JPH0650247U - Battery pack - Google Patents

Abstract

(57) [Summary] [Objective] The purpose of the present invention is to detect the individual battery voltages of at least two secondary batteries connected in series so that the battery voltages do not vary, and the secondary battery is detected. To control the charging and discharging of. According to the present invention, in a pack battery having at least two secondary batteries 1 and 2 connected in series in a battery case 9, a pair of rechargeable batteries 1 and 2 connected in series are charged and discharged. A detection terminal 5 which is derived from the connection between the discharge terminals 3 and 4 and the secondary batteries 1 and 2 and detects the battery voltage of the secondary batteries 1 and 2, and a connection between the connection between the secondary batteries 1 and 2 and the detection terminal 5. The secondary battery 1 provided between the detection terminal 5 and
And the suppressing means 6 for suppressing the charging / discharging of Nos. 2 and 2.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a battery pack containing at least two secondary batteries connected in series.

[0002]

[Prior art]

 In a battery pack containing multiple secondary batteries connected in series, the battery voltage of the entire secondary battery exceeds the charge stop voltage or the discharge stop voltage is exceeded to prevent overcharge or over discharge of the secondary battery. It has been already known to detect whether or not the temperature has fallen below and stop charging or discharging.

However, in this method, as the secondary batteries are repeatedly charged and discharged, the battery voltage varies among the batteries due to the difference in the characteristics of the individual secondary batteries. In particular, in non-aqueous secondary batteries such as lithium-ion secondary batteries that are charged at a constant voltage, the battery voltage fluctuates due to differences in internal resistance and capacity between the batteries during repeated charging and discharging. Therefore, even if the battery voltage of the entire secondary battery is detected, it cannot be said that overcharge or overdischarge of each secondary battery can be reliably prevented.

Therefore, according to Japanese Utility Model Application Laid-Open No. 2-136445, individual battery voltages of secondary batteries connected in series are detected, and at least one battery voltage exceeds a charge stop voltage or a discharge stop voltage is detected. It has been proposed to prevent overcharging or overdischarging of each secondary battery by detecting whether it has fallen below and stopping charging or discharging, regardless of variations in individual battery voltages.

[0005]

[Problems to be solved by the device]

 By the way, as described above, the problem in controlling the charging or discharging by detecting the battery voltage of each secondary battery is to detect the battery voltage of each secondary battery. It is the charging and discharging of the secondary battery through the detection terminal. That is, the detection terminal provided to prevent overcharging or overdischarging of the secondary battery functions as a charging or discharging terminal of the secondary battery, which causes variations in the battery voltage of individual secondary batteries. There is a fear of being lost.

Therefore, an object of the present invention is to prevent charging and discharging of individual secondary batteries through such detection terminals.

[0007]

[Means for Solving the Problems]

 The present invention relates to a pack battery having at least two secondary batteries connected in series in a battery case, and a pair of charging / discharging terminals for charging / discharging the secondary batteries connected in series, and a secondary battery A detection terminal that is derived from the connection between the secondary battery and detects the battery voltage of each secondary battery, and is provided between the connection of the secondary battery and the detection terminal, and the charging of the secondary battery from the detection terminal is performed. It is characterized by comprising a suppressing means for suppressing discharge.

It should be noted that the suppressing means in the present invention includes not only means for reducing charging / discharging from the detection terminal but also means for substantially (or completely) preventing it.

[0009]

[Action]

 In the present invention, the charging / discharging suppressing means, which is derived from the connection between the secondary batteries and is provided at the detection terminal for detecting the battery voltage of each of the secondary batteries, charges and discharges the secondary battery from the detection terminals. Suppress.

[0010]

【Example】

 FIG. 1 is a circuit diagram showing a first embodiment of the present invention. 1 and 2 are two rechargeable batteries connected in series, and 3 and 4 are provided at both ends of the two rechargeable batteries 1 and 2, and are used for charging and discharging the rechargeable batteries 1 and 2. A pair of charging / discharging terminals, 5 are derived from the connection between the secondary batteries 1 and 2, and a voltage detection terminal for detecting the battery voltage of each of the secondary batteries 1 and 2, 6 is a connection between the secondary batteries 1 and 2. It is a charging / discharging suppressing means provided between the voltage detecting terminal 5 and the voltage detecting terminal 5, and is composed of an operational amplifier 7 and a resistance element 8 having a high resistance value (for example, 10 kΩ) connected in series. The operational amplifier 7 has its non-inverting terminal connected between the connection of the secondary batteries 1 and 2, and uses the series output voltage of the secondary batteries 1 and 2 as a driving power source of the operational amplifier 7. Further, reference numeral 9 denotes a battery case, which houses the secondary batteries 1 and 2 and the charge / discharge suppressing means 6, and exposes the charge / discharge terminals 3 and 4 and the voltage detection terminal 5 to the outside.

In such a configuration, when a charging voltage (not shown) is applied to the charging / discharging terminals 3 and 4 from the charger, the secondary batteries 1 and 2 are charged. At this time, the voltage between the positive charging / discharging terminal 3 and the voltage detecting terminal 5 (that is, the battery voltage of the secondary battery 1) and the voltage between the voltage detecting terminal 5 and the negative charging / discharging terminal 4 (that is, The battery voltage of the secondary battery 2) is detected, and when either one of the voltages reaches the charging stop voltage, the charging of the secondary batteries 1 and 2 is stopped.

When a load is applied to the charging / discharging terminals 3 and 4, the secondary batteries 1 and 2 are discharged. Also at this time, the voltage between the positive charging / discharging terminal 3 and the voltage detecting terminal 5 (that is, the battery voltage of the secondary battery 1) and the terminal voltage between the voltage detecting terminal 5 and the negative charging / discharging terminal 4 (that is, , The battery voltage of the secondary battery 2) is detected, and when one of the voltages reaches the discharge stop voltage, the discharge of the secondary batteries 1 and 2 is stopped.

In such charging / discharging, the impedance of the input terminal of the operational amplifier 7 is very high, and the current loss at its non-inverting terminal is almost zero.

Further, even if an external voltage is applied to the voltage detection terminal 5, the current from the voltage detection terminal 5 is limited by the high resistance element 8 and then passed through the operational amplifier 7 to charge / discharge the terminal 4 (that is, Flow to the ground level). Even if the charge / discharge terminal 4 and the voltage detection terminal 5 are short-circuited, a current flows from the charge / discharge terminal 3 through the operational amplifier 7 and the high resistance element 8. In any case, no current flows in or out of the connection point of the secondary battery 1 or 2.

Further, the drive power source of the operational amplifier 7 is obtained from the secondary batteries 1 and 2 as a whole, and the battery voltage of the secondary batteries 1 and 2 due to the operational amplifier 7 does not vary.

Therefore, charging / discharging of the secondary battery 1 or 2 is not performed via the voltage detection terminal 5, and variations in the battery voltage of the secondary batteries 1 and 2 caused by the terminal 5 are prevented. Be stopped.

As described above, the impedance of the input terminal of the operational amplifier 7 is very high, and the current loss at its non-inverting terminal is almost zero. However, in order to guarantee such current loss, the secondary A high resistance (for example, 10 MΩ) bleeder resistance element may be connected in parallel to each of the batteries 1 and 2.

FIG. 2 is a circuit diagram showing a second embodiment of the present invention. In the present embodiment, the charging / discharging suppressing means 6 is composed of a resistance element 10 having a high resistance (for example, 100 kΩ), which is different from the first embodiment in that the operational amplifier 7 connected to the voltage detection terminal 5 is It is built in the charger (or load) 11.

Even with this configuration, the presence of the high-resistance element 10 suppresses the charging / discharging of the secondary battery 1 or 2 from the voltage detection terminal 5, and the secondary batteries 1 and 2 caused by this terminal 5 are suppressed. Variation of the battery voltage is suppressed.

Further, in this embodiment, since the operational amplifier 7 is housed in the charger (or load) 11, the secondary batteries 1 and 2 are not used as the driving power source of the operational amplifier 7. Therefore, it is possible to prevent the capacity reduction of the secondary batteries 1 and 2 due to the driving of the operational amplifier 7.

Further, FIG. 3 is a cross-sectional view of an essential part showing a third embodiment of the present invention. In this embodiment, a recess 12 is formed on one side wall of the battery case 9, and the voltage detection terminal 5 is exposed at the back of the recess 12. Therefore, any undesired discharge body (for example, a metal necklace) does not come into contact with the voltage detection terminal 5, and the discharge from this terminal 5 is prevented.

Further, it is also preferable to dispose the voltage detection terminal 5 and the charging / discharging terminals 3 and 4 separately from each other, specifically, to dispose on different surfaces of the battery case 9.

[0023]

[Effect of device]

 According to the present invention, in a battery pack containing at least two rechargeable batteries connected in series in a battery case, between the detection terminal for detecting the battery voltage of each rechargeable battery and the rechargeable battery described above. A control means for suppressing the charging / discharging of the secondary battery from the detection terminal is provided between the control terminal and the control terminal, so that the charging / discharging of the secondary battery is controlled by detecting the battery voltage of each secondary battery. Thus, charging / discharging of the secondary battery from the detection terminal for detecting the battery voltage of the individual secondary battery can be suppressed. Therefore, charging / discharging of the secondary battery can be appropriately controlled.

[Brief description of drawings]

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

FIG. 2 is a circuit diagram showing a second embodiment of the present invention.

FIG. 3 is a cross-sectional view of an essential part showing a third embodiment of the present invention.

[Explanation of symbols]

 1, 2 Secondary battery 3, 4 Charge / discharge terminal 5 Voltage detection terminal 6 Charge / discharge suppression terminal

Claims (4)

[Scope of utility model registration request] 1. A pack battery having at least two secondary batteries connected in series in a battery case, and a pair of charging / discharging terminals for charging / discharging the secondary batteries connected in series, and the secondary battery. Of the secondary battery, which is derived from the connection between the detection terminals for detecting the battery voltage of each of the secondary batteries and the connection between the connection of the secondary battery and the detection terminal. A battery pack comprising: a suppressing unit that suppresses charge and discharge. 2. The battery pack according to claim 1, wherein the suppressing means is an operational amplifier. 3. The battery pack according to claim 1, wherein the suppressing means is a high resistance element. 4. The battery pack according to claim 1, wherein the suppressing means is a recess formed in the battery case, and the detection terminal is exposed inside the recess.