JP3317513B2 - Charging circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging circuit for suppressing an increase in battery voltage due to charging to prevent electrolysis of an electrolytic solution in a battery.

[0002]

2. Description of the Related Art Conventionally, there has been known a charging circuit in which one or two or more storage batteries such as Ni-Cd batteries and lead storage batteries are connected in series and a large current is supplied to these storage batteries to perform rapid charging. .

[0003]

However, in the above-described charging circuit, when the fully charged battery is recharged by mistake, the battery temperature rises and the temperature rise value exceeds the set ΔT. Since the battery is overcharged until it is terminated, the storage battery may be deteriorated or damaged.

Further, when a storage battery that has been left for a long period of time is connected and quick charging is performed, the internal voltage of the storage battery increases due to the storage, and the battery voltage increases significantly. And
When the battery voltage reaches or exceeds a voltage at which the electrolytic solution in the battery causes electrolysis, that is, for example, 2.0 V or more per cell for each battery of the storage battery, the electrolytic solution is electrolyzed and gas ( (Hydrogen gas). As a result, the storage battery is deteriorated or damaged.

[0005] In addition, the storage battery deteriorates as charging and discharging are repeated, and the battery capacity decreases and the internal resistance increases. However, it is difficult for the user to grasp the degree of the deterioration, and there is a possibility that the use may be hindered.

The present invention has been made in view of the above problems, and has as its object to provide a charging circuit that suppresses a rise in battery voltage during charging and does not overcharge a storage battery.

Another object of the present invention is to provide a charging circuit that suppresses a rise in battery voltage during charging and prevents electrolysis of an electrolytic solution in the battery.

Another object of the present invention is to provide a charging circuit for notifying a user of deterioration of a storage battery.

[0009]

In order to achieve the above object, the present invention provides a charging circuit for charging a storage battery with a first charging current, a voltage detection means for detecting a battery voltage of the storage battery, The first and second control voltages (first control voltage <second control voltage) for charge control based on the number of cells of the storage battery are changed from the first control voltage to the second control when a predetermined time has elapsed from the start of charging. Control voltage setting means for switching and setting the voltage; voltage comparing means for comparing the battery voltage with the set control voltage; and the first charging current when the battery voltage becomes equal to or higher than the set control voltage. A charging current switching means for switching to a second charging current (<first charging current) is provided (claim 1).

Further, in the charging circuit according to the first aspect,
A timer for measuring a first set time and a second set time; and a battery for charging the storage battery when the first set time has elapsed after the start of charging and when the battery voltage has become equal to or higher than the set control voltage. Charge release means for releasing the charge for only the set time of 2, release voltage detection means for detecting the battery voltage within the second set time, and battery voltage of the storage battery from the battery voltage detected by the release voltage detection means. A cell number detecting means for detecting the number of cells, a cell number comparing means for comparing each detected cell number, and comparing the cell numbers as a result of the comparison, if the cell numbers are different, the second control voltage And control voltage changing means for changing and setting the level of the control voltage.

Further, in the charging circuit according to claim 2,
Internal resistance detection means for detecting the internal resistance of the storage battery from the electromotive voltage of the storage battery determined from the detected number of cells, the battery voltage during charging detected by the voltage detection means, and the second charging current And a notifying means for outputting a notifying signal when the detected internal resistance is equal to or more than a predetermined value (claim 3).

Further, in the charging circuit according to the first aspect,
The internal resistance of the storage battery is detected using one of the difference between the battery voltages when the first and second charging currents are supplied and the difference between the battery voltage when the second charging current and the trickle charging current are supplied. A second internal resistance detecting means for outputting a notification signal when the detected internal resistance is equal to or more than a predetermined value.

Further, in the charging circuit according to the first aspect,
Charge completion voltage detecting means for detecting a battery voltage after charging is completed, and display means for displaying a voltage value of the detected battery voltage, a character ranked based on the voltage value, or the number of storage battery cells obtained from the detected voltage. (Claim 5).

[0014]

According to the present invention, charging of the storage battery is started with the first charging current, and the battery voltage of the storage battery is detected. In addition, the first and second control voltages (first control voltage <second control voltage) for charge control based on the number of cells of the storage battery are switched from the first control voltage to the second control voltage when a predetermined time has elapsed from the start of charging. Is switched to the control voltage. Then, the set control voltage is compared with the detected battery voltage, and when the battery voltage becomes equal to or higher than the set control voltage, the first charging current becomes the second charging current.
(The first charging current).

According to the present invention, the storage battery is charged for the second set time when the first set time has elapsed after the start of charging and when the battery voltage has become equal to or higher than the set control voltage. It is released. The battery voltage is detected within the second set time, and the number of cells of the storage battery is detected. Then, as a result of comparing the detected numbers of cells, if the number of cells is different, the level of the second control voltage is changed and set.

According to the third aspect of the present invention, the internal resistance of the storage battery is detected from the electromotive voltage of the storage battery, the battery voltage during charging, and the second charging current. Then, when the internal resistance is equal to or more than a predetermined value, a notification signal is output.

According to the fourth aspect of the present invention, the first
The internal resistance of the storage battery is detected using one of the difference between the battery voltage when supplying the second charging current and the difference between the battery voltage when supplying the second charging current and the trickle charging current. Then, when the internal resistance is equal to or more than a predetermined value, a notification signal is output.

According to the invention, the battery voltage is detected after the charging is completed. Then, the voltage value of the detected battery voltage, characters ranked based on the voltage value, or the number of cells of the storage battery obtained from the detected voltage are displayed.

[0019]

FIG. 1 is a circuit block diagram showing the configuration of a first embodiment of a charging circuit according to the present invention. The rectifier 1 and the capacitor C1 rectify and smooth the AC from the AC power supply 2 and output the rectified and smoothed AC to the transformer T. The FET Q1 switches the current flowing into the primary coil L1 of the transformer T in response to a switching pulse from a PWM control circuit 7 described later. The transformer T induces electric power in the secondary coil L2 by switching the current flowing into the primary coil L1. The rectifying / smoothing circuit 4 includes diodes D1 and D2, a choke coil L3, and a capacitor C2. The rectifying / smoothing circuit 4 rectifies and smoothes the output from the secondary coil L2 and supplies the output to the storage battery 3 as a charging current.

The resistor R 1 outputs a voltage corresponding to the charging current to the feedback amplifier 5. The gain of the feedback amplifier 5 is set by the resistors R2 and R3 and the capacitor C3. The feedback amplifier 5 amplifies the voltage from the resistor R1 at the above-described gain and performs PWM through the resistor R5 and the photocoupler PC.
The data is output to the control circuit 7. Further, the amplification factor of the feedback amplifier 5 is changed when the resistor R4 is connected in parallel with the resistor R3 so as to switch from the first charging current I1 to the second charging current I2 by the microcomputer 6 described later. ing.

The PWM control circuit 7 controls the charging current to the storage battery 3 at a constant current, and feeds back to the storage battery 3 to supply a first charging current I1, a second charging current I2 or a trickle charging current I3 described later. A switching pulse having a duty according to the voltage level from the amplifier 5 is supplied to the FET Q1
Output to Further, the PWM control circuit 7 receives the completion signal (or the inhibition signal) from the microcomputer 6 described later and makes the duty of the switching pulse to the FET Q1 extremely small, or turns off the switching pulse. Thus, trickle charging current I3 (see FIGS. 3 and 4) is supplied to storage battery 3, or the supply current is turned off.

The microcomputer 6 has a built-in timer 61,
When a predetermined time T1 elapses from the start of charging, the switch SW is turned off to stop charging current to the storage battery 3 and bring the battery to a charge releasing state.
Is turned off for a predetermined time T2 (time t1 to time t2 in FIGS. 3 and 4). Further, the microcomputer 6 has a function of detecting the battery voltage Vc of the storage battery 3 via the voltage dividing resistors R6 and R7, a function of comparing the battery voltage Vc at the time t2 with a previously stored threshold value, A function of identifying the number of cells of the storage battery 3;
_1, V ₂ and the function and the battery voltage Vc set in operation is the control voltage V _1, V ₂ or from the first charging current I1 to a resistor R3 of the feedback amplifier 5 to switch to a second charging current I2 It has a function of connecting the resistor R4 in parallel. Note that the threshold value is such that the battery voltage Vc is, for example, 9.6V to 12V.
If it is V, it is identified that it is 8 cells, and 12V to 16V
If so, it is set to a value that can identify that it is 10 cells. That is, from 1.2 V per cell
It has 1.5V.

Further, the microcomputer 6 has a ΔT control unit 60 for detecting the full charge of the storage battery 3.
Battery temperature rise rate per unit time,
That is, when it is detected that the temperature rise rate ΔT exceeds a predetermined value, or when the timer 61 detects that the charging completion time has been reached, it is determined that the storage battery 3 is fully charged, and the resistance R8 and the photo A completion signal is output to the PWM control circuit 7 through the coupler PC.

The temperature sensor 8 detects the battery temperature of the storage battery 3 and outputs it to the amplifier circuit 9. The amplification circuit 9 amplifies the battery temperature signal from the temperature sensor 8 and
0 is output.

Reference numerals 22a, 22b, 22c and 22d are terminals for connecting the charging circuit to the battery pack 11, 22a is a + terminal, 22b is a-terminal, 22c is a ground terminal, and 22d is a sensor terminal.

The microcomputer 6 outputs a suppression signal to the PWM control circuit 7 through the resistor R8 and the photocoupler PC in order to suppress the output from the rectifying / smoothing circuit 4 during the OFF period of the switch SW, that is, the time T2. Is also good.

The resistor R9, capacitor C4 and diode D3 constitute a snubber circuit.

Here, the calculation and setting of the control voltages V ₁ and V ₂ will be described. The control voltage V ₂ is equal to or lower than a critical voltage at which the electrolyte in each cell of the storage battery 3 is electrolyzed (for example, 2 V
/ Cell). That is, for example, 1.2
In the case of charging a battery pack that the Ni-Cd battery V was 10 cells (number) connected in series, the control voltage V ₂ is, V ₂ = 2 (V / cell) × 10 (cells) = 20 (V ) Is set to.

Next, since the control voltage V ₁ is to prevent overcharging at the time of recharging the fully charged battery, the control voltage V ₁ is made lower than the control voltage V ₂ , the current value is reduced, and the overcharge amount is reduced. Reduce. Thus, for example, if it is set to 1.9 (V / cell), then V ₁ = 1.9 (V / cell) × 10 (cell) = 19 (V).

Next, the operation of the charging circuit according to the first embodiment of the present invention will be described with reference to the flowchart of FIG.
This will be described with reference to the time chart of FIG. In the first charging current I1 charging current in a normal state, the second charging current I2 (<I1) is a charging current after the battery voltage Vc rises to the control voltage V _1, V ₂ or more. The trickle charge current I3 (≪I2) is a current that maintains full charge.

When charging is started after the switch SW is turned on, the first charging current I1 is supplied to the storage battery 3 through the switch SW (step S1), and when the time T1 has elapsed (YES in step S2), the charging current is reduced. The switch SW is turned off to stop the operation (step S3), and this charge release state is continued until the time T2 elapses (step S3).
4). After the time T2 elapses (YE in step S4).
S), the battery voltage Vc of the storage battery 3 is read (step S)
5) The battery voltage Vc is compared with a threshold value stored in the microcomputer 6 in advance, and the number of cells of the storage battery 3 is identified based on the comparison result (step S6).

That is, the storage battery 3 connected to the present charging circuit includes an over-discharged battery, a battery that is recharged before almost no capacity is used, and the like.
c is different for each storage battery. On the other hand, the battery voltage Vc of the storage battery 3 rises in a short time immediately after the start of charging, and then stabilizes at almost the same voltage until near full charge. Therefore, before the battery voltage Vc is detected, only the time T1 (t1 in FIGS. 3 and 4)
By charging (up to the point in time), the battery voltage Vc becomes substantially the same regardless of the state of the storage battery 3 before charging. Thereby, even in the case of the overcharged storage battery 3 or the like, the identification error of the number of cells is reduced.

The battery voltage Vc of the storage battery 3 that has been left for a long period of time increases significantly when a charging current flows, and the battery voltage Vc differs depending on the storage period. For this reason, after the charging current flows for the time T1, the time T2 (t1 in FIGS. 3 and 4).
The battery voltage Vc is stabilized by turning off the switch SW for only the time point to the time point t2 and setting the battery to the charge release state.
At this point, the battery voltage Vc is detected. As a result, even if the storage battery 3 has been left for a long time, the identification error of the number of cells is reduced.

Also, when the fully charged battery is recharged, the battery voltage Vc also becomes extremely high, but is stabilized by releasing the charge.

Subsequently, after the control voltages V ₁ and V ₂ are calculated and set as described above from the number of identified cells (step S7), the switch SW is turned on again (step S7).
8). Thereafter, the storage battery 3 is charged again with the first charging current I1 (step S9), the elapsed time is determined (step S10), and the time T5 (time 0 to t5 in FIGS. 3 and 4) elapses. , it compares the battery voltage Vc to the control voltage V ₁ (step S11). Then, as shown in FIG.
If c> V _1, the process proceeds to step S13, while FIG. 3
As shown in, Vc> unless V _1, the flow returns to step S9.

On the other hand, in step S10, if elapsed T5 hours, compares the battery voltage Vc to the control voltage V ₂ (step S12), Vc> V ₂ Otherwise, the process returns to step S9, whereas, Vc> if V _2, the supply current and the second charging current from the first charging current I1 to battery 3 I2
(At time t3 in FIG. 3), and the second charging current I
In step 2, the storage battery 3 is charged (step S13). For this reason, as shown in FIG. 3, the battery voltage Vc after the time t3 becomes equal to or lower than the control voltages V ₁ and V ₂ .

Thereafter, for example, when the temperature rise rate ΔT of the battery temperature becomes equal to or more than a predetermined value at time t4 or when the timer 61 detects that the charging completion time has been reached, trickle charging is performed from the second charging current I2. The current is switched to the current I3 or the supply current is turned off, and the charging is completed.

[0038] That is, for example, a first charging current I1 to perform the rapid charging by setting a large current starts to fast charging, the battery voltage Vc is the control voltage V _1, V ₂ or more, the second charge By switching to the current I2, it is possible to prevent the electrolytic solution in the battery from being electrolyzed due to the battery voltage Vc becoming too high while performing rapid charging.

When the fully charged battery is recharged, the charge current I1 is switched to a smaller current I2, so that the overcharge amount can be suppressed and the battery can be prevented from being deteriorated.

Next, a second embodiment of the charging circuit according to the present invention will be described with reference to FIGS. The configuration of the second embodiment is the same as the configuration of the first embodiment shown in FIG. Next, the operation of the charging circuit according to the second embodiment of the present invention will be described with reference to the flowchart of FIG. 5 and the time charts of FIGS.

Steps S21 to S25 are the same as steps S1 to S5 in FIG. 2, and a description thereof will be omitted.

Subsequent to step S25, the battery voltage Vc is compared with a threshold value stored in the microcomputer 6 in advance, and the number of cells (N1) of the storage battery 3 is identified based on the comparison result (step S26).

Subsequently, control voltages V ₁ and V ₂ (V ₂ ′, where V ₂ ′> V ₂ when step S37 described later is continued) are calculated and set as described above from the number of cells identified above. After that (step S27), the switch SW is turned on again (step S28). Thereafter, again the storage battery 3 is charged by the first charging current I1 (step S29), to determine the elapsed time (step S30), until the passage of T5 hours, compared with the battery voltage Vc to the control voltages V ₁ and if (step S31), Vc> V _1, the process proceeds to step S33, Vc> V ₁ Otherwise, the flow returns to step S29.

On the other hand, if the time T5 has elapsed in step S10, the battery voltage Vc is compared with the control voltage V ₂ (or V ₂ ′) (step S12), and Vc> V ₂ (V
If not ₂ '), the process returns to step S9, while Vc>
If it is V ₂ (V ₂ ′), the process proceeds to step S33.

Then, the switch SW is turned off to stop the charging current again (step S33), and this charging release state is continued until the time T2 elapses (step S3).
4). After the time T2 has elapsed (Y in step S34)
ES), the battery voltage Vc of the storage battery 3 is read (step S35), the battery voltage Vc is compared with a threshold value previously stored in the microcomputer 6, and the number of cells of the storage battery 3 (N2) is determined based on the comparison result. Is identified (step S36).

Next, the number of cells identified in step S26 is compared with the number of cells identified in step S36 (step S37). If N1 is not equal to N2, the process returns to step S27, and the first charging current I1 is set as shown in FIG.
If N1 = N2, as shown in FIG. 6, the storage battery 3 is charged with the second charging current I2 (step S38).

As described above, by recognizing the number of cells of a battery twice, it is possible to reduce the number of cells of the battery even if the voltage is not sufficiently recovered in the first T1 time in the case of a battery which has been significantly overdischarged. It can be prevented that the control voltage is set low due to a small number of erroneous recognitions.

Next, a third embodiment of the charging circuit according to the present invention will be described with reference to FIGS. FIG. 8 is a circuit block diagram showing the configuration of the charging circuit in the third embodiment. The same components as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

The microcomputer 6 'is the microcomputer 6' shown in FIG.
In addition to the function of FIG.
It has a function of reading the voltage Vc (t4) at the four points in time and calculating the internal resistance of the storage battery 3 based on an expression described later, and if the internal resistance is equal to or more than a predetermined value, the display circuit 1
A signal is sent to 0.

The display circuit 10 notifies the user that the storage battery 3 has reached the end of its life, and is constituted by an LED or the like, and is turned on based on a signal from the microcomputer 6 '.

Next, the operation of the third embodiment will be described. Normally, the open circuit voltage of a Ni-Cd battery or the like is about 1.2 V. Therefore, the read voltage Vc (t
From 4), the internal resistance R is obtained from the following equation: R = {Vc (t4) −1.2 × N} / I ₂ (N: number of cells). When this value is R> R ₀ × N (R ₀ : a preset value), it is determined that the life of the battery is reached, and the display circuit 10
Lights up.

In general, a storage battery deteriorates when charging and discharging are repeated, so that the battery capacity decreases and the internal resistance increases. Due to this decrease in capacity, the battery is discharged in a short time, and the output decreases due to an increase in internal resistance. Thus, by performing the life determination as described above, the user can determine whether the cause of the short-time discharge or the decrease in output is due to the life of the battery or the failure of the charger.

The display circuit 10 is not limited to the LED, but may be constituted by a buzzer, a voice IC, or the like so as to notify the user by sound or voice.

Next, a fourth embodiment of the charging circuit according to the present invention will be described with reference to FIG. The configuration of the fourth embodiment is the same as that of the third embodiment shown in FIG. 8 except for some functions of the microcomputer 6 '.

This microcomputer 6 ′ is configured as shown in FIG.
The voltage Vc (t4) immediately before the completion of charging (charging current: I2), that is, immediately before the time t4, and the voltage Vc (t) immediately after the completion of charging (charging current: I3), that is, immediately after the time t4.
4 '), and has a function of calculating the internal resistance of the storage battery based on an expression described later, and sends a signal to the display circuit 10 if the internal resistance is equal to or more than a predetermined value.

Next, the operation of the fourth embodiment will be described. Normally, the open-circuit voltage of a Ni-Cd battery or the like is about 1.2 V. Therefore, the read voltage Vc (t
'From), R = {Vc (t4 ) -Vc (t4' 4) and Vc (t4 _{by)} / (I 2 -I 3} ), obtaining the internal resistance R. When this value is R> R ₀ × N (R ₀ : a preset value, N: the number of cells), it is determined that the life of the battery has been reached, and the display circuit 10
Lights up.

As described above, the same effects as in the third embodiment can be obtained.

In the present embodiment, the internal resistance was calculated before and after the time point t4, that is, the difference between the battery voltages at the charging currents I2 and I3, but before and after the time point t3, that is, at the charging currents I1 and I2. May be used to calculate the internal resistance.

Next, a fifth embodiment of the charging circuit according to the present invention will be described with reference to FIGS. The fifth
The configuration of the embodiment is different from the configuration of the third embodiment shown in FIG.
It is the same except for the function of the display circuit 10. Display circuit 10
Is constituted by an LED or the like, and indicates the number of cells of the storage battery 3 identified.

Next, the operation of the fifth embodiment will be described with reference to the flowchart of FIG. 9 and the time chart of FIG. Steps S51 to S63 are the same as steps S1 to S13 in FIG.

Following step S63, the ΔT control unit 60
Alternatively, when the charging is completed by the timer 61 (at time t4 in FIG. 10) (step S64), the switch SW is turned off to stop the charging current (step S65), and this charging release state is continued until the time T2 elapses. (Step S66). When the time T2 elapses (step S6)
6 (YES at time t6 in FIG. 10), reads the battery voltage Vc of the storage battery 3 (step S67), and reads the battery voltage Vc.
Is compared with a threshold value stored in the microcomputer 6 in advance, and the number of cells of the storage battery 3 is identified based on the comparison result (step S68). Then, the number of identified cells is indicated by the display
0 is displayed (step S69).

As described above, by re-identifying the number of cells of the storage battery 3 after the completion of charging, there is no variation in the battery voltage before charging, and the accurate number of cells can be identified and reported to the user. This allows the user to easily know whether or not any of the battery packs has deteriorated and caused an internal short circuit.

It should be noted that instead of the number of cells, the voltage value itself,
Or you may make it display the numerical value etc. which ranked the voltage value.

Next, a description will be given of a sixth embodiment of the charging circuit according to the present invention, by referring to FIGS. FIG. 11A is a perspective view of a charger and a battery pack, and FIG.
FIG. 1B is a partial cross-sectional perspective view of the charger. FIG. 12 is a side sectional view of a terminal of the charger.

The battery pack 11 houses the storage battery 3. The charger 12 charges the internal storage battery 3 when the battery pack 11 is mounted on the terminal portion 22, and includes a charging circuit and the like as shown in FIG.

The charging circuit includes the battery pack 11 and the charger 1
+ Terminal 22a,-terminal 22b, ground terminal 22c on the second side
After detecting that the sensor terminal 22d and the sensor terminal 22d have come into contact with each other, a signal is output from the microcomputer 6, an oscillation signal is output from the PWM control circuit, oscillation is started, and the charging current is stored in the storage battery 3.
To supply.

Here, as shown in FIG.
The ground terminal 22c and the sensor terminal 22d are configured to be at lower positions than the a terminal and the-terminal 22b.

Thus, the battery pack 11 is connected to the charger 12
When the power supply is disconnected from the power supply, the ground terminal 22c and the sensor terminal 22d of the control system are cut off first, the signal from the PWM control circuit 7 stops, and the charging current is not supplied.
The contact with the terminal 22a and the negative terminal 22b is released.

Therefore, during the supply of the charging current, the positive terminal 22a
When the contact with the negative terminal 22b is released, there is no possibility that an arc is generated and the terminal is deteriorated, and components inside the charging circuit are broken.

Next, a seventh embodiment of the charging circuit according to the present invention will be described with reference to FIGS. 1, 11 and 13. FIG. 13 is a side sectional view of a terminal of the charger 12.
(A) is a state where the battery pack is removed, and (b) is a state where the battery pack is mounted.

The positive terminal 22a 'and the negative terminal 22b' are terminals on the charging circuit side. The support 23 supports the positive terminal 22 a and the negative terminal 22 b of the charger 12. Usually, the + terminal 22a 'and the + terminal 22a, -terminal 2
The 2b 'and the negative terminal 22b are urged by a spring or the like (not shown) so that they do not come into contact with each other, and the insulated state is maintained.

Here, when the battery pack 11 is mounted, as shown in FIG.
b is opened outward with the support 23 as a fulcrum, and the + terminal 2
2a 'and + terminal 22a, -terminal 22b' and -terminal 22b
Contact, and the charging circuit and the storage battery 3 are connected.

With the above configuration, the battery pack 11
Is removed, the output of the circuit is the charger 12
As a result, there is no danger of the output being short-circuited by a foreign object or electric shock to a person.

[0074]

As described above, according to the present invention, when the battery voltage becomes equal to or higher than the control voltage switched and set based on the number of cells of the storage battery, the first charging current is changed to the second charging current (<first charging current). Since overcharging of a fully charged battery can be prevented, leakage due to overcharging, capacity deterioration due to leakage or tracking of the charging circuit can be prevented, and the battery temperature caused by overcharging can be reduced. Deterioration due to the rise can be prevented.

When the first set time comes after the start of charging, the battery is released for the second set time and the battery voltage is detected. Based on the detection result, the number of cells of the storage battery is detected, and the battery voltage is reduced. When the voltage becomes higher than the control voltage, the number of cells is detected in the same manner, and the number of cells is compared, so that insufficient charging due to erroneous detection of the number of cells or prolonged charging time due to switching of the charging current can be prevented. it can.

Further, since the internal resistance of the storage battery is detected and an alarm signal is output when the internal resistance is equal to or more than a predetermined value, it is possible to know the life of the battery and to know the time to replace the battery. In addition, when the required power cannot be obtained, it is easy to determine whether the power is due to the battery life or the charger is defective.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram showing a configuration of a first embodiment of a charging circuit according to the present invention.

FIG. 2 is a flowchart showing an operation of the charging circuit in the first embodiment.

FIG. 3 is a time chart showing an operation when the battery voltage of the charging circuit in the first embodiment is equal to or lower than a control voltage.

FIG. 4 is a time chart showing an operation when the battery voltage of the charging circuit in the first embodiment is higher than a control voltage.

FIG. 5 is a flowchart showing an operation of the charging circuit in the second embodiment.

FIG. 6 is a time chart illustrating an operation when the number of identified cells of the charging circuit in the second embodiment is equal.

FIG. 7 is a time chart illustrating an operation when the number of identified cells of the charging circuit in the second embodiment is different.

FIG. 8 is a circuit block diagram showing a configuration of a third embodiment of the charging circuit according to the present invention.

FIG. 9 is a flowchart showing the operation of the charging circuit in the second embodiment.

FIG. 10 is a time chart showing the operation of the charging circuit in the second embodiment.

FIG. 11A is a perspective view of a charger and a battery pack,
(B) is a partial cross-sectional perspective view of the charger.

FIG. 12 is a side sectional view of a terminal of the charger.

FIGS. 13A and 13B are side sectional views of terminals of the battery charger, wherein FIG. 13A shows a state in which the battery pack is removed, and FIG. 13B shows a state in which the battery pack is mounted.

[Explanation of symbols]

 3 Storage Battery 5 Feedback Amplifier 6 Microcomputer 7 PWM Control Circuit 11 Battery Pack 12 Charger 22 Terminal 22a + Terminal 22b -Terminal 22c Ground Terminal 22d Sensor Terminal Q1 FET R6, R7 Voltage Dividing Resistor SW Switch

Continuation of the front page (56) References JP-A-60-84931 (JP, A) JP-A-2-269421 (JP, A) JP-A-3-251053 (JP, A) JP-A-62-239835 (JP) JP-A-3-293936 (JP, A) JP-A-53-90930 (JP, U) JP-A-53-33127 (JP, Y2) (58) Fields investigated (Int. Cl. ⁷ , DB Name) H02J 7/00-7/12 H02J 7/34-7/36

Claims (5)

(57) [Claims] In a charging circuit for charging a storage battery with a first charging current, a voltage detection means for detecting a battery voltage of the storage battery, and first and second for charge control based on the number of cells of the storage battery. Control voltage setting means for switching and setting the control voltage (first control voltage <second control voltage) from the first control voltage to the second control voltage when a predetermined time has elapsed from the start of charging; Voltage comparing means for comparing the set control voltage with the set control voltage; and charging for switching the first charge current to a second charge current (<first charge current) when the battery voltage becomes equal to or higher than the set control voltage. A charging circuit comprising current switching means. 2. The charging circuit according to claim 1, wherein:
And a timer for measuring the set time and the second set time, and when the first set time has elapsed after the start of charging and when the battery voltage has become equal to or higher than the set control voltage, the storage battery is set to the second set time. Charge release means for releasing the charge for a set time, release voltage detection means for detecting the battery voltage within the second set time, and the number of cells of the storage battery based on the battery voltage detected by the release voltage detection means. Cell number detecting means for respectively detecting the number of cells, cell number comparing means for comparing each detected cell number, and when the number of cells is different as a result of comparison by the comparing means, the level of the second control voltage And control voltage changing means for changing and setting the voltage. 3. The charging circuit according to claim 2, wherein the electromotive voltage of the storage battery determined from the detected number of cells,
An internal resistance detecting means for detecting an internal resistance of the storage battery from the battery voltage and the second charging current during charging detected by the voltage detecting means; and an alert when the detected internal resistance is equal to or more than a predetermined value. A notification circuit for outputting a signal. 4. The charging circuit according to claim 1, wherein the difference between the battery voltage when supplying the first and second charging currents or the difference between the battery voltage when supplying the second charging current and the trickle charging current. Second internal resistance detecting means for detecting the internal resistance of the storage battery using one of the values,
A notification unit that outputs a notification signal when the detected internal resistance is equal to or greater than a predetermined value. 5. The charging circuit according to claim 1, wherein a charging completion voltage detecting means for detecting a battery voltage after completion of charging,
Display means for displaying a voltage value of the detected battery voltage, a character ranked based on the voltage value, or a cell number of the storage battery obtained from the detected voltage.