JP2010160955A - Method of charging battery pack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of charging a battery pack, which suppresses a sharp decrease in a cycle life that happens when four or more serial batteries are connected in parallel and charged together by n-stage constant current charging for capacity increase, and offers both advantages of fine life characteristics and short-time charging. <P>SOLUTION: According to the method of charging the battery pack, serial circuits each composed of a plurality of lead storage batteries connected in series are connected in parallel to supply power to a load. A charging device is connected to each serial circuit to carry out n-stage constant current charging in such a way that the charging device detects a charge voltage for the serial circuit to lower a charge current value step by step in n stages (n denotes an integer satisfying n≥2) when the charge voltage reaches a predetermined control voltage value. When the battery pack supplies power to the load, at least four or more of the serial circuits are connected in parallel in the battery pack. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for charging an assembled battery comprising a lead storage battery.

  In the midst of increasing momentum to suppress carbon dioxide emissions and oil resource depletion, the development of small vehicles that use only secondary batteries such as lead-acid batteries as the power source is desired. Among them, the lead storage battery is considered to be useful as a power source for a transport vehicle, for example, because it is strong for tough use and has an appropriate weight.

  Since a lead storage battery has a nominal voltage of 2 V as is well known, in order to obtain a battery voltage desired as a power source as described above, a plurality of lead storage batteries are connected in series to form an assembled battery. Is generally done.

  On the other hand, regarding the battery capacity, a lead storage battery having a desired capacity is obtained by adjusting the amount of the active material of the positive electrode and the negative electrode contained in the unit cell of the lead storage battery, the sulfuric acid concentration in the electrolytic solution, and the amount of the electrolytic solution. However, because the parts such as the positive electrode plate, the negative electrode plate, the separator, the battery case, and the lid are different for each desired battery capacity, by connecting the standard capacity batteries in parallel, A battery having various capacities, that is, an assembled battery can be obtained efficiently without causing an increase.

  Therefore, a desired assembled battery having a nominal voltage and a rated capacity can be obtained by connecting in parallel a plurality of series batteries obtained by connecting lead storage battery cells in series.

  For example, Patent Document 1 discloses a configuration in which two storage battery cells are connected in series to form a series battery, and two of the series batteries are connected in parallel to supply power to a load. Further, in Patent Document 1, a power supply circuit is connected to each of two series batteries, and the power supply circuit has a constant voltage circuit that maintains a voltage applied to the series battery at a certain value. It is shown that the series battery is charged at a constant voltage.

  In general, regardless of whether it is a liquid type (open type) or a control valve type, a lead-acid battery is, for example, 2.25 V per cell at 25 ° C. for the purpose of suppressing a decrease in moisture in the electrolytic solution. Constant voltage charging is performed at a control voltage of about ~ 2.45V.

  In constant voltage charging, the storage battery is initially charged with a charging current of about 0.6 CA, and the voltage of the storage battery is maintained at the control voltage from the time when the voltage of the storage battery reaches the control voltage described above. The current decays. When the charging current is attenuated to a so-called trickle current of about 0.005 CA to 0.01 CA, the storage battery is fully charged.

  Thus, at the end of constant voltage charging, the charging current is sufficiently small with respect to the battery capacity, so the IR loss is small. Therefore, when the battery cells are connected in series to form a series circuit, and the assembled battery in which this series circuit is further connected in parallel is charged at a constant voltage, due to variations in the capacity of the storage battery cells constituting the assembled battery and the connection resistance between the single batteries, At the beginning of charging, the variation in charging voltage and charging current between storage battery cells is relatively large.

  However, as the charging progresses, the charging voltage applied to each storage battery cell and the charging current flowing through each series circuit gradually converge, and when fully charged, variations in the charging voltage and charging current are suppressed. As a result, each storage battery cell There is an advantage that variation in the state of charge is suppressed.

  However, in the constant voltage charging as described above, the charging current is sufficiently attenuated, and each storage battery cell is fully charged for a long time (for example, when the maximum charging current per series circuit is 0.6 CA, 12 If it can be secured for about 24 hours from the time), it is a charging method suitable for charging the assembled battery, and if it is used for backup, a long charging time is not a problem in practice.

  On the other hand, when such an assembled battery is used as a power source for an electric transportation vehicle, it is difficult to tolerate a long charging time of 12 hours to 24 hours, and attempts have been made to shorten the charging time.

  And the multistage charging system as shown, for example in patent document 2 is proposed as a quick charge method of lead acid battery. In the multistage charging method of Patent Document 2, at the beginning of charging, charging is performed with the charging current I1, and when the storage battery voltage reaches a certain control voltage VR, the charging current is gradually reduced to I2 lower than I1. Thereafter, similarly, the charging current is gradually reduced by the control voltage VR. In addition, the control voltage VR has the structure which suppresses dissipation of the water | moisture content in electrolyte solution out of a storage battery by setting it as about 2.40V per storage battery cell as mentioned above.

In the charging method of Patent Document 2, in the final n-stage charging, the storage battery voltage is not controlled, but the n-th stage charging time is determined by the first stage charging electricity amount and the battery temperature. The Since the forced charging is performed in the n-th stage charging, the charging time until the fully-charged assembled battery is fully charged in the normal constant voltage charging as described above is 12 hours. According to the charging method of Patent Document 2, it takes about 24 hours, but can be shortened to about 5-6 hours.
JP 55-053140 A JP 11-297364 A

  Since the charging method shown in Patent Document 2 as described above can shorten the charging time, it is suitable for cycle applications such as a power supply for transport vehicles. However, when the n-stage constant current charging as described above is applied to a battery pack in which a plurality of series circuits each having storage battery cells connected in series is applied, in particular, when the number of series circuits connected in parallel exceeds four, The inventor of the present invention has found that the life characteristics are rapidly deteriorated.

  In view of the above situation, the present invention suppresses a decrease in cycle life when an n-stage constant current charge as described above is applied to an assembled battery in which series circuits formed by connecting battery cells in series are connected in parallel. It is an object of the present invention to provide a method for charging an assembled battery that achieves both cycle life characteristics of the assembled battery and shortening of the charging time.

  In order to solve the above-described problem, the invention according to claim 1 of the present invention is a method for charging an assembled battery in which a series circuit in which a plurality of lead-acid batteries are connected in series is connected in parallel to supply power to a load. A charging device is connected to each series circuit, and the charging device detects a charging voltage of the series circuit, and when the charging voltage reaches a predetermined control voltage value, the charging current value is set to n (however, , N is an integer satisfying n ≧ 2), and the n-stage constant current charging is performed in a step-wise manner, and at the time of feeding the battery pack to the load, the battery pack includes at least four series circuits. The charging method of the assembled battery formed in parallel is shown.

  Further, the invention according to claim 2 of the present invention is a method of charging an assembled battery in which a series circuit in which a plurality of lead storage batteries are connected in series is connected in parallel to supply power to the load, and the load of the assembled battery At the time of power supply to the battery pack, the battery pack includes at least four or more series circuits connected in parallel, and the battery pack includes two or more parallel circuits in which two or three of the series circuits are connected in parallel. A charging device connected to each parallel circuit, the charging device detects a charging voltage of the parallel circuit, and when the charging voltage reaches a predetermined control voltage value, a charging current value The battery pack charging method is characterized in that n-stage constant current charging is performed in a step-wise manner, n times (where n ≧ 2 is an integer).

  The invention according to claim 3 of the present invention is the method for charging an assembled battery according to claim 1 or 2, wherein the required charge electricity is set by multiplying the discharge electricity of the assembled battery by a certain coefficient. The first stage charging is performed at the first constant current, the charging time at the nth stage n constant current is the charging time required for the first stage charging, and the battery of the lead storage battery at the time of the first stage charging. Setting control is performed based on temperature, and the shortage of the amount of charged electricity due to charging from the first stage to the (n-1) th stage is compensated.

  According to the present invention, it is possible to provide a method for charging an assembled battery that can shorten the charging time without reducing the cycle life of the assembled battery in which series circuits in which battery cells are connected in series are connected in parallel. Play.

(First embodiment)
FIG. 1 is a diagram showing a configuration of a power supply system 101 using the charging method according to the first embodiment of the present invention.

  A power supply system 101 to which a charging method of the present invention is applied includes an assembled battery 104 in which a series circuit 103 in which a plurality of lead-acid battery cells 102 are connected in series is connected in parallel, and a charging device 105 that charges the assembled battery 104. Become.

  In the power supply system 101, at least four or more series circuits 103 are connected in parallel to the assembled battery 104 when power is supplied to the load 106. In the power supply system 101, when charging the assembled battery 104, a charging device 105 is connected to each series circuit 103, and the corresponding series circuit 103 is charged by the charging device 105.

  An external output terminal 108 is provided from the assembled battery 104 as necessary, and a load 106 is connected thereto. When power is supplied from the power supply system 101 to the load 106 in a state where a certain series circuit 103 has failed due to an internal short circuit or the like, a current from another normal series circuit 103 flows into the failed series circuit 103 and is supplied to the load 106. In order to prevent a problem in power feeding, a diode 107 a can be connected in series with the series circuit 103.

  Such a diode 107 a inserted in series in the series circuit 103 is connected to the series circuit 103 from another charging device 105 connected to the other series circuit 103 when the charging device 105 charges the series circuit 103. By preventing the flow of charging current, the series circuit 103 and the pair of charging devices 105 connected to the series circuit 103 become independent from each other, so that each series circuit is charged under the same conditions. The variation in the state of charge between the series circuits 103 can be suppressed.

  Although the diode 107a is provided in the present invention, a switching element (not shown) may be used instead of the diode 107a.

  Further, FIG. 1 shows a mode in which a diode 107b is inserted in series with the charging device, but this diode 107b is arranged for the purpose of preventing the backflow of current from the series circuit 103 to the assembled battery. Instead of the diode 107b, an element or a circuit having a similar action may be arranged. The diode 107b or an element or circuit having the same action may be provided inside the charging device 105 or outside the charging device 105.

  In the present invention, as described above, when the assembled battery 104 supplies power to the load 106, four or more of the series circuits 103 are connected in parallel to the assembled battery 104, and the operation of the charging device 105 is shown in FIG. It is supposed to be an operation. That is, as shown in FIG. 2, the charging device 105 detects the charging voltage V of the series circuit 103, and when the charging voltage V reaches a predetermined control voltage value VR, the charging device 105 sets the charging current value to n ( However, it is lowered step by step to an integer where n ≧ 2.

  Note that the control voltage VR from the first stage to the (n−1) th stage can be set to 2.25 V / cell to 2.45 V / cell in which electrolysis of water in the electrolytic solution is suppressed. Since the control voltage VR has a negative characteristic with respect to a temperature rise, a decrease in moisture in the electrolytic solution can be suppressed. Further, the control voltage VR may be constant at each stage, or may be changed within the above-described range.

  For example, since the temperature of the cell 102 rises due to Joule heat due to the charging current, the control voltage value VR has a negative characteristic (for example, −0.02 V / ° C. to −0.005 V / ° C.) with respect to the temperature rise. In practice, since the control voltage VR changes for each number of charging stages, charging can be switched at an appropriate control voltage VR corresponding to the temperature of the cell 102, and insufficient charging and overcharging can be suppressed.

  In the present invention, since the series circuit 103 is connected in parallel, the temperature varies depending on the position of the cell 102. For example, when the series circuit 103 is arranged in parallel as it is, the heat dissipation of the cells 102 constituting the series circuits 103 on both sides is remarkably higher than the heat dissipation of the cells 102 constituting the other series circuits 103. In the present invention, since temperature measurement is possible for each series circuit 103, each series circuit 103 can be charged without excess or deficiency regardless of the installation position of the series circuit 103.

  In the present invention, in the n-th stage charging, the charging current is interrupted after being charged with the current In without being attenuated continuously unlike the normal constant voltage charging. As a method for controlling the charging time of the n-th stage, for example, with the control voltage VR from the first stage to the (n-1) th stage, the electrolysis of water in the electrolytic solution is suppressed to 2.25 V / cell to 2.45 V / As a cell, when the electrolysis of water in the electrolyte proceeds at the nth stage and reaches 2.6 to 2.7 V / cell just before hydrogen gas starts to be generated from the negative electrode, the nth stage is charged. Stop and complete the charging, or set the charging time of the nth stage to a predetermined time in advance, and at the stage when the timer counts this predetermined time from the start of the charging of the nth stage, It is also conceivable to terminate the charging and complete the charging, and these methods can also reduce the charging time to about 5 to 6 hours.

  Further, the amount of charge electricity at the nth stage can be controlled according to the amount of charge electricity at the first stage. This increases the amount of charge in the nth stage as the amount of charge in the first stage increases, that is, the charge time in the constant current charge in the nth stage becomes longer. According to such a configuration, even if the depth of discharge of the series circuit 103 varies, charging can be performed without excess or deficiency, which is more preferable.

  The number of charging stages can be selected from, for example, 2 to 10 stages, preferably about 3 to 10 stages. If the charging current at the final stage, i.e., the n-th stage is set to a value corresponding to a trickle current such as 0.001 CA to 0.005 CA, the time until the charging is completed becomes long, so 0.02 CA or more, preferably 0.04 CA or more. Moreover, it is preferable to make it high in the range which the charge acceptance of the cell 102 accept | permits about the 1st step | paragraph charging current, For example, it can select within the range of 1CA-0.4CA.

  The inventor of the present invention connects the charging device 105 that performs the n-stage constant current charging operation shown in FIG. 2 to the terminal 108 of the assembled battery 104 in which the parallel number of the series circuit 103 exceeds 4, and collects the assembled battery in a lump. It has been found that when the battery 104 is charged, the cycle life characteristics of the assembled battery 104 are rapidly deteriorated.

  On the other hand, even when the parallel number of the series circuit 103 exceeds 4, a constant voltage charging device (not shown) operating in the pattern shown in FIG. 3 is connected to the terminal 108 and charging is performed for a long time such as 16 to 24 hours. If this is performed, the cycle life characteristics are not deteriorated as described above.

  The cause of such a phenomenon is estimated as follows. That is, the constant voltage charging shown in FIG. 3 (the charging voltage is controlled to be constant at this control value from the time when the charging voltage reaches the control value, and the charging current is continuously attenuated as the charging progresses. In the case of charging the assembled battery 104, each series circuit is caused by variation in capacity of the series circuit 103 constituting the assembled battery, connection resistance, and the like. The charging current flowing through 103 varies.

  However, when the charging current is attenuated, the charging current flowing through each series circuit 103 is attenuated and converges evenly, and finally, the charging variation between the series circuits 103 is eliminated. However, since a very long charging time of 16 to 24 hours is required to reach this state, it is suitable for backup but not practical for cycle use.

  On the other hand, as in the present invention, in the n-stage constant current charging that does not include the process of sequentially switching the charging current in a discontinuous state and continuously decreasing the charging current from 0.001 CA to 0.005 CA, as described above. In addition, the variation in the charging current flowing through the series circuit 103 is not eliminated until the end of charging. As a result, the variation in the charging state of the series circuit 103 occurs, and this variation is enlarged by cyclic use, It is presumed that a specific series circuit is deteriorated by being overcharged or overdischarged, and the cycle life characteristics as the assembled battery 104 are extremely lowered.

  Further, the inventor of the present invention has found that such a rapid decrease in cycle life characteristics when using n-stage constant current charging is very prominent when the parallel number of the series circuit 103 is 4 or more. It is a thing.

  Based on the above knowledge, when combining the assembled battery 104 in which the parallel number of the series circuit 103 is 4 and the charging device 105 performing the n-stage constant current charging operation, by providing the charging device 105 for each series circuit 103 As described above, when the n-stage constant current charging is performed and the number of parallel connections is 4 or more, the decrease in cycle life that occurs remarkably is suppressed, and good life characteristics are obtained. Compared to the voltage charging method, there is a remarkable effect that charging can be performed in an extremely short time.

(Second Embodiment)
The configurations of the power supply system 201 and the power supply system 301 to which the charging method according to the second embodiment of the present invention is applied are shown in FIGS. 3 and 4, respectively.

  As shown in FIG. 4, the power supply system 201 to which the charging method according to the second embodiment of the present invention is applied is configured by connecting a series circuit 103 in which a plurality of lead-acid battery cells 102 are connected in series to each other in parallel. The battery pack 202 connected to the battery pack 106 and a charging device 203 for charging the battery pack 202 are provided.

  The assembled battery 202 is configured by connecting in parallel two or more of the parallel circuits 204 in which two of the series circuits 103 are connected in parallel. When charging the assembled battery 202, the charging device 203 is connected to each parallel circuit 204. Further, when power is supplied from the assembled battery 202 to the load 106, the assembled battery 202 has a configuration in which four or more series circuits 103 are connected in parallel.

  The charging device 203 performs exactly the same control as the charging device 105 in the first embodiment. That is, when the charging voltage of the parallel circuit 204 is detected and the charging voltage reaches a predetermined control voltage value VR, the charging current value is gradually reduced to n (where n ≧ 2). It has a function to make it. However, the charging device 105 charges a single series circuit 103, but the charging device 203 charges two series circuits 103, so that the output current value has a capacity twice that of the charging device 105. It goes without saying that it is preferable to do so.

  In addition, another power supply system 301 to which the charging method according to the second embodiment of the present invention is applied, as shown in FIG. 5, a series circuit 103 in which a plurality of lead-acid battery cells 102 are connected in series is connected in parallel. An assembled battery 302 connected to the load 106 and a charging device 303 for charging the assembled battery 302 are provided.

  The assembled battery 302 is configured by connecting in parallel two or more parallel circuits 304 in which three series circuits 103 are connected in parallel. When charging the assembled battery 302, the charging device 303 is connected to each parallel circuit 304. Further, when power is supplied from the assembled battery 302 to the load 106, the assembled battery 302 has a configuration in which four or more series circuits 103 are connected in parallel.

  The charging device 303 performs exactly the same control as the charging device 105 in the first embodiment. That is, when the charging voltage of the parallel circuit 304 is detected and the charging voltage reaches a predetermined control voltage value VR, the charging current value is gradually reduced to n (where n ≧ 2). It has a function to make it. However, the charging device 105 charges a single series circuit 103, but the charging device 303 charges three series circuits 103, so that the output current value has a capacity three times that of the charging device 105. It goes without saying that it is preferable to do so.

  In the second embodiment described above, the series circuit 103 in the first embodiment is replaced with a parallel circuit 204 in which two series circuits 103 are connected in parallel or a parallel circuit 304 in which three series circuits 103 are connected in parallel. It has a configuration.

  As described above, in the first embodiment, it has been shown that the problem of the present invention becomes significant when the number of parallel connections of the series circuit 103 exceeds four. Therefore, in the second embodiment in which the number of parallel connections is 2 and 3, while the effect of suppressing the life reduction is obtained, the short-time charging is possible and the required number of the charging devices 203 and 303 is also increased. Since it decreases, it is preferable in terms of cost.

  Hereinafter, the effects of the present invention will be described by comparing the examples of the present invention with comparative examples. In this example, the effect of the present invention is shown by a cycle life test. The temperature of the cycle life test is 25 ° C. in both the present invention example and the comparative example.

(Series circuit)
First, the configuration of a series circuit commonly used in the present invention example and the comparative example will be described. The series circuit (corresponding to the series circuit 103 in the first and second embodiments) used in this example is a monoblock type control valve type lead storage battery in which six lead storage battery cells 102 are connected in series. Are connected in series and have a nominal voltage of 60V and a rated capacity of 50Ah for 3 hours. This series circuit has a configuration in which 30 cells 102 are connected in series. Note that, in both the inventive example and the comparative example, the 12 hour series circuit 103 of the assembled battery is substantially connected in parallel, so that the three-hour rate rated capacity is 600 Ah.

(Constant voltage charger)
Next, the specifications of the constant voltage charging device used in the comparative example are a charging voltage of 2.40 V / cell and a maximum charging current of 30 A / series circuit. “30 A / series circuit” means the maximum charging current per series circuit obtained by dividing the maximum charging current by the number of series circuits. This expression is the same in the description of the five-stage charging current device described later.

(5-stage constant current charger)
The specification of the five-stage constant current charging device used in the present invention example and the comparative example is a system in which the control voltage VR = 2.40 V / cell and the charging current is switched in the following five stages. That is, first stage charging current = 40 A / series circuit, second stage charging = 30 A / series circuit, third stage charging current = 0.20 A / series circuit, fourth stage charging current = 10 A / series circuit, fifth stage Charging current = 5 A / series circuit. In the fifth stage charging, the charging was completed when the voltage of the series circuit reached 2.65 V / cell. Note that the charging current uses an expression per series circuit. For example, when charging a parallel circuit in which three series circuits are connected in parallel, the charging current at each stage is three times the above. That is, it corresponds to the number of parallel connections of the series circuit to be connected.

(Invention Sample A1)
Invention Example A1 is according to the first embodiment. After discharging the assembled battery 104 of the power supply system 101 to 1.70 V / cell at 0.3 CA (180 A), the above-described five-stage constant current charging device is used. A cycle life test of the assembled battery 104 was performed by charging until the charging was completed and repeating the discharging and charging. The time when the discharge duration in 0.3 CA (180 A) discharge was reduced to 50% of the initial value was defined as the number of life cycles.

  In the invention sample A1, the assembled battery 104 has a configuration in which twelve series circuits 103 are connected in parallel, and a five-stage constant current charging device (charging device 105) is connected to each series circuit 103.

(Invention Sample A2)
Invention Example A2 is according to the second embodiment. After discharging the assembled battery 202 of the power supply system 201 to 1.70 V / cell at 0.3 CA (180 A), the above-described 5-stage constant current charging device is used. A cycle life test of the assembled battery 202 was performed by charging until the charging was completed and repeating the discharging and charging. The time when the discharge duration in 0.3 CA (180 A) discharge was reduced to 50% of the initial value was defined as the number of life cycles.

  In the present invention example A2, the assembled battery 202 includes six parallel circuits 204 in which two series circuits 103 are connected in parallel, and each parallel circuit 204 is connected to a five-stage constant current charging device (charging). The apparatus 203) is connected.

(Invention Sample A3)
Invention Example A3 is according to the second embodiment. After discharging the assembled battery 302 of the power supply system 301 to 1.70 V / cell at 0.3 CA (180 A), the above-described 5-stage constant current charging device is used. A cycle life test of the assembled battery 302 was performed by charging until the charging was completed and repeating the discharging and charging. The time when the discharge duration in 0.3 CA (180 A) discharge was reduced to 50% of the initial value was defined as the number of life cycles.

  In Example A3 of the present invention, the assembled battery 302 includes four parallel circuits 304 in which three series circuits 103 are connected in parallel, and each parallel circuit 304 is connected to a five-stage constant current charging device (charging). The device 303) is connected.

(Comparative Example A4)
In the comparative example A4, in the power supply system 301, the parallel circuit 304 is configured by three series circuits, and the four series circuits are connected in parallel to form a parallel circuit a4 (not shown). The assembled battery A4 is configured by connecting three in parallel. A five-stage constant current charging device is connected to each of the parallel circuits a4.

  After discharging the assembled battery A4 to 1.70 V / cell at 0.3 CA (180 A), charging it with the above-described 5-stage constant current charging device until charging is completed, and repeating these discharging and charging, The cycle life test of the assembled battery A4 was performed. The time when the discharge duration in 0.3 CA (180 A) discharge was reduced to 50% of the initial value was defined as the number of life cycles.

(Comparative Example A5)
In the comparative example A5, in the power supply system 301, the parallel circuit 304 is constituted by three series circuits. The six series circuits are connected in parallel to form a parallel circuit a5 (not shown). The battery pack A5 is configured by connecting two in parallel. A 5-stage constant current charging device is connected to each of the parallel circuits A5.

  After discharging the assembled battery A5 to 1.70 V / cell at 0.3 CA (180 A), charging it with the above-described 5-stage constant current charging device until charging is completed, and repeating these discharging and charging, The cycle life test of the assembled battery A4 was performed. The time when the discharge duration in 0.3 CA (180 A) discharge was reduced to 50% of the initial value was defined as the number of life cycles.

(Comparative Example A6)
In Comparative Example A6, a battery pack A6 is configured by connecting 12 series circuits in parallel, and a five-stage constant current charging device is connected between terminals of the battery pack A6.

(Comparative Example B1)
In Comparative Example B1, a constant voltage charging device is connected instead of the charging device 105 used in Invention Example A1. The charging time is 8 hours.

(Comparative Example B2)
In Comparative Example B2, a constant voltage charging device is connected instead of the charging device 203 used in Invention Example A2. The charging time is 8 hours.

(Comparative Example B3)
In Comparative Example B3, a constant voltage charging device is connected instead of the charging device 303 used in Invention Example A3. The charging time is 8 hours.

(Comparative Example B4)
In Comparative Example B4, a constant voltage charging device is connected instead of the five-stage constant current charging device used in Comparative Example A4. The charging time is 8 hours.

(Comparative Example B5)
In Comparative Example B5, a constant voltage charging device is connected instead of the five-stage constant current charging device used in Comparative Example A5. The charging time is 8 hours.

(Comparative Example B6)
In Comparative Example B6, a constant voltage charging device is connected instead of the five-stage constant current charging device used in Comparative Example A6. The charging time is 8 hours.

(Comparative Example C1)
In Comparative Example C1, the charging time of Comparative Example B1 was changed from 8 hours to 24 hours.

(Comparative Example C2)
In Comparative Example C2, the charging time of Comparative Example B2 is changed from 8 hours to 24 hours.

(Comparative Example C3)
In Comparative Example C3, the charging time of Comparative Example B3 was changed from 8 hours to 24 hours.

(Comparative Example C4)
In Comparative Example C4, the charging time of Comparative Example B4 was changed from 8 hours to 24 hours.

(Comparative Example C5)
In Comparative Example C5, the charging time of Comparative Example B5 was changed from 8 hours to 24 hours.

(Comparative Example C6)
In Comparative Example C6, the charging time of Comparative Example B5 was changed from 8 hours to 24 hours.

  Table 1 shows the number of series circuits per charging device, the charging method, the charging time, and the cycle life test in the above-described examples of the present invention and comparative examples.

  From the results shown in Table 1, when performing charging for 24 hours with constant voltage charging, the number of series circuits per charging device (the number of series circuits connected to one charging device, except for this number being 1, The series circuits are connected in parallel to each other.) As the number of cycles increases, the number of cycle lives decreases. However, the degree of decrease is less than when the charging time is 8 hours in constant voltage charging.

  This is because, in the constant voltage charging method in which the charging current is continuously attenuated, if the charging time is lengthened and the charging current is reduced to a region called a trickle current of 0.001 CA to 0.005 CA, It is shown that a decrease in cycle life due to an increase in the number of series circuits can be suppressed to some extent. In addition, the average value between the series circuits of the end-of-charge current at the time of constant voltage charging for 8 hours was 0.02 CA per one series circuit, while that for 24 hours charging was 0.005 CA.

  On the other hand, when five-stage constant current charging is used, when the number of series circuits connected to one charging device (the number of series circuits is connected to each other except 1) is 3 or less. The charging time is shorter than when constant voltage charging is used, and the cycle life of the assembled battery is extremely good.

  On the other hand, when the number of series circuits per charging device exceeds 3 and becomes 4 or more, it can be seen that the life characteristics of the assembled battery are drastically lowered. Such a phenomenon is caused by the fact that the variation in the state of charge between the constant voltage charge series circuits increases with the charge / discharge cycle, and one of the series circuits is extremely overcharged or overdischarged.

  Such a decrease in cycle life accompanying an increase in the number of series circuits per charging device also appears when constant voltage charging is used, but in the case of five-stage constant current charging, the degree is extremely significant. In constant voltage charging, such a phenomenon is alleviated by extending the charging time, so that it can be seen that such a phenomenon is particularly noticeable in 5-stage constant current charging.

  Therefore, in order to secure the capacity of the assembled battery, it is a case where the assembled battery is configured by connecting four or more series circuits in parallel, and for the purpose of shortening the charging time, n-stage constant current charging is performed. The number of series circuits per charging device is at least 3 or less, most preferably 1, that is, a charging device is provided for each series circuit.

  As described above, according to the configuration of the present invention, it is possible to charge an assembled battery in which four or more of the series circuits are connected in parallel in a short time, and a charging method that significantly improves the cycle life characteristics of the assembled battery. Can be provided.

  In this example, as an example of n-stage constant current charging, an example in which n = 5 is described. However, as described in the embodiment, even when n ≧ 2, Similar effects can be obtained. This is because, if the charging current value I1 of the first stage and the charging current value Ix of the final stage are determined, it is obvious that the range between I1 and Ix can be divided by an arbitrary number n.

  In the present embodiment, an example is shown in which charging is stopped when the charging voltage at the fifth stage is 2.65 V, which is higher than the control voltage VR, as control for stopping charging at the final stage, that is, the fifth stage. However, the amount of charge electricity at the fifth stage, which is the final stage, is controlled according to the amount of charge electricity at the first stage. That is, as the amount of charge electricity at the first stage increases, By performing control to increase the amount of charged electricity by increasing the charging time in the n-th constant current charging, a remarkable effect was obtained compared to the example.

  That is, in the present invention example A1, the cycle life number is from 440 cycles to 480 cycles in the embodiment, in the present invention example A2, the cycle life number is from 380 cycles to 440 cycles in the embodiment, and in the present invention example A3, the cycle life number. However, the cycle life of Comparative Examples A4 to A6 was slightly increased from 140 cycles, 100 cycles, and 60 cycles to 120 cycles, 90 cycles, and 55 cycles, respectively. Decrease was observed.

  INDUSTRIAL APPLICABILITY The present invention is suitable as a method for charging an assembled battery used for an electric vehicle or the like, particularly for cycle use.

The figure which shows the structure of the power supply system to which the charging method by 1st Embodiment is applied. The figure which shows the time change of voltage-current in n stage constant current charge The figure which shows the time change of the voltage-current in constant voltage charge The figure which shows the structure of the power supply system to which the charging method by 2nd Embodiment is applied. The figure which shows the structure of the power supply system to which the charging method by other 2nd Embodiment is applied.

DESCRIPTION OF SYMBOLS 101 Power supply system 102 Cell 103 Series circuit 104 Battery assembly 105 Charging device 106 Load 107a, 107b Diode 108 Terminal 201 Power supply system 202 Battery assembly 203 Charging device 204 Parallel circuit 301 Power supply system 302 Battery assembly 303 Charging device 304 Parallel circuit

Claims (3)

A method for charging an assembled battery in which a series circuit in which a plurality of lead storage batteries are connected in series is connected in parallel to supply power to a load,
Connect a charging device for each series circuit,
The charging device detects a charging voltage of the series circuit, and when the charging voltage reaches a predetermined control voltage value, sets the charging current value to n (where n ≧ 2 is an integer) stage. N-stage constant current charging,
And at the time of electric power feeding to the said load of the said assembled battery, the said assembled battery is a charging method of the assembled battery by which at least 4 or more said series circuits are connected in parallel. A method for charging an assembled battery in which a series circuit in which a plurality of lead storage batteries are connected in series is connected in parallel to supply power to a load,
At the time of feeding power to the load of the assembled battery, the assembled battery is formed by connecting at least four or more series circuits in parallel,
And the assembled battery is formed by connecting two or more parallel circuits in which two or three of the series circuits are connected in parallel,
Connect a charging device for each parallel circuit,
The charging device detects the charging voltage of the parallel circuit, and at the time when the charging voltage reaches a predetermined control voltage value, the charging current value is set to n (where n ≧ 2) times stepwise. A method for charging an assembled battery, characterized in that n-stage constant current charging is performed. The required charge electricity amount is set by multiplying the discharge electricity amount of the assembled battery by a certain coefficient, the first stage charging is performed at the first constant current, and the charging time at the nth stage n constant current is one stage. Setting control is performed based on the charging time required for the first charging and the temperature of the battery tank of the lead storage battery at the first charging, and the shortage of charging electricity due to the charging from the first to the (n-1) th charging is compensated. The method for charging an assembled battery according to claim 1, wherein the battery pack is charged.

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