JPH03145935A - Charging apparatus - Google Patents

Abstract

PURPOSE:To cause the apparatus to deal with a recoverable or irrecoverable charging battery accurately by changing a charging current from a current within a predetermined range to a minute current through a charging control means and by controlling comparing means, etc. CONSTITUTION:A charging control means 5 having received signals from A/D conversion means 11, maximum value holding means 3 and first comparing means 4 changes a charging current from that of 0.251.0C (C is the rated capacity of a charged battery) ampere to a minute current. The charging control means 5 starts timer circuits 6, 14 and receives the comparison result of the terminal voltage and specified value of a charged battery 1 within a timer period of time from a comparing means 11. When the terminal voltage is higher, the charging control means 5 judges charge to be completed and, when the terminal voltage is lower, stops the timer circuits 6, 14 at the point of time, where the voltage lowers, then charges the battery again, and causes a counting means 15 to count. Thus, it is possible to continue charging a recoverable battery to place it in a fully-charged state quickly and surely and to perform the abnormal battery display of an irrecoverable battery.

Description

[Detailed description of the invention] n Rakudo usage fields The present invention relates to a charging device for a secondary battery.

BACKGROUND OF THE INVENTION In recent years, secondary batteries such as small sealed lead-acid batteries and nickel-cadmium batteries have come into widespread use as power sources for portable electronic devices.

The charging device for these secondary batteries detects when the terminal voltage of the battery to be charged reaches the charging control voltage or when the terminal voltage drops by more than a specified value from the maximum value (hereinafter referred to as -ΔV detection).
Some devices detect the completion of charging by detecting .

A conventional charging device that detects the completion of charging by performing the above-mentioned -Δ■ detection will be described below with reference to the drawings.

Figure 7 shows a battery that is equipped with means for detecting that the terminal voltage has dropped by more than a specified value from the maximum value, and that displays the state of charge.
FIG. 2 is a block diagram of a conventional charging device equipped with a D circuit.

In FIG. 7, 1 is a battery to be charged, 2 is a DC stabilized power supply that outputs a charging current, and 3 is a terminal fli of the battery 1 to be charged.
Maximum value holding means for storing the maximum value of pressure, 4 is the stored value of the maximum value holding means 3 and charging? A first comparing means for comparing the terminal voltages of the lff battery 1; 5 a charging control means for controlling charging in response to a signal from the first comparing means 4; and 6 a maximum value holding means for a timer time T from the start of charging. 3 and the first comparison means 4
This is a first timer circuit that stops the operation of the . 7 is the first
and 8 constitute an LED circuit with an LED. 9 is a first transistor that controls the charging current, and 10 is a second resistor that determines the trickle charging current.

The operation of the charging device configured as described above will be described below.

First, the first transistor is turned on and charging begins.

At the same time as charging starts, L E D 8 lights up to display the charging status, and a first timer circuit is activated to prevent erroneous detection of -Δ■ due to uncertain fluctuations in the terminal voltage of the battery 1 to be charged in the initial stage of charging. is started, and the operation of the highest value holding means 3 and the first comparison means 4 is stopped for a first timer time T1. After the first timer time Tl elapses, the highest value holding means 3 and the first
The operation of the comparing means 4 is started, and the highest value holding means 3 stores the highest value of the terminal voltage value of the charged battery 1 from the start of operation to the present time, and compares this stored value with the current charged value. The terminal voltage of the battery 1 is compared by the first comparing means 4, and the terminal voltage of the battery 1 to be charged is the first specified voltage (ΔV).
When the voltage decreases above or below, a -Δ■ detection signal is sent to the charging control means 5. Upon receiving this ΔV detection signal, the charging control means 5 turns off the first transistor 9, switches to trickle charging, and turns off the LED 8 to indicate the completion of charging.

Problems to be Solved by the Invention However, with the above-mentioned conventional configuration, when charging a battery that has been over-discharged or left unused for a long time and has a high internal resistance, the terminal voltage of the battery to be charged increases at the same time as charging begins. Because it exhibits a charging characteristic of rising and then gradually falling,
Charging completion is detected at the beginning of charging, i.e., 1 ΔV is detected, and if the battery can be recovered by charging, charging will definitely end without being fully charged, and even if there is an abnormal battery that cannot be recovered, charging will end as if it were a normal battery. It had the disadvantage of being

Means for Solving the Problems In order to solve the above-mentioned problems, the charging device of the present invention includes a charging completion detection means for detecting the completion of charging based on the terminal voltage of the battery to be charged, and a terminal voltage of the battery to be charged and a certain specified voltage. a timer circuit that receives a charging completion detection signal, starts operation, and sends out a signal after the timer period has elapsed; and a timer circuit that increases the count value by 1 when transitioning to recharging, until the count value reaches the specified number of times. counting means for sending a signal when the
Charging control means that receives signals from the charging completion detection means, the comparison means, the timer circuit, and the counting means to control charging; and a charging display circuit that receives signals from the charging control means and displays a charging state. The configuration includes a DC stabilized power supply that outputs charging current.

Effect With this configuration, the charging control means that receives the signal from the charging completion detection means switches the charging current from 0.25 to 1.0 C amperes to O to 0.02 C amperes, starts the timer circuit, and completes the charge within the timer time. Receive the comparison result between the terminal voltage of the battery to be charged and the specified value from the comparison means, and if the terminal voltage is higher, charging is completed, and if it is lower, the timer circuit is stopped from the moment it becomes lower, and charging is started again. By repeating the operation of starting from the beginning and increasing the count value of the counting means at the same time, it is possible to detect the completion of charging at the beginning of charging for batteries that are over-discharged or have been left for a long time and have high internal resistance and can be recovered. Charging continues even when the battery is fully charged, allowing the battery to be fully charged quickly and reliably.

On the other hand, for a battery that cannot be recovered, when the count value of the counting means reaches a predetermined number of times, the charging current can be reduced to zero, and an abnormal battery display can be performed.

EXAMPLE An example of the present invention will be described below with reference to the drawings. FIGS. 1 and 2 show block diagrams of a charging device according to an embodiment of the present invention.

In FIG. 2, 1 is a battery to be charged, 2 is a DC stabilized power supply, 3 is a maximum value holding means, 4 is a first comparison means, 5 is a charging control means, 6 is a first timer circuit, and 7 is a first timer circuit. resistance of 1, 8
9 is an LED, 9 is a first transistor, and 10 is a second resistor, which is the same as the configuration shown in FIG. 7. 11 is A that converts the terminal voltage of the battery 1 to be charged from analog to digital;
/D conversion means, 12 is a specified value generation means for generating a specified voltage value, and 13 is a specified voltage value of the specified value generation means 12 and A
A second comparing means 14 which compares the output values of the /D converting means and sends the result to the charging control means 5 receives the signal from the first comparing means 4 and is activated by the charging control means 5 to set the timer time. A second timer circuit 15 sends a signal to the charge control means 5 after T2 has elapsed, and a count 15 increases the count value by 1 in response to a signal from the charge control means 5, and sends a signal to the charge control means 5 when the predetermined number of times has been reached. means 16 are connected in series with the second resistor 10 to control the trickle current;
, 17 is a third resistor that determines the open-circuit voltage measurement current of 0 to 0.02 C amperes, and 18 is a third transistor connected in series with the third resistor 17 to control the open-circuit voltage measurement current. .

Here, 3.4, 5, 6, 11, 12°13 in Figure 2.
14.15 is realized by a microcomputer.

In FIG. 1, 21 is a charging completion detection means, 22 is a comparison means,
23 is a charging control means centered around 5, 24 is a timer circuit, 25 is a counting means, 26 is a charging current control circuit, 27
1 and 2 respectively show charging display circuits.

The operation of the charging device configured as described above will be described below.

First, the control procedure of the charging device of this embodiment will be explained. First, the first transistor 9 is turned on, and the charging current I
[Charging is started by setting + to a current 1o of 0.25 to 1.0 C ampere. At the same time as charging starts, the LED 8 lights up to display the charging status, and the first timer circuit starts to prevent erroneous detection of charging completion due to uncertain fluctuations in the terminal voltage of the battery 1 to be charged in the initial stage of charging. , the operation of the highest value holding means 3 and the first comparison means 4 is stopped for a first timer time T1. After the first timer time T1 has elapsed, the operation of the highest value holding means 3 and the first comparing means 4 is started, and the highest value obtained by converting the terminal voltage of the charged battery 1 into a digital value by the A/D converting means 11 V BMAX is the highest value holding means 3
The highest value V[1MAX and the latest output value V[l of the A/D conversion means 11 are compared in the first comparison means 4, and when VB falls below VBMAX by more than a specified voltage ΔV, charging is started. A completion signal is sent to the charging control means 5.

Upon receiving this charge completion signal, the charging control means 5 turns off the first transistor 9, turns on the third transistor 18, causes the open circuit voltage measurement current 11 to flow, and starts the second timer circuit.

The output value V of the A/D conversion means 11 within the second timer time T2
8 and the output value VR of the specified value generating means 12 are compared by the second comparison means 13, and if 8≧VR, it is determined that charging is complete, the third transistor 18 is turned off, and the second transistor 16 is turned off. The LED 8 is turned on to perform trickle charging with a charging current of 12, and the LED 8 is turned off to display the completion of charging.

In the case of V Ll < VR, even during the second timer time T2, the second
The timer is stopped and reset, and the count value n of the counting means 15 is increased by 1. If n has not reached the specified number of times N, that is, if n<N, charging is performed again from the beginning, and n
reaches the specified number of times N, that is, when n=H, the battery 1 to be charged is determined to be abnormal, and the third transistor 18
is turned off to make one charging current zero, and the LED 8 blinks to indicate a battery abnormality. FIG. 3 is a flowchart showing the control procedure.

Next, the operation of the charging device of this embodiment when charging a battery whose internal resistance has become high due to over-discharging or long-term storage will be described.

When charging a battery whose internal resistance has increased due to over-discharging or long-term storage, the terminal voltage of the charged battery 1 increases instantaneously and then gradually decreases, as shown in FIG. Charging completion detection at the beginning of charging (-ΔV detection)
will be done. However, since the battery 1 to be charged is not fully charged, when the charging current is set to the open circuit voltage measurement current I of O to 0.02 C amperes, V[1<
VII, so it will be charged again from the beginning. This repeated charging operation is performed until the internal resistance of the battery 1 to be charged decreases, and the battery 1 to be charged is recovered and charged. If the rechargeable LiM battery 1 is a recoverable battery, it will have normal charging characteristics after the completion of the recovery charge as shown in FIG. 4, and if it is a non-recoverable battery, it will have normal charging characteristics as shown in FIG. As shown in the figure, after repeated charging has been performed a specified number of times, the charging current is reduced to zero, a battery abnormality display is displayed, and the charging is completed.

As described above, according to this embodiment, charging completion detection (−Δ■
After detection), set the charging current to 11 and set the current V[l to VR
By comparing with the battery, you can repeat the charge again and count the number of repetitions, so if the battery has been over-discharged or has been left for a long time and has a high internal resistance, it can be quickly recovered.
It is possible to fully charge the battery reliably, and if it cannot be recovered, a battery abnormality will be displayed to prevent misuse.

In this embodiment, the -Δ■ charge control method was used as the charge control method, but V Taber charging is used in which the charging current is reduced at a predetermined reduction rate after the terminal voltage of the battery to be charged reaches the charge control voltage. Control methods may also be used. FIG. 6 shows the charging characteristics of over-discharged or neglected batteries when using the V-Taber charging control method.

Effects of the Invention As described above, the present invention reduces the charging current to O~ after detecting the completion of charging.
Switch to the open circuit voltage measurement current of 0.02 C amperes, compare the terminal voltage of the battery to be charged with a certain specified voltage within a specified time, and decide whether to continue charging based on the comparison results and whether the battery is normal or abnormal depending on the number of times of comparison. By providing a charging control means that can determine whether the battery is over-discharged or has been left unused for a long period of time and has a high internal resistance, it is possible to quickly and reliably fully charge the battery that can be recovered, and to fully charge the battery that cannot be recovered. Therefore, it is possible to realize an excellent charging device that can reduce the charging current to zero, display a battery abnormality, and prevent misuse.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the overall configuration of the charging device of the present invention, FIG. 2 is a block diagram of an embodiment of the present invention, and FIG.
FIG. 4 is a flowchart showing the control procedure according to the same embodiment, FIG. 4 is a charging characteristic diagram of a recoverable battery according to the same embodiment, and FIG. 5 is a charging characteristic diagram of a non-recoverable battery according to the same embodiment.
Fig. 6 is a charging characteristic diagram of a recoverable battery when the V Taber charging control method is used as the charging control method of the same embodiment, Fig. 7 is a block diagram of the conventional example, and Fig. 8 is an over-discharge diagram of the conventional example. FIG. DESCRIPTION OF SYMBOLS 1... Battery to be charged, 2... DC stabilized power supply, 21... Charging completion detection means, 22...
... Comparison means, 23 ... Charging control means, 24
...Timer circuit, 25...Counting means, 26
...Charging current control circuit, 27...Charging display circuit.

Claims (3)

[Claims] (1) Detecting that the terminal voltage of the battery to be charged has reached the control voltage, or detecting that the terminal voltage has dropped by more than a first specified voltage from the highest value, and 0.25 to 1.0
In a charging device that terminates charging by reducing the charging current of C amperes (where C is the rated capacity of the battery to be charged) to a minute trickle charging current instantaneously or at a predetermined reduction rate, charging completion detection means for detecting the completion of charging based on the terminal voltage; comparison means for comparing the terminal voltage of the battery to be charged with a second specified voltage; 25~
switching from a current of 1.0 C ampere to a current that measures the open terminal voltage of the battery to be charged, which is finer than a trickle current;
and charging control means for restarting charging from the beginning if the comparison result of the comparison means is lower than the second specified voltage, and for continuing the open-circuit voltage measurement current if the comparison result is higher than the second specified voltage. and a charging current control circuit that receives a signal from the charging control means to control the charging current, a charging display circuit that displays the charging state based on the signal from the charging control means, and a DC stabilized power source that outputs the charging current. A charging device characterized by: (2) A timer circuit controlled by a charging control means, wherein the charging control means activates the timer circuit in response to a signal from the charging completion detection means, and the comparison result of the comparison means is set to a second value before the timer time elapses. If the voltage is lower than the specified voltage, the operation of the timer circuit is stopped and charging starts again from the beginning, and if it is higher than the second specified voltage, the open terminal voltage measurement current is continued, and the timer circuit is stopped for the timer period. 2. The charging device according to claim 1, wherein after the elapse of time, the trickle charging current is applied to terminate charging regardless of the comparison result of the comparing means. (3) comprising a counting means controlled by the charging control means, the charging control means increasing the count value of the counting means when the comparison result of the comparing means becomes lower than the second specified voltage; 2. The charging device according to claim 1, wherein when the count value reaches a predetermined number of times, the charging current is made zero and a battery abnormality signal is sent to the charging display circuit.