JPH0618467B2 - Sealed lead acid battery charger - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealed lead acid battery charger.

2. Description of the Related Art Conventionally, batteries that have been left after being over-discharged (hereinafter referred to as "over-discharged batteries") have been a problem with sealed lead-acid battery chargers.
There is rechargeability for. This is because the charging current is difficult to flow because the internal resistance of the over-discharged battery is high. In particular, in the case of a so-called cathode absorption type sealed lead-acid battery, in which oxygen generated at the anode is consumed by the cathode active material during charging, charging with a minute current (hereinafter referred to as "trickle charging") is detected after the end-of-charge voltage is detected. Is often used.

When an over-discharged battery is charged by this type of charger, the internal resistance of the over-discharged battery is high, so that the charging voltage rises immediately after the start of charging and trickle charging occurs, resulting in almost no charging. As one of the methods for solving this drawback, as described in the specification of Japanese Patent Application No. 61-16196, which was previously filed, after applying a current in the reverse direction to the normal state to an over-discharged battery ( There is a method to return to normal charging (hereinafter referred to as "reverse charging").

Problems to be Solved by the Invention When the above charging method is applied to an actual charger, there is a problem in that it may not be recovered depending on the conditions for ending reverse charging.

As a condition for ending the reverse charge, the simplest method is to make the reverse charge time constant. But with this method,
Overcharged batteries with extremely high internal resistance have poor recoverability, and when the internal resistance is relatively low, reverse charging more than necessary increases the charging time, heat generation during charging, and life characteristics after recovery. There are adverse effects such as deterioration. An example of this is shown below.

The battery used is a sealed lead acid battery of 4V and 4Ah.
The charging characteristics when the reverse charging time is 60 minutes are shown in FIGS. 4 and 5. Figure 4 shows the charging characteristics of an over-discharged battery with an internal resistance of approximately 300Ω, and Figure 5 shows the charging characteristics when the internal resistance is approximately 1600Ω.

When the internal resistance was about 300 Ω, normal charging was started after reverse charging, but when the internal resistance was high at about 1600 Ω, normal charging was resumed, then trickle charging was started early, and charging was not performed. Table 1 shows an overdischarged battery with an internal resistance of about 300Ω. The maximum battery surface temperature when the reverse charging time is changed is shown. Obviously, the longer the reverse charging time, the more heat is generated. FIG. 6 shows the cycle life characteristics after recovery of the over-discharged battery which was recovered after the reverse charge time was 60 minutes. The internal resistance of an over-discharged battery with an internal resistance of approximately 10Ω is approximately 300Ω.
Compared to the case of, the capacity decreases faster, and the life is about 150 cycles.

From the above, when performing reverse charge to recover,
It is considered that a method of performing reverse charging according to the internal resistance of the over-discharged battery is preferable.

Means for Solving the Problems The present invention solves the above problems, and only an over-discharged battery having a high internal resistance performs reverse charging according to the internal resistance, and the AC voltage component included in the charging voltage is In the case of a certain value A or more, the reverse charging current is made to flow for a certain time, and when the AC voltage component included in the charging voltage is lower than the certain value A and is larger than a certain value B, the current in the same direction as the normal direction is made to flow, It is characterized in that a means for entering normal charging is provided only when the AC voltage component included in the charging voltage is smaller than the constant value B.

Action The present invention has the above-mentioned characteristics, and performs reverse charging according to the internal resistance only when the internal resistance of the over-discharged battery is high, and recovers by continuing normal charging when the internal resistance is not high. Is possible. This is because the AC component contained in the charging voltage is large when the internal resistance of the over-discharged battery is high, and the AC component contained in the charging voltage is small when the internal resistance of the over-discharged battery is not high. This is an application of the fact that it is possible to recover by normal charging by passing a current in the same direction as usual until that time.

Therefore, according to the present invention, when an over-discharged battery having a high internal resistance is charged, it is included in the charging voltage after repeating the reverse charging for a certain time until the AC component included in the charging voltage becomes a certain value A or less. Constant value B (A>
It is possible to allow current to flow in the same direction as normal until B) or less and to start normal charging after the AC component contained in the charging voltage has become the constant value B or less and to recover.

In the present invention, when an over-discharged battery having a low internal resistance is charged, the AC component contained in the charging voltage is the constant value B.
It is possible to recover by entering the normal charge after passing the normal current in the same direction until it becomes below.

Embodiment An embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a circuit diagram of a charger using the present invention. During normal charging, trickle charging is started after the end-of-charge voltage is detected. When the voltage detection unit 5 detects the end-of-charge voltage, the control unit 4 operates to control the current control unit 3 to start trickle charging by the resistor 2. .

During charging of the over-discharged battery, the AC voltage component generated in the sealed lead-acid battery 14 is applied to the resistor 11 through the capacitor 10. This AC voltage is detected by the first AC voltage detector 9 whose detection voltage is a constant value A, and the constant value B whose detection voltage is lower than A.
Is input to the second AC voltage detector 8. At the time of charging the over-discharged battery whose internal resistance is not high, only the second AC voltage detection unit 8 operates and controls the control unit 4, and the charging current in the same direction as the normal direction is supplied until the AC voltage becomes B or less. Then go into normal charging. During charging of the over-discharged battery having a high internal resistance, the first AC voltage detection unit 9 also operates and the timer 6 operates for a fixed time. The timer 6 supplies a current to the coil 7 of the relay to switch the contact 12 of the relay and controls the control unit 4 to supply a reverse charging current. With such an operation, the reverse charging can be repeated until the AC voltage component becomes A or less. After the AC voltage component becomes equal to or lower than A, the normal charging is started by the same operation as the charging of the above-mentioned over-discharged battery whose internal resistance is not high.

In FIG. 1, reference numeral 1 is a transformer rectifier, and 13 is a diode.

Charging characteristics when using a sealed lead acid battery of 4V and 4Ah are shown in FIG. 2 and FIG. The end-of-charge detection voltage is 4.9
V, timer setting time is 15 (min), first AC detection voltage A
Is 1.5 V ^PP and the second AC detection voltage B is 0.5 V ^PP .

Fig. 2 shows the charging characteristics when the internal resistance is about 1600Ω, and normal charging starts about 30 minutes after repeating reverse charging four times. Fig. 3 shows the charging characteristics when the internal resistance is about 50Ω, and the normal charging is started about 30 minutes after the start of charging without going into reverse charging. As described above, it was possible to repeat the reverse charging with the one having a high internal resistance, and to recover without the reverse charging with the one having a low internal resistance.

As described above, the present invention focuses on the fact that an AC component contained in a charging voltage and an over-discharged battery whose internal resistance is not high can recover without performing reverse charging. When the internal resistance is low after repeated charging, it is possible to recover without performing reverse charging. Therefore, the industrial value is extremely great in that the reverse charge can be suppressed to the necessary minimum.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIGS. 2 and 3 are charging characteristic curve diagrams when the charger according to the present invention is used, and FIGS. 4 and 5 show reverse charging time. FIG. 6 is a characteristic curve diagram showing the charging characteristic when it is constant, and FIG. 6 is a characteristic curve diagram showing the cycle life characteristic after the reverse charge recovery. 3 is a current control unit, 4 is a control unit, 5 is a voltage detection unit, 6 is a timer, 8 is a second AC voltage detection unit, 9 is a first AC voltage detection unit, and 14 is a sealed lead-acid battery.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akio Komaki 2-1-1, Nishishinjuku, Shinjuku-ku, Tokyo Shin-Kindo Electric Co., Ltd. Examiner Akira Suzuki

Claims (1)

[Claims] 1. When the AC voltage component included in the charging voltage is equal to or higher than a constant value A, a current in a direction opposite to normal charging is applied for a predetermined time, and the AC voltage component included in the charging voltage is equal to the constant value A. When it is lower and larger than a certain constant value B, a current is supplied in the same direction as normal charging, and means for performing normal charging only when the AC voltage component included in the charging voltage is smaller than the certain value B is provided. A sealed lead acid battery charger characterized by the following.