JP3419122B2 - Battery protection device - 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 protection device using a plurality of secondary batteries connected in series or in series and parallel, and more particularly to a battery pack for a non-aqueous electrolyte secondary battery such as a lithium ion battery. Relates to a protective device suitable for

[0002]

2. Description of the Related Art As a power source for an electric vehicle or the like, a plurality of secondary batteries (cells formed of a single battery or a module formed of a plurality of cells) are connected in series or series-parallel in an amount corresponding to a required capacity. An assembled battery is used. Such an assembled battery includes a large number of batteries (for example, 100 to 100 in an electric vehicle).
Since about 250 cells are used, it is important to secure the reliability of the battery system. That is, if the function of any of the batteries forming the assembled battery is deteriorated due to over-discharging or overcharging, the function of the entire assembled battery may be deteriorated.

As a conventional device for protecting a battery, for example, JP-A-59-96655 (hereinafter referred to as Conventional Example 1), JP-A-61-206179 (hereinafter referred to as Conventional Example 2), JP-A-3-208265 (hereinafter referred to as Conventional Example 3), JP-A-3-279883 (hereinafter referred to as Conventional Example 4) and JP-A-5-258778 (hereinafter referred to as Conventional Example 5). Etc. are listed. In the technology described in the above-mentioned conventional example 1, in a nickel-cadmium battery in which a plurality of cells are connected in series, a diode is connected in parallel for each cell so that a constant voltage discharge occurs when the discharge voltage becomes a predetermined value or less. The voltage does not drop below that. In addition, conventional example 2
In the lithium battery in which a plurality of cells are connected in series, the technology described in (1) connects a diode (a Zener diode or a light emitting diode) in parallel to each cell to prevent the imbalance of the charging voltage applied to each cell. This is solved and each cell is charged uniformly. In addition, the technique described in Conventional Example 3 detects a cell whose temperature has dropped to a predetermined value or less in a battery that operates at a high temperature such as a sodium-sulfur battery, and short-circuits the cell to reduce the temperature. It is intended to prevent the reversal of polarity. Further, in the technique described in Conventional Example 4, a voltage detector is provided for each minimum unit of a plurality of cells, and when a cell whose terminal voltage drops below a predetermined value due to overdischarge occurs, an alarm is issued or Alternatively, the power circuit is cut off. Further, in the technique described in Conventional Example 5, in a battery in which a plurality of cells are connected in series, a series circuit of two light-emitting diodes connected in parallel in reverse polarity and a resistor is connected in parallel for each cell, When a difference occurs in the voltage of each cell, the potential difference causes the light emitting diode to emit light.
It is designed to monitor overcharge and overdischarge by detecting with a centralized monitoring device via an optical fiber cable.

[0004]

As described above, in each of the prior arts, overcharge and overdischarge are prevented, but the following points are insufficient. For example, in an electric vehicle or the like, an assembled battery in which a plurality of secondary batteries are connected in series or series / parallel by the required capacity is used. In the case of such an assembled battery, the degree of decrease in discharge capacity (the amount of electricity that can be discharged) differs depending on each battery. For example, there is a variation in manufacturing between batteries, and there is a difference in self-discharge amount and charge acceptance rate (charge / discharge efficiency) due to uneven temperature distribution when used in an assembled battery. The degree of decrease differs for each battery. Therefore, the discharge capacity from DOD (depth of discharge: 100% at full discharge, 0% at full charge) 0% varies among the batteries, and as a result, the discharge capacity as an assembled battery decreases. That is, at the time of discharging, a battery whose discharge capacity has become small is quickly discharged and becomes an over-discharged state, and this over-discharged battery becomes a load of other batteries, and all the batteries do not reach DOD 100%. The voltage drops to the end and the assembled battery ends the discharge.
In addition, at the end of battery discharge, deterioration due to increased internal resistance and increased internal heat generation, deterioration due to instability of battery materials, deterioration due to local flow of large current, etc. As the battery deteriorates, the battery in the overdischarged state has a large deterioration in life. On the other hand, at the time of charging, the battery that did not reach DOD 100% at the time of discharge first reached DOD 0% and the voltage increased,
Charging will end, but the battery that has been over-discharged at the time of discharging will end without charging to DOD 0%.
The difference in OD widens, and the difference in discharge capacity of each battery also widens. As described above, in the assembled battery, the discharge capacity and life of each cell vary during repeated charging and discharging.

By the way, in a transportation system such as an electric vehicle, even if the driving battery is almost discharged,
It may continue to drive to the charging station or home. In such a case, among the many cells that form the driving battery, the cell whose discharge capacity is reduced as described above is discharged before the other cells, and the polarity is changed to the terminal. The voltage may have the opposite polarity (minus). When the over-discharging further progresses, the electrolyte of the battery may be decomposed, and the battery may be rapidly deteriorated to generate gas. Therefore, even if a certain cell of a plurality of cells is over-discharged and re-polarized, if the internal pressure of the battery is below the elastic deformation limit value of the battery case, continue to discharge by other normal cells. When the internal pressure of the battery approaches the elastic deformation limit value of the battery case, it is necessary to detect it reliably. The above-mentioned conventional examples do not have the above-mentioned functions.

The present invention has been made in order to solve the problems of the prior art as described above, and even if a cell with a reversed polarity is generated, another normal battery is provided as long as the battery does not start to rapidly deteriorate. It is an object of the present invention to provide a battery pack protection device that can safely continue discharging by a cell and can reliably detect when the battery approaches the range where deterioration starts rapidly. To do.

[0007]

In order to achieve the above object, the present invention is constructed as described in the claims. That is, in the invention according to claim 1, an assembled battery in which a plurality of cells composed of one secondary battery or a module composed of a plurality of cells are connected in series or series-parallel, and for each cell or each module, A diode connected in parallel with the polarity opposite to the battery polarity, and a circuit connected in parallel with each of the diodes, and when the normal polarity of the battery is in the positive direction, the cell rapidly begins to deteriorate. When the lower limit voltage is Vb, the junction voltage of the diode is Vd when the maximum discharge current of the assembled battery is flown, and the voltage for lighting the light emitting diode is V ₁ , Vb <V ₁ <Vd <0 is satisfied. And a light emitting diode lighting circuit for lighting the light emitting diode. The above configuration corresponds to, for example, the embodiment shown in FIG. 1 described later.

According to a second aspect of the present invention, in addition to the structure of the first aspect, a circuit which is composed of at least a Zener diode and a second light emitting diode in a series circuit and is connected in parallel to each of the diodes is provided. Then, when the upper limit voltage at which the cell rapidly starts to deteriorate is Vc, the Zener voltage of the Zener diode with respect to the maximum charging current is Vz, and the voltage for lighting the second light emitting diode is V ₂ , 0 < A second light emitting diode lighting circuit for lighting the second light emitting diode is added under the condition of Vz <V ₂ <Vc. The above configuration corresponds to, for example, the embodiment shown in FIG.

The invention described in claim 3 is the same as claim 1
Alternatively, the structure according to claim 2 is provided with a means for detecting lighting of the light emitting diode and stopping charging or discharging of the assembled battery at the time of lighting. The above configuration corresponds to, for example, the embodiment shown in FIG. 6 described later. Further, the invention according to claim 4 is such that a circuit for lighting the third light emitting diode when the diode is conducted is added. The above configuration corresponds to, for example, the embodiment shown in FIG. 4 described later. The invention according to claim 5 is the invention according to claim 4, wherein the lighting of the third light-emitting diode is detected, and the integrated time of the lighting state, that is, the sum of the durations of the light-emitting diodes that are lit is equal to or greater than a predetermined value. When it reaches, it is provided with means for controlling discharge current reduction or interruption (load reduction or load drive stop). The above configuration corresponds to, for example, the embodiment shown in FIG. 7 described later. Further, the invention according to claim 6 is provided with means for detecting the pressure and temperature of each unit of the battery, and means for detecting an improper state of the battery according to the pressure and temperature and the voltage of the battery. It is a thing. The above configuration corresponds to, for example, the embodiment shown in FIG. 8 described later. The secondary battery is, for example, a non-aqueous electrolyte secondary battery, for example, a lithium ion battery, as set forth in claim 7. However, the present invention can be applied to an assembled battery of other secondary batteries such as a lead-acid secondary battery.

[0010]

In the secondary battery, even when the discharge end voltage is reached, the rapid deterioration of the battery does not start immediately and there is some margin. For example, as will be described later in detail, in the case of a lithium-ion battery, the normal operating range is about +4.0 V to +2.4 V, but the electrolyte is actually decomposed by over-discharging and the deterioration of the battery starts. Is
This is from about -4.4V after reversing. Therefore, even if the voltage drops and becomes higher than -4.4V even after the voltage is switched to 0V or less, if it is possible to operate another normal battery even if the power cannot be taken out from the battery,
The function as an assembled battery can be maintained. The present invention has been made based on the above consideration, and in the configuration of claim 1, each cell or each module is provided with a diode connected in parallel to the polarity opposite to the polarity of the battery, The current is allowed to flow through the above-mentioned diode after the polarity has been changed, so that the normal operation of the other battery is not hindered, and the battery is not further discharged. When the voltage of the battery further decreases and rapid deterioration of the battery is likely to occur, the light emitting diode is turned on to notify that the battery is in a state immediately before the rapid deterioration.

According to a second aspect of the present invention, in addition to the structure of the first aspect, a protection circuit at the time of overcharge and a light emitting diode for notifying a state immediately before rapid deterioration due to overcharge are added. Further, in claim 3, a means for detecting the lighting of the light emitting diode and stopping charging or discharging of the assembled battery at the time of lighting (for example, the photocouplers 21 and 22 and the protection control device 23 in FIG. 6) is provided, and the The charging / discharging is automatically stopped in the state immediately before deterioration.
Further, in claim 4, a third light emitting diode is provided to display the diode when the diode is conducted, that is, when the battery is polarized.

By doing so, it is possible to notify that there is a battery that has been discharged and the remaining capacity of the battery pack is insufficient and urge the driver or the like to go to the nearest charging station.

According to a fifth aspect of the present invention, the lighting of the third light emitting diode of the fourth aspect is detected, and when the integrated time of the lighting state reaches a predetermined value or more, the discharge current is reduced or cut off. It is something to do. The fact that the third light emitting diode is turned on is not the state immediately before the rapid deterioration itself, but when the number of batteries that have been poled or the duration is long, the remaining capacity as an assembled battery is small, It is intended to reduce or interrupt the discharge current. In addition, according to claim 6, in addition to detection of an improper condition based on the voltage of the battery, the pressure and temperature of the battery are also detected, and even if an improper condition occurs, a protection operation such as load stop is performed. Is. That is, when the electrolyte is decomposed and gas is generated, the pressure greatly increases and the temperature also largely increases. Therefore, even if the voltage shows an appropriate value for some reason, it is possible to determine that the battery is in an improper state if the pressure or temperature rises significantly. Moreover, as described in claim 7, the present invention is particularly suitable for a non-aqueous electrolyte secondary battery such as a lithium ion battery. Generally, since the unit of a non-aqueous electrolyte secondary battery is completely sealed, the pressure may increase significantly when the electrolyte decomposes and gas is generated, and the temperature also increases significantly. Therefore, it is particularly beneficial to provide a protection device such as the present invention.

[0014]

EXAMPLES The present invention will be described in detail below based on examples. FIG. 1 is a diagram of a first embodiment of the present invention. First, in FIG. 1A, reference numeral 1 denotes an assembled battery, in which batteries 1a to 1n (cells each including a single battery or a module including a plurality of cells) are connected in series. It should be noted that they may be connected in series and parallel. Reference numeral 2 denotes a control device, which controls power supply when the load 3 is driven by the power of the battery pack 1. For example, the control device 2 is a circuit including a DC / AC converter and a control computer in an electric vehicle, and the load 3 is an electric vehicle driving motor. The control device 2 and the load 3 are the output (discharge) circuit of the assembled battery, and the part 4 described below is the protection circuit part of this embodiment. Reference numeral 4 denotes a protection circuit, which includes a diode 5 connected in parallel to the battery 1a with a reverse polarity, a light emitting diode 6, and a zener diode 7.
And a series circuit of resistor 8 (connected in parallel to diode 5)
It consists of and. 1 shows only the protection circuit connected to the battery 1a, the protection circuit 4 is provided in each of the batteries 1a to 1n. Further, instead of the series circuit of the light emitting diode 6, the Zener diode 7 and the resistor 8 as described above, a series circuit of the light emitting diode 6 ′ and the resistor 8 ′ is used, as shown in FIG. To do.

The operation will be described below with reference to FIG. FIG. 2 is a diagram showing an operating region in the battery 1a and a current path in the protection circuit 4. In FIG. 2, line segments,
,, show the operating region of the battery 1a, are the normal operating region, are the reversing region due to over-discharge, are the bypass region at the time of overcharging (details are explained in the embodiment of FIG. 5), and rapid deterioration is occurring The non-existence area and the rapid deterioration area are shown. Further, the upper limit voltage Vc that causes rapid deterioration is a voltage at which the battery starts to deteriorate rapidly due to overcharge, and the lower limit voltage Vb that causes rapid deterioration is a voltage at which the battery starts rapid deterioration due to overdischarge. Is. Vd is the junction voltage of the diode 5 when the maximum discharge current of the assembled battery is flowed, Vd
₁ is a voltage for lighting the light emitting diode 6. In addition,
If the normal polarity of the battery 1a is in the positive direction, the above Vd,
V ₁ and Vb have negative values as shown. Also,
V ₂ and Vz will be described in the embodiment of FIG.

As shown in FIG. 2, in the operation of the unit battery 1a, the range from the end of charge (end of charge voltage) to the end of discharge (end of discharge voltage) is the normal operation range. However, the battery does not immediately start to deteriorate rapidly, and there is some margin between the upper limit voltage Vc at which the battery starts rapid deterioration and the lower limit voltage Vb at which rapid deterioration occurs.

The discharge will be described below. In the normal operation area, the current path is the battery 1 as shown in '.
Flow through a in the normal direction. When the discharge is continued in that state and the discharge is continued even after the discharge end voltage (the end of discharge) is reached, the battery voltage further decreases and becomes lower than 0V. In this state, when the discharge capacities remain in the other batteries 1b to 1n, the other batteries continue to be discharged, but in the battery 1a,
Inversion occurs and the voltage has the opposite polarity. When the battery 1a is polarized, the diode 5 becomes conductive because it is forward-biased, and the current path becomes a path passing through the protection circuit 4 as indicated by '. Therefore, as shown in the diode characteristics of FIG. 3, the maximum discharge current (maximum load current) Ima of the assembled battery is
If the junction voltage Vd of the diode 5 when x is flowed is set not to reach the lower limit voltage Vb that causes rapid deterioration, the battery 1 that has finished discharging earlier than other batteries
It is possible to continue the operation of the load by effectively utilizing the electric power of other batteries while preventing the rapid deterioration of a.
The junction voltage Vd of a normal diode is 0.6 V to 1.
While it is about 0 V (-0.6 V to -1.0 V in the direction of FIG. 1), the lower limit voltage Vb that causes rapid deterioration of the lithium-ion battery is about -4.4 V. The condition can be fully satisfied. Also, for some reason, the reduced voltage of the battery 1a is further reaches a predetermined value V _1, the zener diode 7 conducts the light emitting diode 6 is turned, the voltage to notify that it has reduced the out of the proper range. This predetermined value V ₁ is the junction voltage V of the diode 5
If a value between d and the lower limit voltage Vb that causes rapid deterioration is set, when the limit of the protection effect of the diode 5 is exceeded, an improper state is notified before the battery deteriorates rapidly. You can do it. When such an improper condition is detected, rapid deterioration of the battery is prevented by taking measures such as manually or automatically cutting off the load, as will be described in the embodiment of FIG. 6 below. You can do it. As shown in FIG. 1B, when the Zener diode 7 is omitted, the predetermined value V for turning on the light emitting diode 6 '
₁ becomes a little inaccurate, but basically works as above. As described above, in the embodiment of FIG. 1, even if any of the batteries in the battery pack has finished discharging first, the power of the other batteries can be used without causing rapid deterioration of the battery. Since the load driving can be continued, for example, in the case of an electric vehicle, it is possible to continue traveling to the nearest charging station or home. In addition, if there is a risk of rapid deterioration due to further voltage drop of the battery, it will be notified before the rapid deterioration.
It is possible to surely avoid rapid deterioration of the battery by taking appropriate measures such as load stop. In the above description, the battery 1a is described as an example, but the same applies to any of the batteries 1a to 1n.

Next, FIG. 4 is a second embodiment of the present invention. In this embodiment, a circuit for notifying that the diode 5 has been conducted, that is, the battery has been reversed is added to the embodiment shown in FIG. In FIG. 4, 9 is a transistor, 10 to 12 are resistors, 13 is a light emitting diode, 14 is a backup battery, and
The same reference numerals as in FIG.

As in the case of FIG. 1, when the battery 1a is polarized and the diode 5 becomes conductive, the transistor 9 becomes conductive and the power of the battery 14 turns on the light emitting diode 13. As described above, in the circuit of FIG. 4, since the light emitting diode 13 is turned on when the battery 1a is polarized, it is notified at an early stage that there is an over-discharged battery, and the operation of the load is terminated or charging is completed. Appropriate measures such as urging can be taken. Other functions and effects are the same as in the case of FIG.

Next, FIG. 5 is a diagram showing a third embodiment of the present invention. In this embodiment, an overcharge protection function is added to the embodiment of FIG. In FIG. 5, 15 is a Zener diode for overcharge protection, 16 is a resistor, 17 and 18 are light emitting diodes, and 19 and 20 are resistors. The series circuit of the light emitting diode 17 and the resistor 19 has the same function as the series circuit of the light emitting diode 6'and the resistor 8'of FIG. 1 (b),
As described above, when the voltage of the battery 1a drops and reaches the predetermined value V ₁ , the light emitting diode 17 is turned on to notify that the voltage falls outside the proper range. In addition, in order to turn on the light with the above-mentioned predetermined value V ₁ , the value of the resistor 19 may be set according to the characteristics of the light emitting diode 17.

On the other hand, the series circuit of the Zener diode 15 and the resistor 16 is an overcharge protection circuit. Battery 1 when charging
When the voltage of a rises and reaches the Zener voltage of the Zener diode 15, the Zener diode 15 becomes conductive and the current path becomes a path passing through the protection circuit 4 as shown in FIG. Therefore, the voltage of the battery 1a does not rise further and the battery is kept safe. Further, when the voltage of the battery 1a further rises to a predetermined value V ₂ for some reason, the light emitting diode 18 is turned on to notify that the voltage has risen outside the proper range. If this predetermined value V ₂ is set to a value between the Zener voltage Vz of the Zener diode 15 and the upper limit voltage Vc at which the battery rapidly starts to deteriorate, the limit of the protective action by the Zener diode 15 is exceeded. In this case, an improper condition can be notified before the battery deteriorates rapidly. When such an improper condition is detected, rapid deterioration of the battery can be prevented by taking measures such as manually or automatically shutting off the charging device, as will be described later in the embodiment of FIG. It can be prevented. In order to turn on the light with the above-mentioned predetermined value V ₂ , the value of the resistor 20 may be set according to the characteristics of the light emitting diode 18. The charging bypass region of FIG.
To V ₂ . Other functions and effects are similar to those of the embodiment shown in FIG. As described above, the embodiment shown in FIG. 5 has the protection function and the notification function at the time of over-discharge and the protection function and the notification function at the time of over-charge.

Next, FIG. 6 is a diagram showing a fourth embodiment of the present invention. In this embodiment, a protection control device for stopping charging / discharging is added to the embodiment of FIG. In FIG. 6, reference numerals 21 and 22 are photocouplers, and 23 is a protection control device including a computer and an analog circuit. The photocoupler 21 detects the light emission of the light emitting diode 18, and the photocoupler 22 detects the light emission of the light emitting diode 17. Therefore, as described above, when the light emitting diode 17 is turned on during overdischarge or the light emitting diode 18 is turned on during overcharge, the photocouplers 21 and 22 send signals to the protection control device 23. When the protection control device 23 detects a photocoupler signal, the protection control device 23 controls the load driving control device 2 and a charging device (not shown) to prevent further overcharging and overdischarging. Although only the battery 1a is shown in FIG. 6, the batteries 1a-1
Each of the n light emitting diodes is a photocoupler 21, 2
It is coupled with the No. 2 and can detect an improper condition in any battery.

Next, FIG. 7 is a fifth embodiment of the present invention. In FIG. 7, 13a to 13n are the light emitting diodes 13 described in FIG. 4, that is, the light emitting diodes that are turned on when the battery is polarized. The photocouplers 24a to 24n are connected to the respective light emitting diodes 13a.
.. 13n and when their light emitting diodes emit light, it sends a detection signal to the protection controller 25. The protection control device 25 obtains the sum of the above-mentioned integrated time of the detection signals, that is, the sum of the durations of the respective light-emitting diodes that are turned on, and issues an alarm according to the value. For example, when the accumulated time reaches the first predetermined value, it is displayed on the display device 26, and when it reaches the larger second predetermined value, an alarm signal is generated. Also, the load control device 2 is controlled to reduce the load (discharge current reduction).
Alternatively, the load driving may be stopped. The fact that the batteries are poled and the light emitting diodes 13a to 13n are lit does not mean that an improper state has occurred, but when the number of poled batteries or the duration is long, the remaining capacity as an assembled battery becomes small. Therefore, the discharge current is reduced or interrupted when the number of batteries that have been poled or the duration is large, that is, when the integrated time is large. Other functions and effects are similar to those of the embodiment shown in FIG.

Next, FIG. 8 is a diagram showing a sixth embodiment of the present invention. In FIG. 8, 27 is a photocoupler, 28 is a pressure sensor that detects the pressure in each battery unit, 29 is a temperature sensor that detects the temperature of each battery unit, and 30 is a protection control device. In this embodiment, in addition to detecting an improper state due to the voltage of the battery, the pressure and temperature of the battery are also detected, and even when an improper state occurs, the protection control device 30 performs a protective operation such as a load stop. This is done, and comprehensive battery protection is performed based on each element of voltage, pressure, and temperature. That is, when the electrolyte is decomposed and gas is generated, the pressure greatly increases and the temperature also largely increases. Therefore, even if the voltage does not show the value in the improper state for some reason, it can be determined that the improper state has occurred in the battery if the pressure or the temperature significantly rises. In such a case, the protection control device 30 controls to stop the load driving. Although the protection circuit 4 shown in FIG. 8 is shown in FIG. 8, a protection circuit having a charge protection function as shown in FIG. 5 may be used. In that case, two systems of photocouplers 27 to be coupled to the light emitting diodes 17 and 18 (FIG. 5) of FIG. 5 are required. Further, in FIG. 8, only the portion of the battery 1a is shown, but each light emitting diode of the batteries 1a to 1n is coupled to the photocoupler 27, so that an improper state of any battery can be detected. ing. The embodiments described above may be combined with each other as appropriate.

Next, an example of an actual battery will be described.
For example, in a non-aqueous electrolyte secondary battery such as a lithium ion battery, as shown in FIG. 9, the battery voltage is ± 4.4 V.
If it exceeds, the decomposition of the electrolytic solution will start and the battery will rapidly deteriorate. In the normal operation range, the end-of-charge voltage is about 4.0V and the end-of-discharge voltage is about 2.4V. Therefore, as shown in FIG. 10, the upper limit voltage Vc≈4.4 V at which the battery of FIG. 2 starts to rapidly deteriorate, the lower limit voltage Vb≈−4.4 V at which rapid deterioration starts, and the maximum discharge of the assembled battery Junction voltage Vd≈− of the diode 5 when a current is applied
1.0V, Zener voltage of Zener diode 15 Vz≈4.
The voltage V ₁ for setting the light emitting diode 6 to light is set to about ₁ V and has a value between -1.0 V and -4.4 V (eg -1.5 V).
V), the voltage V ₂ for lighting the light emitting diode 18 is 4.1.
It may be set to a value between V and 4.4V (for example, 4.3V).

[0026]

As described above, according to the present invention, even if one of the batteries in the assembled battery has finished discharging first, the power of the other battery can be used without rapidly deteriorating the battery. Since the load drive can be continued, the capacity of the assembled battery can be used to the maximum in an emergency. Also, if there is a risk of rapid deterioration due to further voltage drop in the battery, it will be notified before the rapid deterioration, so appropriate measures such as load stop will be taken to ensure rapid deterioration of the battery. The effect that can be obtained is obtained. In addition, in the configuration provided with the charge protection function,
Even during charging, the same protection as above can be performed. Further, in the configuration in which the lighting of the light emitting diode is detected to stop the charging / discharging, the charging / discharging is automatically stopped immediately before the rapid deterioration of the battery, and the battery can be protected safely. In addition, in the configuration in which the light emitting diode is turned on when the battery is polarized, notify that there is an over-discharged battery at an early stage and take appropriate measures such as prompting the end of load operation and charging. Can be done. Further, in the configuration provided with means for controlling the discharge current reduction or interruption when the integrated time of the lighting state reaches a predetermined value or more, the number of batteries that have been poled and the duration of the battery are long, When the remaining capacity of the battery becomes small, the battery can be protected by reducing or interrupting the discharge current. Further, in the case where the pressure and temperature of the battery unit are added to the control element, it is possible to obtain an effect that comprehensive battery protection can be performed based on each element of voltage, pressure and temperature.

[Brief description of drawings]

FIG. 1 is a diagram of a first embodiment of the present invention.

FIG. 2 is a diagram showing an operating region and a current path in a secondary battery.

FIG. 3 is a characteristic diagram showing a characteristic curve of a diode.

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

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

FIG. 6 is a diagram of a fourth embodiment of the present invention.

FIG. 7 is a fifth embodiment of the present invention.

FIG. 8 is a diagram of a sixth embodiment of the present invention.

FIG. 9 is a characteristic diagram showing decomposition characteristics of a lithium-ion battery.

FIG. 10 is a diagram showing an operating region in a lithium ion battery.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Assembly battery 5 ... Diodes 1a-1n ... Battery 6,6 '... Light emitting diode 2 ... Control device 7 ... Zener diode 3 ... Load 8, 8' ... Resistor 4 ... Protection circuit 9 ... Transistor 10-12 ... Resistor 15 ... Zener diode 13 ... Light emitting diode 16 ... Resistor 14 ... Battery 17, 18 ... Light emitting diode 19, 20 ... Resistor 26 ... Display device 21, 22 ... Photo coupler 27 ... Photo coupler 23 ... Protection control device 28 ... Pressure sensor 24 ... Photo coupler 29 ... Temperature sensor 25 ... Protection control device 30 ... Protection control device

Front page continued (58) Fields surveyed (Int.Cl. ⁷ , DB name) H02J ^7/ 00-7/12 H02J ⁷ /34-7/36

Claims (7)

(57) [Claims] 1. An assembled battery in which a plurality of cells each composed of one secondary battery or a module composed of a plurality of cells are connected in series or series-parallel, and each cell or each module has a polarity opposite to that of the battery. A diode connected in parallel, and a circuit connected in parallel for each of the above diodes, where the lower limit voltage at which the cell rapidly begins to deteriorate when the normal polarity of the battery is the + direction is Vb, When the junction voltage of the diode is Vd and the voltage for lighting the light emitting diode is V ₁ when the maximum discharge current of the battery is passed, the light emitting diode is lighted under the condition of Vb <V ₁ <Vd <0. An assembled battery protection device comprising: a light emitting diode lighting circuit. 2. An assembled battery in which a plurality of cells each composed of a single secondary battery or a module composed of a plurality of cells are connected in series or series-parallel, and each cell or each module has a polarity opposite to that of the battery. A diode connected in parallel, and a circuit connected in parallel for each of the above diodes, where the lower limit voltage at which the cell rapidly begins to deteriorate when the normal polarity of the battery is the + direction is Vb, When the maximum discharge current of the battery is passed, the junction voltage of the diode is Vd, and the voltage for lighting the first light emitting diode is Vd.
_When it is set to ₁ , it comprises a first light emitting diode lighting circuit for lighting the first light emitting diode under the condition of Vb <V ₁ <Vd <0, and at least a series circuit of a Zener diode and a second light emitting diode. , A circuit connected in parallel for each of the diodes, wherein the upper limit voltage at which the cell rapidly starts to deteriorate is Vc, the Zener voltage of the Zener diode with respect to the maximum charging current is Vz, and the second light emitting diode is When the voltage to be turned on is V ₂ , a second light emitting diode lighting circuit for lighting the second light emitting diode under the condition of 0 <Vz <V ₂ <Vc, and an assembled battery comprising: Protector. 3. The battery pack protector according to claim 1, further comprising means for detecting lighting of the light emitting diode and stopping charging or discharging of the battery pack when the light emitting diode is turned on. 4. The circuit according to claim 1, wherein a circuit for lighting the third light emitting diode when the diode is conductive is provided for each cell or each module. Battery protector. 5. The discharge current is reduced or cut off when the lighting of the third light emitting diode is detected and the integrated time of the lighting state, that is, the sum of the durations of the light emitting diodes that have been lit reaches a predetermined value or more. 5. The assembled battery protection device according to claim 4, further comprising means for controlling. 6. A means for detecting the pressure and temperature of each unit of the battery, and a means for detecting an improper state of the battery according to the pressure and temperature and the voltage of the battery. The battery pack protection device according to any one of claims 1 to 5. 7. The battery pack protector according to claim 1, wherein the secondary battery is a non-aqueous electrolyte secondary battery.