JP3121963B2 - battery pack - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery pack, and more particularly to a battery pack capable of detecting an abnormal state of a lithium ion battery from outside a case.

[0002]

2. Description of the Related Art Conventionally, a plurality of secondary batteries are connected in series,
A battery pack stored in a case is used for various electronic devices. By using such a battery pack, there is an advantage that the handling is simpler than when a single battery is handled, and the configuration of the battery storage unit in the electronic device is simplified.

Conventional secondary batteries include lead storage batteries, nickel-cadmium batteries, nickel-hydrogen batteries and the like. In recent years, mobile communication devices, laptop computers, notebook computers, palmtop computers, In order to reduce the size and weight of electronic devices such as integrated video cameras, portable CD players, MD players, DCC players, portable word processors, headphone stereos, cordless phones, cellular phones, etc. There is a demand for higher capacity secondary batteries, and lithium ion secondary batteries using carbonaceous materials capable of doping / dedoping lithium ions (for example, Japanese Patent Publication No. 4-248)
No. 31, publication No. 31) has attracted attention because it is much more excellent in safety than a lithium secondary battery using lithium metal or an alloy thereof for the negative electrode and can obtain a high energy density.

The above-mentioned lithium ion secondary battery is lighter and has a higher capacity than a nickel-cadmium battery, a nickel-hydrogen storage alloy battery, and a 2.0 V lead storage battery as a secondary battery having a voltage of 1.2 V. And the average voltage is 3.
It is as high as 5 V to 3.6 V, and has an advantage that the discharge voltage is inclined and the remaining amount can be displayed. Further, as the battery shape, there are a cylindrical shape, a thin shape, a button type, and the like.

However, in the lithium ion secondary battery, in view of the electrochemical stability of the electrolyte solution, when the battery voltage is 4.5 V or more, the solvent used in the solution is decomposed, gas is generated, and the internal pressure of the battery is increased. Rises, and the gas release rupture is activated. Under normal use, it is desirable to prevent overcharging in the range of 4.4V to 4.3V per cell. Further, the cutoff voltage is set to 2.7 V to 2.5 V per cell, but if the cutoff voltage is 2.0 V or less, the current collector may be dissolved depending on the combination of the current collector and the carbonaceous material used. It is necessary to avoid such overdischarge.

As a battery pack using such a lithium ion secondary battery, there is known a battery pack incorporating a battery protection circuit as shown in FIGS. 2A and 2B, for example. A battery pack 1 shown in FIG. 2A includes a plurality of lithium ion batteries 2a and 2b connected in series, an overcharge / overdischarge detection circuit 3, and a field effect transistor used as a switching element for overcharge detection. (Hereinafter F
ET) 4 and a battery protection circuit 5 composed of an FET 6 used as a switching element for detecting overdischarge.

[0007] The overcharge detection is performed by the lithium ion battery 2a,
At the time of charging the battery 2b, the voltage Vs of each of the lithium ion batteries 2a and 2b connected in series is detected, and this voltage Vs
When s becomes the overcharge voltage, the FET 4 is turned off to disconnect the connection between the lithium ion battery 2a and the positive input / output terminal 1a.

In the example shown in FIG. 2B, the connection between the lithium ion battery 2b and the negative input / output terminal 1b is cut off.

[0009] The overdischarge is detected in the lithium ion battery 2a,
The voltage Vs of each of the lithium-ion batteries 2a and 2b connected in series at the time of discharging from the battery 2b is detected, and the voltage Vs
When s reaches the overdischarge voltage, the FET 6 is turned off, and the connection between the lithium ion battery 2b and the negative input / output terminal 1b is cut off.

As a result, the charging of each lithium ion battery in the overcharged state or the continuation of discharging in the overdischarged state can be avoided, and the deterioration or breakage of the lithium ion batteries 2a and 2b can be prevented. .

[0011]

However, in the conventional battery pack 1 described above, it is possible to detect the overcharged state and the overdischarged state of each of the lithium ion batteries 2a and 2b and stop the energization. However, even if an abnormality occurs in the battery in the battery pack,
Only turned off, and no battery abnormality could be detected from outside the battery pack.

In view of the above problems, it is an object of the present invention to provide a battery pack capable of monitoring the voltage of each lithium-ion battery outside the case and an abnormal state such as an over-discharge state or an over-charge state of any of the lithium-ion batteries. It is an object of the present invention to provide a battery pack that outputs a signal to the outside of the case when the battery pack becomes inactive.

[0013]

According to the present invention, in order to achieve the above object, there are provided two or more serially connected power supply units.
Lithium ion battery in the case, and
Battery having a pair of output terminals connected to both ends of a pond
In the case of a pack, an abnormal signal output terminal
And two or more lithium-ion batteries
And the lithium ion
Outputs a detection signal when an abnormal state of the battery unit is detected
Two or more abnormal state detection circuits,
From at least one of the abnormal state detection circuits.
When the detection signal is output, the abnormal signal output terminal
An abnormal signal output circuit that outputs an abnormal signal to the outside of the case
And the two or more abnormal state detection circuits are cascaded.
Suggest a battery pack that is.

According to a second aspect, the battery according to the first aspect is provided.
In the terry pack, detected from the abnormal state detection circuit
When a signal is output, the lithium ion battery and the
A battery equipped with a shutoff circuit that shuts off the connection to the output terminal
Suggest a Reapak.

According to a third aspect of the present invention, there is provided a battery pack according to the first aspect.
In the terry pack, the abnormal state detection circuit includes a first
And a second input terminal, an output terminal, and the second input terminal.
Connected between the output terminal and based on the control signal
Switches between the conducting state and the non-conducting state, and detects an abnormality
When the connection between the second input terminal and the output terminal is not
A switching element to be turned on and a second input terminal.
An applied voltage is applied to the first input terminal based on the applied voltage.
The first input is compared with the threshold voltage.
Switch when an abnormality occurs in the voltage applied to the input terminal.
A signal for bringing the switching element into a non-conductive state is used as the control signal.
Provide a battery pack with a comparison means for outputting
Plan.

According to a fourth aspect, the battery according to the third aspect is provided.
In the terry pack, except for one abnormal condition detection time
A first input terminal of the path is connected to a switch of another abnormal state detection circuit.
Terminal voltage of the lithium-ion battery via a switching element
Is applied and each abnormal condition detection circuit is cascaded.
A battery pack.

[0017]

According to the first aspect of the present invention, the cascaded 2
Each abnormal condition detection circuit
The overcharge state or overdischarge state of the
A normal state is detected, and a detection signal is output when the abnormal state is detected.
Is output. In addition, at least one of the abnormal state detection circuits is used.
When the detection signal is output from the one abnormal state detection circuit
In this case, the abnormal connection is made to another abnormal state detection circuit by the subordinate connection.
The abnormal state detection is transmitted sequentially, and finally the abnormal signal output circuit
Abnormal signal from the abnormal signal output terminal to the outside of the case
Is output. As a result, a plurality of lithium
That one of the MION batteries has become abnormal
Can be found outside the case.

According to the second aspect, the abnormal state detection is performed.
When a detection signal is output from the output circuit,
The connection between the lithium ion battery and the output terminal is
Will be shut off.

According to a third aspect of the present invention, an abnormal state detecting circuit is provided.
Applied between a first input terminal and a second input terminal of a path
The output voltage of the single ion battery is determined by the comparison means.
It is compared with the threshold voltage. As a result of this comparison,
When it is not output, the second
The conduction state is set between the input terminal and the output terminal. Ma
Also, when an abnormality occurs in the voltage applied to the first input terminal.
Means that the comparing means is in a non-conductive state of the switching element.
Is output as the control signal. This
And the second input terminal is connected to the second input terminal by the switching element.
The connection with the output terminal is made non-conductive.

Further , according to the present invention, an abnormal state detecting circuit is provided.
A switch of another abnormal state detection circuit is connected to the first input terminal of the road.
Terminal voltage of the lithium-ion battery via the switching element
This is repeated in order and each abnormal condition detection circuit
It is cascaded. As a result, any one abnormal state detection
Output circuit detects an abnormal state of the lithium-ion battery.
The switch of the abnormal state detection circuit that has detected the abnormality
Starting with the switching element set to a non-conducting state.
The switching elements of the subsequent abnormal state detection circuit are sequentially turned off.
It is set to the communication state.

[0021]

1 is a perspective view showing an external appearance of a battery pack according to a first embodiment of the present invention, and FIG. 3 is a circuit diagram thereof. In the figure, the same components as those of the above-described conventional example are denoted by the same reference numerals, and description thereof will be omitted. That is, reference numeral 1 denotes a battery pack body having a substantially rectangular parallelepiped shape, and a pair of input / output terminals 1a and 1b and two cell voltage output terminals 1 on one surface.
c and 1d are provided.

The main body 1 has a lithium ion 2
Three lithium-ion batteries 2a to 2c composed of secondary batteries,
A battery protection circuit 5 and resistors 6a and 6b are provided, and a voltage at a connection point of the lithium ion batteries 2a to 2c is output to the cell voltage output terminals 1c and 1d via the resistors 6a and 6b. That is, the positive terminal of the lithium ion battery 2a is an FET
4, the negative terminal is connected to the positive terminal of the lithium ion battery 2b, and also connected to the cell voltage output terminal 1c via the resistor 6a. The negative terminal of the lithium ion battery 2b is connected to the positive terminal of the lithium ion battery 2c and to the cell voltage output terminal 1d via the resistor 6b. Further, the negative terminal of the lithium ion battery 2c is the input / output terminal 1
b. An overcharge detection circuit 3 is connected between the positive terminal of the lithium ion battery 2a and the negative terminal of the lithium ion battery 2c.
FET4 is turned on by the detection signal output from
The off state is switched.

According to the above-described configuration, when charging the lithium ion batteries 2a to 2c, the voltage Vs between both ends of the lithium ion batteries 2a to 2c connected in series is detected by the overcharge detection circuit 3, and this voltage is detected. When the overcharge voltage is reached, the FET 4 is turned off. As a result, the connection between the lithium ion battery 2a and the positive electrode output terminal 5a is cut off, so that continuation of charging in an overcharged state can be avoided, and deterioration or breakage of the lithium ion batteries 2a to 2c can be prevented. Can be.

Further, by using the input / output terminals 1a and 1b and the cell voltage output terminals 1c and 1d, the voltage of each of the lithium ion batteries 2a to 2c can be monitored in a host device using this battery pack. Also, even when an abnormality occurs in the battery protection circuit 5, the power supply can be stopped when the lithium ion batteries 2a to 2c are overcharged. In addition, the lithium ion battery 2a
2c and the cell voltage output terminals 1c and 1d are connected via the resistors 6a and 6b. Therefore, when the cell voltage output terminals 1c and 1d are short-circuited, the lithium ion batteries 2a to 2c are connected. Does not hurt.

Next, a second embodiment of the present invention will be described.
FIG. 4 is a circuit diagram of the battery pack of the second embodiment. The appearance of the battery pack of the second embodiment is the same as that of the first embodiment. In FIG. 4, reference numeral 10 denotes a battery pack main body, a plurality of lithium ion batteries 11a and 11b each composed of a lithium ion secondary battery, overcharge detection circuits 12a and 12b provided for each of the lithium ion batteries 11a and 11b, a cutoff circuit 13, and Resistors 14 and 15 are provided in the case, and a battery protection circuit is configured by the overcharge detection circuits 12a and 12b and the cutoff circuit 13.

The lithium ion batteries 11a and 11b and the shutoff circuit 13 are connected in series between the input / output terminals 10a and 10b, and the shutoff circuit 13 is connected between the positive electrodes of the lithium ion batteries 11a and 11b connected in series and the input / output terminal 10a. Connected between them.

The overcharge detection circuits 12a and 12b have the same I
C, a constant voltage generation circuit 121, a comparator OP, and a P-channel MOS type field effect transistor (hereinafter referred to as FET).
Q1, N-channel MOS type FET Q2
Q4 and resistors R1 to R4.

In each of the overcharge detection circuits 12a and 12b, the constant voltage generation circuit 121 generates a predetermined reference voltage Vth from the voltage applied between the input terminals IN1 and IN2, and this reference voltage Vth is inverted by the comparator OP. Applied to the input terminal. Here, the reference voltage Vth is the value of the lithium-ion battery 1
It is set to a value corresponding to a voltage value slightly lower than the maximum voltage at the time of full charge of 1a and 11b.

The non-inverting input terminal of the comparator OP is connected to a resistor R1.
Is connected to the input terminal IN1 via a resistor R
2, and R3 are connected to the input terminal IN2. Further, the output terminal of the comparator OP is connected to the gates of the FETs Q1 and Q2.

The source of the FET Q1 is connected to the input terminal IN1, and the drain is connected to the drain of the FET Q2 and the gates of the FETs Q3 and Q4 via a resistor R4. The sources of the FETs Q2 to Q4 are connected to the input terminal IN2, the drain of the FET Q3 is connected to the output terminal OUT, and the drain of the FET Q4 is connected to the resistor R2.
Each is connected to a connection point of R3.

On the other hand, the input terminal I of the overcharge detection circuit 12a
N1 is connected to the positive terminal of the lithium ion battery 11a located on the side of the cutoff circuit 13, is connected to the cell voltage output terminal 10c via the resistor 14, and has the input terminal IN2.
Is connected to the negative electrode terminal of the lithium ion battery 11a and to the cell voltage output terminal 10d via the resistor 15. Further, the output terminal OUT of the overcharge detection circuit 12a is connected to the input terminal IN1 of the overcharge detection circuit 12b. The input terminal I of the overcharge detection circuit 12b
N2 is connected to the negative terminal and the input / output terminal 10b of the lithium ion battery 11b, and the output terminal OUT is connected to the shutoff circuit 13
It is connected to the.

The cutoff circuit 13 comprises a P-channel MOS type FET Qa and resistors Ra and Rb.
Is connected to the output terminal OUT of the overcharge detection circuit 12b, connected to its source and the input / output terminal 10a via the resistor Ra, and the drain of the FET Qa is connected to the positive terminal of the lithium ion battery 11a. At the same time, it is connected to the output terminal OUT of the overcharge detection circuit 12a via the resistor Rb.

Next, the operation of the second embodiment having the above configuration will be described. Normally, when the battery pack 10 is used, the FET Qa of the cutoff circuit 13 is kept in the ON state. That is, in the overcharge detection circuit 12a, the terminal voltage Vc1 of the lithium ion battery 11a
The voltage is divided by R2 and applied as a voltage V1 to the non-inverting input terminal of the comparator OP. At this time, since the voltage V1 is lower than the reference voltage Vth, the comparator OP outputs a low-level voltage V2. As a result, the FETs Q1, Q
3, Q4 is on, and FET Q2 is off. Accordingly, the output terminal OUT of the overcharge detection circuit 12a is connected to the input terminal IN2.

As a result, the positive terminal of the lithium ion battery 11b is connected to the input terminal IN1 of the overcharge detection circuit 12b, and the lithium ion battery 11b is connected between the input terminals IN1 and IN2 of the overcharge detection circuit 12b. The terminal voltage Vc2 is applied, and the input terminal IN2 and the output terminal OUT of the overcharge detection circuit 12b are similarly connected.

Accordingly, the gate of the FET Qa of the shutoff circuit 13 is connected to the negative terminal of the lithium ion battery 11b, and the gate and source of the FET Qa are in a forward bias state, so that the FET Qa is kept on.

On the other hand, the battery pack is charged,
When any one of the lithium ion batteries 11a and 11b is in an overcharged state, the FET Qa of the cutoff circuit 13 is turned off, and the power supply from the charger (not shown) to the lithium ion batteries 11a and 11b is cut off.

For example, when only the lithium ion battery 11a is in an overcharged state,
When the terminal-to-terminal voltage Vc1 reaches the voltage at the time of full charge, the voltage V1 applied to the non-inverting input terminal of the comparator OP
Becomes higher than the reference voltage Vth, and the comparator OP outputs a high-level voltage V2. As a result, the FETs Q1, Q
3, Q4 is turned off, FET Q2 is turned on, and the output terminal OUT of the overcharge detection circuit 12a is disconnected from its input terminal IN2. Therefore, the overcharge detection circuit 12
A voltage obtained by adding the inter-terminal voltage Vc1 of the lithium ion battery 11a and the inter-terminal voltage Vc2 of the lithium ion battery 11b is applied between the input terminals IN1 and IN2 of b.

As a result, also in the overcharge detection circuit 12b, the voltage V1 becomes higher than the reference voltage Vth, the input terminal IN2 and the output terminal OUT thereof are cut off, and the FET
The state is such that the gate and drain of Qa are connected via the resistor Rb.

Accordingly, in the cutoff circuit 13, the FET Qa
, The forward bias voltage between the gate and the source becomes substantially 0 V, the FET Qa is turned off, and the power supply from the charger to the lithium ion batteries 11a and 11b is cut off.

When only the lithium ion battery 11b is overcharged, the output terminal OUT of the overcharge detection circuit 12b is disconnected from its input terminal IN2. The potential difference between the sources becomes 0, and the FET Qa is turned off. Thereby, the power supply from the charger to the lithium ion batteries 11a and 11b is cut off.

Further, by using the input / output terminals 10a, 10b and the cell voltage detection terminals 10c, 10d, the voltage of each lithium ion battery 11a, 11b alone can be monitored in a host device using this battery pack. Even when an abnormality occurs in the overcharge detection circuits 12a and 12b or the cutoff circuit 13, the power supply can be stopped when the lithium ion batteries 11a and 11b are in an overcharged state. In addition, the lithium ion battery 11
Since the terminals a and 11b and the cell voltage output terminals 10c and 10d are connected via the resistors 14 and 15, the lithium ion batteries 11a and 11b are used when the cell voltage output terminals 10c and 10d are short-circuited. Does not hurt.

Next, a third embodiment of the present invention will be described.
FIG. 5 is a circuit diagram showing a third embodiment. In the figure, reference numeral 20 denotes a battery pack main body, which is substantially similar in appearance to that of the first embodiment described above, and includes a pair of input / output terminals 20a and 20b and two cell voltage output terminals 20.
c.

Further, in the battery pack body 20, a plurality of lithium ion batteries 21a and 21b, overdischarge detection circuits 22a and 22b provided for each of the lithium ion batteries 21a and 21b, a cutoff circuit 23, and resistors 24a to 24b are provided.
4e and a diode 25 are provided in a case, and overdischarge detection circuits 22a and 22b, an interruption circuit 23, and resistors 24a to
24d forms a battery protection circuit.

The lithium ion batteries 21a and 21b and the shutoff circuit 23 are connected in series between the input / output terminals 20a and 20b. The shutoff circuit 23 is connected between the negative electrodes of the serially connected lithium ion batteries 21a and 21b and the input / output terminal 20b. Connected between them.

The overdischarge detection circuits 22a and 22b are connected to the same I
A constant voltage generating circuit 221, a comparator OP, a P-channel MOS type FET Q1, N-channel MOS type FETs Q2 to Q4, and resistors R1 to R4.

In each of the overdischarge detection circuits 22a and 22b, the constant voltage generation circuit 221 generates a predetermined reference voltage Vth from the voltage applied between the input terminals IN1 and IN2, and this reference voltage Vth is inverted by the comparator OP. Applied to the input terminal. Here, the reference voltage Vth is the value of the lithium ion battery 2
It is set to a value corresponding to a voltage value slightly higher than the lowest dischargeable voltage at the time of discharging 1a and 21b.

The non-inverting input terminal of the comparator OP is connected to a resistor R1.
Is connected to the input terminal IN1 via a resistor R
2, and R3 are connected to the input terminal IN2. Further, the output terminal of the comparator OP is connected to the gates of the FETs Q1 and Q2.

The source of the FET Q1 is connected to the input terminal IN1, and the drain is connected to the drain of the FET Q2 and the gates of the FETs Q3 and Q4 via a resistor R4. The sources of the FETs Q2 to Q4 are connected to the input terminal IN2, the drain of the FET Q3 is connected to the output terminal OUT, and the drain of the FET Q4 is connected to the resistor R2.
Each is connected to a connection point of R3.

On the other hand, the input terminal I of the overdischarge detection circuit 22a
N1 is connected to the lithium ion battery 21 via the resistor 24a.
a, and is connected to the output terminal OUT of the overdischarge detection circuit 22b via a resistor 24b. Further, the input terminal IN2 of the overdischarge detection circuit 22a is connected to the negative electrode terminal of the lithium ion battery 21a and connected to the cell voltage output terminal 20c via the resistor 24c and the diode 25, and the output terminal OUT is connected to the cutoff circuit 23. It is connected. At this time, the cathode of the diode 25 is connected to the cell voltage output terminal 20.
c. The input terminal IN1 of the overdischarge detection circuit 22b is connected to the negative terminal of the lithium ion battery 21a via the resistor 24d, and the input terminal IN2 is connected to the input / output terminal 20b.

The shutoff circuit 23 includes an N-channel MOS type FET Qa, a PNP type transistor Tr and a resistor R
The drain of the FET Qa is connected to the input / output terminal 20b and the input terminal IN2 of the overdischarge detection circuit 22b, and the source is connected to the negative terminal of the lithium ion battery 21b. Further, the gate of the FET Qa is connected to the source via the resistor Ra and to the collector of the transistor Tr.

The emitter of the transistor Tr is connected to the output terminal of the over-discharge detection circuit 22a and to the positive terminal of the lithium ion battery 21a via a resistor Rb, and the base is over-discharged via a resistor Rc. Detection circuit 2
2a and the input terminal IN1 of the overdischarge detection circuit 22b.

Next, the operation of the third embodiment having the above configuration will be described. Normally, when the battery pack 20 is used, the FET Qa of the cutoff circuit 23 is kept in the ON state. That is, in the overdischarge detection circuit 22b, the voltage Vc2 between the terminals of the lithium ion battery 21b is changed to the resistors R1, R2.
2 and is applied to the non-inverting input terminal of the comparator OP as the voltage V1. At this time, since the voltage V1 is higher than the reference voltage Vth, the comparator OP outputs a high-level voltage V2. Thereby, the FETs Q1, Q3,
Q4 is turned off, and FET Q2 is turned on. Therefore, the output terminal OUT of the overdischarge detection circuit 22b is in an open state.

As a result, the voltage Vc1 between the terminals of the lithium ion battery 21a is applied between the input terminals IN1 and IN2 of the overdischarge detection circuit 22a, and the output terminal OUT of the overdischarge detection circuit 22a is similarly opened. Has become.

Accordingly, in the cutoff circuit 23, a predetermined forward bias voltage is applied between the base and the emitter of the transistor Tr, and the transistor Tr is turned on. As a result, a forward bias is applied between the gate and the source of the FET Qa, and the FET Qa is maintained in the ON state.

On the other hand, the battery pack is connected to the load, and discharges the lithium ion batteries 21a, 21b to the load, and any one of the lithium ion batteries 21a, 21b
Is in the overdischarged state, the FET of the cutoff circuit 23
Qa is turned off, and the lithium ion batteries 21a, 21a
The power supply from 1b to the load is cut off.

For example, when only the lithium ion battery 21a is in the overdischarge state, the voltage V1 applied to the non-inverting input terminal of the comparator OP becomes lower than the reference voltage Vth in the overdischarge detection circuit 22a. OP outputs a low-level voltage V2. Thereby, the FET Q
1, Q3 and Q4 are turned on and FTQ2 is turned off, and the output terminal OUT of the overdischarge detection circuit 22a is connected to its input terminal IN2. Therefore, the transistor Tr
Becomes almost 0 V, and the transistor Tr is turned off. As a result, the voltage between the gate and the source of the FET Qa also becomes substantially 0 V, and the FET Qa is turned off, thereby cutting off the power supply from the lithium ion batteries 21a and 21b to the load.

When only the lithium ion battery 21b is over-discharged, the output terminal OUT of the over-discharge detection circuit 22b is connected to its input terminal IN2.
The voltage applied to the input terminal IN1 of the over-discharge detection circuit 22a decreases, and the voltage V1 applied to the non-inverting input terminal of the comparator OP becomes equal to or lower than the reference voltage Vth and the FET Q
a is turned off, and the lithium ion batteries 21a, 21a
The power supply from b to the load is cut off.

As described above, according to the third embodiment, when any one of the series-connected lithium ion batteries 21a and 21b in the battery pack 20 is in an overdischarged state, the FET Qa is turned off, Since the power supply from the lithium ion batteries 21a and 21b to the load is shut off,
Even when the balance between the discharge states of the individual lithium ion batteries 21a and 21b is lost, no lithium ion battery is discharged in the overdischarge state, and the deterioration or damage of the lithium ion battery can be prevented. Further, malfunction of the load device due to a voltage drop can be avoided.

Further, by using the input / output terminals 20a and 20b and the cell voltage output terminal 20c, the voltage of each of the lithium ion batteries 21a and 21b can be monitored in the host device using this battery pack. Even when an abnormality occurs in the cutoff circuit 23, the power supply can be stopped when the lithium ion batteries 21a and 21b are in an overdischarged state. Also, at the time of charging, the charging can be stopped by detecting that the lithium ion batteries 21a and 21b are in the overcharged state. Furthermore, since the terminals of the lithium ion batteries 21a and 21b and the cell voltage output terminal 20c are connected via the resistor 24c and the diode 25, the cell voltage output terminal 2
No current flows when the input / output terminal 20a of the positive electrode 0c and the positive electrode is short-circuited.
No damage to 1b.

Next, a fourth embodiment of the present invention will be described.
FIG. 6 is an external perspective view showing the battery pack of the fourth embodiment, and FIG. 7 is a circuit diagram thereof. In the figure, reference numeral 30 denotes a battery pack body having a substantially rectangular parallelepiped shape, and a pair of input / output terminals 30a and 30b and one abnormal signal output terminal 30c are provided on one surface thereof.

Further, inside the main body 30, a plurality of lithium ion batteries 31a to 31a to 31c including lithium ion secondary batteries are provided.
31c, an overcharge detection circuit 32a to 32c provided for each of the lithium ion batteries 31a to 31c, a cutoff circuit 33, and an abnormal signal output circuit 34 are provided in the case, and the battery is protected by the overcharge detection circuits 32a to 32c and the cutoff circuit 33. The circuit is configured. Here, the overcharge detection circuits 32a to
Reference numeral 32c denotes an IC having the same circuit as the above-described overcharge detection circuits 12a and 12b.
3, the detailed description thereof will be omitted. The reference voltage Vth in each of the overcharge detection circuits 32a to 32c is set to a value corresponding to a voltage value slightly lower than the maximum voltage of the lithium ion batteries 31a to 31c when fully charged.

The lithium ion batteries 31a to 31c and the shutoff circuit 33 are connected in series between the input / output terminals 30a and 30b, and the shutoff circuit 33 is connected between the positive electrodes of the lithium ion batteries 31a to 31c connected in series and the input / output terminal 30a. Connected between them.

The input terminal I of the overcharge detection circuit 32a
N1 is connected to the positive terminal of the lithium ion battery 31a located on the side of the shutoff circuit 33, and the input terminal IN2 is connected to the negative terminal of the lithium ion battery 31a. Further, the output terminal OUT of the overcharge detection circuit 32a is connected to the input terminal IN1 of the overcharge detection circuit 32b. The input terminal IN2 of the overcharge detection circuit 32b is connected to the negative terminal of the lithium ion battery 31b, and the output terminal OU
T is connected to the input terminal IN1 of the overcharge detection circuit 32c and is connected to the lithium ion battery 31b via the resistor 35.
Is connected to the positive electrode terminal. Furthermore, the input terminal IN2 of the overcharge detection circuit 32c is connected to the lithium ion battery 31.
The output terminal OUT is connected to the cutoff circuit 33 and the abnormal signal output circuit 34.

The gate of the FET Qa of the cutoff circuit 33 is connected to the output terminal OUT of the overcharge detection circuit 32c, and its source and the input / output terminal 10 are connected via a resistor Ra.
a, the drain of the FET Qa is connected to the positive terminal of the lithium ion battery 31a, and the resistor Rb
Is connected to the output terminal OUT of the overcharge detection circuit 32a.

The abnormal signal output circuit 34 is a P channel M
OS type FET341, N-channel MOS type FET34
2 and a resistor 343, the source of the FET 341 is connected to the input / output terminal 30a, and the drain is the drain of the FET 342 and the abnormal signal output terminal 30 via the resistor 343.
c. The gates of the FETs 341 and 342 are connected to the output terminal OUT of the overcharge detection circuit 32c, and the source of the FET 342 is connected to the input / output terminal 30b.

Next, the operation of the third embodiment having the above-described configuration will be described. Normally, the gate of the FET Qa of the cutoff circuit 33 is connected to the negative terminal of the lithium ion battery 31c, so that the gate and source of the FET Qa are forward biased and the FET Qa is kept on. further,
In the abnormal signal output circuit 34, the FET 341 is turned on and the FET 342 is turned off.
From 0c, a high-level signal is output.

On the other hand, the battery pack is charged and
When any one of the lithium ion batteries 31a to 31c is in an overcharged state, the FET Qa of the cutoff circuit 33 is turned off, and the power supply from the charger (not shown) to the lithium ion batteries 31a to 31c is cut off. In the abnormal signal output circuit 34, the FET 341 is turned off, and the FET 34
2 is turned on, and a low-level signal is output from the abnormal signal output terminal 30c.

Therefore, the lithium ion batteries 31a-31
It can be easily known outside of the battery pack main body 30 that any one of c has become overcharged,
Charging in the overcharged state can be stopped. Thereby, the deterioration or breakage of the lithium ion batteries 31a to 31c can be prevented.

Further, according to the fourth embodiment, it is possible to detect an abnormality of a lithium ion battery without providing a cell voltage output terminal for each lithium ion battery, and it is possible to reduce the number of externally provided terminals. . Furthermore, short-circuit between terminals and complicated terminal routing can be prevented.

In the first, second and fourth embodiments, the overcharge detecting circuit 3 (or 12a, 12b, 32a to 32a) is used.
battery pack 1 with c) (or 10, 30)
However, the present invention is not limited to this. For example, a battery pack including an overdischarge detection circuit may be configured. Further, in the third embodiment, the overdischarge detection circuit 22a,
Although the battery pack 20 including the battery pack 22b is configured, an overcharge detection circuit may be provided, or a battery pack including both of them may be configured.

In the first to third embodiments, three or two lithium-ion batteries 2a to 2c (or 11a, 11a) are provided in the battery pack 1 (or 10, 20).
b, 21a, 21b), the number of lithium ion batteries can be changed as appropriate, and the same effect can be obtained by providing a plurality of cell voltage output terminals corresponding to the connection points of the lithium ion batteries. It goes without saying that you can do it.

[0072]

As described above, according to the first aspect of the present invention,
According to claim 4, each lithium ion
That the battery is in an abnormal state.
Thus, in a higher-level device using the battery pack,
The status of the lithium-ion battery can be monitored.
When the charge state or discharge state of the
These states can be detected. This allows charging
Overcharge or charge the lithium-ion battery
Over-discharge from the on-battery to the load can be avoided,
It can prevent deterioration or breakage of the lithium ion battery.
You.

According to the second aspect, in addition to the above effects,
The detection signal was output from the abnormal state detection circuit.
When the lithium ion battery is shut off by the shutoff circuit
Since the connection with the output terminal is interrupted, lithium ion
When the charge state or discharge state of the battery varies
Overcharge the lithium-ion battery with the charger, or
Avoid over-discharge from lithium-ion battery to load
To prevent deterioration or breakage of lithium-ion batteries
It has a very good effect that it can be done.

[0074]

[0075]

[Brief description of the drawings]

FIG. 1 is an external perspective view showing a first embodiment of the present invention.

FIG. 2 is a circuit diagram showing a conventional example.

FIG. 3 is a circuit diagram of a first embodiment of the present invention.

FIG. 4 is a circuit diagram showing a second embodiment of the present invention.

FIG. 5 is a circuit diagram showing a third embodiment of the present invention.

FIG. 6 is an external perspective view showing a fourth embodiment of the present invention.

FIG. 7 is a circuit diagram showing a fourth embodiment of the present invention.

[Explanation of symbols]

1 ... battery pack body, 1a, 1b ... input / output terminals
1c, 1d: Cell voltage output terminals, 2a to 2c: Lithium ion battery, 3: Overcharge detection circuit, 4: FET, 5: Battery protection circuit, 6a, 6b: Resistor, 10: Battery pack body, 10a, 10b ... Input / output terminals, 10c, 10
d: cell voltage output terminal, 11a, 11b: lithium ion battery, 12a, 12b: overcharge detection circuit, 13: cutoff circuit, 14, 15: resistor, 20: battery pack body, 20a, 20b: input / output terminal, 20c: cell voltage output terminal, 21a, 21b: lithium ion battery, 22
a, 22b: overdischarge detection circuit, 23: interruption circuit, 24a
-24d: resistor, 25: diode, 30: battery pack body, 30a, 30b: input / output terminal, 30c ...
Abnormal signal output terminal, 31a to 31c: lithium ion battery, 32a to 32c: overcharge detection circuit, 33: cutoff circuit, 34: abnormal signal output circuit, 35: resistor.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-331425 (JP, A) JP-A-4-96629 (JP, A) JP-A-5-258778 (JP, A) JP-A-7- 183051 (JP, A) JP-A-6-105458 (JP, A) JP-A-1-59516 (JP, A) JP-A-7-241040 (JP, A) JP-A-5-43463 (JP, U) 62-13077 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02J 7/00 H01M 10/44

Claims (4)

(57) [Claims] 1. A battery pack comprising two or more lithium ion batteries connected in series in a case and having a pair of output terminals connected to both ends of the battery, further comprising: outputting an abnormal signal to the case. A terminal is provided, and two or more abnormal state detection circuits are provided corresponding to each of the two or more lithium ion batteries and output a detection signal when detecting an abnormal state of the lithium ion battery alone. when the detection signal from at least one abnormality detecting circuit of the plurality of abnormality detecting circuit is output, Bei example an abnormality signal output circuit that outputs an abnormality signal to the outside of the case from the abnormal signal output terminal And the two or more abnormal state detection circuits are cascaded . 2. The battery according to claim 1, further comprising a disconnection circuit that disconnects the connection between the lithium ion battery and the output terminal when a detection signal is output from the abnormal state detection circuit. pack. 3. The abnormal condition detecting circuit according to claim 1, wherein
An input terminal, an output terminal , connected between the second input terminal and the output terminal;
Switching between conducting and non-conducting states based on control signals
And when no abnormality is detected, the second input terminal
A switching element for establishing a conductive state between the output terminal and the second input terminal;
(1) comparing the voltage applied to the input terminal with a threshold voltage,
As a result of the comparison, an abnormality occurred in the voltage applied to the first input terminal.
Sometimes, a signal to make the switching element non-conductive is
This to and a comparison means for outputting as the control signal
The battery pack according to claim 1, wherein: 4. All other abnormal state detection circuits except one
Of the other abnormal state detection circuit
The terminal voltage of the lithium-ion battery is
In addition, make sure that each abnormal condition detection circuit is cascaded.
The battery pack according to claim 3, wherein: