JPH0670481A - Charger - Google Patents

Abstract

PURPOSE:To prevent an early-switching-off and an overcharge in the charging of a battery and perform the completed charging of the battery surely, by providing a temperature sensing means for sensing the rising rate of the temperature of the battery to be charged, and by performing the charging control of the battery when the temperature of the battery is lowered from its peak value by a predetermined value and the rising rate of the temperature of the battery is not smaller than a predetermined value. CONSTITUTION:Based on the sensing voltage of a voltage sensing part 3, a charging control part 1 senses the fact that a voltage V of a battery B to be charged is lowered by DELTAV. At this time, based on the sensing temperature of a temperature sensing part 4, the charging control part 1 decides whether a rising rate DELTAT of the temperature of the battery B to be charged is not smaller than a predetermined value or not. When the rising rate DELTAT of the temperature of the battery B to be charged is not smaller than the predetermined value, the charging control part 1 decides that the charging of the battery B to be charged should be completed, and stops the boosting charge of the battery B, and further, indicates the completion of the charging on an indicating part 6. Thereafter, a torque-charging is initiated, and when the predetermined torque-charging is completed, the charging operation of the battery B is completed. Thereby, without generating any early-switching-off and any overcharge in the charging of a secondary battery, its full charging can be performed surely.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging device which detects a battery voltage of a battery to be charged, detects that the battery voltage has dropped from a peak value by a predetermined amount, and controls charging.

[0002]

2. Description of the Related Art A secondary battery such as a nickel-cadmium battery has a property that the voltage gradually increases as it is charged, and when the battery is fully charged, the voltage reaches a peak and then drops.
Therefore, the battery voltage is a predetermined amount (so-called ΔV) from the peak value.
It is possible to fully charge the secondary battery by detecting that the battery voltage has dropped and stopping charging, or by switching from quick charging to trickle charging.

In the above description, it is preferable that the value of ΔV is small so that the secondary battery is not overcharged. However, if this is done, there is a risk that the charge will be prematurely cut off due to fluctuations in the power supply during the charging, noise, etc. There is. Therefore, JP-A-2-
According to Japanese Patent Laid-Open No. 101934, when the rising gradient of the battery voltage is detected and it is detected that the rising gradient changes from a gradual state to a steep state, it is determined to be the end of charging, and Δ
Charging is controlled by detecting V.

[0004]

As described above, the device for detecting the full charge of the secondary battery based on both ΔV and the rising slope of the battery voltage is compared with the device for detecting only ΔV. Although it can prevent premature disconnection, the remaining capacity is 70-80
When charging a secondary battery that is close to full charge (%), overcharge may occur. This is because the rising slope of the battery voltage when charging a secondary battery close to full charge is
This is because it is steep from the beginning, and a change from a gentle rise to a steep rise is unlikely to appear.

Therefore, an object of the present invention is to reliably charge a secondary battery to full charge without causing premature disconnection or overcharge.

[0006]

SUMMARY OF THE INVENTION The present invention provides a charging device for detecting battery voltage of a battery to be charged, detecting that the battery voltage has dropped from a peak value by a predetermined amount, and controlling charging.
The charging control is performed when the battery voltage is decreased by a predetermined amount from a peak value and the temperature increase degree is equal to or higher than a predetermined value, including temperature detection means for detecting a degree of increase in battery temperature of the battery to be charged. It is characterized by

[0007]

The control of charging in the present invention is performed when the battery voltage decreases from the peak value by a predetermined amount and the temperature increase degree of the battery is equal to or higher than the predetermined value.

[0008]

FIG. 1 is a block circuit diagram showing an embodiment of the present invention. Reference numeral 1 denotes a RAM, a ROM that stores a charge control program and various charge conditions, a charge control unit that includes a microcomputer and other peripheral circuits, and B denotes a battery to be charged that includes a nickel-cadmium battery, a nickel-hydrogen battery, or the like, 2 Is a power supply unit that receives an alternating current from a commercial power source (not shown) and supplies a constant current to the battery to be charged B, and the voltage V of the battery to be charged B being charged is sampled and detected at a predetermined cycle, The voltage detection unit 4 input to the charging control unit 1 samples and detects the battery temperature T of the battery B to be charged during charging at a predetermined cycle, and inputs the temperature detection unit to the charging control unit 1.
5 is a timer circuit in which the charge protection timer time of the charged battery B is set and counts the protection timer time from the charging start time of the charged battery B; 6 is an LED and its drive circuit, Is a display unit for displaying.

FIG. 2 is a flow chart showing the charging operation of such a charging device. When the charging operation is started, a large constant current is supplied from the power source section 2 to the battery to be charged B in step S1, and the battery to be charged is charged. The rapid charge of B is started.
At this time, the counting of the protection timer time by the timer circuit 5 is also started at the same time. In step S2, whether or not the battery voltage V of the battery B to be charged has decreased by ΔV is detected based on the voltage detection of the voltage detection unit 3. Now ΔV
Is detected, the degree of increase ΔT of the battery temperature of the battery to be charged B is calculated in step S3 based on the temperature detection of the temperature detector 4 (the degree of increase ΔT in the present embodiment is
Means the temperature rise of the battery B to be charged per predetermined time)
Is determined to be equal to or greater than a predetermined value.

That is, in the rising curve of the battery voltage V and the battery temperature T shown by the solid line in FIG. 3, when ΔV is detected during the charging of the battery B to be charged due to fluctuations in the power supply section 2, noise, etc. (FIG. 3), the battery temperature T at that time is gradually increasing, and the increase degree ΔT is smaller than the predetermined value. On the other hand, when ΔV is detected when the battery B to be charged is fully charged (time point B in FIG. 3), the battery temperature T at that time point is sharply increased, and the increase degree ΔT becomes larger than the predetermined value.

As described above, it is possible to determine whether the battery B to be charged is in the middle of charging or is fully charged depending on whether or not the degree of increase ΔT in the battery temperature of the battery B to be charged is equal to or more than a predetermined value. Is. Therefore, in step S3, when the degree of increase ΔT of the battery temperature of the battery to be charged B is equal to or less than the predetermined value, it is determined that the battery to be charged B is being charged, and the process returns to step S1. Then, the rapid charging is continued until ΔV is detected again in step S2.

On the other hand, in step S3, the battery to be charged B is charged.
If the degree of increase ΔT in the battery temperature is above a predetermined value,
It is determined that the battery B to be charged is fully charged, and step S4
At, the quick charge ends, and the display unit 6 displays the full charge. Thereafter, in step S5, trickle charging is started by the trickle current, and when the predetermined trickle charging ends, the charging operation ends.

In step S2, the voltage detector 3
The battery voltage V of the battery B to be charged is Δ
When the decrease of V is not detected and the counting of the protection timer time in the timer circuit 5 is completed in step S6, the process is forcibly shifted to step S4 and the rapid charging is ended, and the display unit 6 displays the full charge. To be done. In this case, although the battery B to be charged may not be in a fully charged state, it is almost in a fully charged state. Therefore, the charging state is forcibly terminated after the elapse of the protection timer time so that the charging state is maintained for a long period of time and the life of the battery B to be charged does not decrease.

By the way, when charging a fully charged battery B having a remaining capacity of 70 to 80%, the rising curves of the battery voltage V and the battery temperature T of the charged battery B are indicated by broken lines in FIG. As shown, it becomes steep from the beginning, and step S
Whether or not the degree of increase ΔT in the battery temperature of the battery-to-be-charged B in 3 is greater than or equal to a predetermined value is reliably determined. Therefore, the battery B to be charged is fully charged without being overcharged.

In the present embodiment, the temperature rise of the battery B to be charged B is detected as the degree of increase ΔT of the battery temperature T of the battery B to be charged, but the battery B to be charged from the start of charging is detected. You may make it detect the absolute value of the rising temperature of B. Further, after detecting the full charge, the quick charge is shifted to the trickle charge, but the trickle charge is not always necessary, and the charge may be ended immediately.

[0016]

According to the present invention, the battery voltage of the battery to be charged is controlled by detecting the battery voltage of the battery to be charged and detecting that the battery voltage has dropped from the peak value by a predetermined amount. Equipped with temperature detecting means for detecting the degree of temperature rise, the battery voltage is reduced from the peak value by a predetermined amount, and the charging control is performed when the degree of temperature increase is equal to or higher than a predetermined value, so premature charge termination It also prevents overcharging and ensures a full charge.

[Brief description of drawings]

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

FIG. 2 is a flowchart showing the operation of the embodiment of the present invention.

FIG. 3 is a characteristic diagram of a battery voltage and a battery temperature of a non-charged battery.

[Explanation of symbols]

 1 Charge control unit 3 Voltage detection unit 4 Temperature detection unit B Battery to be charged

Claims (1)

[Claims] 1. A charging device for controlling charging by detecting a battery voltage of a battery to be charged, detecting that the battery voltage has dropped from a peak value by a predetermined amount, and detecting a degree of increase in battery temperature of the battery to be charged. A charging device comprising: a temperature detecting means for controlling the charging when the battery voltage decreases from a peak value by a predetermined amount and the temperature increase degree is a predetermined value or more.