in battery voltage is called ΔV. The battery voltage is affected by the ambient temperature and increases as the ambient temperature decreases. on the other hand,
The battery temperature hardly rises until the charge level reaches 100%,
This sudden increase that occurs when the charge amount exceeds 100% is called ΔT.

FIG. 4 shows the discharge characteristics. In FIG. 4, the solid line showing the change in battery voltage with respect to the discharge amount shown on the upper side indicates normal discharge characteristics. The dotted line indicates when the memory effect was activated. The memory voltage is denoted by VM. When a memory effect occurs, a battery will discharge in a short period of time no matter how much it is charged. The relationship between the amount of discharge and battery voltage shown at the bottom shows that the amount of charge changes depending on the ambient temperature.

The battery charging device of the present invention has been developed by focusing on the charging characteristics and discharging characteristics of such batteries, and includes:
The block diagram is as shown in FIG. In FIG. 1, a battery charging device 1 of the present invention includes a discharging means 3 connected to a secondary battery 2 and discharging the secondary battery 2;
While being connected to the secondary battery 2, this secondary battery 2
Charging means 4 that charges by switching the magnitude of the charging current applied to the
, a voltage detecting means 5 for detecting the voltage of the secondary battery 2, a battery temperature detecting means 6 for detecting the temperature of the secondary battery, and a time period during which the discharging means 3 is connected to the secondary battery 2. a time measuring means 7 for measuring the temperature around the secondary battery 2; an ambient temperature detecting means 8 for detecting the temperature around the secondary battery 2; The connection with the secondary battery 2 is switched from the discharging means 3 in accordance with the output of the time measuring means 7 (timer), and the voltage detection is performed while the charging means 4 is connected to the secondary battery 2. a control means 9 configured to switch the charging current of the charging means 4 according to the output of the means 5 and then disconnect the charging means from the secondary battery according to the output of the battery temperature detection means 6; The charging characteristic of the charging means 4 is changed depending on the ambient temperature detected by the ambient temperature detecting means 8. 10 is a DC power supply.

Next, the flow step of the control means 9 will be explained using FIG. This control means 9 is a control circuit including a microcomputer (hereinafter referred to as microcomputer). First, the secondary battery 2 is attached to the battery charging device 1 of the present invention. S1 The battery voltage V1 is taken in as data to the microcomputer via the A/D converter.

S2 Battery voltage V1 and discharge end voltage V
Compare with 0. The discharge end voltage V0 is input in advance as data into the memory of the microcomputer. V1 ≦
Compare whether it is V0. If YES, S8
If NO, go to S3. S3 If NO, operate the timer and start discharging. S4 Compare the battery voltage V1 and the memory effect voltage V2. The memory effect voltage V2 is input in advance as data into the memory of the microcomputer. V1 > V2
Compare whether If YES, go to S5; if NO, go to S6.

S5 Compare the discharge time t and the time tM at which the memory effect occurs. That is, compare t>tM. Y
If ES, the process goes to S7; if NO, the process returns to before S4. The time tM for the memory effect to occur is 1/1 of the normal battery usage time.
Occurs within 2. tM is previously input as data into the memory of the microcomputer. S6 If NO in S4, go to S6. Here, the battery voltage V1 is compared with the discharge end voltage V0. That is, V1
It is compared whether ≦V0. If YES, proceed to S7; if NO, proceed to S4.

S7 S4 is YES and S6 is YES
Then, come to this S7. At this point, the timer stops operating and the discharge is stopped. S8 When S2 is YES and S7 is YES, this S
Come to 8. Start charging here. S9 Charge current I1 is applied. I1 = (4-5)C
It is.

S10 Measure whether the battery voltage V1 has increased by ΔV. That is, it is compared whether V1 ≧V1 +ΔV. If YES, the process advances to S11; if NO, the process returns to S9. S11 Charge current I2 is applied. I2 = 1C. S12 Compare whether the battery voltage T has increased by ΔT. That is, it is compared whether T≧T+ΔT. If YES, S
Proceed to S13, and if NO, return to before S11.

[0016] S13: Display the completion of charging. The charging current I3 is set to I3 = 0.1C. This charging is called trickle charging. Discharging and charging are performed through the steps described above. Since the discharge characteristics and charge characteristics change depending on the ambient temperature, the data stored in the memory in the microcomputer is corrected according to the ambient temperature.

[0017]

As explained above, the battery charging device of the present invention is connected to a secondary battery and includes a discharging means for discharging the secondary battery, and a discharging means that is connected to the secondary battery and discharges the secondary battery. a charging means for charging the secondary battery by switching the magnitude of the charging current flowing through the secondary battery; a voltage detecting means for detecting the voltage of the secondary battery; a battery temperature detecting means for detecting the temperature of the secondary battery; a time measuring means for measuring the time during which the means is connected to the secondary battery; an ambient temperature detecting means for detecting the temperature around the secondary battery; and a state in which the discharging means is connected to the secondary battery. The connection with the secondary battery is switched from the discharging means in accordance with the outputs of the voltage detecting means and the time measuring means, and while the charging means is connected to the secondary battery, the voltage detecting means is switched. control means configured to switch the charging current of the charging means according to the output, and then open the connection of the charging means to the secondary battery according to the output of the battery temperature detection means; It is characterized in that the charging characteristics of the charging means are controlled by the control means based on the ambient temperature detected by the temperature detection means, and as a discharging means, it is possible to eliminate the memory effect, and it is also possible to reduce the size and generate less heat. Furthermore,
It is possible to provide a battery charging device that uses ΔV, battery temperature detection, and ambient temperature detection in combination to shorten charging time.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of a battery charging device of the present invention.

FIG. 2 is a flowchart of control of the battery charging device of the present invention.

FIG. 3 is a diagram of charging characteristics of a battery.

FIG. 4 is a diagram of discharge characteristics of a battery.

[Explanation of symbols]

1 Battery charging device 2 Secondary battery 3 Discharging means 4 Charging means 5 Voltage detection means 6 Battery temperature detection means 7 Time measurement means 8 Ambient temperature detection means 9 Control means 10 DC power supply

Claims (1)

[Claims] 1. A discharging means connected to a secondary battery and discharging the secondary battery; and a discharging means connected to the secondary battery and charged by switching the magnitude of a charging current flowing to the secondary battery. a charging means for detecting the voltage of the secondary battery, a voltage detecting means for detecting the voltage of the secondary battery, a battery temperature detecting means for detecting the temperature of the secondary battery, and a time period during which the discharging means is connected to the secondary battery. an ambient temperature detection means for detecting the temperature around the secondary battery; and an ambient temperature detection means for detecting the temperature around the secondary battery; and a time measurement means for detecting the temperature in response to the outputs of the voltage detection means and the time measurement means while the discharge means is connected to the secondary battery. and switching the connection with the secondary battery from the discharging means, and switching the charging current of the charging means according to the output of the voltage detection means while the charging means is connected to the secondary battery. , a control means configured to open the connection of the charging means to the secondary battery in accordance with the output of the battery temperature detection means, and charging the charging means using the ambient temperature detected by the ambient temperature detection means. A battery charging device characterized in that characteristics are controlled by the control means.