JPH0515076A - Battery charging method and battery charger - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] Even when the battery pack is repeatedly charged and discharged, the situation in which the variations in the charge and discharge status of each storage battery accumulate and gradually increase, is avoided, and the original performance of the battery pack is maintained. Make full use. [Configuration] When the assembled battery 2 is set in a charger, the battery voltage of the assembled battery 2 is detected by the battery voltage detector 5, and when this data is below a set value, the controller 6 discharges the switches 4a, 4b, 4c. ... are switched on sequentially or simultaneously. Then, the storage batteries 1b, 1c ...
By b, 3c ..., it is completely discharged once by storage battery unit,
The remaining capacity of each storage battery becomes substantially equal. When each discharging switch is turned off by the control unit 6 and the charging switch 7 is turned on, the battery pack 2 is charged by the charging power source 8.
Is charged. At this time, since the remaining capacities of the storage batteries are made substantially equal, the storage batteries of the assembled battery 2 are also charged almost equally.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a charger for charging an assembled battery which is a plurality of storage batteries connected in series.

[0002]

2. Description of the Related Art In charging a battery pack of this type, a method is applied in which a voltage corresponding to the sum of the charging voltages of the storage batteries is applied to the output terminal of the battery pack.

[0003]

However, although the same type of storage battery is often used as the storage battery forming the assembled battery, even if the storage battery of the same type has a slight variation in its characteristics. Therefore, if the assembled battery is charged by the above method, the following problems will occur.

That is, when the charge and discharge of the battery pack are repeated in the state where there are slight variations in the characteristics such as the capacity and internal resistance of the storage battery, the variations in the charge and discharge states of the storage batteries are accumulated and gradually increase, and the battery pack is gradually increased. The original performance of is reduced.

For example, when the method of controlling the stop of charging and the stop of discharging by the voltage of the entire assembled battery is adopted, even if a specific storage battery is insufficiently charged as compared with other storage batteries, this shortage causes the other storage battery to be overcharged. If the charging stop voltage is reached as a whole, the charging of the battery pack is stopped with the insufficiently charged storage battery included.

When this assembled battery is discharged, the storage battery that is insufficiently charged finishes discharging earlier and its voltage drops, but the discharge of the other storage batteries is not completed. The voltage is not reached and discharge continues.
If this discharge is continued, the storage batteries that are insufficiently charged will be in a deeper discharge state, while the other storage batteries will maintain a shallow discharge state, and when the entire assembled battery reaches the end-of-discharge voltage, the discharge will end and each storage battery The next charge is performed in the state where there is a variation in the charge / discharge state.

When such charging / discharging is repeated, the insufficiently charged storage battery becomes more and more insufficiently charged, while the other storage batteries become overcharged because the charging voltage when charging is stopped becomes larger than the set value. Any of these causes a decrease in battery life. There is also a drawback that the charge capacity of the assembled battery is greatly affected by the insufficiently charged storage battery. Note that FIG. 2 shows the discharge characteristics of the assembled battery when the assembled battery in which ten NiCd batteries are connected in series is repeatedly charged and discharged.

As a means for solving these various problems, a method of individually charging each storage battery has been proposed, but since the same number of charging circuits as the storage batteries are required, the structure of the charger is complicated. Is disadvantageous in terms of cost. A method has also been proposed in which the output of one charging circuit is switched to each storage battery and the batteries are sequentially charged, but this is not practical because the charging time becomes long.

The present invention was created in view of the above background, and an object of the present invention is to provide a battery pack charging method and a battery charger which do not cause the above problems.

[0010]

A method for charging an assembled battery according to claim 1 of the present invention is a method for charging an assembled battery, which is a plurality of storage batteries connected in series, and each storage battery constituting the assembled battery. The battery pack is characterized in that the assembled battery is charged after the battery has been completely discharged in units of storage batteries.

A battery charger for an assembled battery according to claim 2 of the present invention is a device for charging an assembled battery which is a plurality of storage batteries connected in series, and includes a charging power source for charging the assembled battery and the assembled battery. A charging switch connected between the battery pack, a battery voltage detector that detects the voltage of the battery pack, a discharge resistor that discharges each storage battery that constitutes the battery pack, and an output terminal of the discharge resistor and the storage battery. Between the discharge switch and the discharge switch connected to the battery voltage detector sequentially or simultaneously from OFF to ON based on the detection data of the battery voltage detector, and then the discharge switch is turned OFF again, the charging And a control section for switching the power switch from off to on.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a battery pack charging method and battery charger according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of the charger.

First, the structure of the charger will be described. In the figure, reference numeral 2 is an assembled battery in which storage batteries 1a, 1b, 1c, etc. such as NiCd batteries are connected in series. A charging power source 8 is connected to the output terminal of the assembled battery 2 via a charging switch 7, and a battery voltage detector 5 is connected thereto separately. Storage battery
A discharge resistor 3a and a discharge switch 4a are connected to the output terminal of 1a. The storage batteries 1b, 1c ... Are also the same, so description thereof will be omitted, but the discharge resistors 3a, 3b, 3c ...
・ The resistance values of are the same.

The battery voltage detector 5 is configured to detect the battery voltage of the assembled battery 2 and sequentially output the detection data to the control unit 6. The control unit 6 controls the assembled battery 2
If it is determined that the battery voltage of is less than or equal to a predetermined set value, the discharge switches 4a, 4b, 4c ... Are switched from off to on sequentially or simultaneously, while the storage batteries 1a, 1b, If it is determined that 1c ... Is completely discharged, the discharging switches 4a, 4b, 4c ... Are returned to the off state, and the charging switch 7 is switched from the off state to the on state. When it is determined that the battery voltage of the assembled battery 2 has exceeded the predetermined set value, the charging switch 7 is turned back on.

Each time the assembled battery 2 is charged, the storage battery 1
Since it is not preferable to temporarily put b, 1c, ... Into the over-discharged state, the control unit 6 discharges when the charge-discharge cycle reaches a certain number of times. Also, when the user determines that the charge / discharge states of the storage batteries 1b, 1c ... Are not uniform, and when the battery pack 2 is charged, pressing the external switch provided in the control unit 6 causes the battery to be manually discharged. May be.

Next, a method of charging the assembled battery 2 using the above-mentioned charger will be specifically described. First,
Set the assembled battery 2 in the charger. Then, the output terminal of the assembled battery 2 and the battery voltage detector 5 are electrically connected, and the battery voltage of the assembled battery 2 is detected by the battery voltage detector 5. When the detection data is less than or equal to a predetermined set value, the control unit 6 switches the discharge switches 4a, 4b, 4c ... From OFF to ON sequentially or simultaneously. Then the storage battery
.. are once completely discharged in units of storage batteries by discharge resistors 3a, 3b, 3c .... At this time, the discharge resistors 3a, 3
Since the resistance values of b, 3c ... Are set to be the same, among the storage batteries 1b, 1c, ..., which have a large remaining capacity, the discharge current is larger because the battery voltage is high, and the discharge progresses rapidly. Eventually, the residual capacities of the storage batteries 1b, 1c ... Are substantially equal.

Thereafter, the control unit 6 controls the discharge switch 4
When a, 4b, 4c ... Are returned from on to off and the charging switch 7 is switched from off to on, the battery pack 2 is charged by the charging power supply 8. At this time, storage batteries 1b, 1c
Since the remaining capacities of the battery packs are made substantially equal, the storage batteries 1b, 1c of the battery pack 2 are also charged almost equally.

Therefore, no matter how many times the battery pack 2 is charged and discharged as described above, the storage battery 1 is charged during the charging in one process.
Since the residual capacities of b, 1c ... Are made substantially equal, it is possible to avoid the situation in which variations in the charging / discharging state of the storage batteries 1b, 1c. Moreover, the battery life of the assembled battery 2 is not shortened, and the charging capacity is not greatly affected by the insufficiently charged storage battery. Therefore, the inherent performance of the battery pack 2 can be fully exerted.

Further, as for the charger, only one charging circuit such as the charging power source 8 may be provided for the assembled battery 2, so that the disadvantage in terms of cost can be avoided. Moreover, since there is no problem in charging time, it is very practical.

The method of charging the assembled battery according to the present invention may be performed in any other manner as long as it takes a method of completely discharging each storage battery in a unit of storage battery before charging the assembled battery. Further, the battery charger for the assembled battery according to the present invention is not limited to the above-mentioned embodiment, and may have a form in which, for example, a discharge resistor and a switch are incorporated on the assembled battery side.

[0021]

As described above, in the case of the method for charging the assembled battery according to claim 1 of the present invention, since the remaining capacities of the storage batteries constituting the assembled battery are made substantially equal before charging, the storage batteries are almost equal to each other. It will be charged evenly. Therefore, in the process of repeated charging / discharging of the battery pack, it is possible to avoid the situation where the variation in the charging / discharging state of each storage battery is accumulated and gradually becomes large, and the battery life of the battery pack is reduced accordingly. In addition, the charging capacity is not significantly affected by the insufficiently charged storage battery. As a result, the inherent performance of the assembled battery can be fully exhibited.

In the case of the battery charger for an assembled battery according to claim 2 of the present invention, in addition to the above-mentioned merits due to its configuration, only one charging circuit is required for the assembled battery, which is cost-effective. In addition to avoiding the disadvantages, there is no problem in the charging time, which is an advantage that it is very practical.

[Brief description of drawings]

FIG. 1 is a diagram for explaining an embodiment of the present invention,
It is a block diagram of the battery pack charger.

FIG. 2 is a diagram for explaining a conventional method of charging an assembled battery, showing the discharge characteristics of the assembled battery that is repeatedly charged and discharged.

[Explanation of symbols]

2 batteries 1a, 1b, 1c storage battery 3a, 3b, 3c discharge resistance 4a, 4b, 4c discharge switch 5 Battery voltage detector 6 control unit 7 Charge switch 8 charging power supply

Claims (2)

[Claims] 1. A method of charging an assembled battery, which is a plurality of storage batteries connected in series, wherein each of the storage batteries forming the assembled battery is once completely discharged in a unit of storage battery, and then the assembled battery is charged. A method of charging an assembled battery, characterized in that 2. An apparatus for charging an assembled battery, which is a plurality of storage batteries connected in series, wherein a charging power source for charging the assembled battery and a charging switch connected between the assembled battery and the assembled battery. A battery voltage detector that detects the voltage of the battery, a discharge resistor that discharges each storage battery that constitutes the assembled battery, a discharge switch connected between the discharge resistor and the output terminal of the storage battery, and the battery A controller for switching the discharging switch from off to on sequentially or simultaneously based on the detection data of the voltage detector, and then returning the discharging switch to off again, and switching the charging switch from off to on. An assembled battery charger characterized in that