JP2542278B2 - Recharge prevention device for fully charged secondary battery, battery pack and charger thereof - Google Patents

Description

TECHNICAL FIELD The present invention relates to a device for preventing recharge of a fully charged secondary battery, a battery pack used for the device, and a charger for the battery pack.

[Prior Art] Generally, when a secondary battery such as a nickel-cadmium battery is rapidly charged by a charger, the charging voltage (battery terminal voltage) gradually increases and reaches a peak voltage as shown in FIG. Slightly descended to full charge. The charger detects that the charging voltage has dropped as described above, shuts off the rapid charging current (large current), and prevents overcharging. After that, only a minute current for trickle charging is passed.

[Problems to be Solved by the Invention] By the way, in the above charger, when a fully charged secondary battery is removed from the charger and reattached without use, the battery is rapidly charged again. . If such rapid charging is performed about twice, since the temperature of the secondary battery is not so high, the charging voltage drops as described above and this is detected, and the rapid charging current is cut off. Then, the temperature of the secondary battery rises, so that the charging voltage does not drop and the rapid charging current is not cut off, resulting in overcharging.

In this overcharged state, the secondary battery heats up, which is dangerous and shortens the life of the secondary battery.

The present invention solves the above problems and provides a device for preventing recharge of a fully charged secondary battery, a battery pack used in the device, and a charger for the battery pack.

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a battery pack through a secondary battery, a Zener diode, and the Zener diode in which a charging current from the secondary battery is forward. A capacitor connected to the secondary battery via the Zener diode so that the battery pack can be detected by the charger, and the terminal voltage of the capacitor is higher than a predetermined voltage. When it is detected that the battery level is low, and when it is not detected that the secondary battery is fully charged, the quick charging state of the secondary battery is maintained and the detected Recharge prevention device for a fully charged secondary battery, configured not to maintain the rapid charging state of the secondary battery when the terminal voltage of the capacitor is higher than a predetermined voltage A secondary battery, a Zener diode, and a capacitor connected to the secondary battery via the Zener diode so that the charging current from the secondary battery can flow through the Zener diode in the forward direction. A battery pack for use in the device, wherein the first battery pack is for detecting that the battery pack is mounted.
Detecting means, second detecting means for detecting whether or not the terminal voltage of the capacitor housed in the mounted battery pack is lower than a predetermined voltage, and the second detecting means housed in the mounted battery pack. The third detecting means for detecting that the secondary battery is fully charged, and the first detecting means detects the mounting of the battery pack,
When the detection means detects that the terminal voltage of the capacitor is lower than the predetermined voltage, and the third means does not detect that the secondary battery is fully charged,
A means for holding the rapid charge state of the secondary battery,
When the second detecting means detects that the terminal voltage of the capacitor is higher than a predetermined voltage, the quick charging state of the secondary battery is not maintained. is there.

[Operation] In the recharge prevention device for a fully charged secondary battery, battery pack and charger thereof configured as described above, the charging voltage of the secondary battery exceeds the peak voltage due to rapid charging. Even if it drops, the terminal voltage of the capacitor does not drop so much and does not become lower than the above-mentioned specified voltage.Therefore, even if a fully charged secondary battery is installed in the charger, rapid charging of the secondary battery is performed. The state is not maintained and recharge of the fully charged secondary battery is prevented.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit diagram of a battery pack, FIG. 2 is a block diagram showing a circuit of a charger, FIG. 3 is a perspective view showing a state where a battery pack is attached to a charger, and FIG. 4 is a perspective view of the charger. 5 and 5 are perspective views showing the back side of the battery pack.

In FIG. 3, reference numeral 1 is a charger, which is a control knob 2 for a power switch and an indicator lamp 3 for indicating a charging state.
And a power cord 4 and the like. Reference numeral 5 denotes a battery pack, which is shown mounted on the charger 1.

4, the same symbols as those in FIG. 3 indicate the same components. FIG. 4 shows the charger from which the battery pack 5 has been removed, which is provided in the battery pack mounting portion.
The terminal 6, the negative terminal 7, the detection terminal 8, the plurality of mounting fitting claws 30 protruding inward, and the switch 9 for detecting that the battery pack 5 is mounted are shown. The arrow indicates the mounting direction of the battery pack to the charger 1.

FIG. 6 shows the battery pack 5, and 10 is +
A terminal, 11 is a negative terminal, 12 is a detection terminal, and 31 is a fitting space into which the fitting claw 30 is fitted. These terminals 10
In the state where the battery pack 5 is mounted on the charger 1, the parts 1 to 12 are brought into contact with the terminals 6 to 8, respectively, and the fitting claws 30 are fitted into the fitting spaces 31 respectively. The arrow indicates the mounting direction of the battery pack 5 to the charger 1.

In FIG. 1, reference numeral 13 is a secondary battery such as a Nicad battery,
Reference numeral 14 is a Zener diode, 15 is a capacitor, 16 is a thermal fuse, and 17 is a protective resistor, which are housed in the battery pack 5. The capacitor 15 is a secondary battery 13
Is connected to the secondary battery 13 via the zener diode and the protection resistor 17 so that the charging current from the can flows through the zener diode 14 in the forward direction. Incidentally, in FIG. 1, the same symbols as those in FIG. 5 indicate the same components.

In FIG. 2, reference numeral 18 is a stabilized power supply, 19 is a trickle charging resistor, 20 is a quick charging circuit, 21 is a switch, 22 is an AND gate, and 23 is a -ΔV detection circuit. This −ΔV detection circuit detects a predetermined minute voltage drop after the voltage reaches the peak value. As described above, the secondary battery drops the charging voltage past the peak voltage in the rapid charging process. Detect this when you do. 24 is a delay circuit, 25 is a timer, 26 is an AND gate, 27 is a diode, and 28 is a comparator. Incidentally, in FIG. 2, the same reference numerals as those in FIG. 4 indicate the same parts.

 Next, the operation of this embodiment will be described.

First, it is assumed that a nickel-cadmium battery having a rated voltage of 9.6V is used as the secondary battery 13 of the battery pack 5. Assuming that the secondary battery 13 has been discharged by use, and its terminal voltage is, for example, 8.4V, the terminal voltage of the capacitor 15, that is, the voltage of the detection terminal 12 is a Zener diode.
The Zener voltage of 2.5V of 14 is added up to 10.9V.

When the battery pack 5 is attached to the charger 1, the terminals 10 to 12 of the battery pack 5 are connected to the terminals 6 to 8 of the charger 1.
And the switch 9 is turned on.
When the knob 2 is operated in this state to turn on the power switch of the charger 1, the power supply current supplied from the power cord 4 is stabilized by the stabilizing power supply 18, and the trickle charging resistor is turned on.
The voltage of “H” is applied to the AND gate 26 via the switch 9 which is supplied to the AND circuit 19 and the quick charging circuit 20.

The terminal voltage (10.9V) of the capacitor 15 is applied to the comparator 28 via the detection terminals 8 and 12, and the terminal 29
Is compared to the reference voltage of 13.0V applied to the. When the terminal voltage of the capacitor 15 is lower than the reference voltage,
The output of the comparator 28 becomes "H", and this is applied to the AND gate 26. In this AND gate 26, both the input terminals are "H", so the output is "H".
Then, the timer 25 is started by the output. The set time of the timer 25 is slightly longer than the normal time required for the secondary battery 13 to be rapidly charged. Further, after the timer is started, the voltage of "H" is applied from the output to the AND gate 26 via the diode 27. Therefore, even if the output of the comparator 28 becomes "L" after the timer is started, The timer continues to operate. The output of the timer 25 is applied to the AND gate 22 as the voltage of "H" through the delay circuit 24.

As described above, the −ΔV detection circuit 23 detects a minute voltage drop after the voltage reaches the peak value, and is a terminal of the secondary battery 13 applied via the + terminals 10 and 6. When the voltage has not dropped, the output is "H". The output of "H" is applied to the AND gate 22, the output of the AND gate becomes "H", and the switch 21 is turned on.

When the switch 21 is turned on in this way, the charging current from the stabilized power supply 18 through the quick charging circuit 20 is supplied to the secondary battery 13 via the switch 21, the + terminals 6, 10 and the temperature fuse 16. , The secondary battery is rapidly charged.

Due to this charging, when the charging voltage of the secondary battery 13 drops below its peak voltage, this is detected by the −ΔV detection circuit 23, the output of the −ΔV detection circuit becomes “L”, and the AND gate 22. Output becomes "L", and the switch
21 is turned off, and the rapid charging current to the secondary battery 13 is cut off.

Although the secondary battery 13 is almost fully charged by the end of this quick charging, a minute charging current is still supplied to the secondary battery 13 via the trickle charging resistor 19 after that.

The timer 25 is for limiting the rapid charging time when the −ΔV detection circuit 23 does not detect a decrease in the charging voltage of the secondary battery 13. In addition, the delay circuit 24 switches before the output “H” of the timer 25 via the diode 27 is applied to the AND gate 26.
21 is turned on, the secondary battery 13 is rapidly charged, the terminal voltage of the capacitor 15 becomes higher than the reference voltage,
The output of the comparator 28 is prevented from becoming "L", and as a result, the output of the AND gate 26 is prevented from becoming "L".

As described above, when the NiCd battery is used as the secondary battery 13, the charging voltage due to the rapid charging thereof gradually increases as shown in FIG. 6 and gradually decreases after the peak voltage. As described above, when the rated voltage of the secondary battery 13 is 9.6V, the peak voltage when it is rapidly charged is 13.6V to 14.0V or more, so the capacitor 15 is 1
Charged to 3.0V-13.4V or higher. When this charging voltage starts to drop and the quick charging ends, the terminal voltage of the secondary battery 13 changes
Although it is stable at about 11.0V to 11.5V, the above-mentioned voltage of 13.0V to 13.4V remains as the terminal voltage of the capacitor 15 due to the Zener voltage of 2.5V of the Zener diode 14.

Next, it is assumed that the battery pack 5 in which the secondary battery 13 is fully charged due to the end of the quick charge is attached to the charger 1 again without being used and the battery pack 5 is to be recharged. At this time, since the terminal voltage of the capacitor 15 is 13.0V to 13.4V, the comparator 28 receives 13.0V via the detection terminals 12 and 8.
The above voltage is applied, and the output of the comparator is "L".
Therefore, the switch 21 cannot be turned on and rapid charging is not performed.

Further, the terminal voltage of the secondary battery 13 in use when it is used for about half becomes 9.6V to 10.0V. Even if this terminal voltage is 10.0 V, which is the higher voltage, the capacitor 1
Since the terminal voltage of 5 is 12.5V, the detection terminals 12 and 8
The voltage applied to the comparator 28 via 1 becomes lower than 13.0V, the output of the comparator 28 becomes "H", the switch 21 is turned on, and rapid charging is performed.

Note that the terminal voltage of the capacitor 15 will decrease after a long time due to leakage current, etc., but in that case, the temperature of the secondary battery 13 will also be room temperature, and the peak voltage of the charging voltage will remain even if temporary recharging is performed. Since the voltage drop that has passed is detected, it is not overcharged by recharging.

[Effects of the Invention] As described above, the present invention provides a battery pack in which a secondary battery, a Zener diode, and a Zener diode such that a charging current from the secondary battery can flow through the Zener diode in the forward direction. A charger connected to the secondary battery via the charger, and when the charger detects that the battery pack is mounted and that the terminal voltage of the capacitor is lower than a predetermined voltage. Then, when it is not detected that the secondary battery is fully charged, the rapid charging state of the secondary battery is maintained, and the detected terminal voltage of the capacitor is lower than a predetermined voltage. Since the quick charge state of the secondary battery is not maintained when it is too high, it is possible to prevent recharge of the fully charged secondary battery, and It is possible to provide a battery pack used for the prevention device and its charger.

[Brief description of drawings]

1 to 5 show an embodiment of the present invention. FIG. 1 is a circuit diagram of a battery pack, FIG. 2 is a block diagram showing a circuit of a charger, and FIG. 3 is a battery pack. FIG. 4 is a perspective view of the attached charger, FIG. 4 is a perspective view of the charger with no battery pack attached, FIG. 5 is a perspective view showing the back surface of the battery pack, and FIG. 6 is a charging voltage of the nicad battery. It is a characteristic diagram. 1: Charger, 5: Battery pack, 9: Switch, 13: Secondary battery, 14: Zener diode, 15: Capacitor, 18: Stabilized power supply, 20: Rapid charging circuit, 21: Switch, 22: AND gate, 23: -ΔV detection circuit, 26: AND gate, 27: diode, 28: comparator.

Claims (3)

(57) [Claims] 1. A battery pack includes a secondary battery, a Zener diode, and a secondary battery through the Zener diode so that a charging current from the secondary battery can flow through the Zener diode in a forward direction. The battery is provided with a connected capacitor, and when the charger detects that the battery pack is mounted and the terminal voltage of the capacitor is lower than a predetermined voltage, the secondary battery is When it is not detected that the battery is fully charged, the rapid charging state of the secondary battery is maintained, and when the detected terminal voltage of the capacitor is higher than a predetermined voltage, the secondary battery A recharge prevention device for a fully charged secondary battery, which is configured so that the quick charge state is not maintained. 2. A secondary battery, a zener diode, and a zener diode connected to the secondary battery so that a charging current from the secondary battery can flow through the zener diode in the forward direction. A battery pack for use in the device according to claim 1, further comprising a capacitor. 3. The first detection means for detecting that the battery pack according to claim 2 is mounted, and whether the terminal voltage of the capacitor housed in the mounted battery pack is lower than a predetermined voltage. Second detecting means for detecting whether the secondary battery housed in the mounted battery pack is fully charged; and third detecting means for detecting whether the secondary battery is fully charged. Detects that the battery pack is mounted, the second detecting means detects that the terminal voltage of the capacitor is lower than a predetermined voltage, and the third means detects that the secondary battery is fully charged. And a means for holding the rechargeable battery in a rapidly charged state, the second detection means detects that the terminal voltage of the capacitor is higher than a predetermined voltage. Charger, characterized in that the rapid charging state of the battery is prevented from being held.